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Sample records for bgc-lurgi slagging process

  1. Slag processing system for direct coal-fired gas turbines

    DOEpatents

    Pillsbury, Paul W.

    1990-01-01

    Direct coal-fired gas turbine systems and methods for their operation are provided by this invention. The systems include a primary combustion compartment coupled to an impact separator for removing molten slag from hot combustion gases. Quenching means are provided for solidifying the molten slag removed by the impact separator, and processing means are provided forming a slurry from the solidified slag for facilitating removal of the solidified slag from the system. The released hot combustion gases, substantially free of molten slag, are then ducted to a lean combustion compartment and then to an expander section of a gas turbine.

  2. Progress in Slag Foaming in Metallurgical Processes

    NASA Astrophysics Data System (ADS)

    Zhu, Tai Xi; Coley, K. S.; Irons, G. A.

    2012-08-01

    Professor Fruehan has been a pioneer in the fundamental understanding of slag foaming in ironmaking and steelmaking processes. Although considerable progress has been made in our understanding of the phenomena, there are still unanswered questions regarding the mechanisms in industrial processes and how to control them. At McMaster University, we have been working on conditions that are relevant to foaming in electric arc furnaces (EAFs) where these phenomena are central to modern EAF practices. This work will be reviewed and put in the context of what is known from a fundamental standpoint.

  3. 40 CFR 424.30 - Applicability; description of the slag processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... subpart are applicable to discharges resulting from slag processing, wherein: (a) The residual metallic values in the furnace slag are recovered via concentration for return to the furnace, or (b) the slag...

  4. 40 CFR 424.30 - Applicability; description of the slag processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... subpart are applicable to discharges resulting from slag processing, wherein: (a) The residual metallic values in the furnace slag are recovered via concentration for return to the furnace, or (b) the slag...

  5. Induction slag reduction process for purifying metals

    DOEpatents

    Traut, Davis E.; Fisher, II, George T.; Hansen, Dennis A.

    1991-01-01

    A continuous method is provided for purifying and recovering transition metals such as neodymium and zirconium that become reactive at temperatures above about 500.degree. C. that comprises the steps of contacting the metal ore with an appropriate fluorinating agent such as an alkaline earth metal fluosilicate to form a fluometallic compound, and reducing the fluometallic compound with a suitable alkaline earth or alkali metal compound under molten conditions, such as provided in an induction slag metal furnace. The method of the invention is advantageous in that it is simpler and less expensive than methods used previously to recover pure metals, and it may be employed with a wide range of transition metals that were reactive with enclosures used in the prior art methods and were hard to obtain in uncontaminated form.

  6. Process of discharging charge-build up in slag steelmaking processes

    DOEpatents

    Pal, Uday B.; Gazula, Gopala K. M.; Hasham, Ali

    1994-01-01

    A process and apparatus for improving metal production in ironmaking and steelmaking processes is disclosed. The use of an inert metallic conductor in the slag-containing crucible and the addition of a transition metal oxide to the slag are the disclosed process improvements.

  7. A novel process for comprehensive utilization of vanadium slag

    NASA Astrophysics Data System (ADS)

    Liu, Li-ying; Du, Tao; Tan, Wen-jun; Zhang, Xin-pu; Yang, Fan

    2016-02-01

    Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas, which cause serious environmental problems. In this study, a new process for the comprehensive utilization of vanadium slag was proposed, wherein zeolite A and a V2O5/TiO2 system were synthesized. The structural properties of the as-synthesized zeolite A and the V2O5/TiO2 system were characterized using various experimental techniques, including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and infrared spectroscopy. The results reveal that zeolite A and the V2O5/TiO2 system are successfully obtained with high purity. The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO2 over N2 and is a candidate material for CO2 capture from flue-gas streams.

  8. Slag foaming phenomena and its suppression techniques in BOF steelmaking process

    SciTech Connect

    Pak, J.J.; Min, D.J.; You, B.D.

    1996-12-31

    Some basic studies using the X-ray fluoroscopy technique were carried out to understand slag foaming phenomena in BOF process. The BOF slag in contact with hot metal showed a generation of very fine size CO bubbles at the slag-metal interface, and formed a stable foam. The lump iron ore added into BOF slag decomposed faster, but showed less foaming than sinter ore did. The anti-foaming agent and coke were added into foamed BOF slag to compare their effectiveness of foam suppression. At the same time, various attempts were made to control the excessive slag foaming during BOF operation. Practice modifications such as oxygen blowing pattern and ore addition, and the installation of the slopping control button were effective and significantly reduced slopping. The slopping detection system involving oxygen lance vibration measurements were on-line installed for prompt and accurate control of slag foaming in BOF converter.

  9. Effects of Carbo-Nitridation Process of Ti-Bearing Blast Furnace Slag on Iron Content

    NASA Astrophysics Data System (ADS)

    Shi, Z.; Zhang, X. M.; Xu, Y.

    In order to prepare corrosion-resistant refractory material, experiment chooses Ti-bearing Blast Furnace Slag as raw materials which were treated by the method of carbo-nitridation. Finally, the corrosion resistance properties of the material can be improved by this method. The carbo-nitridation process affects the iron content of the slag in the study, which have a beneficial effect on the synthesis of Ti (C. N). The results indicated that the iron content of the slag significantly increased in process of Ti (C. N) synthesis: and the iron content of slag showed an upward trend with the increase of holding time.

  10. Design of a continuous process setup for precipitated calcium carbonate production from steel converter slag.

    PubMed

    Mattila, Hannu-Petteri; Zevenhoven, Ron

    2014-03-01

    A mineral carbonation process "slag2PCC" for carbon capture, utilization, and storage is discussed. Ca is extracted from steel slag by an ammonium salt solvent and carbonated with gaseous CO2 after the separation of the residual slag. The solvent is reused after regeneration. The effects of slag properties such as the content of free lime, fractions of Ca, Si, Fe, and V, particle size, and slag storage on the Ca extraction efficiency are studied. Small particles with a high free-lime content and minor fractions of Si and V are the most suitable. To limit the amount of impurities in the process, the slag-to-liquid ratio should remain below a certain value, which depends on the slag composition. Also, the design of a continuous test setup (total volume ∼75 L) is described, which enables quick process variations needed to adapt the system to the varying slag quality. Different precipitated calcium carbonate crystals (calcite and vaterite) are generated in different parts of the setup.

  11. Effects of slag composition and process variables on decontamination of metallic wastes by melt refining

    SciTech Connect

    Heshmatpour, B.; Copeland, G. L.

    1981-01-01

    Melt refining has been suggested as an alternative for decontamination and volume reduction of low-level-contaminated metallic wastes. Knowledge of metallurgical and thermochemical aspects of the process is essential for effective treatment of various metals. Variables such as slag type and composition, melting technique, and refractory materials need to be identified for each metal or alloy. Samples of contaminated metals were melted with fluxes by resistance furnace or induction heating. The resulting ingots as well as the slags were analyzed for their nuclide contents, and the corresponding partition ratios were calculated. Compatibility of slags and refractories was also investigated, and proper refractory materials were identified. Resistance furnace melting appeared to be a better melting technique for nonferrous scrap, while induction melting was more suitable for ferrous metals. In general uranium contents of the metals, except for aluminum, could be reduced to as low as 0.01 to 0.1 ppM by melt refining. Aluminum could be decontaminated to about 1 to 2 ppM U when certain fluoride slags were used. The extent of decontamination was not very sensitive to slag type and composition. However, borosilicate and basic oxidizing slags were more effective on ferrous metals and Cu; NaNO/sub 3/-NaCl-NaOH type fluxes were desirable for Zn, Pb, and Sn; and fluoride type slags were effective for decontamination of Al. Recrystallized alumina proved to be the most compatible refractory for melt refining both ferrous and nonferrous metals, while graphite was suitable for nonferrous metal processing. In conclusion, melt refining is an effective technique for volume reduction ad decontamination of contaminated metal scrap when proper slags, melting technique, and refractories are used.

  12. Synthesis and Characterization of Titanium Slag from Ilmenite by Thermal Plasma Processing

    NASA Astrophysics Data System (ADS)

    Samal, Sneha

    2016-09-01

    Titanium rich slag has emerged as a raw material for alternative titanium source. Ilmenite contains 42-50% TiO2 as the mineralogical composition depending on the geographical resources. Application of titanium in paper, plastic, pigment and other various industries is increasing day by day. Due to the scarcity of natural raw mineral rutile (TiO2), ilmenite is considered as precursor for the extraction of TiO2. Ilmenite is reduced at the initial stage for the conversion of complex iron oxide into simpler form. Therefore, pre-reduction of ilmenite concentrate is essential to minimize the energy consumption during thermal plasma process. Thermal plasma processing of ilmenite for the production of titania rich slag is considered to be the direct route to meet the current demand of industrial needs of titanium. Titania rich slag contains 70-80% TiO2 as the major component with some other minor impurities, like oxide phases of Si, Al, Cr, Mg, Mn, Ca, etc. Usually titanium is present in tetravalent forms with globular metallic iron in the slag. Titania rich slag undergoes leaching for the removal of iron and transforming the slag into synthetic rutile having 85-95% of TiO2.

  13. Synthesis and Characterization of Titanium Slag from Ilmenite by Thermal Plasma Processing

    NASA Astrophysics Data System (ADS)

    Samal, Sneha

    2016-02-01

    Titanium rich slag has emerged as a raw material for alternative titanium source. Ilmenite contains 42-50% TiO2 as the mineralogical composition depending on the geographical resources. Application of titanium in paper, plastic, pigment and other various industries is increasing day by day. Due to the scarcity of natural raw mineral rutile (TiO2), ilmenite is considered as precursor for the extraction of TiO2. Ilmenite is reduced at the initial stage for the conversion of complex iron oxide into simpler form. Therefore, pre-reduction of ilmenite concentrate is essential to minimize the energy consumption during thermal plasma process. Thermal plasma processing of ilmenite for the production of titania rich slag is considered to be the direct route to meet the current demand of industrial needs of titanium. Titania rich slag contains 70-80% TiO2 as the major component with some other minor impurities, like oxide phases of Si, Al, Cr, Mg, Mn, Ca, etc. Usually titanium is present in tetravalent forms with globular metallic iron in the slag. Titania rich slag undergoes leaching for the removal of iron and transforming the slag into synthetic rutile having 85-95% of TiO2.

  14. Slag processing system for direct coal-fired gas turbines

    DOEpatents

    Pillsbury, Paul W.

    1990-01-01

    Direct coal-fired gas turbine systems and methods for their operation are provided by this invention. The gas turbine system includes a primary zone for burning coal in the presence of compressed air to produce hot combustion gases and debris, such as molten slag. The turbine system further includes a secondary combustion zone for the lean combustion of the hot combustion gases. The operation of the system is improved by the addition of a cyclone separator for removing debris from the hot combustion gases. The cyclone separator is disposed between the primary and secondary combustion zones and is in pressurized communication with these zones. In a novel aspect of the invention, the cyclone separator includes an integrally disposed impact separator for at least separating a portion of the molten slag from the hot combustion gases.

  15. The evaluation of X-ray fluorescence (XRF) for process monitoring of slag from the plasma hearth process

    SciTech Connect

    Carney, K.P.; Smith, M.A.; Crane, P.J.

    1995-12-31

    Slag material produced by the Plasma Hearth Process (PHP) varies in chemical composition due to the heterogeneous nature of the input sample feed. X-ray fluorescence (XRF) is a spectroscopic technique which has been evaluated to perform elemental analyses on surrogate slag material for process control. The intensity of Si, Al and Fe in the slag samples was utilized to determine the appropriate matrix standard set for the determination of Ce. The precision of the XRF technique was better than 5% RSD. The limit of detection for Ce varied with sample matrix and was typically below 0.01 % by weight. The linear dynamic range for the technique was evaluated over 2 orders of magnitude. The Ce determinations performed directly on slag material by the XRF technique were similar to ICP-AES analyses. No addition waste streams were created from the analyses by the XRF technique.

  16. Evaluation of the economic feasibility of a processing plant for steelmaking slag.

    PubMed

    Gonçalves, Deyvid R R; Fontes, Wanna C; Mendes, Julia C; Silva, Guilherme J B; Peixoto, Ricardo A F

    2016-02-01

    The utilisation of steelmaking slag as recycled aggregate for concretes is a widely investigated solution for mitigating the expenditure and environmental impacts of its storage. The Brazilian steel industry is investing in research and slag reprocessing practices, aiming to reuse most of its metallic fraction and properly allocate the non-metallic fraction, saving energy and reducing mining impacts. Research results demonstrate the technical and environmental feasibility of steel slag aggregates for civil construction. However, it is essential to evaluate whether the processing of the slag is economically feasible for this purpose. Economic analysis of the processing of steel slag was conducted through simulation - Monte Carlo method - in which it is possible to determine the risks and uncertainties inherent to the project. The costs that comprise the proposed project, from design through construction and operation itself, were estimated at US$2.8 million. The result of the simulation indicates economic feasibility of the project with 98% certainty, and an estimated profit of around 42%.

  17. Dependence of Temperature and Slag Composition on Dephosphorization at the First Deslagging in BOF Steelmaking Process

    NASA Astrophysics Data System (ADS)

    Zhou, Chao-gang; Li, Jing; Shi, Cheng-bin; Yu, Wen-tao; Zhang, Zhi-ming; Liu, Zhi-ming; Deng, Chang-fu

    2016-04-01

    Effects of temperature and slag composition on dephosphorization in a 120 ton top-bottom combined blown converter steelmaking process by double slag method were studied. The slag properties were determined by scanning electron microscope- energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD). The results show that the transition oxidation temperature between dephosphorization and decarbonization Tf is not the favorable temperature for the first deslagging. The optimum first deslagging temperature is confirmed to be approximately 1,673 K which is about 70 K higher than Tf. High melting temperatures phases (such as 3CaO·SiO2) in the slag with high basicity and MgO content are unfavorable to the dephosphorization. The optimum process condition for dephosphorization at the first deslagging in present work is approximately 1,673 K in temperature, 2.0 in slag basicity, 6 and 17 mass% in MgO and T.Fe content, 6 mass% ≤ MnO content.

  18. Crystallization Behavior and Growing Process of Rutile Crystals in Ti-Bearing Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Zhang, Wu; Zhang, Li; Li, Yuhai; Li, Xin

    2016-09-01

    The aim of the present work is to elucidate crystallization and growing process of rutile crystals in Ti-bearing blast furnace slag. The samples were taken from the liquid slag and quenched at once at elevated temperatures in order to analyze phase transaction of titanium and grain size of rutile crystals. Crystallization and growing kinetics of rutile crystals under elevated temperature conditions were calculated, and the crystallization process of rutile crystals under isothermal conditions was expressed by Avrami equation. The effects of experimental parameters, such as experimental temperatures, SiO2 addition, cooling rate, crystal seed addition and oxygen flow, were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), the optimal conditions for rutile crystals to grow up were obtained. Distribution and movement state of rutile crystals in the slag were analyzed.

  19. Removal of hexavalent chromium in carbonic acid solution by oxidizing slag discharged from steelmaking process in electric arc furnace

    NASA Astrophysics Data System (ADS)

    Yokoyama, Seiji; Okazaki, Kohei; Sasano, Junji; Izaki, Masanobu

    2014-02-01

    Hexavalent chromium (Cr(VI)) is well-known to be a strong oxidizer, and is recognized as a carcinogen. Therefore, it is regulated for drinking water, soil, groundwater and sea by the environmental quality standards all over the world. In this study, it was attempted to remove Cr(VI) ion in a carbonic acid solution by the oxidizing slag that was discharged from the normal steelmaking process in an electric arc furnace. After the addition of the slag into the aqueous solution contained Cr(VI) ion, concentrations of Cr(VI) ion and total chromium (Cr(VI) + trivalent chromium (Cr(III)) ions decreased to lower detection limit of them. Therefore, the used slag could reduce Cr(VI) and fix Cr(III) ion on the slag. While Cr(VI) ion existed in the solution, iron did not dissolve from the slag. From the relation between predicted dissolution amount of iron(II) ion and amount of decrease in Cr(VI) ion, the Cr(VI) ion did not react with iron(II) ion dissolved from the slag. Therefore, Cr(VI) ion was removed by the reductive reaction between Cr(VI) ion and the iron(II) oxide (FeO) in the slag. This reaction progressed on the newly appeared surface of iron(II) oxide due to the dissolution of phase composed of calcium etc., which existed around iron(II) oxide grain in the slag.

  20. The use of SHS-process slag for the preparation of foundry sand

    NASA Astrophysics Data System (ADS)

    Safronov, N.; Kharisov, L.

    2015-06-01

    The article presents the construction of a linear approximation of the response function (strength of molding sand on tensile strength and air permeability) in a given area by changing the investigated factors for which charge makeup of SHS-cast iron obtaining process and content of the slag product of this process in the molding mixture were used. The analysis of regression coefficients significance of the objective function was done to identify the most important input parameters.

  1. Advances in chemical and physical properties of electric arc furnace carbon steel slag by hot stage processing and mineral mixing.

    PubMed

    Liapis, Ioannis; Papayianni, Ioanna

    2015-01-01

    Slags are recognised as a highly efficient, cost effective tool in the metal processing industry, by minimising heat losses, reducing metal oxidation through contact with air, removing metal impurities and protecting refractories and graphite electrodes. When compared to natural aggregates for use in the construction industry, slags have higher specific weight that acts as an economic deterrent. A method of altering the specific weight of EAFC slag by hot stage processing and mineral mixing, during steel production is presented in this article. The method has minimal interference with the production process of steel, even by limited additions of appropriate minerals at high temperatures. Five minerals are examined, namely perlite, ladle furnace slag, bauxite, diatomite and olivine. Measurements of specific weight are accompanied by X-ray diffraction (XRD) and fluorescence (XRF) analysis and scanning electron microscopy spectral images. It is also shown how altering the chemical composition is expected to affect the furnace refractory lining. Additionally, the process has been repeated for the most suitable mix in gas furnace and physical properties (FI, SI, LA, PSV, AAV, volume stability) examined. Alteration of the specific weight can result in tailoring slag properties for specific applications in the construction sector. PMID:25261762

  2. Advances in chemical and physical properties of electric arc furnace carbon steel slag by hot stage processing and mineral mixing.

    PubMed

    Liapis, Ioannis; Papayianni, Ioanna

    2015-01-01

    Slags are recognised as a highly efficient, cost effective tool in the metal processing industry, by minimising heat losses, reducing metal oxidation through contact with air, removing metal impurities and protecting refractories and graphite electrodes. When compared to natural aggregates for use in the construction industry, slags have higher specific weight that acts as an economic deterrent. A method of altering the specific weight of EAFC slag by hot stage processing and mineral mixing, during steel production is presented in this article. The method has minimal interference with the production process of steel, even by limited additions of appropriate minerals at high temperatures. Five minerals are examined, namely perlite, ladle furnace slag, bauxite, diatomite and olivine. Measurements of specific weight are accompanied by X-ray diffraction (XRD) and fluorescence (XRF) analysis and scanning electron microscopy spectral images. It is also shown how altering the chemical composition is expected to affect the furnace refractory lining. Additionally, the process has been repeated for the most suitable mix in gas furnace and physical properties (FI, SI, LA, PSV, AAV, volume stability) examined. Alteration of the specific weight can result in tailoring slag properties for specific applications in the construction sector.

  3. Enhanced humification by carbonated basic oxygen furnace steel slag--II. Process characterization and the role of inorganic components in the formation of humic-like substances.

    PubMed

    Qi, Guangxia; Yue, Dongbei; Fukushima, Masami; Fukuchi, Shigeki; Nishimoto, Ryo; Nie, Yongfeng

    2012-06-01

    Enhanced humification by abiotic catalysts is a potentially promising supplementary composting method for stabilizing organic carbon from biowastes. In this study, the role of steel slag in the transformation of humic precursors was directly characterized by measuring the variance in dissolved organic carbon (DOC), spectroscopic parameters (E(600)), and the concentration and molecular weight change of humic-like substances (HLS) during the process. In addition, a mechanistic study of the process was explored. The results directly showed that steel slag greatly accelerated the formation of HLS. The findings indicate that Fe(III)-and Mn(IV)-oxides in steel slag act as oxidants and substantially enhance the polycondensation of humic precursors. Moreover, the reaction appears to suppress the release of metals from steel slag to a certain extent under acidic conditions. This can be attributed to the cover of HLS on the external surface of steel slag, which is significant for its environmentally sound reuse.

  4. Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process

    NASA Astrophysics Data System (ADS)

    Zhang, Ying-yi; Lü, Wei; Qi, Yuan-hong; Zou, Zong-shu

    2016-08-01

    A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w(CaO)/ w(SiO2) ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al2O3 grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100:16.17:59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recovery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca2SiO4 and Ca12Al14O33, with small amounts of FeAl2O4, CaAl2O4, and Ca2Al2SiO7.

  5. Model Investigations on the Stability of the Steel-Slag Interface in Continuous-Casting Process

    NASA Astrophysics Data System (ADS)

    Hagemann, René; Schwarze, Rüdiger; Heller, Hans P.; Scheller, Piotr R.

    2013-02-01

    In the continuous-casting mold, the mold powder in contact with the liquid steel surface forms a liquid slag layer. The flow along the steel-slag interface generates shear stress at the interface, waves, and leads to fingerlike protrusions of liquid slag into steel. Reaching a critical flow velocity and thereby shear stress, the protrusions can disintegrate into slag droplets following the flow in the liquid steel pool. These entrained droplets can form finally nonmetallic inclusions in steel material, cause defects in the final product, and therefore, should be avoided. In the current work, the stability of a liquid-liquid interface without mass transfer between phases was investigated in cold model study using a single-roller driven flow in oil-water systems with various oil properties. Applying the similarity theory, two dimensionless numbers were identified, viz. capillary number Ca and the ratio of kinematic viscosities ν 1/ ν 2, which are suitable to describe the force balance for the problem treated. The critical values of the dimensionless capillary number Ca* marking the start of lighter phase entrainment into the heavier fluid, are determined over a wide range of fluid properties. The dimensionless number ν 1/ ν 2 was defined as the ratio of kinematic viscosities of the lighter phase ν 1 and heavier phase ν 2. The ratios of kinematic viscosities of different steel-slag systems were calculated using measured thermophysical properties. With the knowledge of thermophysical properties of steel-slag systems, Ca* for slag entrainment as a function of v 1/ v 2 is derived. Assuming no reaction between the phases and no interfacial flow, slag entrainment should not occur under the usual casting conditions.

  6. Structure, Growth Process, and Growth Mechanism of Perovskite in High-Titanium-Bearing Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Liu, Lu; Hu, Meilong; Xu, Yuzhou; Bai, Chenguang; Gan, Yunhua

    2015-08-01

    The isothermal crystallization of perovskite in TiO2-CaO-SiO2-Al2O3-MgO high-titanium-bearing blast furnace slag was observed in situ at 1698 K (1425 °C) using a confocal scanning laser microscope. The dendrite structure of perovskite (CaTiO3) thus obtained showed vividly the primary dendrite trunks and secondary dendrite arms. Furthermore, the dendritic growth of perovskite in liquid slag was clearly observed on line. The results showed that the dendrite arrays in which the primary dendrite trunks observed on slag surface were parallel with each other grew toward the same direction. The secondary dendrite arms grew in the perpendicular direction with the primary trucks and stopped growing when they encounter. The perovskite dendrites showed a linear growth at two stages. The dendrites grew faster at early stage at about 5 to 7 μm/s and grew with a lower growth rate at about 1 to 2 μm/s in later stage. Finally, the growth mechanism of perovskite in melt was analyzed with the solidification theory. Based on the theoretical calculation of equilibrium phases in slag, the initial slag could be considered as a binary component system. One component was perovskite and the other component was the sum of all the other species that did not attend the crystallization of perovskite (included SiO2, Al2O3, and MgO, as well as CaO and TiO2 that were not involved in the solid formation). The formation of perovskite required the diffusion of CaO and TiO2 to the solid/liquid interface and the rejection of the other species from the interface. The solid/liquid equilibrium schematic diagram was made based on the calculation.

  7. Mineral resource of the month: ferrous slag

    USGS Publications Warehouse

    ,

    2009-01-01

    The article offers information on mineral resource ferrous slag. Ferrous slag is produced through the addition of materials such as limestone and dolomite to blast and steel furnaces to remove impurities from iron ore and to lower the heat requirements for processes in iron and steel making. It is stated that the method of cooling is important for the market uses and value of ferrous slag. Some types of slag can be used in construction, glass manufacturing and thermal insulation.

  8. Slagging gasifier

    SciTech Connect

    Schulz, H.

    1982-07-20

    A slagging gasifier for the gasification of coal and organic waste materials is disclosed. The gasifier includes a vertical blast furnace having a hearth section at the bottom thereof. A slag tap hole is formed in hearth section and opens into a quenching vessel. A honeycomb structure is formed on the inner surface of said hearth section in the area surrounding said slag tap hole, and the inner wall of the hearth section. A plurality of tuyeres extend into the hearth section and feed the furnace with steam and oxygen so as to permit the oxidation of coal and organic waste materials fed into the furnace. As a result of the oxidation, gas and molten slag are formed in the furnace. The slag is collected in the hearth section and exits the hearth section via the tap hole. One or more conduits are provided for recycling (Either internally or externally) the gas exiting the top of the gasifier with the tars, oils, and particulates entrained therein to the partial combustion zone of the gasifier where the tars, oils and particulates are converted to noncondensible gases. A portion of the tar-free product gas is removed from an intermediate point in the gasifier below the pyrolysis and coking zone.

  9. A Novel Conversion Process for Waste Slag: The Preparation of Aluminosilicate Glass with Evaluation of the Dielectric Properties from Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Li, Sheng; Huang, Sanxi; Liu, Hongting; Wu, Fengnian; Chang, Ziyuan; Yue, Yunlong

    2015-11-01

    In this paper, aluminosilicate glass was prepared from blast furnace slag and quartz sand. Fourier transform infrared, differential scanning calorimetry and density measurements were carried out to investigate the effects of SiO2 on the aluminosilicate glass network rigidity. The results indicate that glass structure would be enhanced if more SiO2 was introduced into the glass system. Meanwhile, both the glass transition temperature ( T g) and the glass crystallization temperature ( T c) increase slightly; the increase in density of the glass being further evidence of the enhancement in glass network rigidity. Dielectric measurements show that the dielectric constant and dielectric loss decrease with more SiO2. The properties of the prepared aluminosilicate glasses are comparable to those of E glass, indicating that blast furnace slags are suitable for producing aluminosilicate glass with low dielectric constant and dielectric loss.

  10. Evaluation of electric arc furnace-processed steel slag for dermal corrosion, irritation, and sensitization from dermal contact.

    PubMed

    Suh, Mina; Troese, Matthew J; Hall, Debra A; Yasso, Blair; Yzenas, John J; Proctor, Debora M

    2014-12-01

    Electric arc furnace (EAF) steel slag is alkaline (pH of ~11-12) and contains metals, most notably chromium and nickel, and thus has potential to cause dermal irritation and sensitization at sufficient dose. Dermal contact with EAF slag occurs in many occupational and environmental settings because it is used widely in construction and other industrial sectors for various applications including asphaltic paving, road bases, construction fill, and as feed for cement kilns construction. However, no published study has characterized the potential for dermal effects associated with EAF slag. To assess dermal irritation, corrosion and sensitizing potential of EAF slag, in vitro and in vivo dermal toxicity assays were conducted based on the Organisation for Economic Co-operation and Development (OECD) guidelines. In vitro dermal corrosion and irritation testing (OECD 431 and 439) of EAF slag was conducted using the reconstructed human epidermal (RHE) tissue model. In vivo dermal toxicity and delayed contact sensitization testing (OECD 404 and 406) were conducted in rabbits and guinea pigs, respectively. EAF slag was not corrosive and not irritating in any tests. The results of the delayed contact dermal sensitization test indicate that EAF slag is not a dermal sensitizer. These findings are supported by the observation that metals in EAF slag occur as oxides of low solubility with leachates that are well below toxicity characteristic leaching procedure (TCLP) limits. Based on these results and in accordance to the OECD guidelines, EAF slag is not considered a dermal sensitizer, corrosive or irritant.

  11. Study on the foaming of CaO-SiO2-FeO slags: Part II. Dimensional analysis and foaming in iron and steelmaking processes

    NASA Astrophysics Data System (ADS)

    Ito, Kimihisa; Fruehan, R. J.

    1989-08-01

    An empirical equation for the foaming index Σ of a CaO-SiO2-FeO slag was obtained by dimensional analysis. The effect of second-phase particles on slag foaming was well described by calculating the viscosity of the mixture using the modified Einstein equation. The anticipated foaming in basic oxygen furnace (BOF), electric arc furnace (EAF), and bath-smelting processes was estimated using the parameter Σ for various operating conditions and slag compositions. For BOF operations, it is predicted that foaming is most extreme in the middle of the blow, and a stable foam in EAF is achieved with less basic slags with low FeO contents. For bath smelting, foam heights of 5 m are possible, and a higher degree of prereduction prior to smelting will reduce foaming (because of smaller gas evolution) and possibly increase production rates. Running the process at a higher pressure will also reduce foam heights, because the volume of gas generated is less.

  12. Development of a Steel-Slag-Based, Iron-Functionalized Sorbent for an Autothermal Carbon Dioxide Capture Process.

    PubMed

    Tian, Sicong; Jiang, Jianguo; Hosseini, Davood; Kierzkowska, Agnieszka M; Imtiaz, Qasim; Broda, Marcin; Müller, Christoph R

    2015-11-01

    We propose a new class of autothermal CO2 -capture process that relies on the integration of chemical looping combustion (CLC) into calcium looping (CaL). In the new process, the heat released during the oxidation of a reduced metallic oxide is utilized to drive the endothermic calcination of CaCO3 (the regeneration step in CaL). Such a process is potentially very attractive (both economically and technically) as it can be applied to a variety of oxygen carriers and CaO is not in direct contact with coal (and the impurities associated with it) in the calciner (regeneration step). To demonstrate the practical feasibility of the process, we developed a low-cost, steel-slag-based, Fe-functionalized CO2 sorbent. Using this material, we confirm experimentally the feasibility to heat-integrate CaCO3 calcination with a Fe(II)/Fe(III) redox cycle (with regards to the heat of reaction and kinetics). The autothermal calcination of CaCO3 could be achieved for a material that contained a Ca/Fe ratio of 5:4. The uniform distribution of Ca and Fe in a solid matrix provides excellent heat transfer characteristics. The cyclic CO2 uptake and redox stability of the material is good, but there is room for further improvement.

  13. Development of a Steel-Slag-Based, Iron-Functionalized Sorbent for an Autothermal Carbon Dioxide Capture Process.

    PubMed

    Tian, Sicong; Jiang, Jianguo; Hosseini, Davood; Kierzkowska, Agnieszka M; Imtiaz, Qasim; Broda, Marcin; Müller, Christoph R

    2015-11-01

    We propose a new class of autothermal CO2 -capture process that relies on the integration of chemical looping combustion (CLC) into calcium looping (CaL). In the new process, the heat released during the oxidation of a reduced metallic oxide is utilized to drive the endothermic calcination of CaCO3 (the regeneration step in CaL). Such a process is potentially very attractive (both economically and technically) as it can be applied to a variety of oxygen carriers and CaO is not in direct contact with coal (and the impurities associated with it) in the calciner (regeneration step). To demonstrate the practical feasibility of the process, we developed a low-cost, steel-slag-based, Fe-functionalized CO2 sorbent. Using this material, we confirm experimentally the feasibility to heat-integrate CaCO3 calcination with a Fe(II)/Fe(III) redox cycle (with regards to the heat of reaction and kinetics). The autothermal calcination of CaCO3 could be achieved for a material that contained a Ca/Fe ratio of 5:4. The uniform distribution of Ca and Fe in a solid matrix provides excellent heat transfer characteristics. The cyclic CO2 uptake and redox stability of the material is good, but there is room for further improvement. PMID:26616682

  14. A Sulfide Capacity Prediction Model of CaO-SiO2-MgO-FeO-MnO-Al2O3 Slags during the LF Refining Process Based on the Ion and Molecule Coexistence Theory

    NASA Astrophysics Data System (ADS)

    Yang, Xue-Min; Zhang, Meng; Shi, Cheng-Bin; Chai, Guo-Ming; Zhang, Jian

    2012-04-01

    A sulfide capacity prediction model of CaO-SiO2-MgO-FeO-MnO-Al2O3 ladle furnace (LF) refining slags has been developed based on the ion and molecule coexistence theory (IMCT). The predicted sulfide capacity of the LF refining slags has better accuracy than the measured sulfide capacity of the slags at the middle and final stages during the LF refining process. Increasing slag binary basicity, optical basicity, and the Mannesmann index can lead to an increase of the predicted sulfide capacity for the LF refining slags as well as to an increase of the sulfur distribution ratio between the slags and molten steel at the middle and final stages during the LF refining process. The calculated equilibrium mole numbers, mass action concentrations of structural units or ion couples, rather than mass percentages of components, are recommended to represent the slag composition for correlating with the sulfide capacity of the slags. The developed sulfide capacity IMCT model can calculate not only the total sulfide capacity of the slags but also the respective sulfide capacity of free CaO, MgO, FeO, and MnO in the slags. The comprehensive contribution of the combined ion couples (Ca2+ + O2-) and (Mn2+ + O2-) on the desulfurization reactions accounts for 96.23 pct; meanwhile, the average contribution of the ion couple (Fe2+ + O2-) and (Mg2+ + O2-) only has a negligible contribution as 3.13 pct and 0.25 pct during the LF refining process, respectively. The oxygen activity of bulk molten steel in LF is controlled by the [Al]-[O] equilibrium, and the oxygen activity of molten steel at the slag-metal interface is controlled by the (FeO)-[O] equilibrium. The ratio of the oxygen activity of molten steel at the slag-metal interface to the oxygen activity of bulk molten steel will decrease from 37 to 5 at the initial stage, and further decrease from 28 to 4 at the middle stage, but will maintain at a reliable constant as 5 to 14 at the final stage during the LF refining process. The

  15. An overview of recovery of metals from slags.

    PubMed

    Shen, Huiting; Forssberg, E

    2003-01-01

    Various slags are produced as by-products in metallurgical processes or as residues in incineration processes. According to the origins and the characteristics, the main slags can be classified into three categories, namely ferrous slag, non-ferrous slag and incineration slag. This paper analysed and summarised the generation, characteristics and application of various slags, and discussed the potential effects of the slags on the environment. On this basis, a review of a number of methods for recovery of metals from the slags was made. It can be seen that a large amount of slags is produced each year. They usually contain a quantity of valuable metals except for blast furnace slag and they are actually a secondary resource of metals. By applying mineral processing technologies, such as crushing, grinding, magnetic separation, eddy current separation, flotation and so on, leaching or roasting, it is possible to recover metals such as Fe, Cr, Cu, Al, Pb, Zn, Co, Ni, Nb, Ta, Au, and Ag etc. from the slags. Recovery of metals from the slags and utilisation of the slags are important not only for saving metal resources, but also for protecting the environment.

  16. The evaluation of the x-ray fluorescence (XRF) technique for process monitoring of vitreous slag from thermal waste treatment systems: A comparative study of the analysis of Plasma Hearth slag for Ce, Fe and Cr by XRF and inductively coupled plasma spectrometries

    SciTech Connect

    Sutton, M.A.H.; Crane, P.J.; Cummings, D.G.; Carney, K.P.

    1995-05-01

    Slag material produced by the Plasma Hearth Process (PHP) varies in chemical composition due to the heterogeneous nature of the input sample feed. X-ray fluorescence (XRF) is a spectroscopic technique which has been evaluated to perform elemental analyses on surrogate slag material for process control. Vitreous slag samples were ground to a fine powder in an impact ball mill and analyzed directly using laboratory prepared standards. The fluorescent intensities of Si, Al and Fe in the slag samples was utilized to determine the appropriate matrix standard set for the determination of Ce. The samples were analyzed for Cr, Ni, Fe and Ce using a wavelength dispersive XRF polychromator. Split samples were dissolved and analyzed by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The precision of the XRF technique was better than 5% RSD. The limit of detection for Ce varied with sample matrix and was typically below 0.01% by weight. The linear dynamic range for the technique was evaluated over two orders of magnitude. Typical calibration standards ranged from 0.01% Ce to 1% Ce. The Ce determinations performed directly on ground slag material by the XRF techniques were similar to ICP-AES analyses. Various chemical dissolution and sample preparation techniques were evaluated for the analysis of Ce in slag samples. A fusion procedure utilizing LiBO{sub 2} was found to provide reliable analyses for the actinide surrogate in a variety of slag matrices. The use of the XRF technique reduced the time of analysis for Ce and Cr from three days to one day for five samples. No additional waste streams were created from the analyses by the XRF technique, while the ICP technique generated several liters of liquid waste.

  17. Equilibrium uptake, sorption dynamics, process optimization, and column operations for the removal and recovery of malachite green from wastewater using activated carbon and activated slag

    SciTech Connect

    Gupta, V.K.; Srivastava, S.K.; Mohan, D.

    1997-06-01

    The waste slurry generated in fertilizer plants and slag (blast furnace waste) have been converted into low-cost adsorbents, activated carbon and activated slag, respectively, and these are utilized for the removal of malachite green (a basic dye) from wastewater. In the batch experiments, parameters studied include the effect of pH, sorbent dosage, adsorbate concentration, temperature, and contact time. Kinetic studies have been performed to have an idea of the mechanistic aspects and to obtain the thermodynamic parameters of the process. The uptake of the dye is greater on carbonaceous material than on activated slag. Sorption data have been correlated with both Langmuir and Freundlich adsorption models. The presence of anionic surfactants does not affect the uptake of dye significantly. The mass transfer kinetic approach has been applied for the determination of various parameters necessary for the designing of fixed-bed contactors. Chemical regeneration has been achieved with acetone in order to recover the loaded dye and restore the column to its original capacity without dismantling the same.

  18. Recycling SAW slag proves reliable and repeatable

    SciTech Connect

    Beck, H.P.; Jackson, A.R.

    1996-06-01

    Submerged arc welding (SAW) slag is recycled by taking the fused part of the slag after welding and processing it in a manner that allows it to be reused for the same SAW operation. This slag recycling process has been around the welding industry for many years, and trial-and-error experimentation through the years has made it a reliable and accepted process. Two major reasons why a welding manufacturer would consider the use of recycled submerged arc welding slag are cost savings and the environment. The cost of processing recycled slag is less than the purchase of new flux from the manufacturer. Many times this can amount to savings of 50% or greater. Savings can also be realized by eliminating the need to collect the slag and have it removed to an approved landfill. Environmentally, recycling slag minimizes the use of nonrenewable resources such as minerals, and it reduces the mass of material that must be sent to a landfill. It should be noted, though, that in most recycling processes there is some loss in weight, and not all the slag is processed into reusable flux. Also, there is magnetic separation during processing in which magnetic impurities are removed and disposed of as waste. An average for this loss is 25% of the total weight processed. To realize all of the advantages of recycling, it is essential that the process is performed properly and according to the standards established by industry. Below are steps required for recycling slag as established by two standards setting organizations.

  19. Ladle and Continuous Casting Process Models for Reduction of SiO2 in SiO2-Al2O3-CaO Slags by Al in Fe-Al(-Si) Melts

    NASA Astrophysics Data System (ADS)

    Park, Jiwon; Sridhar, S.; Fruehan, Richard J.

    2015-02-01

    Based on a mixed control or two-phase mass transfer model considering mass transport in the metal and the slag phases, process models for ladle and continuous castor mold were developed to predict the changes in the metal and the slag chemistry and viscosity. In the ladle process model, the rate of reaction is primarily determined by stirring gas flow rate, which greatly alters the mass transports of the metal and the slag phases. In the continuous casting process model, the effects of the Al, Si, and SiO2 contents in the incoming flow of the fluid phases, casting speed, mold flux consumption rate, and depth of the liquid mold flux pool on the steady-state compositions of the metal and the mold flux were assessed.

  20. Understanding Slag Freeze Linings

    NASA Astrophysics Data System (ADS)

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Jak, Evgueni

    2014-09-01

    Slag freeze linings, the formation of protective deposit layers on the inner walls of furnaces and reactors, are increasingly used in industrial pyrometallurgical processes to ensure that furnace integrity is maintained in these aggressive, high-temperature environments. Most previous studies of freeze-linings have analyzed the formation of slag deposits based solely on heat transfer considerations. These thermal models have assumed that the interface between the stationary frozen layer and the agitated molten bath at steady-state deposit thickness consists of the primary phase, which stays in contact with the bulk liquid at the liquidus temperature. Recent experimental studies, however, have clearly demonstrated that the temperature of the deposit/liquid bath interface can be lower than the liquidus temperature of the bulk liquid. A conceptual framework has been proposed to explain the observations and the factors influencing the microstructure and the temperature of the interface at steady-state conditions. The observations are consistent with a dynamic steady state that is a balance between (I) the rate of nucleation and growth of solids on detached crystals in a subliquidus layer as this fluid material moves toward the stagnant deposit interface and (II) the dissolution of these detached crystals as they are transported away from the interface by turbulent eddies. It is argued that the assumption that the interface temperature is the liquidus of the bulk material represents only a limiting condition, and that the interface temperature can be between T liquidus and T solidus depending on the process conditions and bath chemistry. These findings have implications for the modeling approach and boundary conditions required to accurately describe these systems. They also indicate the opportunity to integrate considerations of heat and mass flows with the selection of melt chemistries in the design of future high temperature industrial reactors.

  1. Safe disposal of metal values in slag

    SciTech Connect

    Halpin, P.T.; Zarur, G.L.

    1982-10-26

    The method of safely disposing of sludge containing metal values capable of displaying toxic ecological properties includes the steps of deriving from an organic or inorganic sludge an intermediate product such as a dewatered sludge or an incinerated ash, and adding this intermediate product to a metal smelting step of a type producing a slag such that most of the metal values become encapsulated in the slag. Some precious metal values may be recovered with the metal being smelted, and may be subsequently separated therefrom by appropriate metal winning steps. The sludge product brings to the smelting process certain additives needed therein such as silica and phosphates for the slag, alumina and magnesium to lower the viscosity of the molten slag, and organic matter serving as reducing agents.

  2. Influence of amount of oxidizing slag discharged from stainless steelmaking process of electric arc furnace on elution behavior into fresh water

    NASA Astrophysics Data System (ADS)

    Yokoyama, S.; Shimomura, T.; Hisyamudin, M. N. N.; Takahashi, T.; Izaki, M.

    2012-03-01

    Fundamental study was carried out for provision for acidification of soil due to acid rain. The influence of weight of the additive slag on elution behavior of the slag into water was studied in this study. Elution experiment was carried out on a basis of JIS K 0058-1. Generally, the pH in the aqueous solution increased with an increase in weight of the additive slag. The pH converged to approximately eight. Calcium, magnesium and manganese, which were essential elements for plants, were eluted from the slag irrespective to elution condition. The eluted concentrations of Ca and Mg increased with an increase in weight of the additive slag. Silicon and zinc were also eluted depending on the conditions. Aluminum that was harmful for plants was not eluted from the used slag.

  3. Reprocessing of metallurgical slag into materials for the building industry

    SciTech Connect

    Pioro, L.S.; Pioro, I.L

    2004-07-01

    Several methods of reprocessing metallurgical (blast furnace) slag into materials for the building industry, based on melting aggregates with submerged combustion, were developed and tested. The first method involves melting hot slag with some additives directly in a slag ladle with a submerged gas-air burner, with the objective of producing stabilized slag or glass-ceramic. The second method involves direct draining of melted slag from a ladle into the slag receiver, with subsequent control of the slag draining into the converter where special charging materials are added to the melt, with the objective of producing glass-ceramic. A third method involves melting cold slag with some additives inside a melting converter with submerged gas-air burners, with the objective of producing glass-ceramic fillers for use in road construction. Specific to the melting process is the use of a gas-air mixture with direct combustion inside the melt. This feature provides melt bubbling to help achieve maximum heat transfer from combustion products to the melt, improve mixing (and therefore homogeneity of the melt), and increases the rate of chemical reactions. The experimental data for different aspects of the proposed methods are presented. The reprocessed blast-furnace slag in the form of granules can be used as fillers for concretes, asphalts, and as additives in the production of cement, bricks and other building materials. As well, reprocessed blast-furnace slag can be poured into forms for the production of glass-ceramic tiles.

  4. Reprocessing of metallurgical slag into materials for the building industry.

    PubMed

    Pioro, L S; Pioro, I L

    2004-01-01

    Several methods of reprocessing metallurgical (blast furnace) slag into materials for the building industry, based on melting aggregates with submerged combustion, were developed and tested. The first method involves melting hot slag with some additives directly in a slag ladle with a submerged gas-air burner, with the objective of producing stabilized slag or glass-ceramic. The second method involves direct draining of melted slag from a ladle into the slag receiver, with subsequent control of the slag draining into the converter where special charging materials are added to the melt, with the objective of producing glass-ceramic. A third method involves melting cold slag with some additives inside a melting converter with submerged gas-air burners, with the objective of producing glass-ceramic fillers for use in road construction. Specific to the melting process is the use of a gas-air mixture with direct combustion inside the melt. This feature provides melt bubbling to help achieve maximum heat transfer from combustion products to the melt, improve mixing (and therefore homogeneity of the melt), and increases the rate of chemical reactions. The experimental data for different aspects of the proposed methods are presented. The reprocessed blast-furnace slag in the form of granules can be used as fillers for concretes, asphalts, and as additives in the production of cement, bricks and other building materials. As well, reprocessed blast-furnace slag can be poured into forms for the production of glass-ceramic tiles.

  5. Energy effective approach for activation of metallurgical slag

    NASA Astrophysics Data System (ADS)

    Mazov, I. N.; Khaydarov, B. B.; Mamulat, S. L.; Suvorov, D. S.; Saltikova, Y. S.; Yudin, A. G.; Kuznetsov, D. V.

    2016-01-01

    The paper presents results of investigation of the process of mechanical activation of metallurgical slag using different approaches - ball milling and electromagnetic vortex apparatus. Particle size distribution and structure of mechanically activated slag samples were investigated, as well as energetic parameters of the activation process. It was shown that electromagnetic vortex activation is more energy effective and allows to produce microscale milled slag-based concrete using very short treatment time. Activated slag materials can be used as clinker-free cement in civilian and road construction, providing ecology-friendly technology and recycling of high-tonnage industrial waste.

  6. Sulfide capacities of fayalite-base slags

    NASA Astrophysics Data System (ADS)

    Simeonov, S. R.; Sridhar, R.; Toguri, J. M.

    1995-04-01

    The sulfide capacities of fayalite-base slags were measured by a gas-slag equilibration technique under controlled oxygen and sulfur potentials similar to those encountered in the pyrometallurgical processing of nonferrous metals. The oxygen pressure range was from 10-9.5 to 10-11 MPa and the sulfur pressure range from 10-3 to 10-4.5 MPa, over a temperature range of 1473 to 1623 K. The slags studied were FeO-SiO2 at silica saturation and those with addition of CaO, MgO, and Al2O3 to determine their effect on sulfide capacities. For these slags, the sulfide capacities were found to vary from 10-3.3 to 10-5. The sulfide capacities increased with increasing temperature from 1473 to 1623 K. A comparison of the reported plant data on sulfur content of industrial slags shows good agreement with the present experimental results. The present data will be useful in estimating metal losses in slag due to metal sulfide entrainment in nonferrous smelters.

  7. Critical Evaluation of Prediction Models for Phosphorus Partition between CaO-based Slags and Iron-based Melts during Dephosphorization Processes

    NASA Astrophysics Data System (ADS)

    Yang, Xue-Min; Li, Jin-Yan; Chai, Guo-Ming; Duan, Dong-Ping; Zhang, Jian

    2016-08-01

    According to the experimental results of hot metal dephosphorization by CaO-based slags at a commercial-scale hot metal pretreatment station, the collected 16 models of equilibrium quotient k_{{P}} or phosphorus partition L_{{P}} between CaO-based slags and iron-based melts from the literature have been evaluated. The collected 16 models for predicting equilibrium quotient k_{{P}} can be transferred to predict phosphorus partition L_{{P}} . The predicted results by the collected 16 models cannot be applied to be criteria for evaluating k_{{P}} or L_{{P}} due to various forms or definitions of k_{{P}} or L_{{P}} . Thus, the measured phosphorus content [pct P] in a hot metal bath at the end point of the dephosphorization pretreatment process is applied to be the fixed criteria for evaluating the collected 16 models. The collected 16 models can be described in the form of linear functions as y = c0 + c1 x , in which independent variable x represents the chemical composition of slags, intercept c0 including the constant term depicts the temperature effect and other unmentioned or acquiescent thermodynamic factors, and slope c1 is regressed by the experimental results of k_{{P}} or L_{{P}} . Thus, a general approach to developing the thermodynamic model for predicting equilibrium quotient k_{{P}} or phosphorus partition L P or [pct P] in iron-based melts during the dephosphorization process is proposed by revising the constant term in intercept c0 for the summarized 15 models except for Suito's model (M3). The better models with an ideal revising possibility or flexibility among the collected 16 models have been selected and recommended. Compared with the predicted result by the revised 15 models and Suito's model (M3), the developed IMCT- L_{{P}} model coupled with the proposed dephosphorization mechanism by the present authors can be applied to accurately predict phosphorus partition L_{{P}} with the lowest mean deviation δ_{{L_{{P}} }} of log L_{{P}} as 2.33, as

  8. Skid resistance performance of asphalt wearing courses with electric arc furnace slag aggregates.

    PubMed

    Kehagia, Fotini

    2009-05-01

    Metallurgical slags are by-products of the iron and steel industry and are subdivided into blast furnace slag and steel slag according to the different steel-producing processes. In Greece, slags are mostly produced from steelmaking using the electric arc furnace process, and subsequently are either disposed in a random way or utilized by the cement industry. Steel slag has been recently used, worldwide, as hard aggregates in wearing courses in order to improve the skidding resistance of asphalt pavements. At the Highway Laboratory, Department of Civil Engineering of Aristotle University of Thessaloniki research has been carried out in the field of steel slags, and especially in electric arc furnace (EAF) slag, to evaluate their possible use in highway engineering. In this paper, the recent results of anti-skidding performance of steel slag aggregates in highway pavements are presented.

  9. Skid resistance performance of asphalt wearing courses with electric arc furnace slag aggregates.

    PubMed

    Kehagia, Fotini

    2009-05-01

    Metallurgical slags are by-products of the iron and steel industry and are subdivided into blast furnace slag and steel slag according to the different steel-producing processes. In Greece, slags are mostly produced from steelmaking using the electric arc furnace process, and subsequently are either disposed in a random way or utilized by the cement industry. Steel slag has been recently used, worldwide, as hard aggregates in wearing courses in order to improve the skidding resistance of asphalt pavements. At the Highway Laboratory, Department of Civil Engineering of Aristotle University of Thessaloniki research has been carried out in the field of steel slags, and especially in electric arc furnace (EAF) slag, to evaluate their possible use in highway engineering. In this paper, the recent results of anti-skidding performance of steel slag aggregates in highway pavements are presented. PMID:19423603

  10. Modeling of Manganese Ferroalloy Slag Properties and Flow During Tapping

    NASA Astrophysics Data System (ADS)

    Muller, Jacques; Zietsman, Johannes Hendrik; Pistorius, Petrus Christiaan

    2015-12-01

    Stable operation of submerged-arc furnaces producing high-carbon ferromanganese (HCFeMn) and silicomanganese (SiMn) requires tapping of consistent amounts of liquid slag and metal. Minimal effort to initiate and sustain tapping at reasonable rates is desired, accommodating fluctuations in especially slag chemical composition and temperature. An analytical model is presented that estimates the tapping rate of the liquid slag-metal mixture as a function of taphole dimensions, coke bed particulate properties, and slag and metal physicochemical properties with dependencies on chemical composition and temperature. This model may be used to evaluate the sensitivity to fluctuations in these parameters, and to determine the influence of converting between HCFeMn and SiMn production. The model was applied to typical HCFeMn and SiMn process conditions, using modeled slag viscosities and densities. Tapping flow rates estimated were comparable to operational data and found to be dependent mostly on slag viscosity. Slag viscosities were generally lower for typical SiMn slags due to the higher temperature used for calculating viscosity. It was predicted that flow through the taphole would mostly develop into laminar flow, with the pressure drop predominantly over the coke bed. Flow rates were found to be more dependent on the taphole diameter than on the taphole length.

  11. UTILIZATION OF LIGHTWEIGHT MATERIALS MADE FROM COAL GASIFICATION SLAGS

    SciTech Connect

    1999-03-29

    The integrated-gasification combined-cycle (IGCC) process is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of ''as-generated'' slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for ''as-generated'' slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700 F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase I, comprising the production of LWA and ULWA from slag at the large pilot scale, and

  12. Utilization of lightweight materials made from coal gasification slags

    SciTech Connect

    1999-09-30

    The integrated-gasification combined-cycle (IGCC) process is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of as-generated slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, the authors found that it would be extremely difficult for as-generated slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1,400 and 1,700 F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase 1, comprising the production of LWA and ULWA from slag at the large pilot scale

  13. UTILIZATION OF LIGHTWEIGHT MATERIALS MADE FROM COAL GASIFICATION SLAGS

    SciTech Connect

    Unknown

    2000-04-24

    The integrated-gasification combined-cycle (IGCC) process is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of ''as-generated'' slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for ''as-generated'' slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700 F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for, various applications. The project goals are to be accomplished in two phases Phase I, comprising the production of LWA and ULWA from slag at the large pilot scale, and

  14. The enhancement effect of pre-reduction using zero-valent iron on the solidification of chromite ore processing residue by blast furnace slag and calcium hydroxide.

    PubMed

    Li, Jinchunzi; Chen, Zhonglin; Shen, Jimin; Wang, Binyuan; Fan, Leitao

    2015-09-01

    A bench scale study was performed to assess the effectiveness of the solidification of chromite ore processing residue (COPR) by blast furnace slag and calcium hydroxide, and investigate the enhancement effect of pre-reduction using zero-valent iron (ZVI) on the solidification treatment. The degree of Cr immobilization was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) as well as the solid waste-extraction procedure for leaching toxicity-sulfuric acid & nitric acid method (Chinese standard HJ/T299-2007). Strength tests and semi-dynamic leaching tests were implemented to investigate the potential for reusing the final treatment product as a readily available construction material. The experimental results showed that the performance of pre-reduction/solidification (S/S) was superior to that of solidification alone. After pre-reduction, all of the S/S treated COPR samples met the TCLP limit for total Cr (5 mg L(-1)), whereas the samples with a COPR content below 40% met the pollution control limit of bricks and building block products (Chinese standard HJ/T 301-2007) produced with COPR for total Cr (0.3 mg L(-1)). At the same time, all of the S/S treated specimens tested were suitable for utilization at certain levels.

  15. [Solidification/Stabilization of Chromite Ore Processing Residue (COPR) Using Zero-Valent Iron and Lime-Activated Ground Granulated Blast Furnace Slag].

    PubMed

    Chen, Zhong-lin; Li, Jin-chunzi; Wang, Bin-yuan; Fan, Lei-tao; Shen, Ji-min

    2015-08-01

    The solidification/stabilization (S/S) of chromite ore processing residue (COPR) was performed using zero-valent iron (ZVI) and lime-activated ground granulated blast furnace slag (GGBFS). The degree of Cr immobilization was evaluated using the leaching procedure, mineral composition analysis and morphology analysis. Semi-dynamic leaching tests were implemented to investigate the potential for reusing the final treatment product as a readily available construction material. The results showed that after reduction, all of the S/S treated COPR samples met the pollution control limit of bricks and building block products (Chinese standard HJ/T 301-2007) produced with COPR for total Cr (0.3 mg x L(-1)), the compressive strength of all the S/S samples could meet the compressive strength standard (15 MPa) for producing clay bricks, and Cr existed as the specie that bound to Fe/Mn oxides in the S/S samples. At the same time, all of the S/S treated specimens tested were suitable for utilization at certain levels.

  16. Slag Penetration into Refractory Lining of Slagging Coal Gasifier

    SciTech Connect

    Matyas, Josef; Sundaram, S. K.; Rodriguez, Carmen P.; Edmondson, Autumn B.; Arrigoni, Benjamin M.

    2008-10-25

    The impurities in coal are converted into molten slag typically containing SiO2, FeO, CaO, and Al2O3 when coal feedstock is burned in slagging gasifiers. The slag flows down the gasifier sidewalls, dissolves, and penetrates and reacts with the refractory lining that protects the stainless steel shell of the gasifier from elevated temperatures (1300–1600°C). Refractories composed primarily of Cr2O3 have been found most resistant to slag corrosion, but they continue to fail performance requirements because of low resistance to spalling. Post-mortem analysis of high-chromia refractory bricks collected from commercial gasifiers suggests that the spalling is affected by the depth of slag penetration that is in turn affected by the wettability and interconnected porosity of the refractory as well as the slag viscosity. Laboratory tests were conducted to measure the viscosity of slags (Wyoming Powder River Basin [PRB], Pocahontas #3, and Pittsburgh #8), their contact angle on refractories (chromia-alumina [Aurex 75SR] and high-chromia [Serv 95 and Aurex 95P]), and the apparent porosity of selected refractories. In addition, the depth of slag penetration as a function of time and temperature was determined for various refractory-slag combinations. The results of laboratory tests were used to develop a refractory material that has high resistance to penetration by molten slag and thus has a potential to have a substantially longer service life than the materials currently being used.

  17. Determination of slagging behavior of various coal ash samples by using DTF

    SciTech Connect

    Kim, H.T.; Choi, B.C.; Park, S.W.

    1999-07-01

    The objective of this study is to investigate slagging behavior of various ash samples with the conjunction to the properties of ashes and original coal such as concentration of each ash components, ash slagging temperature and slag viscosity. To simulate actual ash melting condition in coal combustion as well as gasification, DTF (drop tube furnace) is utilized for the acquisition of slag sample with different reaction condition. The sampled slag is photographed for the visual inspection and the shape of the slag is evaluated with ash properties. The sampled ash slag is also analyzed with XRD for the determination of phase transition during the ash melting. Furthermore, coal ashes are processed with Ash Fusion Determinator for the fusion temperature and High-Temperature Viscometer for the slag viscosity. Such ash-related properties are also determined by empirical formulation for the refinement of the result. So far, three different coal samples, Alaska, Datong, Cyprus are investigated. For the 3 ash samples, slag formation shows similar shape in combustion as well as gasification condition and completely different shape with different coal types. Alaska slag, which represents higher fluidity, is penetrated into alumina disk so that small half-cone shape of slag is produced. However, Cyprus slag is formed with more circular shape of sphere and Datong slag represents an in-between shape. More coal samples will be studied for the determination of slag behavior. The shape data will be analyzed with ash composition, fluidity behavior and ash fusion determination of original coal. Such relationship will be the baseline to determine the operation parameter of slag removal in the 3 ton/day coal gasifier located in the Ajou University, Suwon, Korea.

  18. Decalcification resistance of alkali-activated slag.

    PubMed

    Komljenović, Miroslav M; Baščarević, Zvezdana; Marjanović, Nataša; Nikolić, Violeta

    2012-09-30

    This paper analyses the effects of decalcification in concentrated 6M NH(4)NO(3) solution on mechanical and microstructural properties of alkali-activated slag (AAS). Portland-slag cement (CEM II/A-S 42.5 N) was used as a benchmark material. Decalcification process led to a decrease in strength, both in AAS and in CEM II, and this effect was more pronounced in CEM II. The decrease in strength was explicitly related to the decrease in Ca/Si atomic ratio of C-S-H gel. A very low ratio of Ca/Si ~0.3 in AAS was the consequence of coexistence of C-S-H(I) gel and silica gel. During decalcification of AAS almost complete leaching of sodium and tetrahedral aluminum from C-S-H(I) gel also took place. AAS showed significantly higher resistance to decalcification in relation to the benchmark CEM II due to the absence of portlandite, high level of polymerization of silicate chains, low level of aluminum for silicon substitution in the structure of C-S-H(I), and the formation of protective layer of polymerized silica gel during decalcification process. In stabilization/solidification processes alkali-activated slag represents a more promising solution than Portland-slag cement due to significantly higher resistance to decalcification. PMID:22818592

  19. Slag Characterization: A Necessary Tool for Modeling and Simulating Refractory Corrosion on a Pilot Scale

    NASA Astrophysics Data System (ADS)

    Gregurek, D.; Wenzl, C.; Reiter, V.; Studnicka, H. L.; Spanring, A.

    2014-09-01

    The slag in pyrometallurgical operations plays a major role affecting the life of furnace refractory. As such, comprehensive mineralogical and chemical slag examination, physical property determination including the slag melting point or liquidus, and viscosity are necessary for precise understanding of a slag. At the RHI Technology Center Leoben, Austria, the main objective of slag characterization work is to reach a better understanding of refractory corrosion. This corrosion testwork is performed at the laboratory and pilot scale. Typically, corrosion tests are performed in an induction furnace or rotary kiln, with the main purpose being the improved selection of the most suitable refractory products to improve refractory performance in operating metallurgical furnaces. This article focuses on characterization of samples of six non-ferrous, customer-provided slags. This includes slag from a copper Peirce-Smith converter, a short rotary furnace for lead smelting, a titania-processing furnace, and a Ni-Cu top blowing rotary converter (TBRC) plant.

  20. Critical Assessment of P2O5 Activity Coefficients in CaO-based Slags during Dephosphorization Process of Iron-based Melts

    NASA Astrophysics Data System (ADS)

    Yang, Xue-min; Li, Jin-yan; Chai, Guo-Ming; Duan, Dong-ping; Zhang, Jian

    2016-08-01

    According to the experimental results of hot metal dephosphorization by CaO-based slags at a commercial-scale hot metal pretreatment station, activity a_{{{{P}}_{ 2} {{O}}_{ 5} }} of P2O5 in the CaO-based slags has been determined using the calculated comprehensive mass action concentration N_{{{{Fe}}t {{O}}}}{} of iron oxides by the ion and molecule coexistence theory (IMCT) for representing the reaction ability of Fe t O, i.e., activity of a_{{{{Fe}}t {{O}}}}{} . The collected ten models from the literature for predicting activity coefficient γ_{{{{P}}_{ 2} {{O}}_{ 5} }} of P2O5 in CaO-based slags have been evaluated based on the determined activity a_{{{{P}}_{ 2} {{O}}_{ 5} }} of P2O5 by the IMCT as the criterion. The collected ten models of activity coefficient γ_{{{{P}}_{ 2} {{O}}_{ 5} }} of P2O5 in CaO-based slags can be described in the form of a linear function as log γ_{{{{P}}_{ 2} {{O}}_{ 5} }} ≡ y = c0 + c1 x , in which independent variable x represents the chemical composition of slags, intercept c0 including the constant term depicts temperature effect and other unmentioned or acquiescent thermodynamic factors, and slope c1 is regressed by the experimental results. Thus, a general approach for obtaining good prediction results of activity a_{{{{P}}_{ 2} {{O}}_{ 5} }} of P2O5 in CaO-based slags is proposed by revising the constant term in intercept c0 for the collected ten models. The better models with an ideal revising possibility or flexibility in the collected ten models have been selected and recommended.

  1. Monitoring the Thickness of Coal-Conversion Slag

    NASA Technical Reports Server (NTRS)

    Walsh, J. V.

    1984-01-01

    Technique adapts analogous ocean-floor-mapping technology. Existing ocean floor acoustic technology adapted for real-time monitoring of thickness and viscosity of flowing slag in coal-conversion processing.

  2. Slag remelt purification of irradiated vanadium alloys

    SciTech Connect

    Carmack, W.J.; Smolik, G.R.; McCarthy, K.A.; Gorman, P.K.

    1995-07-01

    This paper describes theoretical and scoping experimental efforts to investigate the decontamination potential of a slag remelting process for decontaminating irradiated vanadium alloys. Theoretical calculations, using a commercial thermochemical computer code HSC Chemistry, determined the potential slag compositions and slag-vanadium alloy ratios. The experiment determined the removal characteristics of four surrogate transmutation isotopes (Ca, Y - to simulate Sc, Mn, and Ar) from a V-5Ti-5Cr alloy with calcium fluoride slag. An electroslag remelt furnace was used in the experiment to melt and react the constituents. The process achieved about a 90 percent removal of calcium and over 99 percent removal of yttrium. Analyses indicate that about 40 percent of the manganese may have been removed. Argon analyses indicates that 99.3% of the argon was released from the vanadium alloy in the first melt increasing to 99.7% during the second melt. Powder metallurgy techniques were used to incorporate surrogate transmutation products in the vanadium. A powder mixture was prepared with the following composition: 90 wt % vanadium, 4.7 wt % titanium, 4.7 wt % chromium, 0.35 wt % manganese, 0.35 wt % CaO, and 0.35 wt % Y{sub 2}O{sub 3}. This mixture was packed into 2.54 cm diameter stainless steel tubes. Argon was introduced into the powder mixture by evacuating and backfilling the stainless steel containers to a pressure of 20 kPa (0.2 atm). The tubes were hot isostatically pressed at 207 MPa (2000 atm) and 1473 K to consolidate the metal. An electroslag remelt furnace (crucible dimensions: 5.1 cm diameter by 15.2 cm length) was used to process the vanadium electrodes. Chemical analyses were performed on samples extracted from the slags and ingots. Ingot analyses results are shown below. Values are shown in percent removal of the four targeted elements of the initial compositions.

  3. Slag recycling of irradiated vanadium

    SciTech Connect

    Gorman, P.K.

    1995-04-05

    An experimental inductoslag apparatus to recycle irradiated vanadium was fabricated and tested. An experimental electroslag apparatus was also used to test possible slags. The testing was carried out with slag materials that were fabricated along with impurity bearing vanadium samples. Results obtained include computer simulated thermochemical calculations and experimentally determined removal efficiencies of the transmutation impurities. Analyses of the samples before and after testing were carried out to determine if the slag did indeed remove the transmutation impurities from the irradiated vanadium.

  4. Utilizing steel slag in environmental application - An overview

    NASA Astrophysics Data System (ADS)

    Lim, J. W.; Chew, L. H.; Choong, T. S. Y.; Tezara, C.; Yazdi, M. H.

    2016-06-01

    Steel slags are generated as waste material or byproduct every day from steel making industries.The potential environmental issues which are related with the slag dump or reprocessing for metal recovery are generally being focused in the research. However the chemistry and mineralogy of slag depends on metallurgical process which is able to determine whether the steel slag can be the reusable products or not. Nowadays, steel slag are well characterized by using several methods, such as X-ray Diffraction, ICP-OES, leaching test and many more. About the industrial application, it is mainly reused as aggregate for road construction, as armour stones for hydraulic engineering constructions and as fertilizers for agricultural purposes. To ensure the quality of steel slag for the end usage, several test methods are developed for evaluating the technical properties of steel slag, especially volume stability and environmental behaviour. In order to determine its environmental behaviour, leaching tests have been developed. The focus of this paper however is on those applications that directly affect environmental issues including remediation, and mitigation of activities that negatively impact the environment.

  5. UTILIZATION OF LIGHTWEIGHT MATERIALS MADE FROM COAL GASIFICATION SLAGS

    SciTech Connect

    Vas Choudhry; Stephen Kwan; Steven R. Hadley

    2001-07-01

    The objective of the project entitled ''Utilization of Lightweight Materials Made from Coal Gasification Slags'' was to demonstrate the technical and economic viability of manufacturing low-unit-weight products from coal gasification slags which can be used as substitutes for conventional lightweight and ultra-lightweight aggregates. In Phase I, the technology developed by Praxis to produce lightweight aggregates from slag (termed SLA) was applied to produce a large batch (10 tons) of expanded slag using pilot direct-fired rotary kilns and a fluidized bed calciner. The expanded products were characterized using basic characterization and application-oriented tests. Phase II involved the demonstration and evaluation of the use of expanded slag aggregates to produce a number of end-use applications including lightweight roof tiles, lightweight precast products (e.g., masonry blocks), structural concrete, insulating concrete, loose fill insulation, and as a substitute for expanded perlite and vermiculite in horticultural applications. Prototypes of these end-use applications were made and tested with the assistance of commercial manufacturers. Finally, the economics of expanded slag production was determined and compared with the alternative of slag disposal. Production of value-added products from SLA has a significant potential to enhance the overall gasification process economics, especially when the avoided costs of disposal are considered.

  6. Leaching modelling of slurry-phase carbonated steel slag.

    PubMed

    Costa, G; Polettini, A; Pomi, R; Stramazzo, A

    2016-01-25

    In the present work the influence of accelerated mineral carbonation on the leaching behaviour of basic oxygen furnace steel slag was investigated. The environmental behaviour of the material as evaluated through the release of major elements and toxic metals under varying pH conditions was the main focus of the study. Geochemical modelling of the eluates was used to derive a theoretical description of the underlying leaching phenomena for the carbonated material as compared to the original slag. Among the investigated elements, Ca and Si were most appreciably affected by carbonation. A very clear effect of carbonation on leaching was observed for silicate phases, and lower-Ca/Si-ratio minerals were found to control leaching in carbonated slag eluates as compared to the corresponding untreated slag sample as a result of Ca depletion from the residual slag particles. Clear evidence was also gained of solubility control for Ca, Mg and Mn by a number of carbonate minerals, indicating a significant involvement of the original slag constituents in the carbonation process. The release of toxic metals (Zn, V, Cr, Mo) was found to be variously affected by carbonation, owing to different mechanisms including pH changes, dissolution/precipitation of carbonates as well as sorption onto reactive mineral surfaces. The leaching test results were used to derive further considerations on the expected metal release levels on the basis of specific assumptions on the relevant pH domains for the untreated and carbonated slag.

  7. Slag-Refractory Interaction in Slagging Coal Gasifiers

    SciTech Connect

    Matyas, Josef; Sundaram, S. K.; Hicks, Brent J.; Edmondson, Autumn B.; Arrigoni, Benjamin M.

    2008-03-03

    The combustion chamber of slagging coal gasifiers is lined with refractories to protect the stainless steel shell of the gasifier from elevated temperatures and corrosive attack of the coal slag. Refractories composed primarily of Cr2O3 have been found most resistant to slag corrosion, but they continue to fail performance requirements. Post-mortem analysis of high-chromia refractory bricks collected from commercial gasifiers suggests that slag penetration and subsequent spalling of refractory are the cause of significantly shorter service life of gasifier refractories. Laboratory tests were conducted to determine the penetration depth of three slags representative of a wide variety of coals in the United States into chromia-alumina and two high-chromia refractories. Variables tested were refractory-slag combinations and two partial pressures of O2. Slag penetration depths were measured from spliced images of each refractory. Samples heated to 1470°C for 2 hrs had maximum penetration depths ranging from 1.99±0.15 mm to at least 21.6 mm. Aurex 95P, a high-chromia refractory containing 3.3% phosphorous pentoxide (P2O5), showed the least slag penetration of all refractories tested. P2O5 likely reacts with the slags to increase their viscosity and restrict molten slag penetration. Experimental data on the slag-refractory interaction will be incorporated into mathematical model that will be used to 1) identify critical conditions at which refractory corrosion sharply increases, and 2) predict the service life of a gasifier refractory.

  8. Characterization of structure and thermophysical properties of three ESR slags

    NASA Astrophysics Data System (ADS)

    Plotkowski, A.; deBarbadillo, J.; Krane, Matthew J. M.

    2016-07-01

    The structure and properties of electroslag remelting (ESR) slags were characterized. Slags samples of three compositions were obtained from industrial remelting processes at Special Metals Corporation and from casting in a laboratory vacuum induction melter. The structure of the slag samples was observed using optical and electron microscopy, and phases were identified and their relative amounts quantified using X-ray diffraction. Laser flash thermal diffusivity, density, and differential scanning calorimetry measurements for specific heat were performed to determine the bulk thermal conductivity of the samples. Sample porosity was measured as a function of depth using a serial sectioning technique, and a onedimensional computational model was developed to estimate the thermal conductivity of the fully dense slags. These results are discussed in context with previous studies, and opportunities for future research are identified. AFRL Case Number: 88ABW-2015-1871.

  9. The behavior of sulfur in industrial pyrometallurgical slags

    NASA Astrophysics Data System (ADS)

    Nagamori, Meguru

    1994-08-01

    Dissolution of sulfur in industrial slags, even at such a low level as 1 mass% S or so, increases the solubility of certain valuable metals by an order of magnitude. The phenomenon is accounted for in terms of Flood-Førland-Grjotheim's model for dianionic salt solutions, whereas its rigorous analysis requires the digaseous Gibbs-Duhem integration. In the research described here, the distribution of sulfur among gas, slag, and metallic iron phases in the bath smelting of iron ore was computer-simulated based on a two-sites model coupled with sulfide capacity data. The solubilities of Ag, Cu, Co, and Ni in industrial slags are reviewed by applying the sulfidic-oxidic dissolution model to copper-matte smelting, nickel-slag cleaning (Falconbridge, Canada), and the imperial smelting process for zinc and lead (Hachinohe, Japan).

  10. A discussion on improving hydration activity of steel slag by altering its mineral compositions.

    PubMed

    Wang, Qiang; Yan, Peiyu; Feng, Jianwen

    2011-02-28

    This study aims to investigate the ways to improve the cementitious properties of steel slag. The results show that the cementitious phase of steel slag is composed of silicate and aluminate, but the large particles of these phases make a very small contribution to the cementitious properties of steel slag. RO phase (CaO-FeO-MnO-MgO solid solution), Fe(3)O(4), C(2)F and f-CaO make no contribution to the cementitious properties of steel slag. A new kind of steel slag with more cementitious phase and less RO phase can be obtained by removing some large particles. This new steel slag possesses better cementitious properties than the original steel slag. The large particles can be used as fine aggregates for concrete. Adding regulating agent high in CaO and SiO(2) during manufacturing process of steel slag to increase the cementitious phase to inert phase ratio is another way to improve its cementitious properties. The regulating agent should be selected to adapt to the specific steel slag and the alkalinity should be increased as high as possible on the premise that the f-CaO content does not increase. The cooling rate should be enhanced to improve the hydration activity of the cementitious phase at the early ages and the grindability of steel slag.

  11. Experimental Investigation and Modeling of Copper Smelting Slags

    NASA Astrophysics Data System (ADS)

    Starodub, Konstantin; Kuminova, Yaroslava; Dinsdale, Alan; Cheverikin, Vladimir; Filichkina, Vera; Saynazarov, Abdukahhar; Khvan, Alexandra; Kondratiev, Alex

    2016-07-01

    Effective extraction of copper from sulfide ores requires careful operation of a copper smelter, which in turn depends very much on chemistry of the feed and resulted slag and matte. For example, chemical composition of copper smelting slags has to be in a certain range to ensure that their properties are within specific limits. Disobeying these rules may lead to complications in smelting operation, poor quality of the copper products, and premature shutdown of the copper smelter. In the present paper the microstructure and phase composition of slags from the Almalyk copper flash smelter were investigated experimentally and then modeled thermodynamically to evaluate potential ways of improvement and optimization of the copper smelting process and its products. The slag samples were taken at different stages of the copper smelting process: on slag tapping, after slag transportation to a deposition site, and at the site. Experimental investigation included the XRD, XRF, and SEM techniques, which were also confirmed by the traditional wet chemistry analysis. Thermodynamic modeling was carried out using thermochemical software package MTDATA, which enables thermodynamic and physical properties of the matte, slag, and gas phases to be calculated in a wide range of temperatures, pressures, and chemical compositions. In addition, slag viscosities and corresponding matte settling rates were estimated using the modified Urbain and Utigard-Warczok models, and the Hadamard-Rybczynski equation, respectively. It was found that the copper content in the slags may vary significantly depending on the location of slag sampling. Cu was found to be present as sulfide particles, almost no Cu was found to be dissolved in the slag. Analysis of microstructure and phase composition showed that major phase found in the samples is fayalite, while other phases are complex spinels (based on magnetite), different sulfides, and a glass-like phase. Thermodynamic calculations demonstrated the

  12. Experimental Investigation and Modeling of Copper Smelting Slags

    NASA Astrophysics Data System (ADS)

    Starodub, Konstantin; Kuminova, Yaroslava; Dinsdale, Alan; Cheverikin, Vladimir; Filichkina, Vera; Saynazarov, Abdukahhar; Khvan, Alexandra; Kondratiev, Alex

    2016-10-01

    Effective extraction of copper from sulfide ores requires careful operation of a copper smelter, which in turn depends very much on chemistry of the feed and resulted slag and matte. For example, chemical composition of copper smelting slags has to be in a certain range to ensure that their properties are within specific limits. Disobeying these rules may lead to complications in smelting operation, poor quality of the copper products, and premature shutdown of the copper smelter. In the present paper the microstructure and phase composition of slags from the Almalyk copper flash smelter were investigated experimentally and then modeled thermodynamically to evaluate potential ways of improvement and optimization of the copper smelting process and its products. The slag samples were taken at different stages of the copper smelting process: on slag tapping, after slag transportation to a deposition site, and at the site. Experimental investigation included the XRD, XRF, and SEM techniques, which were also confirmed by the traditional wet chemistry analysis. Thermodynamic modeling was carried out using thermochemical software package MTDATA, which enables thermodynamic and physical properties of the matte, slag, and gas phases to be calculated in a wide range of temperatures, pressures, and chemical compositions. In addition, slag viscosities and corresponding matte settling rates were estimated using the modified Urbain and Utigard-Warczok models, and the Hadamard-Rybczynski equation, respectively. It was found that the copper content in the slags may vary significantly depending on the location of slag sampling. Cu was found to be present as sulfide particles, almost no Cu was found to be dissolved in the slag. Analysis of microstructure and phase composition showed that major phase found in the samples is fayalite, while other phases are complex spinels (based on magnetite), different sulfides, and a glass-like phase. Thermodynamic calculations demonstrated the

  13. Utilization of lightweight materials made from coal gasification slags. Quarterly report, December 1, 1995--February 28, 1996

    SciTech Connect

    1996-12-31

    The project scope consists of collecting a 20-ton sample of slag (primary slag), processing it for chart removal, and subjecting it to pyroprocessing to produce expanded slag aggregates of various size gradations and unit weights, ranging from 12 to 50 lb/fg{sup 3}. A second smaller slag sample will be used for confirmatory testing. The expanded slag aggregates will then be tested for their suitability in manufacturing precast concrete products (e.g., masonry blocks and roof tiles) and insulating concrete, first at the laboratory scale and subsequently in commercial manufacturing plants. These products will be evaluated using ASTM and industry test methods. Technical data generated during production and testing of the products will be used to assess the overall technical viability of expanded slag production. In addition, a market assessment will be made based on an evaluation of both the expanded slag aggregates and the final products, and market prices for these products will be established in order to assess the economic viability of these utilization technologies. Relevant cost data for physical and pyroprocessing of slag to produce expanded slag aggregates will be gathered for comparison with (1) the management and disposal costs for slag or similar wastes and (2) production costs for conventional materials which the slag aggregates would replace. This will form the basis for an overall economic evaluation of expanded slag utilization technologies.

  14. TRW advanced slagging coal combustor utility demonstration

    SciTech Connect

    Not Available

    1990-01-01

    The TRW Advanced Entrained Coal Combustor Demonstration Project consists of retrofitting Orange and Rockland (O R) Utility Corporation's Lovett Plant Unit No. 3 with four (4) slagging combustors which will allow the gas/oil unit to fire 2.5% sulfur coal. The slagging combustor process will provide NO{sub x} and SO{sub x} emissions that meet NSPS and New York State Environmental Standards. The TRW-Utility Demonstration Unit (UDU) is responsible for the implementation of program policies and overall direction of the project. The following projects will be carried out: process and design development of clean coal technology CCT-1 the development and operation of the entrained coal combustor will enable the boiler to burn low and medium sulfur coal while meeting all the Federal/State emission requirements; demonstrate sulfur dioxide emissions control by pulverized limestone injection into the entrained coal combustor system.

  15. Partitioning of heavy metals in a soil contaminated by slag: A redistribution study

    SciTech Connect

    Bunzl, K.; Trautmannsheimer, M.; Schramel, P.

    1999-08-01

    In order to interpret reasonably the partitioning of heavy metals in a contaminated soil as observed from applying a sequential extraction procedure, information on possible redistribution processes of the metals during the various extraction steps is essential. For this purpose, sequential extraction was used to study the chemical partitioning of Ag, Cu, Ni, Pb, and Zn in a soil contaminated wither by a slag from coal firing or by a slag from pyrite roasting. Through additional application of sequential extraction to the pure slags as well as to the uncontaminated soil, it was shown that during the various extraction steps applied to the soil/slag mixtures, substantial redistribution processes of the metals between the slag- and soil particles can occur. In many cases, metals ions released during the extraction with acid hydroxylamine or acid hydrogen peroxide are partially readsorbed by solid constituents of the mixture and will therefore be found in the subsequent fractions extracted. As a result, one has to realize that (1) it will be difficult to predict the chemical partitioning of these metals in contaminated soils by investigating pure slags only, and (2) information on the partitioning of a metal in a slag contaminated soil will not necessarily give any relevant information on the form of this metal in the slag or in the slag/soil mixture, because the redistribution processes during sequential extraction will not be the same as those occurring in the soil solution under natural conditions.

  16. The Effect of Propellant Variables on Slag in Subscale Spin Motors. Part 1; Design and Qualification of a Slag Discrimination Motor

    NASA Technical Reports Server (NTRS)

    Perkins, F. M.; Beus, R. W.; May, D. H.

    1995-01-01

    The formation, collection, and expulsion of aluminum oxide slag is known to affect the performance of many solid rocket motor systems. Slag expulsion, in particular, is believed to be capable of causing pressure and thrust perturbations. Propellant combustion studies, performed and documented by many investigators, have shown that variations in propellant raw materials and processing affect the nature of alumina droplets at the burning propellant surface, and hence, may affect the quantity of slag retained in the motor chamber, available for expulsion. Thiokol has completed an experimental and analytical evaluation to determine the effects of several material and process variables on Space SHuttle propellant and its propensity to 'slag'. This paper describes the test article, a small scale spin motor with special nozzle, designed and qualified as a slag discriminating tool for use in the evaluation.

  17. Structure and properties of the slags of continuous converting of copper nickel-containing mattes and concentrates: II. Effect of the SiO2/CaO ratio on the structure and liquidus temperature of the slags

    NASA Astrophysics Data System (ADS)

    Pigarev, S. P.; Tsymbulov, L. B.; Selivanov, E. N.; Chumarev, V. M.

    2012-03-01

    The structure and liquidus temperature of the SiO2-CaO-Al2O3-FeO x -Cu2O-NiO slags that form during continuous converting of copper mattes and concentrates into blister copper are analyzed. The slag melt compositions are varied over a wide SiO2/CaO range. The slags are studied by X-ray diffraction, scanning electron microscopy, and electron-probe microanalysis. The liquidus temperature of the slags is determined by differential thermal analysis. It is found that, depending on the SiO2/CaO ratio, the structure and liquidus temperature of the slags change and the forms of copper in a slag also change. The SiO2/CaO range in a slag is recommended for the process of continuous converting of a copper nickel-containing sulfide raw materials.

  18. An Empirical Viscosity Model for Coal Slags

    SciTech Connect

    Matyas, Josef; Cooley, Scott K.; Sundaram, S. K.; Rodriguez, Carmen P.; Edmondson, Autumn B.; Arrigoni, Benjamin M.

    2008-10-25

    Slags of low viscosity readily penetrate the refractory lining in slagging gasifiers, causing rapid and severe corrosion called spalling. In addition, a low-viscosity slag that flows down the gasifier wall forms a relatively thin layer of slag on the refractory surface, allowing the corrosive gases in the gasifier to participate in the chemical reactions between the refractory and the slag. In contrast, a slag viscosity of <25 Pa•s at 1400°C is necessary to minimize the possibility of plugging the slag tap. There is a need to predict and optimize slag viscosity so slagging gasifiers can operate continuously at temperatures ranging from 1300 to 1650°C. The approach adopted in this work was to statistically design and prepare simulated slags, measure the viscosity as a function of temperature, and develop a model to predict slag viscosity based on slag composition and temperature. Statistical design software was used to select compositions from a candidate set of all possible vertices that will optimally represent the composition space for 10 main components. A total of 21 slag compositions were generated, including 5 actual coal slag compositions. The Arrhenius equation was applied to measured viscosity versus temperature data of tested slags, and the Arrhenius coefficients (A and B in ln(vis) = A + B/T) were expressed as linear functions of the slag composition. The viscosity model was validated using 1) data splitting approach, and 2) viscosity/temperature data of selected slag compositions from the literature that were formulated and melted at Pacific Northwest National Laboratory. The capability of the model to predict the viscosity of coal slags was compared with the model developed by Browning et al. because this model can predict the viscosity of slags from coal ash better than the most commonly used empirical models found in the literature.

  19. A Thermodynamic Model for Predicting Phosphorus Partition between CaO-based Slags and Hot Metal during Hot Metal Dephosphorization Pretreatment Process Based on the Ion and Molecule Coexistence Theory

    NASA Astrophysics Data System (ADS)

    Yang, Xue-min; Li, Jin-yan; Chai, Guo-ming; Duan, Dong-ping; Zhang, Jian

    2016-08-01

    A thermodynamic model for predicting phosphorus partition L P between a CaO-based slags and hot metal during hot metal dephosphorization pretreatment process has been developed based on the ion and molecule coexistence theory (IMCT), i.e., the IMCT- L P model. The reaction abilities of structural units or ion couples in the CaO-based slags have been represented by the calculated mass action concentrations N i through the developed IMCT- N i model based on the IMCT. The developed IMCT- L P model has been verified to be valid through comparing with the measured L P as well as the predicted L P by two reported L P models from the literature. Besides the total phosphorus partition L P between the CaO-based slag and hot metal, the respective phosphorus partitions L P, i of nine dephosphorization products as P2O5, 3FeO·P2O5, 4FeO·P2O5, 2CaO·P2O5, 3CaO·P2O5, 4CaO·P2O5, 2MgO·P2O5, 3MgO·P2O5, and 3MnO·P2O5 can also be accurately predicted by the developed IMCT- L P model. The formed 3CaO·P2O5 accounts for 99.20 pct of dephosphorization products comparing with the generated 4CaO·P2O5 for 0.08 pct. The comprehensive effect of CaO+Fe t O, which can be described by the mass percentage ratio (pct Fe t O)/(pct CaO) or the mass action concentration ratio N_{Fe}t O/N_{Fe}t O N_{CaO}. N_{CaO}} as well as the mass percentage product (pct Fe t O) × (pct CaO) or the mass action concentration product N_{{{{Fe}}t {{O}}}}5 × N_{{CaO}}3 , controls dephosphorization ability of the CaO-based slags. A linear relationship of L P against (pct Fe t O)/(pct CaO) can be correlated compared with a parabolic relationship of L P against N_{Fe}t O/N_{Fe}t O N_{CaO}. N_{CaO}, while the linear relationship of L P against (pct Fe t O) × (pct CaO) or N_{Fe}t O5 × N_{CaO}3 can be established. Thus, the mass percentage product (pct Fe t O) × (pct CaO) and the mass action concentration product N_{Fe}t O5 × N_{CaO}3 are recommended to represent the comprehensive effect of CaO+Fe t O on

  20. Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

    SciTech Connect

    Massoudi, Mehrdad; Wang, Ping

    2013-02-07

    The viscosity of slag and the thermal conductivity of ash deposits are among two of the most important constitutive parameters that need to be studied. The accurate formulation or representations of the (transport) properties of coal present a special challenge of modeling efforts in computational fluid dynamics applications. Studies have indicated that slag viscosity must be within a certain range of temperatures for tapping and the membrane wall to be accessible, for example, between 1,300 °C and 1,500 °C, the viscosity is approximately 25 Pa·s. As the operating temperature decreases, the slag cools and solid crystals begin to form. Since slag behaves as a non-linear fluid, we discuss the constitutive modeling of slag and the important parameters that must be studied. We propose a new constitutive model, where the stress tensor not only has a yield stress part, but it also has a viscous part with a shear rate dependency of the viscosity, along with temperature and concentration dependency, while allowing for the possibility of the normal stress effects. In Part I, we reviewed, identify and discuss the key coal ash properties and the operating conditions impacting slag behavior.

  1. Hydrology and geochemistry of a slag-affected aquifer and chemical characteristics of slag-affected ground water, northwestern Indiana and northeastern Illinois

    USGS Publications Warehouse

    Bayless, E. Randall; Greeman, T.K.; Harvey, C.C.

    1998-01-01

    ?aquifer interface. The solid-phase analyses indicated that calcite, dolomite, and quartz generally were present throughout the slag?aquifer system; barian celestite, cristobalite, manganese-bearing calcite, and minrecordite were present in fewer samples. Trace elements that are liberated from the slag may be incorporated as impurities during precipitation of major minerals, sorbed onto clays and other grainsize fractions not analyzed as part of this study, or present in low-abundance minerals that were not detected by the X-ray analysis. Mass-balance and speciation programs were used to identify geochemical processes that may be occurring as water infiltrates through the slag, flows into the aquifer, and discharges into Lake George. The geochemical models indicate that precipitation of calcite may be occurring where slag-affected water enters the aquifer. Models also indicate that dolomite precipitation and clay-mineral dissolution may be occurring at the slag?aquifer interface; however, dolomite precipitation is generally believed to require geologically long time periods. Silica may be dissolving where slag-affected ground water enters the aquifer and may be precipitating where slag-affected ground water discharges to the lakebed of Lake George. In addition to the site-specific study, a statistical analysis of regional water quality was done to compare ground water in wells affected and unaffected by slag. When com-pared to wells in background locations in the Calumet aquifer, wells screened in slag across northwestern Indiana and northeastern Illinois generally had relatively higher pH and specific-conductance values and relatively higher concentrations of alkalinity, dissolved solids, suspended solids, total organic carbon, calcium, potassium, sodium, chloride, aluminum, barium, and possibly magnesium, sulfate, chromium, cobalt, copper, cyanide, manganese, mercury, nickel, and vanadium. When compared to wells in slag and wells in background locations, ground water from immediat

  2. UTILIZATION OF LIGHTWEIGHT MATERIALS MADE FROM COAL GASIFICATION SLAGS

    SciTech Connect

    1998-12-24

    The integrated-gasification combined-cycle (IGCC) process is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of ''as-generated'' slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for ''as-generated'' slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700 F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase I, comprising the production of LWA and ULWA from slag at the large pilot scale, and

  3. Utilization of lightweight materials made from coal gasification slags

    SciTech Connect

    1998-09-30

    The integrated-gasification combined-cycle (IGCC) process is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of ''as-generated'' slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for ''as-generated'' slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700 F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase I, comprising the production of LWA and ULWA from slag at the large pilot scale, and

  4. Utilization of lightweight materials made from coal gasification slags

    SciTech Connect

    1999-12-30

    The integrated-gasification combined-cycle (IGCC) process is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of as-generated slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, the authors found that it would be extremely difficult for as-generated slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1,400 and 1,700 F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase 1, comprising the production of LWA and ULWA from slag at the large pilot scale

  5. Investigation of the phosphorus removal capacities of basic oxygen furnace slag under variable conditions.

    PubMed

    Han, Chong; Wang, Zhen; Yang, Wangjin; Wu, Qianqian; Yang, He; Xue, Xiangxin

    2016-01-01

    Effects of reaction time, initial phosphorus concentration, basic oxygen furnace slag (BOF-slag) dosage and size, and temperature on the phosphorus removal capacities (PRCs) of BOF-slag have been investigated in detail through batch tests. Weakly bound phosphorus, Fe- and Al-associated phosphorus, and Ca-associated phosphorus from fresh and reacted BOF-slag were analysed using sequential chemical extraction processes. It was determined that the PRCs of BOF-slag increased with the increase of initial phosphorus concentration and temperature while it decreased with the increase of BOF-slag dosage and size. The phosphorus removed by BOF-slag was primarily assigned to weakly bound phosphorus and Ca-associated phosphorus. Weakly bound phosphorus showed a significant decrease with the increase in all experimental parameter values. However, Ca-associated phosphorus exhibited a prominent increase with increasing reaction time, initial phosphorus concentration, and temperature. These demonstrate that experimental parameters can simultaneously affect the PRCs of BOF-slag and the ways of phosphorus removal by BOF-slag.

  6. Vanadium removal from LD converter slag using bacteria and fungi.

    PubMed

    Mirazimi, S M J; Abbasalipour, Z; Rashchi, F

    2015-04-15

    Removal of vanadium from Linz-Donawits (LD) converter slag was investigated by means of three different species of microbial systems: Acidithiobacillus thiooxidans (autotrophic bacteria), Pseudomonas putida (heterotrophic bacteria) and Aspergillus niger (fungi). The bioleaching process was carried out in both one-step and two-step process and the leaching efficiencies in both cases were compared. Formation of inorganic and organic acids during the leaching process caused mobilization of vanadium. In order to reduce toxic effects of the metal species on the above mentioned microorganisms, a prolonged adaptation process was performed. Both bacteria, A. thiooxidans and P. putida were able to remove more than 90% of vanadium at slag concentrations of 1-5 g L(-1) after 15 days. Also, the maximum achievable vanadium removal in the fungal system was approximately 92% at a slag concentration of 1 g L(-1) after 22 days.

  7. Alteration of municipal and industrial slags under atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Rafał Kowalski, Piotr; Michalik, Marek

    2014-05-01

    The Waste Management System in Poland is being consequently built since 1998. After important changes in legislation, local governments have taken over the duty of waste collection. New points of selective collection of wastes have been opened and new sorting and composting plants were built. The last stage of introducing the Waste Management System is construction of waste incineration power plants. From nine installations which were planned, six are now under construction and they will start operating within the next two years. It is assumed that the consumption of raw wastes for these installations will reach 974 thousand tons per year. These investments will result in increased slags and ashes production. Now in Poland several local waste incinerators are operating and predominant amount of produced incineration residues is landfilled. These materials are exposed to atmospheric conditions in time of short term storage (just after incineration) and afterwards for a longer period of time on the landfill site. During the storage of slags low temperature mineral transformations and chemical changes may occur and also some components can be washed out. These materials are stored wet because of the technological processes. The aim of this study is to investigate the influence of storage in atmospheric conditions on slags from incineration of industrial and municipal wastes. The experiment started in January 2013. During this period slag samples from incineration of industrial and municipal wastes were exposed to atmospheric conditions. Samples were collected after 6 and 12 months. Within this time the pH value was measured monthly, and during the experimental period remained constant on the level of 9.5. After 6 months of exposure only slight changes in mineral compositions were observed in slags. The results of XRD analysis of municipal slags showed increase in content of carbonate minerals in comparison to the raw slag samples. In industrial slags, a decrease in

  8. Molybdate adsorption from steel slag eluates by subsoils.

    PubMed

    Matern, K; Rennert, T; Mansfeldt, T

    2013-11-01

    Steel slags are industrial by-products which are generated in large amounts worldwide, e.g. 150-230×10(6) Mg in 2012, and which are partly used for construction. Molybdenum (Mo) can be added during steel processing in order to harden the steel. The objective of this study was to evaluate the adsorption behaviour of molybdate (MoO4(2-)) from slag eluates in subsoils. Molybdate batch adsorption experiments were carried out with eluates obtained from two different kinds of steel slags (i) LD slag (Linz-Donawitz operation, LDS) and (ii) electric arc furnace slag (EAF) to assess the risk that may arise from the contamination of groundwater by the leaching of molybdate. Six different subsoils were chosen in order to provide a wide range of chemical properties (pH 4.0-7.6; dithionite-extractable Fe 0.73-14.7 g kg(-1)). Molybdate adsorption experiments were carried out at the pH of the steel slag eluates (pH 11-12) as well as at pH values adjusted to the soil pH. The data were evaluated with the Freundlich equation. Molybdate adsorption exhibited a maximum near pH 4 for steel slag eluates adjusted to the soil pH, and decreased rapidly with increasing pH until adsorption was virtually zero at pH>11. Adsorption was greater for soils with high amounts of dithionite-extractable Fe oxides. The extent and behaviour of molybdate adsorption from both eluates was similar. After a reaction time of 24h, the pH of the EAF slag eluate was lower than that of the LD steel slag eluate, which was caused by different acid buffer capacities. Some soils were able to decrease the pH of the EAF slag eluates by about 4 pH units, enhancing the adsorption of molybdate. Transport simulations indicated that molybdate discharge is low in acidic soils.

  9. Crystallization Behavior of Copper Smelter Slag During Molten Oxidation

    NASA Astrophysics Data System (ADS)

    Fan, Yong; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

    2015-10-01

    Copper slag is composed of iron silicate obtained by smelting copper concentrate and silica flux. One of the most important criteria for the utilization of this secondary resource is the recovery of iron from the slag matrix to decrease the volume of dumped slag. The molten oxidation process with crushing magnetic separation appears to be a more sustainable approach and is based on directly blowing oxidizing gas onto molten slag after the copper smelting process. In the current study, using an infrared furnace, the crystallization behavior of the slag during molten oxidation was studied to better understand the trade-off between magnetite and hematite precipitations, as assessed by X-ray diffraction (using an internal standard). Furthermore, the crystal morphology was examined using a laser microscope and Raman imaging system to understand the iron oxide transformation, and the distribution of impurities such as Cu, Zn, As, Cr, and Pb were complemented with scanning electron microscopy and energy dispersive spectroscopy. In addition, the reaction mechanism was investigated with a focus on the oxidation processes.

  10. Utilization of lightweight materials made from coal gasification slags. Quarterly report, September--November 1995

    SciTech Connect

    1995-12-01

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. Slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln. The potential exists for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed. The project scope consists of collecting a 20-ton sample of slag (primary slag), processing it for char removal, and subjecting it to pyroprocessing to produce expanded slag aggregates of various size gradations and unit weights, ranging from 12 to 50 lb/ft{sup 3}. A second smaller slag sample will be used for confirmatory testing. The expanded slag aggregates will then be tested for their suitability in manufacturing precast concrete products (e.g., masonry blocks and roof tiles) and insulating concrete, first at the laboratory scale and subsequently in commercial manufacturing plants. These products will be evaluated using ASTM and industry test methods. Technical data generated during production and testing of the products will be used to assess the overall technical viability of expanded slag production. In addition, a market assessment will be made based on an evaluation of both the expanded slag aggregates and the final products, and market prices for these products will be established in order to assess the economic viability of these utilization technologies.

  11. Utilization of Lightweight Materials Made from Coal Gasificaiton Slags

    SciTech Connect

    Choudhry, V.; Hadley, S.

    1996-12-31

    The integrated gasification combined-cycle (IGCC) coal conversion process has been demonstrated to be a clean, efficient, and environmentally acceptable method of generating power; however, it generates solid waste materials in relatively large quantities. For example, a 400-MW power plant using 4000 tons of 10% ash coal per day may generate over 440 tons/day of solid waste of slag, consisting of vitrified mineral matter and unburned carbon. The disposal of the wastes represents significant costs. Regulatory trends with respect to solid wastes disposal, landfill development costs and public concern make utilization of solid wastes a high-priority issue. As coal gasification technologies find increasing commercial applications for power generation or production of chemical feed stocks, it becomes imperative that slag utilization methods be developed, tested and commercialized in order to offset disposal costs. Praxis is working on a DOE/METC funded project to demonstrate the technical and economic feasibility of making lightweight and ultra-lightweight aggregates from slags left as solid by-products from the coal gasification process. The project objectives are to develop and demonstrate the technology for producing slag-based lightweight aggregates (SLA), to produce 10 tons of SLA products with different unit weights from two slags, to collect operational and emissions data from pilot-scale operations, and to conduct laboratory and commercial scale evaluations of SLA with conventional lightweight and ultra-lightweight aggregates.

  12. Products of steel slags an opportunity to save natural resources.

    PubMed

    Motz, H; Geiseler, J

    2001-01-01

    In Germany, and in the most industrial countries, the use of blast furnace and steel slags as an aggregate for civil engineering, for metallurgical use and as fertiliser has a very long tradition. Since the introduction of the basic oxygen steel making furnace (BOF) process and the electric arc furnace (EAF) process the German steel industry started extensive research on the development of fields of application for BOF and EAF slags. These investigations have been mainly performed by Forschungsgemeinschaft Eisenhüttenschlacken e. V. (FEhS), the Research Association for blast furnace and steel slags. Today steel slags are well characterised and long-term experienced materials mainly used as aggregates for road construction (e.g. asphaltic or unbound layers), as armour-stones for hydraulic engineering constructions (e.g. stabilisation of shores), and as fertiliser for agriculture purposes. These multifarious fields of application could only be achieved because the steelworks influence the quality of slags by a careful selection of raw materials and a suitable process route. Furthermore, subsequent procedures like a treatment of the liquid slag, an appropriate heat treatment and a suitable processing have been developed to ensure that the quality of steel slags is always adequate for the end use. Depending on the respective field of application, the suitability of steel slags has to be proven by determining the technical properties, as well as the environmental compatibility. For this reason test methods have been developed to evaluate the technical properties especially the volume stability and the environmental behaviour. To evaluate the volume stability a suitable test (steam test) has been developed and the results from laboratory tests were compared with the behaviour of steel slags under practical conditions, e.g. in a road. To determine the environmental behaviour leaching tests have been developed. In the meanwhile most of these test methods are drafted or

  13. High Temperature Millimeter Wave Radiometric and Interferometric Measurements of Slag-Refractory Interaction for Application to Coal Gasifiers

    NASA Astrophysics Data System (ADS)

    McCloy, John S.; Crum, Jarrod V.; Sundaram, S. K.; Slaugh, Ryan; Woskov, Paul P.

    2011-11-01

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments such as in slagging coal gasifiers, where sensors have been identified as a key enabling technology need for process optimization. We present a dual-channel MMW heterodyne radiometer with active interferometric capability that allows simultaneous measurements of sample temperature, emissivity, and flow dynamics. Interferometric capability at 137 GHz is supplied via a probe signal originating from a local oscillator allowing monitoring of sample dynamics such as volume expansion and thickness change. This capability has been used to monitor characteristic behavior between refractories and slag such as slag infiltration, slag melting, viscous flow, foaming, and crucible corrosion by the molten slag. These results show the promise of the MMW system for extracting process parameters from operating slagging coal gasifiers, providing valuable information for process efficiency, control, and increased productivity.

  14. Utilization of lightweight materials made from coal gasification slags. Quarterly report, September 15--November 30, 1994

    SciTech Connect

    1997-07-01

    Coal gasification technologies are finding increasing commercial applications for power generation or production of chemical feedstocks. The integrated-gasification-combined-cycle (IGCC) coal conversion process has been demonstrated to be a clean, efficient, and environmentally acceptable method of generating power. However, the gasification process produces relatively large quantities of a solid waste termed slag. Regulatory trends with respect to solid waste disposal, landfill development costs, and public concern make utilization of slag a high-priority issue. Therefore, it is imperative that slag utilization methods be developed, tested, and commercialized in order to offset disposal costs. This project aims to demonstrate the technical and economic viability of the slag utilization technologies developed by Praxis to produce lightweight aggregates (LWA) and ultra-lightweight aggregates (ULWA) from slag in a large-scale pilot operation, followed by total utilization of these aggregates in a number of applications.

  15. Artificial intelligence-based computer modeling tools for controlling slag foaming in electric arc furnaces

    NASA Astrophysics Data System (ADS)

    Wilson, Eric Lee

    Due to increased competition in a world economy, steel companies are currently interested in developing techniques that will allow for the improvement of the steelmaking process, either by increasing output efficiency or by improving the quality of their product, or both. Slag foaming is one practice that has been shown to contribute to both these goals. However, slag foaming is highly dynamic and difficult to model or control. This dissertation describes an effort to use artificial intelligence-based tools (genetic algorithms, fuzzy logic, and neural networks) to both model and control the slag foaming process. Specifically, a neural network is trained and tested on slag foaming data provided by a steel plant. This neural network model is then controlled by a fuzzy logic controller, which in turn is optimized by a genetic algorithm. This tuned controller is then installed at a steel plant and given control be a more efficient slag foaming controller than what was previously used by the steel plant.

  16. Mineralogical Characterization of Copper Slag from Tongling Nonferrous Metals Group China

    NASA Astrophysics Data System (ADS)

    Chun, Tiejun; Ning, Chao; Long, Hongming; Li, Jiaxin; Yang, Jialong

    2016-09-01

    In this paper, the mineralogical characterization of typical copper slag supplied by the Tongling Nonferrous Metals Group China was performed based on x-ray fluorescence, x-ray diffraction, and scanning electron microscopy with energy dispersive spectroscopy. The results show that the dominant phases of the slag are fayalite, glassy substance and magnetite. The minor accessory phases consist of copper matte, metallic copper and other complex lead and zinc minerals. The contents of iron, copper, lead and zinc in copper slag are 40.21%, 0.79%, 0.24%, and 2.80%, respectively. The mineralogy of copper slag indicates that these valuable elements are difficult to recover by beneficiation processes due to the complicated occurrences. Instead, the pyro-metallurgical processes appear promising in recovering the valuable metals from copper slag.

  17. Removal kinetics of phosphorus from synthetic wastewater using basic oxygen furnace slag.

    PubMed

    Han, Chong; Wang, Zhen; Yang, He; Xue, Xiangxin

    2015-04-01

    Removal kinetics of phosphorus through use of basic oxygen furnace slag (BOF-slag) was investigated through batch experiments. Effects of several parameters such as initial phosphorus concentration, temperature, BOF-slag size, initial pH, and BOF-slag dosage on phosphorus removal kinetics were measured in detail. It was demonstrated that the removal process of phosphorus through BOF-slag followed pseudo-first-order reaction kinetics. The apparent rate constant (kobs) significantly decreased with increasing initial phosphorus concentration, BOF-slag size, and initial pH, whereas it exhibited an opposite trend with increasing reaction temperature and BOF-slag dosage. A linear dependence of kobs on total removed phosphorus (TRP) was established with kobs=(3.51±0.11)×10(-4)×TRP. Finally, it was suggested that the Langmuir-Rideal (L-R) or Langmuir-Hinshelwood (L-H) mechanism may be used to describe the removal process of phosphorus using BOF-slag.

  18. Phase chemical composition of slag from a direct nickel flash furnace and associated slag cleaning furnace

    NASA Astrophysics Data System (ADS)

    Waanders, F. B.; Nell, J.

    2013-04-01

    During the recovery of base metals from the Bushveld Igneous Complex ores, South Africa, a two-stage process is used to ensure complete recovery of nickel from the ore. A nickel flash smelting furnace is initially used to obtain the valuable metal but the loss of nickel in the slag amounts to about 4 % and thus an electric slag-cleaning furnace has to be subsequently used to reduce the loss of the valuable metal to less than 0.5 % nickel oxide in the slag. The Fe2 + /Fe3 + ratio and mineralogy in the two different furnaces differ and can be used as a tool to determine the efficiency of the nickel recovered in the two-stage process. By means of XRD, SEM/EDS and Mössbauer spectroscopy the Fe2 + /Fe3 + ratio and the amount of magnetite was determined in each furnace, which was then used as an indicator of the effectiveness of the whole process.

  19. Applying ausmelt technology to recover Cu, Ni, and Co from slags

    NASA Astrophysics Data System (ADS)

    Hughes, Stephen

    2000-08-01

    The technical feasibility of recovering copper, nickel, and cobalt from smelting and converting slags using Ausmelt’s top-submerged lancing process has been demonstrated at the pilot-plant scale and in several commercial applications. Process conditions may be tailored to achieve the maximum economic recovery of valuable metals and to yield a product composition that is suitable for downstream processing requirements. Strong economic justification for a slag-cleaning process exists where the contained value of metals recovered exceeds 50 per tonne of slag treated. The top-submerged lance system offers a relatively low-cost solution where this value is predominantly associated with the recovery of cobalt.

  20. COAL SLAGGING AND REACTIVITY TESTING

    SciTech Connect

    Donald P. McCollor; Kurt E. Eylands; Jason D. Laumb

    2003-10-01

    Union Fenosa's La Robla I Power Station is a 270-MW Foster Wheeler arch-fired system. The unit is located at the mine that provides a portion of the semianthracitic coal. The remaining coals used are from South Africa, Russia, Australia, and China. The challenges at the La Robla I Station stem from the various fuels used, the characteristics of which differ from the design coal. The University of North Dakota Energy & Environmental Research Center (EERC) and the Lehigh University Energy Research Center (LUERC) undertook a program to assess problematic slagging and unburned carbon issues occurring at the plant. Full-scale combustion tests were performed under baseline conditions, with elevated oxygen level and with redistribution of air during a site visit at the plant. During these tests, operating information, observations and temperature measurements, and coal, slag deposit, and fly ash samples were obtained to assess slagging and unburned carbon. The slagging in almost all cases appeared due to elevated temperatures rather than fuel chemistry. The most severe slagging occurred when the temperature at the sampling port was in excess of 1500 C, with problematic slagging where first-observed temperatures exceeded 1350 C. The presence of anorthite crystals in the bulk of the deposits analyzed indicates that the temperatures were in excess of 1350 C, consistent with temperature measurements during the sampling period. Elevated temperatures and ''hot spots'' are probably the result of poor mill performance, and a poor distribution of the coal from the mills to the specific burners causes elevated temperatures in the regions where the slag samples were extracted. A contributing cause appeared to be poor combustion air mixing and heating, resulting in oxygen stratification and increased temperatures in certain areas. Air preheater plugging was observed and reduces the temperature of the air in the windbox, which leads to poor combustion conditions, resulting in unburned

  1. Enhancing performance and durability of slag made from incinerator bottom ash and fly ash.

    PubMed

    Chiou, Ing-Jia; Wang, Kuen-Sheng; Tsai, Chen-Chiu

    2009-02-01

    This work presents a method capable of melting the incinerator bottom ash and fly ash in a plasma furnace. The performance of slag and the strategies for recycling of bottom ash and fly ash are improved by adjusting chemical components of bottom ash and fly ash. Ashes are separated by a magnetic process to improve the performance of slag. Analytical results indicate that the air-cooled slag (ACS) and magnetic-separated slag (MSS) have hardness levels below 590 MPa, indicating fragility. Additionally, the hardness of crystallized slag (RTS) is between 655 and 686 MPa, indicating toughness. The leached concentrations of heavy metals for these three slags are all below the regulatory limits. ACS appears to have better chemical stability than MSS, and is not significantly different from RTS. In the potential alkali-silica reactivity of slag, MSS falls on the border between the harmless zone and the potentially harmful zone. ACS and RTS fall in the harmless zone. Hence, the magnetic separation procedure of ashes does not significantly improve the quality of slag. However, RTS appears to improve its quality. PMID:18544471

  2. Rapid Dissolution of Quicklime into Molten Slag by Internally Formed Gas

    NASA Astrophysics Data System (ADS)

    Maruoka, Nobuhiro; Nogami, Hiroshi

    2016-07-01

    In steelmaking process, quicklime is used to produce CaO-based slag. Although rapid dissolution of quicklime is required for high-efficiency refining, it is known that the rate decreases when dicalcium silicate (C2S) layer forms around the quicklime by reacting with slag. The equation that driving force is the difference of CaO content between in slag and a liquid phase of slag saturated by C2S has been often used for estimating the dissolution rate of lime, in which this saturated value is thermodynamically determined. The authors, however, revealed that the quicklime used in actual operation showed much faster dissolving rate than that of completely calcined lime that is covered by C2S layer during dissolution into slag. This was caused by a gas formation due to a thermal decomposition of residual limestone existed in quicklime. In this study, the dissolution rate of quicklime with the gas formation is quantitatively investigated.

  3. Tiles made from slag sitall based on chemical industry slag

    SciTech Connect

    Batalin, B.S.; Moskalets, N.B.; Klyuchnik, I.A.; Golius, T.E.

    1987-11-01

    The authors establish the feasibility of obtaining ceramic silicate-based facing tiles from fluoroamphibole slag sitall wastes from the hydropyrolytic production of hydrogen fluoride. The recovered ceramic is tested by x-ray diffraction and electron microscopy for its crystallization behavior, structure, workability, corrosion resistance, phase composition, impact strength, and other properties.

  4. Kinetics of the dissolution of zinc sulfide in an oxidizing slag

    NASA Astrophysics Data System (ADS)

    Gupta, Suresh K.

    1990-10-01

    A new concept has been developed for the production of zinc from zinc and complex zinc concentrates. It is a two-stage process involving oxidation of zinc sulfide to oxide and dissolution into slag and the fuming of zinc from the slag by injecting carbonaceous materials into it to produce zinc vapors which can be subsequently condensed in a lead-splash condenser such as those used in the Imperial Smelting Process (ISP). In this paper, the effects of the quantity of air, temperature, and concentrate feed rate have been discussed on the production of zinc-rich slag, which is the first stage of the proposed process.

  5. Phosphate removal from domestic wastewater using thermally modified steel slag.

    PubMed

    Yu, Jian; Liang, Wenyan; Wang, Li; Li, Feizhen; Zou, Yuanlong; Wang, Haidong

    2015-05-01

    This study was performed to investigate the removal of phosphate from domestic wastewater using a modified steel slag as the adsorbent. The adsorption effects of alkalinity, salt, water, and thermal modification were investigated. The results showed that thermal activation at 800°C for 1 hr was the optimum operation to improve the adsorption capacity. The adsorption process of the thermally modified slag was well described by the Elovich kinetic model and the Langmuir isotherm model. The maximum adsorption capacity calculated from the Langmuir model reached 13.62 mg/g. Scanning electron microscopy indicated that the surface of the modified slag was cracked and that the texture became loose after heating. The surface area and pore volume did not change after thermal modification. In the treatment of domestic wastewater, the modified slag bed (35.5 kg) removed phosphate effectively and operated for 158 days until the effluent P rose above the limit concentration of 0.5 mg/L. The phosphate fractionation method, which is often applied in soil research, was used to analyze the phosphate adsorption behavior in the slag bed. The analysis revealed that the total contents of various Ca-P forms accounted for 81.4%-91.1%, i.e., Ca10-P 50.6%-65.1%, Ca8-P 17.8%-25.0%, and Ca2-P 4.66%-9.20%. The forms of Al-P, Fe-P, and O-P accounted for only 8.9%-18.6%. The formation of Ca10-P precipitates was considered to be the main mechanism of phosphate removal in the thermally modified slag bed. PMID:25968262

  6. Phosphate removal from domestic wastewater using thermally modified steel slag.

    PubMed

    Yu, Jian; Liang, Wenyan; Wang, Li; Li, Feizhen; Zou, Yuanlong; Wang, Haidong

    2015-05-01

    This study was performed to investigate the removal of phosphate from domestic wastewater using a modified steel slag as the adsorbent. The adsorption effects of alkalinity, salt, water, and thermal modification were investigated. The results showed that thermal activation at 800°C for 1 hr was the optimum operation to improve the adsorption capacity. The adsorption process of the thermally modified slag was well described by the Elovich kinetic model and the Langmuir isotherm model. The maximum adsorption capacity calculated from the Langmuir model reached 13.62 mg/g. Scanning electron microscopy indicated that the surface of the modified slag was cracked and that the texture became loose after heating. The surface area and pore volume did not change after thermal modification. In the treatment of domestic wastewater, the modified slag bed (35.5 kg) removed phosphate effectively and operated for 158 days until the effluent P rose above the limit concentration of 0.5 mg/L. The phosphate fractionation method, which is often applied in soil research, was used to analyze the phosphate adsorption behavior in the slag bed. The analysis revealed that the total contents of various Ca-P forms accounted for 81.4%-91.1%, i.e., Ca10-P 50.6%-65.1%, Ca8-P 17.8%-25.0%, and Ca2-P 4.66%-9.20%. The forms of Al-P, Fe-P, and O-P accounted for only 8.9%-18.6%. The formation of Ca10-P precipitates was considered to be the main mechanism of phosphate removal in the thermally modified slag bed.

  7. Utilization of lightweight materials made from coal gasification slags. Quarterly report, June 1--August 31, 1996

    SciTech Connect

    1996-12-31

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of ``as-generated`` slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for ``as-generated`` slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 17000F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase 1, comprising the production of LWA and ULWA from slag at the large pilot-scale, and Phase 2, which involves commercial evaluation of these aggregates in a number of applications. Accomplishments are described.

  8. Visualisation and quantification of heavy metal accessibility in smelter slags: The influence of morphology on availability.

    PubMed

    Morrison, Anthony L; Swierczek, Zofia; Gulson, Brian L

    2016-03-01

    The Imperial Smelting Furnace (ISF) for producing lead and zinc simultaneously has operated on four continents and in eleven countries from the 1950's. One of the process changes that the ISF introduced was the production of a finely granulated slag waste. Although this slag contained significant amounts of residual lead (Pb) and zinc (Zn), because of its glassy nature it was considered environmentally benign. From the Cockle Creek smelter near Boolaroo at the northern end of Lake Macquarie, NSW, Australia, it is estimated that around 2.1 million tonnes of the fine slag was distributed into the community and most remains where it was originally utilised. Residual tonnages of slag of this magnitude are common worldwide wherever the ISF operated. Studies of base metal smelting slags have concluded that mineralogical and morphological characteristics of the slag play a critical role in moderating environmental release of toxic elements. Scanning electron microscopy (SEM) and microanalysis of the ISF slags has shown that the Pb and associated elements are present as discrete nodules (∼6-22 μm) in the slag and that they are not associated with Zn which is contained in the glass slag phase. Using an automated SEM and analysis technique (QEMSCAN(®)) to "map" the mineralogical structure of the particles, it was possible to quantitatively determine the degree of access infiltrating fluids might have to the reaction surface of the Pb phases. The level of access decreases with increasing particle size, but in even the largest sized particles (-3350 + 2000 μm) nearly 80% of the Pb-containing phases were totally or partially accessible. These results provide evidence that the toxic elements in the slags are not contained by the glassy phase and will be vulnerable to leaching over time depending on their individual phase reactivity. PMID:26784748

  9. Aluminium salt slag characterization and utilization--a review.

    PubMed

    Tsakiridis, P E

    2012-05-30

    Aluminium salt slag (also known as aluminium salt cake), which is produced by the secondary aluminium industry, is formed during aluminium scrap/dross melting and contains 15-30% aluminium oxide, 30-55% sodium chloride, 15-30% potassium chloride, 5-7% metallic aluminium and impurities (carbides, nitrides, sulphides and phosphides). Depending on the raw mix the amount of salt slag produced per tonne of secondary aluminium ranges from 200 to 500 kg. As salt slag has been classified as toxic and hazardous waste, it should be managed in compliance with the current legislation. Its landfill disposal is forbidden in most of the European countries and it should be recycled and processed in a proper way by taking the environmental impact into consideration. This paper presents a review of the aluminium salt slag chemical and mineralogical characteristics, as well as various processes for metal recovery, recycling of sodium and potassium chlorides content back to the smelting process and preparation of value added products from the final non metallic residue.

  10. A study of slag freezing in metallurgical furnaces

    NASA Astrophysics Data System (ADS)

    Guevara, Fernando

    Many smelting and slag-cleaning furnaces operate with cooling systems designed to freeze a slag layer over the refractory to protect it. The fluid flow and heat transfer conditions associated with the freeze layer and mushy zones are poorly understood. This study was conducted to understand the chill layer formation and heat transfer that is required to design cooling systems in pyrometallurgical operations where a slag layer is required to protect the furnace wall. The freeze layer formation and heat transfer in mushy zones were experimentally study at room temperature in a 2-dimensional square cavity differentially heated, using an aqueous solution of calcium chloride to simulate the slag. Reasonable similarity with conditions encountered with copper and nickel smelting systems was achieved (Pr ≈ 50 and Ra ≈ 108, in the laminar-turbulent transition). Measurements of velocities were made with the Particle Image Velocimetry (PIV) technique. The freeze layer development was tracked using a digital camera. Direct Numerical Simulations (DNS) of the mean flow using a finite control volume technique with a fixed domain method were also made of the unsteady fluid flow and heat transfer problem. It was found that the macro solidification process is well described using an improved model for high molecular viscosity in the mushy zone. Solid front growth, isothermal profiles, velocity profiles and heat transfer through the walls showed good agreement between the PIV and DNS results. Experimental and numerical velocity profiles close to the freeze layer show a parabolic behaviour in the vertical velocity profile which is completely different from the calculation of heat transfer using a sharp interface model. The reason for this is attributed to the effects of the mushy zone with a high viscosity and high shear stresses acting on that area. In Part III of this Thesis, effects of slag viscosity temperature relationship were analysed with a two-dimensional mathematical

  11. Experimental study on sulfur removal from ladle furnace refining slag in hot state by blowing air

    NASA Astrophysics Data System (ADS)

    Zhao, Li-hua; Lin, Lu; Wu, Qi-fan

    2016-01-01

    In view of the present problem of sulfur enrichment in the metallurgical recycling process of ladle furnace (LF) refining slag, a simple and efficient method of removing sulfur from this slag was proposed. The proposed method is compatible with current steelmaking processes. Sulfur removal from LF refining slag for SPHC steel (manufactured at a certain steel plant in China) by blowing air in the hot state was studied by using hot-state experiments in a laboratory. The FactSage software, a carbon/sulfur analyzer, and scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy were used to test and analyze the sulfur removal effect and to investigate factors influencing sulfur removal rate. The results show that sulfur ions in LF refining slag can be oxidized into SO2 by O2 at high temperature by blowing air into molten slag; SO2 production was observed to reach a maximum with a small amount of blown O2 when the temperature exceeded 1350°C. At 1370°C and 1400°C, experimental LF refining slag is in the liquid state and exhibits good fluidity; under these conditions, the sulfur removal effect by blowing air is greater than 90wt% after 60 min. High temperature and large air flow rate are beneficial for removing sulfur from LF refining slag; compared with air flow rate, temperature has a greater strongly influences on the sulfur removal.

  12. Toxicity assessment and geochemical model of chromium leaching from AOD slag.

    PubMed

    Liu, Bao; Li, Junguo; Zeng, Yanan; Wang, Ziming

    2016-02-01

    AOD (Argon Oxygen Decarburization) slag is a by-product of the stainless steel refining process. The leaching toxicity of chromium from AOD slag cannot be ignored in the recycling process of the AOD slag. To assess the leaching toxicity of the AOD slag, batch leaching tests have been performed. PHREEQC simulations combined with FactSage were carried out based on the detailed mineralogical analysis and petrophysical data. Moreover, Pourbaix diagram of the Cr-H2O system was protracted by HSC 5.0 software to explore the chromium speciation in leachates. It was found that AOD slag leachate is an alkaline and reductive solution. The Pourbaix diagram of the Cr-H2O system indicated that trivalent chromium, such as Cr(OH)4(-), is the major chromium species in the experimental Eh-pH region considered. However, toxic hexavalent chromium was released with maximum concentrations of 30 µg L(-1) and 18 µg L(-1) at L/S 10 and 100, respectively, during the earlier leaching stage. It concluded that the AOD slag possessed a certain leaching toxicity. After 10 d of leaching, trivalent chromium was the dominant species in the leachates, which corresponded to the results of PHREEQC simulation. Leaching toxicity of AOD slag is based on the chromium speciation and its transformation. Great attention should be focused on such factors as aging, crystal form of chromium-enriched minerals, and electrochemical characteristics of the leachates.

  13. Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag.

    PubMed

    Zhang, Na; Li, Hongxu; Zhao, Yazhao; Liu, Xiaoming

    2016-04-01

    Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al2O3 from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C-A-S-H gel, rod-like ettringite and hexagonal-sheet Ca(OH)2 with small amount of zeolite-like minerals such as CaAl2Si2O8·4H2O and Na2Al2Si2O8·H2O. As the predominant hydration products, rod-like ettringite and amorphous C-A-S-H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities.

  14. Effect of Coal Properties and Operation Conditions on Flow Behavior of Coal Slag in Entrained Flow Gasifiers: A Brief Review

    SciTech Connect

    Wang,Ping; Massoudi, Mehrdad

    2011-01-01

    Integrated gasification combined cycle (IGCC) is a potentially promising clean technology with an inherent advantage of low emissions, since the process removes contaminants before combustion instead of from flue gas after combustion, as in a conventional coal steam plant. In addition, IGCC has potential for cost-effective carbon dioxide capture. Availability and high capital costs are the main challenges to making IGCC technology more competitive and fully commercial. Experiences from demonstrated IGCC plants show that, in the gasification system, low availability is largely due to slag buildup in the gasifier and fouling in the syngas cooler downstream of the gasification system. In the entrained flow gasifiers used in IGCC plants, the majority of mineral matter transforms to liquid slag on the wall of the gasifier and flows out the bottom. However, a small fraction of the mineral matter (as fly ash) is entrained with the raw syngas out of the gasifier to downstream processing. This molten/sticky fly ash could cause fouling of the syngas cooler. Therefore, it is preferable to minimize the quantity of fly ash and maximize slag. In addition, the hot raw syngas is cooled to convert any entrained molten fly slag to hardened solid fly ash prior to entering the syngas cooler. To improve gasification availability through better design and operation of the gasification process, better understanding of slag behavior and characteristics of the slagging process are needed. Slagging behavior is affected by char/ash properties, gas compositions in the gasifier, the gasifier wall structure, fluid dynamics, and plant operating conditions (mainly temperature and oxygen/carbon ratio). The viscosity of the slag is used to characterize the behavior of the slag flow and is the dominating factor to determine the probability that ash particles will stick. Slag viscosity strongly depends on the temperature and chemical composition of the slag. Because coal has varying ash content and

  15. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO2 pressure.

    PubMed

    van Zomeren, André; van der Laan, Sieger R; Kobesen, Hans B A; Huijgen, Wouter J J; Comans, Rob N J

    2011-11-01

    Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios. The aim of this study is to investigate the potential of accelerated steel slag carbonation, at relatively low pCO2 pressure (0.2 bar), to improve the environmental pH and the leaching properties of steel slag, with specific focus on the leaching of vanadium. Carbonation experiments are performed in laboratory columns with steel slag under water-saturated and -unsaturated conditions and temperatures between 5 and 90 °C. Two types of steel slag are tested; free lime containing (K3) slag and K1 slag with a very low free lime content. The fresh and carbonated slag samples are investigated using a combination of leaching experiments, geochemical modelling of leaching mechanisms and microscopic/mineralogical analysis, in order to identify the major processes that control the slag pH and resulting V leaching. The major changes in the amount of sequestered CO2 and the resulting pH reduction occurred within 24h, the free lime containing slag (K3-slag) being more prone to carbonation than the slag with lower free lime content (K1-slag). While carbonation at these conditions was found to occur predominantly at the surface of the slag grains, the formation of cracks was observed in carbonated K3 slag, suggesting that free lime in the interior of slag grains had also reacted. The pH of the K3 slag (originally pH±12.5) was reduced by about 1.5 units, while the K1 slag showed a smaller decrease in pH from about 11.7 to 11.1. However, the pH reduction after carbonation of the K3 slag was observed to lead to an increased V-leaching. Vanadium leaching from the K1 slag resulted in levels above the limit values of the Dutch Soil Quality Decree, for both the untreated and carbonated slag. V-leaching from the carbonated K3 slag remained

  16. Effects of Microwave Roasting on the Kinetics of Extracting Vanadium from Vanadium Slag

    NASA Astrophysics Data System (ADS)

    Zhang, Guoquan; Zhang, Ting-an; Lü, Guozhi; Zhang, Ying; Liu, Yan; Zhang, Weiguang

    2016-02-01

    The kinetics of extracting vanadium (V) from microwave-roasted (MR) vanadium slag (V-slag) with concentrated H2SO4 were investigated. The microwave irradiation experiments were performed in a modified microwave muffle furnace at temperatures ranging from 150°C to 750°C. The x-ray diffraction analysis indicated that the spinel phase of the V-slag is destroyed after 10 min of roasting. The phase composition of the V-slag was changed by the roasting process, and a new Fe2O3 phase appeared in the samples roasted at higher temperatures. Compared to the raw slag, the surface area, pore volume, and pore size of the MR slags were much lower. It was easier to leach V from the MR samples than the raw sample with the H2SO4 solution, and the leaching process was accelerated in the MR samples. When the V-slag was roasted at 150°C and 350°C (MR@150 and MR@350, respectively), the apparent activation energy was decreased from 77.65 kJ/mol to 68.42 kJ/mol and 66.68 kJ/mol, respectively. The process of leaching V from the raw and MR slags was controlled by both the surface chemical reactions and internal diffusion. The reaction orders of the raw, MR@150, and MR@350 V-slags, with respect to the H2SO4 concentration, were 1.23, 0.75, and 0.70, respectively.

  17. 50. Taken from highline; "B" furnace slag pots, pipe is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. Taken from high-line; "B" furnace slag pots, pipe is main blast furnace gas line from "C" furnace dust catcher; levy, slag hauler, removing slag. Looking east - Rouge Steel Company, 3001 Miller Road, Dearborn, MI

  18. NONEQUILIBRIUM SULFUR CAPTURE & RETENTION IN AN AIR COOLED SLAGGING COAL COMBUSTOR

    SciTech Connect

    Bert Zauderer

    2003-04-21

    Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles. The reacted particles impact and melt in the liquid slag layer on the combustor wall by the centrifugal force of the swirling combustion gases. Due to the low solubility of sulfur in slag, it must be rapidly drained from the combustor to limit sulfur gas re-evolution. Prior analyses and laboratory scale data indicated that for Coal Tech's 20 MMBtu/hour, air-cooled, slagging coal combustor slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 42-month project was to validate this sulfur-in-slag model in a group of combustor tests. A total of 36 days of testing on the combustor were completed during the period of performance of this project. This was more that double the 16 test days that were required in the original work statement. The extra tests were made possible by cost saving innovations that were made in the operation of the combustor test facility and in additional investment of Coal Tech resources in the test effort. The original project plan called for two groups of tests. The first group of tests involved the injection of calcium sulfate particles in the form of gypsum or plaster of Paris with the coal into the 20 MMBtu/hour-combustor. The second group of tests consisted of the entire two-step process, in which lime or limestone is co-injected with coal and reacts with the sulfur gas released during combustion to form calcium sulfate particles that impact and dissolve in the slag layer. Since this sulfur capture process has been validated in numerous prior tests in this combustor, the primary effort in the present project was on achieving the high slag flow rates needed to retain the sulfur in the slag.

  19. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, Max E.

    1996-01-01

    A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an eletrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable.

  20. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, M.E.

    1996-10-22

    A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an electrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable. 1 fig.

  1. Interfaces Between Coke, Slag, and Metal in the Tuyere Level of a Blast Furnace

    NASA Astrophysics Data System (ADS)

    Li, Kejiang; Zhang, Jianliang; Liu, Zhengjian; Barati, Mansoor; Zhong, Jianbo; Wei, Mengfang; Wang, Guangwei; Jiao, Kexin; Yang, Tianjun

    2015-04-01

    An in-depth understanding about the reactions in the high-temperature zone of a blast furnace is significant to optimize both the current and future blast furnace process. The interfaces between coke, slag, and metal were observed using scanning electronic microscope with samples obtained from the tuyere level of a blast furnace. Two types of slag phases were identified, one originating from coke ash and the other from the bosh slag. Slag formed by coke ash was seen to cover the coke surface, which may hinder the reaction of coke with both gas and liquid iron. The reduction of FeO from the bosh slag (originated from the primary slag) occurs in the coke/slag interface with the reduced iron forming a metal layer surrounding the coke surface. The reduction of SiO2 occurs both in and outside the coke, and the reduced silicon reacts with iron to form iron silicide if the two species come into contact. Further study is proposed based on the results of this study.

  2. Effect of blast furnace slag on self-healing of microcracks in cementitious materials

    SciTech Connect

    Huang, Haoliang; Ye, Guang; Damidot, Denis

    2014-06-01

    The physico-chemical process of self-healing in blast furnace slag cement paste was investigated in this paper. With a high slag content i.e., 66% in cement paste and saturated Ca(OH)₂ solution as activator, it was found that the reaction products formed in cracks are composed of C-S-H, ettringite, hydrogarnet and OH–hydrotalcite. The fraction of C-S-H in the reaction products is much larger than the other minerals. Large amount of ettringite formed in cracks indicates the leaching of SO₄⁻² ions from the bulk paste and consequently the recrystallization. Self-healing proceeds fast within 50 h and then slows down. According to thermodynamic modeling, when the newly formed reaction products are carbonated, the filling fraction of crack increases first and then decreases. Low soluble minerals such as silica gel, gibbsite and calcite are formed. Compared to Portland cement paste, the potential of self-healing in slag cement paste is higher when the percentage of slag is high. Highlights: • Self-healing reaction products in slag cement paste were characterized. • Self-healing reaction products formed in time were quantified with image analysis. • Self-healing in slag cement paste was simulated with a reactive transport model. • Effect of carbonation on self-healing was investigated by thermodynamic modeling. • Effect of slag on self-healing was discussed based on experiments and simulation.

  3. Phosphogypsum slag aggregate-based asphaltic concrete mixes

    SciTech Connect

    Foxworthy, P.T.; Nadimpalli, R.S.; Seals, R.K.

    1996-07-01

    Phosphogypsum is a by-product from the production of phosphoric acid used in the fertilizer and chemical industries. Large production rates and problems associated with its stockpiling have led researchers to seek alternative uses for phosphogypsum, primarily as a construction material. One such use is the extraction of sulfur dioxide for the production of sulfuric acid, a process that also generates a by-product slag aggregate. This study investigated the feasibility of using this slag aggregate in asphaltic concrete binder course mixes. The physical properties of the slag aggregate, such as gradation, specific gravity, absorption, unit weight, and void content, were determined, as well as its durability and environmental characteristics. The Marshall mix design method was used to obtain the optimum asphalt content for this aggregate, while moisture susceptibility was examined using the boiling and modified Lottman tests. Indirect tensile, resilient modulus, and dynamic creep tests were performed on the mix to evaluate its performance potential. The results of the study indicate that phosphogypsum-based slag aggregate can be successfully employed in asphaltic concrete binder course mixtures.

  4. Kinetics of steel slag leaching: Batch tests and modeling

    SciTech Connect

    De Windt, Laurent; Chaurand, Perrine; Rose, Jerome

    2011-02-15

    Reusing steel slag as an aggregate for road construction requires to characterize the leaching kinetics and metal releases. In this study, basic oxygen furnace (BOF) steel slag were subjected to batch leaching tests at liquid to solid ratios (L/S) of 10 and 100 over 30 days; the leachate chemistry being regularly sampled in time. A geochemical model of the steel slag is developed and validated from experimental data, particularly the evolution with leaching of mineralogical composition of the slag and trace element speciation. Kinetics is necessary for modeling the primary phase leaching, whereas a simple thermodynamic equilibrium approach can be used for secondary phase precipitation. The proposed model simulates the kinetically-controlled dissolution (hydrolysis) of primary phases, the precipitation of secondary phases (C-S-H, hydroxide and spinel), the pH and redox conditions, and the progressive release of major elements as well as the metals Cr and V. Modeling indicates that the dilution effect of the L/S ratio is often coupled to solubility-controlled processes, which are sensitive to both the pH and the redox potential. A sensitivity analysis of kinetic uncertainties on the modeling of element releases is performed.

  5. Kinetics of steel slag leaching: Batch tests and modeling.

    PubMed

    De Windt, Laurent; Chaurand, Perrine; Rose, Jerome

    2011-02-01

    Reusing steel slag as an aggregate for road construction requires to characterize the leaching kinetics and metal releases. In this study, basic oxygen furnace (BOF) steel slag were subjected to batch leaching tests at liquid to solid ratios (L/S) of 10 and 100 over 30 days; the leachate chemistry being regularly sampled in time. A geochemical model of the steel slag is developed and validated from experimental data, particularly the evolution with leaching of mineralogical composition of the slag and trace element speciation. Kinetics is necessary for modeling the primary phase leaching, whereas a simple thermodynamic equilibrium approach can be used for secondary phase precipitation. The proposed model simulates the kinetically-controlled dissolution (hydrolysis) of primary phases, the precipitation of secondary phases (C-S-H, hydroxide and spinel), the pH and redox conditions, and the progressive release of major elements as well as the metals Cr and V. Modeling indicates that the dilution effect of the L/S ratio is often coupled to solubility-controlled processes, which are sensitive to both the pH and the redox potential. A sensitivity analysis of kinetic uncertainties on the modeling of element releases is performed.

  6. The Sulfide Capacity of Iron Oxide-Rich Slags

    NASA Astrophysics Data System (ADS)

    Motlagh, M.

    1988-03-01

    The relationship between the sulfide capacity of slags rich in iron oxide and the sulfur partition ratio between the metal and slag is strongly related to the slag's iron oxide concentration. For slags containing little or no lime, this relationship is linear for a constant concentration of iron oxide in the slag. The effect of silica on changes in the sulfide capacity of slags rich in iron oxide is similar to that of basic steel-making slags, particularly at low activity of silica in slag.

  7. High temperature millimeter wave radiometric and interferometric measurements of slag-refractory interaction for application to coal gasifiers

    SciTech Connect

    McCloy, John S.; Crum, Jarrod V.; Sundaram, S. K.; Slaugh, Ryan W.; Woskov, Paul P.

    2011-09-17

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments) such as in slagging coal gasifiers, where sensors have been identified as a key enabling technology need for process optimization. We present a state-of-the-art dual-channel MMW heterodyne radiometer with active interferometric capability that allows simultaneous radiometric measurements of sample temperature, emissivity, and flow dynamics to over 1873 K. Interferometric capability is supplied via a probe signal originating from the 137 GHz radiometer local oscillator (LO). The interferometric 'video' channels allow measurement of additional parameters simultaneously, such as volume expansion, thickness change, and slag viscosity along with temperature or emissivity. This capability has been used to demonstrate measurement of temperature and simulated coal slag infiltration into a chromia refractory brick sample as well as slag flow down a vertically placed refractory brick. Observed phenomena include slag melting and slumping, slag reboil and foam with oxygen evolution, and eventual failure of the alumina crucible through corrosion by the molten slag. These results show the promise of the MMW system for extracting quantitative and qualitative process parameters from operating slagging coal gasifiers, providing valuable information for process efficiency, control, and increased productivity.

  8. Utilization of lightweight materials made from coal gasification slags. Quarterly report, June--August 1995

    SciTech Connect

    1995-09-01

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of {open_quotes}as-generated{close_quotes} slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for {open_quotes}as-generated{close_quotes} slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700{degrees}F. These results indicated the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications.

  9. Recycling of nickel smelter slag for arsenic remediation--an experimental study.

    PubMed

    Chowdhury, Saidur Rahman; Yanful, Ernest K; Pratt, Allen R

    2014-09-01

    In this study, recycled Ni smelter slag has been used as a reactive medium for arsenic (As) removal from aqueous solutions. The results of the study showed that 10.16-11.43-cm long columns containing 451-550 g of slag operated for at least 65 days were able to remove 99-100 % As species from continuously flowing contaminated water at an initial As concentration of 10 mg/L. The removal capacities were found to be 1.039 to 1.054 mg As per g of slag. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy data also showed that electrostatic attraction and oxidation-reduction reactions between As species and mixed iron oxides present in the slag were the main mechanisms for the removal of arsenic from aqueous solutions. Theoretical multiplet analysis of XPS data revealed that the amount of goethite in the slag increased from 22 to 60 % during arsenic removal by adsorption and the percentage of magnetite decreased from 50 to 40 %. These changes indicate that redox-mediated reactions occurred as part of the As(V) removal process. Raman spectroscopy studies confirmed that, in addition to surface reactions, internal interactions between the slag and arsenic also occurred. The findings of the study suggest that recycled Ni smelter slag could be an effective low-cost reactive medium for a subsurface remediation system, such as a permeable reactive barrier. Recycling of waste material (slag) for the removal of another waste (arsenic) can significantly reduce the environmental footprint of metallurgical operations and hence contribute to sustainable development. Such recycling also decreases slag disposal costs and eliminates the need to purchase commercial reactive material or obtain expensive natural material for remediation purposes. PMID:24770924

  10. Thermodynamic modeling of restoring items converter vanadium slag

    NASA Astrophysics Data System (ADS)

    Golodova, M. A.; Rogihina, I. D.; Nohrina, O. I.; Rybenko, I. A.

    2016-09-01

    Calculations of parameters for equilibrium processes of iron, manganese, vanadium and titanium reduction from converter vanadium slag by carbon from small-sized coke and silica from ferrosilicon were performed by the method of thermodynamic modeling using the program complex “Terra”. Calculations were made for each type of reductant separately and in combination. Dependences of process parameters on reducing agents consumption were drawn. The analysis of the results was carried out.

  11. Functional design of refractories for slagging gasifiers

    SciTech Connect

    Kwong, Kyei-Sing; Dogan, Cynthia P.; Bennett, James P.; Chinn, Richard E.; Dahlin, Cheryl L.

    2002-09-01

    Refractories are used in coal slagging gasifiers to protect the outer steel shell from coal slag attack and to insulate it from heat. Corrosion by the aggressive coal slags and unexpected temperature shock severely shorten the service life of these refractories. Currently, the best refractories available for the slagging coal gasifiers last from 6 to 18 months. The down time for the installation of new refractory lining reduces on-line availability of the gasifier. Researchers at the Albany Research Center (ARC) have found that structural spalling by slag penetration into the refractory is responsible for the early failure of refractories in some gasifiers. The low melting point of coal slags, the low thermal gradient in the refractory, and the improper design of refractory microstructure contribute to promote slag penetration. Work at ARC has demonstrated that refractories with an improved functional design are more resistant to slag penetration. Cooperation with commercial refractory companies and gasifier designers/operators is underway to produce and test improved refractories.

  12. Cleaning of waste smelter slags and recovery of valuable metals by pressure oxidative leaching.

    PubMed

    Li, Yunjiao; Perederiy, Ilya; Papangelakis, Vladimiros G

    2008-04-01

    Huge quantities of slag, a waste solid product of pyrometallurgical operations by the metals industry are dumped continuously around the world, posing a potential environmental threat due to entrained values of base metals and sulfur. High temperature pressure oxidative acid leaching of nickel smelter slags was investigated as a process to facilitate slag cleaning and selective dissolution of base metals for economic recovery. Five key parameters, namely temperature, acid addition, oxygen overpressure, solids loading and particle size, were examined on the process performance. Base metal recoveries, acid and oxygen consumptions were accurately measured, and ferrous/ferric iron concentrations were also determined. A highly selective leaching of valuable metals with extractions of >99% for nickel and cobalt, >97% for copper, >91% for zinc and <2.2% for iron was successfully achieved for 20 wt.% acid addition and 25% solids loading at 200-300 kPa O(2) overpressure at 250 degrees C in 2h. The acid consumption was measured to be 38.5 kg H(2)SO(4)/t slag and the oxygen consumption was determined as 84 kg O(2)/t slag which is consistent with the estimated theoretical oxygen consumption. The as-produced residue containing less than 0.01% of base metals, hematite and virtually zero sulfidic sulfur seems to be suitable for safe disposal. The process seems to be able to claim economic recovery of base metals from slags and is reliable and feasible.

  13. Cleaning of waste smelter slags and recovery of valuable metals by pressure oxidative leaching.

    PubMed

    Li, Yunjiao; Perederiy, Ilya; Papangelakis, Vladimiros G

    2008-04-01

    Huge quantities of slag, a waste solid product of pyrometallurgical operations by the metals industry are dumped continuously around the world, posing a potential environmental threat due to entrained values of base metals and sulfur. High temperature pressure oxidative acid leaching of nickel smelter slags was investigated as a process to facilitate slag cleaning and selective dissolution of base metals for economic recovery. Five key parameters, namely temperature, acid addition, oxygen overpressure, solids loading and particle size, were examined on the process performance. Base metal recoveries, acid and oxygen consumptions were accurately measured, and ferrous/ferric iron concentrations were also determined. A highly selective leaching of valuable metals with extractions of >99% for nickel and cobalt, >97% for copper, >91% for zinc and <2.2% for iron was successfully achieved for 20 wt.% acid addition and 25% solids loading at 200-300 kPa O(2) overpressure at 250 degrees C in 2h. The acid consumption was measured to be 38.5 kg H(2)SO(4)/t slag and the oxygen consumption was determined as 84 kg O(2)/t slag which is consistent with the estimated theoretical oxygen consumption. The as-produced residue containing less than 0.01% of base metals, hematite and virtually zero sulfidic sulfur seems to be suitable for safe disposal. The process seems to be able to claim economic recovery of base metals from slags and is reliable and feasible. PMID:17728060

  14. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO{sub 2} pressure

    SciTech Connect

    Zomeren, Andre van; Laan, Sieger R. van der; Kobesen, Hans B.A.; Huijgen, Wouter J.J.; Comans, Rob N.J.

    2011-11-15

    Highlights: > Accelerated carbonation studied to improve environmental properties of steel slag. > Carbonation found to occur predominantly at surface of the steel slag grains. > Combined geochemical modelling and mineral analysis revealed controlling processes. > Enhanced V-leaching with di-Ca silicate (C2S) dissolution identified as major source. > Identified mineral transformations provide guidance for further quality improvement. - Abstract: Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios. The aim of this study is to investigate the potential of accelerated steel slag carbonation, at relatively low pCO{sub 2} pressure (0.2 bar), to improve the environmental pH and the leaching properties of steel slag, with specific focus on the leaching of vanadium. Carbonation experiments are performed in laboratory columns with steel slag under water-saturated and -unsaturated conditions and temperatures between 5 and 90 {sup o}C. Two types of steel slag are tested; free lime containing (K3) slag and K1 slag with a very low free lime content. The fresh and carbonated slag samples are investigated using a combination of leaching experiments, geochemical modelling of leaching mechanisms and microscopic/mineralogical analysis, in order to identify the major processes that control the slag pH and resulting V leaching. The major changes in the amount of sequestered CO{sub 2} and the resulting pH reduction occurred within 24 h, the free lime containing slag (K3-slag) being more prone to carbonation than the slag with lower free lime content (K1-slag). While carbonation at these conditions was found to occur predominantly at the surface of the slag grains, the formation of cracks was observed in carbonated K3 slag, suggesting that free lime in the interior of slag grains had also reacted

  15. Utilization of lightweight materials made from coal gasification slags. Quarterly report, March 1--May 31, 1996

    SciTech Connect

    1996-12-31

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of lightweight aggregates (LWA) and ultra-lightweight (ULWA) from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase 1, comprising the production of LWA and ULWA from slag at the large pilot-scale, and Phase 2, which involves commercial evaluation of these aggregates in a number of applications. The following significant events occurred during this reporting period: testing of slag-based lightweight aggregates for roof tile and concrete applications.

  16. Utilization of lightweight materials made from coal gasification slags. Quarterly report, December 1994--February 1995

    SciTech Connect

    1995-03-01

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, this process generates large amounts of solid waste, consisting of vitrified ash (slag) along with some unconverted carbon, which is disposed of as solid waste. The objectives of this project is to demonstrate the technical and economic viability of slag utilization technologies for commercial production of lightweight aggregates (LWA) and ultra-lightweight aggregates (ULWA) from slag and to test the suitability of these aggregates for various applications. The scheduled date for completing Phase I, which includes production of LWA and ULWA from slag at the large pilot-scale, is 14 December 1995. The scheduled start date for Phase II, which involves commercial utilization of these aggregates in a number of applications, is 15 December 1995, and the scheduled completion date of the project is 14 March 1997.

  17. Study of slag content and properties after plasma melting of incineration ash

    NASA Astrophysics Data System (ADS)

    Park, Hyun-Seo

    2011-06-01

    The paper presents the investigation of plasma melting of the mixed bottom and fly incineration ash at various mixing ratios of the components. Chemical compound of the bottom and fly ash as well as the slag after its melting was analyzed by different methods, and the content of toxic components in them was determined. It is demonstrated that the direct disposal of the fly and bottom incineration ash may cause dioxin and heavy metal contamination of the environment. The influence of melted ash basicity on the resulting slag compound was studied. The mass balance of the melting process was defined. The tests were performed to determine the heavy-metals leaching from the ash and slag. It is also shown that the slag after plasma melting is dioxin-free and environmentally friendly.

  18. Study on the Kinetics of Aluminum Removal from Liquid Silicon to Slag with Mechanical Stirring

    NASA Astrophysics Data System (ADS)

    Lee, Jaewoo; White, Jesse F.; Hildal, Kjetil; Sichen, Du

    2016-08-01

    The kinetics of aluminum removal from silicon melt to CaO-SiO2-Al2O3 slag was studied. A recently designed experimental setup using mechanical stirring was employed to focus the study on the chemical reaction. The slag and metal were found to reach chemical equilibrium in 300 seconds. A simple model could reproduce the experimental data satisfactorily. Both the experimental results and the model prediction further confirmed that the process was controlled by the chemical reaction, since the reaction rate constant was found to be independent of the amount of slag and the initial slag composition. The experimental data at equilibrium were compared with the model calculations. The discrepancy between the model calculations and the experimental data strongly suggests the need for careful thermodynamic measurements.

  19. LWA demonstration applications using Illinois coal gasification slag: Phase II. Technical report, 1 March--31 May 1994

    SciTech Connect

    Choudhry, V.; Steck, P.

    1994-09-01

    The major objective of this project is to demonstrate the suitability of using ultra-lightweight aggregates (ULWA) produced by thermal expansion of solid residues (slag) generated during the gasification of Illinois coals as substitutes for conventional aggregates, which are typically produced by pyroprocessing of perlite ores. To meet this objective, expanded slag aggregates produced from an Illinois coal slag feed in Phase I will be subjected to characterization and applications-oriented testing. Target applications include the following: aggregates in precast products (blocks and rooftiles); construction aggregates (loose fill insulation and insulating concrete); and other applications as identified from evaluation of expanded slag properties. The production of value-added products from slag is aimed at eliminating a solid waste and possibly enhancing the overall economics of the gasification process, especially when the avoided costs of disposal are taken into consideration.

  20. Bioleaching of metals from steel slag by Acidithiobacillus thiooxidans culture supernatant.

    PubMed

    Hocheng, Hong; Su, Cheer; Jadhav, Umesh U

    2014-12-01

    The generation of 300–500 kg of slag per ton of the steel produced is a formidable amount of solid waste available for treatment. They usually contain considerable quantities of valuable metals. In this sense, they may become either important secondary resource if processed in eco-friendly manner for secured supply of contained metals or potential pollutants, if not treated properly. It is possible to recover metals from steel slag by applying bioleaching process. Electric arc furnace (EAF) slag sample was used for bioleaching of metals. In the present study, before bioleaching experiment water washing of an EAF slag was carried out. This reduced slag pH from 11.2 to 8.3. Culture supernatants of Acidithiobacillus thiooxidans (At. thiooxidans), Acidithiobacillus ferrooxidans (At. ferrooxidans), and Aspergillus niger (A. niger) were used for metal solubilization. At. thiooxidans culture supernatant containing 0.016 M sulfuric acid was found most effective for bioleaching of metals from an EAF slag. Maximum metal extraction was found for Mg (28%), while it was least for Mo (0.1%) in six days. Repeated bioleaching cycles increased metal recovery from 28% to 75%, from 14% to 60% and from 11% to 27%, for Mg, Zn and Cu respectively.

  1. Leaching characteristics of steel slag components and their application in cementitious property prediction.

    PubMed

    Li, Zaibo; Zhao, Sanyin; Zhao, Xuguang; He, Tusheng

    2012-01-15

    High-efficiency recovery and utilization of steel slag are important concerns for environmental protection and sustainable development. To establish a rapid method to evaluate the cementitious properties of steel slag, leaching tests were carried out on steel slag components via an evaporation-condensation method; the leaching characteristics and mechanism of the slag were also investigated. The relationship between leaching characteristics and cementitious properties, which were represented by mortar compressive strength, was analyzed. Results show that there exist significant differences among the amounts of chemically active leached components. The leaching process can be described by the shrinking unreacted core model controlled by intra-particle diffusion, and is in accordance with Kondo R hydration kinetics equation. The leaching process showed a good linear relationship between the amounts of components leached from steel slag and the mortar compressive strength of cementitious materials prepared from reference cement and steel slag with mass ratios of 50:50 and 70:30. The compressive strengths of mortars subjected to 7, 28, and 90 days of curing can be accurately predicted by the sum of leached (CaO+Al(2)O(3)) obtained after a certain length of leaching time.

  2. Remediation of TCE-contaminated groundwater using acid/BOF slag enhanced chemical oxidation.

    PubMed

    Tsai, T T; Kao, C M; Wang, J Y

    2011-04-01

    The objective of this study was to evaluate the potential of applying acid/H(2)O(2)/basic oxygen furnace slag (BOF slag) and acid/S(2)O(8)(2-)/BOF slag systems to enhance the chemical oxidation of trichloroethylene (TCE)-contaminated groundwater. Results from the bench-scale study indicate that TCE oxidation via the Fenton-like oxidation process can be enhanced with the addition of BOF slag at low pH (pH=2-5.2) and neutral (pH=7.1) conditions. Because the BOF slag has iron abundant properties (14% of FeO and 6% of Fe(2)O(3)), it can be sustainably reused for the supplement of iron minerals during the Fenton-like or persulfate oxidation processes. Results indicate that higher TCE removal efficiency (84%) was obtained with the addition of inorganic acid for the activation of Fenton-like reaction compared with the experiments with organic acids addition (with efficiency of 10-15% lower) (BOF slag=10gL(-1); initial pH=5.2). This could be due to the fact that organic acids would compete with TCE for available oxidants. Results also indicate that the pH value had a linear correlation with the observed first-order decay constant of TCE, and thus, lower pH caused a higher TCE oxidation rate.

  3. Effect of MgO and MnO on Phosphorus Utilization in P-Bearing Steelmaking Slag

    NASA Astrophysics Data System (ADS)

    Lin, Lu; Bao, Yan-Ping; Wang, Min; Li, Xiang

    2016-04-01

    In order to recycle the phosphorus in P-bearing converter slag and make it used as slag phosphate fertilizer, the effect of MgO and MnO in P-bearing steelmaking slag on phosphorus existence form, P2O5 solubility and magnetic separation behavior were researched systematically. The results show that the phosphorus in slag is mainly in the form of n2CaO · SiO2-3CaO · P2O5 (for short nC2S-C3P) solid solution in the P-rich phase for CaO-SiO2-FetO-P2O5-X (X stands for MgO and MnO, respectively). And the increasing of MgO and MnO content has no influence on precipitation of nC2S-C3P solid solution in slag, MnO and MgO mainly enter into RO phase and base phase to form MnFe2O4 and MgFe2O4, which has little effect on the P2O5 content of P-rich phase, so which has little effect on the degree of phosphorus enrichment and phosphorus occurrence form of the P-bearing slag. And adding MgO and MnO into CaO-SiO2-P2O5-Fe2O3 slag system can break the complex net structure formed by Si-O on certain degree, and also hinder the precipitation of β-Ca3(PO4)2 crystal with low citric acid solubility during the melting-cooling process. Therefore, adding appropriate MgO and MnO content into slag can improve the slag P2O5 solubility, but the effect of different amounts of MgO and MnO on the P2O5 solubility has little difference. Meanwhile, adding MgO and MnO into slag can improve the metallization of slag and magnetism of iron-rich phase, make the magnetic substances content increase and separation of phosphorus and iron incomplete, so it is adverse to phosphorus resources recovery from P-bearing slag by magnetic separation method. In order to recycle the phosphorus in P-bearing converter slag, the MgO and MnO content in the P-bearing slag should be controlled in the steelmaking process.

  4. A Brief Review of Viscosity Models for Slag in Coal Gasification

    SciTech Connect

    Massoudi, Mehrdad; Wang, Ping

    2011-11-01

    Many researchers have defined the phenomenon of 'slagging' as the deposition of ash in the radiative section of a boiler, while 'fouling' refers to the deposition of ash in the convective-pass region. Among the important parameters affecting ash deposition that need to be studied are ash chemistry, its transport, deposit growth, and strength development; removability of the ash deposit; heat transfer mechanisms; and the mode of operation for boilers. The heat transfer at the walls of a combustor depends on many parameters including ash deposition. This depends on the processes or parameters controlling the impact efficiency and the sticking efficiency. For a slagging combustor or furnace, however, the temperatures are so high that much of the coal particles are melted and the molten layer, in turn, captures more particles as it flows. The main problems with ash deposition are reduced heat transfer in the boiler and corrosion of the tubes. Common ways of dealing with these issues are soot blowing and wall blowing on a routine basis; however, unexpected or uncontrolled depositions can also complicate the situation, and there are always locations inaccessible to the use of such techniques. Studies have indicated that slag viscosity must be within a certain range of temperatures for tapping and the membrane wall to be accessible, for example, between 1300 C and 1500 C, the viscosity is approximately 25 Pa {center_dot} s. As the operating temperature decreases, the slag cools and solid crystals begin to form. In such cases the slag should be regarded as a non-Newtonian suspension, consisting of liquid silicate and crystals. A better understanding of the rheological properties of the slag, such as yield stress and shear-thinning, are critical in determining the optimum operating conditions. To develop an accurate heat transfer model in any type of coal combustion or gasification process, the heat transfer and to some extent the rheological properties of ash and slag

  5. Glassy slags for minimum additive waste stabilization. Interim progress report, May 1993--February 1994

    SciTech Connect

    Feng, X.; Wronkiewicz, D.J.; Bates, J.K.; Brown, N.R.; Buck, E.C.; Dietz, N.L.; Gong, M.; Emery, J.W.

    1994-05-01

    Glassy slag waste forms are being developed to complement glass waste forms in implementing Minimum Additive Waste Stabilization (MAWS) for supporting DOE`s environmental restoration efforts. The glassy slag waste form is composed of various crystalline and metal oxide phases embedded in a silicate glass phase. The MAWS approach was adopted by blending multiple waste streams to achieve up to 100% waste loadings. The crystalline phases, such as spinels, are very durable and contain hazardous and radioactive elements in their lattice structures. These crystalline phases may account for up to 80% of the total volume of slags having over 80% metal loading. The structural bond strength model was used to quantify the correlation between glassy slag composition and chemical durability so that optimized slag compositions were obtained with limited crucible melting and testing. Slag compositions developed through crucible melts were also successfully generated in a pilot-scale Retech plasma centrifugal furnace at Ukiah, California. Utilization of glassy slag waste forms allows the MAWS approach to be applied to a much wider range of waste streams than glass waste forms. The initial work at ANL has indicated that glassy slags are good final waste forms because of (1) their high chemical durability; (2) their ability to incorporate large amounts of metal oxides; (3) their ability to incorporate waste streams having low contents of flux components; (4) their less stringent requirements on processing parameters, compared to glass waste forms; and (5) their low requirements for purchased additives, which means greater waste volume reduction and treatment cost savings.

  6. Design of a Subscale Propellant Slag Evaluation Motor Using Two-Phase Fluid Dynamic Analysis

    NASA Technical Reports Server (NTRS)

    Whitesides, R. Harold; Dill, Richard A.; Purinton, David C.; Sambamurthi, Jay K.

    1996-01-01

    Small pressure perturbations in the Space Shuttle Reusable Solid Rocket Motor (RSRM) are caused by the periodic expulsion of molten aluminum oxide slag from a pool that collects in the aft end of the motor around the submerged nozzle nose during the last half of motor operation. It is suspected that some motors produce more slag than others due to differences in aluminum oxide agglomerate particle sizes that may relate to subtle differences in propellant ingredient characteristics such as particle size distributions or processing variations. A subscale motor experiment was designed to determine the effect of propellant ingredient characteristics on the propensity for slag production. An existing 5 inch ballistic test motor was selected as the basic test vehicle. The standard converging/diverging nozzle was replaced with a submerged nose nozzle design to provide a positive trap for the slag that would increase the measured slag weights. Two-phase fluid dynamic analyses were performed to develop a nozzle nose design that maintained similitude in major flow field features with the full scale RSRM. The 5 inch motor was spun about its longitudinal axis to further enhance slag collection and retention. Two-phase flow analysis was used to select an appropriate spin rate along with other considerations, such as avoiding bum rate increases due to radial acceleration effects. Aluminum oxide particle distributions used in the flow analyses were measured in a quench bomb for RSRM type propellants with minor variations in ingredient characteristics. Detailed predictions for slag accumulation weights during motor bum compared favorably with slag weight data taken from defined zones in the subscale motor and nozzle. The use of two-phase flow analysis proved successful in gauging the viability of the experimental program during the planning phase and in guiding the design of the critical submerged nose nozzle.

  7. Experimental pavement using household waste slag

    SciTech Connect

    Kouda, Masahiro

    1996-12-31

    Municipal wastes used to be simply landfilled, but because of increasing difficulty in finding disposal sites, it became common practice to incinerate wastes and landfill the ash. In view of rapidly dwindling landfill sites, the author thought that the landfill site problem might be solved by finding a way to utilize slag made from incinerator ash. In this paper, a method for utilizing water-granulated slag as an asphalt pavement material is discussed. On the basis of laboratory test results, trial paving using base course materials consisting of crushed stone and 25 or 50% slag was carried out, paying attention primarily to bearing capacity. Marshall tests and fatigue resistance tests were conducted to determine the optimum content of water-granulated slag, and it was concluded that quality comparable to that of conventional asphalt concrete was attained at the slag content of 25% or less and that no problem would arise if the slag content was kept at 60% or less of the fine aggregate content. The mix proportions thus determined were also tested through experimental paving. A follow-up study to evaluate the durability of the experimental pavements confirmed that the experimental pavements were comparable in performance with conventional asphalt concrete pavements. This paper also reports on some problems encountered that need to be solved before utilizing water-granulated slag.

  8. Chemical and mineralogical characterizations of LD converter steel slags: A multi-analytical techniques approach

    SciTech Connect

    Waligora, J.; Bulteel, D.; Degrugilliers, P.; Damidot, D.; Potdevin, J.L.; Measson, M.

    2010-01-15

    The use of LD converter steel slags (coming from Linz-Donawitz steelmaking process) as aggregates in road construction can in certain cases lead to dimensional damage due to a macroscopic swelling that is the consequence of chemical reactions. The aim of this study was to couple several analytical techniques in order to carefully undertake chemical and mineralogical characterizations of LD steel slags and identify the phases that are expected to be responsible for their instability. Optical microscopy, scanning electron microscopy and electron probe microanalyses revealed that LD steel slags mainly contain calcium silicates, dicalcium ferrites, iron oxides and lime. However, as a calcium silicate phase is heterogeneous, Raman microspectrometry and transmitted electron microscopy had to be used to characterize it more precisely. Results showed that lime is present under two forms in slag grains: some nodules observed in the matrix whose size ranges from 20 to 100 {mu}m and some micro-inclusions, enclosed in the heterogeneous calcium silicate phase whose size ranges from 1 to 3 {mu}m. It was also established that without the presence of magnesia, lime is expected to be the only phase responsible for LD steel slags instability. Nevertheless, the distribution of lime between nodules and micro-inclusions may play a major role and could explain that similar amounts of lime can induce different instabilities. Thus, it appears that lime content of LD steel slags is not the only parameter to explain their instability.

  9. Digested sewage sludge solidification by converter slag for landfill cover.

    PubMed

    Kim, Eung-Ho; Cho, Jin-Kyu; Yim, Soobin

    2005-04-01

    A new technology for solidification of digested sewage sludge referred to as converter slag solidification (CSS) has been developed using converter slag as the solidifying agent and quick lime as the solidifying aid. The CSS technology was investigated by analyzing the physicochemical properties of solidified sludge and determining its microstructural characteristics. The feasibility of using solidified sludge as a landfill cover material was considered in the context of the economical recycling of waste. Sludge solidified using the CSS technology exhibited geotechnical properties that are appropriate for replacing currently used cover soil. Microscopic analyses using XRD, SEM and EDS revealed that the main hydrated product of solidification was CSH (CaO . SiO2 . nH2O), which may play an important role in the effective setting process. Negligible leaching of heavy metals from the solidified sludge was observed. The solidification process of the hydrated sludge, slag and quicklime eliminated the coliform bacteria. Recycled sewage sludge solidified using CCS technology could be used as an effective landfill cover. PMID:15763091

  10. Molten Slag Would Boost Coal Conversion

    NASA Technical Reports Server (NTRS)

    Ferrall, J. F.

    1984-01-01

    Reactor increases residence time of uncovered char. Near-100percent carbon conversion achievable in reactor incorporating moltenslag bath. Slag maintains unconverted carbon impinging on surface at high temperatures for longer period of time, enhancing conversion.

  11. Settling of copper drops in molten slags

    NASA Astrophysics Data System (ADS)

    Warczok, A.; Utigard, T. A.

    1995-02-01

    The settling of suspended metal and sulfide droplets in liquid metallurgical, slags can be affected by electric fields. The migration of droplets due to electrocapillary motion phenomena may be used to enhance the recovery of suspended matte/metal droplets and thereby to increase the recovery of pay metals. An experimental technique was developed for the purpose of measuring the effect of electric fields on the settling rate of metallic drops in liquid slags. Copper drops suspended in CaO-SiO2-Al2O3-Cu2O slags were found to migrate toward the cathode. Electric fields can increase the settling rate of 5-mm-diameter copper drops 3 times or decrease the settling until levitation by reversal of the electric field. The enhanced settling due to electric fields decreases with increasing Cu2O contents in the slag.

  12. Improving thermocouple service life in slagging gasifiers

    SciTech Connect

    Bennett, James P.; Kwong, Kyei-Sing; Powell, Cynthia A.; Thomas, Hugh; Krabbe, Rick

    2005-01-01

    The measurement of temperature within slagging gasifiers for long periods of time is difficult/impossible because of sensor failure or blockage of inputs used to monitor gasifier temperature. One of the most common means of temperature measurement in a gasifier is physically, through the use of thermocouples in a gasifier sidewall. These units can fail during startup, standby, or during the first 40-90 days of gasifier service. Failure can be caused by a number of issues; including thermocouple design, construction, placement in the gasifier, gasifier operation, and molten slag attack of the materials used in a thermocouple assembly. Lack of temperature control in a gasifier can lead to improper preheating, slag buildup on gasifier sidewalls, slag attack of gasifier refractories used to line a gasifier, or changes in desired gas output from a gasifier. A general outline of thermocouple failure issues and attempts by the Albany Research Center to improve the service life of thermocouples will be discussed.

  13. Seismic behavior of geogrid reinforced slag wall

    SciTech Connect

    Edincliler, Ayse; Baykal, Gokhan; Saygili, Altug

    2008-07-08

    Flexible retaining structures are known with their high performance under earthquake loads. In geogrid reinforced walls the performance of the fill material and the interface of the fill and geogrid controls the performance. Geosynthetic reinforced walls in seismic regions must be safe against not only static forces but also seismic forces. The objective of this study is to determine the behavior of a geogrid reinforced slag wall during earthquake by using shaking table experiments. This study is composed of three stages. In the first stage the physical properties of the material to be used were determined. In the second part, a case history involving the use of slag from steel industry in the construction of geogrid reinforced wall is presented. In the third stage, the results of shaking table tests conducted using model geogrid wall with slag are given. From the results, it is seen that slag can be used as fill material for geogrid reinforced walls subjected to earthquake loads.

  14. Evaluation of novel reactive MgO activated slag binder for the immobilisation of lead and zinc.

    PubMed

    Jin, Fei; Al-Tabbaa, Abir

    2014-12-01

    Although Portland cement is the most widely used binder in the stabilisation/solidification (S/S) processes, slag-based binders have gained significant attention recently due to their economic and environmental merits. In the present study, a novel binder, reactive MgO activated slag, is compared with hydrated lime activated slag in the immobilisation of lead and zinc. A series of lead or zinc-doped pastes and mortars were prepared with metal to binder ratio from 0.25% to 1%. The hydration products and microstructure were studied by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The major hydration products were calcium silicate hydrate and hydrotalcite-like phases. The unconfined compressive strength was measured up to 160 d. Findings show that lead had a slight influence on the strength of MgO-slag paste while zinc reduced the strength significantly as its concentration increased. Leachate results using the TCLP tests revealed that the immobilisation degree was dependent on the pH and reactive MgO activated slag showed an increased pH buffering capacity, and thus improved the immobilisation efficiency compared to lime activated slag. It was proposed that zinc was mainly immobilised within the structure of the hydrotalcite-like phases or in the form of calcium zincate, while lead was primarily precipitated as the hydroxide. It is concluded, therefore, that reactive MgO activated slag can serve as clinker-free alternative binder in the S/S process. PMID:25123653

  15. Calculation of sulfide capacities of multicomponent slags

    NASA Astrophysics Data System (ADS)

    Pelton, Arthur D.; Eriksson, Gunnar; Romero-Serrano, Antonio

    1993-10-01

    The Reddy-Blander model for the sulfide capacities of slags has been modified for the case of acid slags and to include A12O3 and TiO2 as components. The model has been extended to calculate a priori sulfide capacities of multicomponent slags, from a knowledge of the thermodynamic activities of the component oxides, with no adjustable parameters. Agreement with measurements is obtained within experimental uncertainty for binary, ternary, and quinary slags involving the components SiO2-Al2O3-TiO2-CaO-MgO-FeO-MnO over wide ranges of composition. The oxide activities used in the computations are calculated from a database of model parameters obtained by optimizing thermodynamic and phase equilibrium data for oxide systems. Sulfur has now been included in this database. A computing system with automatic access to this and other databases has been developed to permit the calculation of the sulfur content of slags in multicomponent slag/metal/gas/solid equilibria.

  16. Triple-activated blast furnace slag

    SciTech Connect

    Clarke, W.J.

    1995-12-31

    The current shortage of portland cement in the world will require the use of Ground Granulated Blast Furnace Slag (GGBFS) to fill demands in many industrialized countries. Therefore, an extensive series of triple-activated slag experiments have been undertaken to optimize an economical combination of mechanical properties for alkali-activated slags. Na{sub 2}OSiO{sub 2} (N Grade), Ca(OH){sub 2}, H{sub 2}O and Na{sub 2}CO{sub 3} have been added as activators in 5 to 10, 0 to 5 and 0 to 5 weight percentages of water and slag in a mix with a water:cement ratio of 1:1. Silica Fume and Sika 10 superplasticizer have been added as 1 and 10 weight percent of slag. Set times, initial hardening times and compressive strengths at percentages of the mix to identify more refined formulations. Finally, the resulting aggregate to develop a triple-activated slag formulation with the ultimate objective of contributing toward satisfying the world shortage of high performance concrete.

  17. Utilization of lightweight materials made from coal gasification slags. Quaterly report, March 1, 1997--May 30, 1997

    SciTech Connect

    1998-12-31

    The integrated-gasification combined-cycle (IGCC) process is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of {open_quotes}as-generated{close_quotes} slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for {open_quotes}as-generated{close_quotes} slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700{degrees}F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications.

  18. Recycling of Malaysia's electric arc furnace (EAF) slag waste into heavy-duty green ceramic tile.

    PubMed

    Teo, Pao-Ter; Anasyida, Abu Seman; Basu, Projjal; Nurulakmal, Mohd Sharif

    2014-12-01

    Recently, various solid wastes from industry such as glass waste, fly ash, sewage sludge and slag have been recycled into various value-added products such as ceramic tile. The conventional solutions of dumping the wastes in landfills or incineration, including in Malaysia are getting obsolete as the annual huge amount of the solid wastes would boost-up disposal cost and may cause permanent damage to the flora and fauna. This recent waste recycling approach is much better and greener as it can resolve problems associated with over-limit storage of industrial wastes and reduce exploration of natural resources for ceramic tile to continuously sustain the nature. Therefore, in this project, an attempt was made to recycle electric arc furnace (EAF) slag waste, obtained from Malaysia's steel making industry, into ceramic tile via conventional powder compaction method. The research work was divided into two stages. The first stage was to evaluate the suitability of EAF slag in ceramic tile by varying weight percentage of EAF slag (40 wt.%, 50 wt.% and 60 wt.%) and ball clay (40 wt.%, 50 wt.% and 60 wt.%), with no addition of silica and potash feldspar. In the second stage, the weight percentage of EAF slag was fixed at 40 wt.% and the percentage of ball clay (30 wt.% and 40 wt.%), feldspar (10 wt.% and 20 wt.%) and silica (10 wt.% and 20 wt.%) added was varied accordingly. Results obtained show that as weight percentage of EAF slag increased up to 60 wt.%, the percentage of apparent porosity and water absorption also rose, with a reduction in tile flexural strength and increased porosity. On the other hand, limiting the weight percentage of EAF slag to 40 wt.% while increasing the weight percentage of ball clay led to a higher total percentage of anorthite and wollastonite minerals, resulting in higher flexural strength. It was found that introduction of silica and feldspar further improved the flexural strength due to optimization of densification process. The highest

  19. Recycling of Malaysia's electric arc furnace (EAF) slag waste into heavy-duty green ceramic tile.

    PubMed

    Teo, Pao-Ter; Anasyida, Abu Seman; Basu, Projjal; Nurulakmal, Mohd Sharif

    2014-12-01

    Recently, various solid wastes from industry such as glass waste, fly ash, sewage sludge and slag have been recycled into various value-added products such as ceramic tile. The conventional solutions of dumping the wastes in landfills or incineration, including in Malaysia are getting obsolete as the annual huge amount of the solid wastes would boost-up disposal cost and may cause permanent damage to the flora and fauna. This recent waste recycling approach is much better and greener as it can resolve problems associated with over-limit storage of industrial wastes and reduce exploration of natural resources for ceramic tile to continuously sustain the nature. Therefore, in this project, an attempt was made to recycle electric arc furnace (EAF) slag waste, obtained from Malaysia's steel making industry, into ceramic tile via conventional powder compaction method. The research work was divided into two stages. The first stage was to evaluate the suitability of EAF slag in ceramic tile by varying weight percentage of EAF slag (40 wt.%, 50 wt.% and 60 wt.%) and ball clay (40 wt.%, 50 wt.% and 60 wt.%), with no addition of silica and potash feldspar. In the second stage, the weight percentage of EAF slag was fixed at 40 wt.% and the percentage of ball clay (30 wt.% and 40 wt.%), feldspar (10 wt.% and 20 wt.%) and silica (10 wt.% and 20 wt.%) added was varied accordingly. Results obtained show that as weight percentage of EAF slag increased up to 60 wt.%, the percentage of apparent porosity and water absorption also rose, with a reduction in tile flexural strength and increased porosity. On the other hand, limiting the weight percentage of EAF slag to 40 wt.% while increasing the weight percentage of ball clay led to a higher total percentage of anorthite and wollastonite minerals, resulting in higher flexural strength. It was found that introduction of silica and feldspar further improved the flexural strength due to optimization of densification process. The highest

  20. Analysis of arc emission spectra of stainless steel electric arc furnace slag affected by fluctuating arc voltage.

    PubMed

    Aula, Matti; Mäkinen, Ari; Fabritius, Timo

    2014-01-01

    Control of chromium oxidation in the electric arc furnace (EAF) is a significant problem in stainless steel production due to variations of the chemical compositions in the EAF charge. One potential method to control chromium oxidation is to analyze the emission spectrum of the electric arc in order to find indicators of rising chromium content in slag. The purpose of this study was to determine if slag composition can be gained by utilizing electric arc emission spectra in the laboratory environment, despite electric arc voltage fluctuations and varying slag composition. The purpose of inducing voltage fluctuation was to simulate changes in the industrial EAF process. The slag samples were obtained from Outokumpu Stainless Oy Tornio Works, and three different arc currents were used. The correlation analysis showed that the emission spectra offer numerous peak ratios with high correlations to the X-ray fluorescence-measured slag CrO(x)/FeO(x) and MnO/SiO2 ratios. These ratios are useful in determining if the reduction agents have been depleted in the EAF. The results suggest that analysis of laboratory-scale electric arc emission spectra is suitable for indicating the high CrO(x) or MnO content of the slag despite the arc fluctuations. Reliable analysis of other slag components was not successful.

  1. Investigation of Copper Losses to Synthetic Slag at Different Oxygen Partial Pressures in the Presence of Colemanite

    NASA Astrophysics Data System (ADS)

    Rusen, Aydın; Derin, Bora; Geveci, Ahmet; Topkaya, Yavuz Ali

    2016-09-01

    Copper losses to slag are crucial for copper matte smelting and converting stages. One factor affecting the copper losses to slag during these processes is partial pressure of oxygen. In this study, theoretical and experimental investigations of oxygen partial pressure effect on copper losses to fayalite type slag in the presence of colemanite were investigated. Theoretical considerations include liquidus temperatures and phase diagrams of the fayalite type slag calculated by the FactSage software program. In the experiments, a synthetic matte-slag (SM-SS) was produced by melting certain amounts of reagent grade Fe2O3-SiO2 and metallic Fe as starting materials. Experiments were carried out with SM-SS pair by the addition of calcined colemanite (from 0% to 6%) under various partial pressures of oxygen (10-7, 10-9, 10-11 atm) at 1250°C for 2 h. From the experimental results, it was found that the amount of copper in slag decreased slowly when colemanite was increased under all oxidizing atmospheres. The lowest copper content in synthetic slag was obtained as 0.38% after 6% colemanite addition.

  2. Phosphorus partitioning and recovery of low-phosphorus iron-rich compounds through physical separation of Linz-Donawitz slag

    NASA Astrophysics Data System (ADS)

    Makhija, Dilip; Rath, Rajendra Kumar; Chakravarty, Kaushik; Patra, Abhay Shankar; Mukherjee, Asim Kumar; Dubey, Akhilesh Kumar

    2016-07-01

    The Linz-Donawitz (LD) steelmaking process produces LD slag at a rate of about 125 kg/t. After metallic scrap recovery, the non-metallic LD slag is rejected because its physical/chemical properties are unsuitable for recycling. X-ray diffraction (XRD) studies have indicated that non-metallic LD slag contains a substantial quantity of mineral phases such as di- and tricalcium silicates. The availability of these mineral phases indicates that LD slag can be recycled by iron (Fe)-ore sintering. However, the presence of 1.2wt% phosphorus (P) in the slag renders the material unsuitable for sintering operations. Electron probe microscopic analysis (EPMA) studies indicated concentration of phosphorus in dicalcium silicate phase as calcium phosphate. The Fe-bearing phases (i.e., wustite and dicalcium ferrite) showed comparatively lower concentrations of P compared with other phases in the slag. Attempts were made to lower the P content of LD slag by adopting various beneficiation techniques. Dry high-intensity magnetic separation and jigging were performed on as-received samples with particle sizes of 6 and 3 mm. Spiral separation was conducted using samples ground to sizes of less than 1 and 0.5 mm. Among these studies, grinding to 0.5 mm followed by spiral concentration demonstrated the best results, yielding a concentrate with about 0.75wt% P and 45wt% Fe.

  3. Research on slag steam generator: Final report

    SciTech Connect

    Jablin, R.

    1987-12-01

    A substantial effort has been made to conclude a contract for a large-scale SSG unit to be installed adjacent to a blast furnace. This effort has been unsuccessful during the time period of this contract for two reasons which are described in detail. A potential application for installation of the SSG has been investigated for the electric arc furnaces at Nucor Steel Company in Darlington, South Carolina. This application has several advantages but Nucor is currently bringing on line two major new technologies in steelmaking and the company is unable to devote additional man hours to the SSG process. Because of these other commitments, further investigation by Nucor will be held in abeyance until 1988. Contractural arrangements to license the SSG press has been sought with Paul Wurth Cy. and with Nippon Kokan K.K. Wurth has put the project in abeyance and response from Nippon Kokan is still forthcoming. Negotiations with both companies will be reopened in 1988. A potential application which relates to the DOE project for a coal-fired, gas turbine has been discovered for the SSG process. It appears that consideration of slag handling will probably take place in about two years, at which time further contacts will be made with them. Richard Jablin and Associates plans to continue work on this project without seeking further financial support from the DOE, or from another federal agency.

  4. Viscosity measurements and empirical predictions for coal slags

    SciTech Connect

    Matyas, Josef; Sundaram, S K; Rodriguez, Carmen P; Heredia-Langner, Alejandro; Arrigoni, Benjamin M

    2009-10-25

    Slag viscosity in slagging coal gasifier is an important factor affecting the gasification regime and operating cost. Most of the empirical viscosity models of coal slags that are available in the literature are applicable to only limited ranges of temperature and composition. To develop a reliable slag viscosity model, additional data are needed. Slag viscosity was measured under air or reducing atmosphere (calculated pO2~1.2 10-12 atm at 1400°C) at temperatures in the range of 1150-1550°C on 63 statistically designed slags, including 5 actual coal slag compositions and 4 validation slag compositions. The Arrhenius equation, with Arrhenius coefficients A = constant and B expressed as linear function of mass fractions of nine major components was used to fit the viscosity/temperature data. This Arrhenius relationship represents the viscosity–temperature relationship of tested slags reasonably well, = 0.981 (reducing atmosphere) and = 0.974 (air atmosphere). The validation of the model with four randomly selected slags (two from the SciGlass database and two from experimental design) indicated an accurately measured viscosity-temperature data and a fairly good predictive performance of slag viscosity models over designed compositions. The capability of the developed model to predict the viscosity of coal slags under reducing atmosphere was found to be a superior to a number of the most commonly used empirical models in the literature that are based on simplified oxide melts and British or Australian coal ash slags.

  5. Utilization of lightweight materials made from coal gasification slags. Quarterly report, March 1995--May 1995

    SciTech Connect

    1995-06-01

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, this process generates large amounts of solid waste, consisting of vitrified ash (slag) along with some unconverted carbon, which is disposed of as solid waste. In previous projects, Praxis investigated the utilization of {open_quotes}as-generated{close_quotes} slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for {open_quotes}as-generated{close_quotes} slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag could be made into a lightweight material by controlled heating in a kiln at temperatures between 1400 and 1700{degrees}F. These results indicated the potential for using such materials as substitutes for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project, funded by DOE`s Morgantown Energy Technology Center (METC), are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications.

  6. Utilization of lightweight materials made from coal gasification slags. Quaterly report, December 1, 1996--February 28, 1997

    SciTech Connect

    1998-12-31

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of {open_quotes}as-generated{close_quotes} slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for {open_quotes}as-generated{close_quotes} slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700{degrees}F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis with funding from the Electric Power Research Institute (EPRI), Illinois Clean Coal Institute (ICCI), and internal resources. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications.

  7. Mechanism of Mineral Phase Reconstruction for Improving the Beneficiation of Copper and Iron from Copper Slag

    NASA Astrophysics Data System (ADS)

    Guo, Zhengqi; Zhu, Deqing; Pan, Jan; Zhang, Feng

    2016-08-01

    To maximize the recovery of iron and copper from copper slag, the modification process by adding a compound additive (a mixture of hematite, pyrite and manganous oxide) and optimizing the cooling of the slag was studied. The phase reconstruction mechanism of the slag modification process was revealed by thermodynamic calculations, x-ray diffraction, optical microscopy and scanning electron microscopy. The results show that the synergy between the burnt lime and the compound additive promotes the generation of target minerals, such as magnetite and copper matte. In addition, the multifunctional compound additive is able to improve the fluidity of the molten slag, which facilitates the coalescence and growth of fine particles of the target minerals. As a result, the percentage of iron distributed in the form of magnetite increased from 32.9% to 65.1%, and that of the copper exiting in the form of metallic copper and copper sulfide simultaneously increased from 80.0% to 90.3%. Meanwhile, the grains of the target minerals in the modified slag grew markedly to a mean size of over 50 μm after slow cooling. Ultimately, the beneficiation efficiency of copper and iron was improved because of the ease with which the target minerals could be liberated.

  8. Mechanism of Mineral Phase Reconstruction for Improving the Beneficiation of Copper and Iron from Copper Slag

    NASA Astrophysics Data System (ADS)

    Guo, Zhengqi; Zhu, Deqing; Pan, Jan; Zhang, Feng

    2016-09-01

    To maximize the recovery of iron and copper from copper slag, the modification process by adding a compound additive (a mixture of hematite, pyrite and manganous oxide) and optimizing the cooling of the slag was studied. The phase reconstruction mechanism of the slag modification process was revealed by thermodynamic calculations, x-ray diffraction, optical microscopy and scanning electron microscopy. The results show that the synergy between the burnt lime and the compound additive promotes the generation of target minerals, such as magnetite and copper matte. In addition, the multifunctional compound additive is able to improve the fluidity of the molten slag, which facilitates the coalescence and growth of fine particles of the target minerals. As a result, the percentage of iron distributed in the form of magnetite increased from 32.9% to 65.1%, and that of the copper exiting in the form of metallic copper and copper sulfide simultaneously increased from 80.0% to 90.3%. Meanwhile, the grains of the target minerals in the modified slag grew markedly to a mean size of over 50 μm after slow cooling. Ultimately, the beneficiation efficiency of copper and iron was improved because of the ease with which the target minerals could be liberated.

  9. Removal of contaminants in leachate from landfill by waste steel scrap and converter slag.

    PubMed

    Oh, Byung-Taek; Lee, Jai-Young; Yoon, Jeyong

    2007-08-01

    This study may be the first investigation to be performed into the potential benefits of recycling industrial waste in controlling contaminants in leachate. Batch reactors were used to evaluate the efficacy of waste steel scrap and converter slag to treat mixed contaminants using mimic leachate solution. The waste steel scrap was prepared through pre-treatment by an acid-washed step, which retained both zero-valent iron site and iron oxide site. Extensive trichloroethene (TCE) removal (95%) occurred by acid-washed steel scrap within 48 h. In addition, dehalogenation (Cl(-) production) was observed to be above 7.5% of the added TCE on a molar basis for 48 h. The waste steel scrap also removed tetrachloroethylene (PCE) through the dehalogenation process although to a lesser extent than TCE. Heavy metals (Cr, Mn, Cu, Zn, As, Cd, and Pb) were extensively removed by both acid-washed steel scrap and converter slag through the adsorption process. Among salt ions (NH (4)(+) , NO (3)(-) , and PO (4)(3-) ), PO (4)(3-) was removed by both waste steel scrap (100% within 8 h) and converter slag (100% within 20 min), whereas NO (3)(-) and NH (4)(+ ) were removed by waste steel scrap (100% within 7 days) and converter slag (up to 50% within 4 days) respectively. This work suggests that permeable reactive barriers (PRBs) with waste steel scrap and converter slag might be an effective approach to intercepting mixed contaminants in leachate from landfill.

  10. Estimation Model for Electrical Conductivity of CaF2-CaO-Al2O3 Slags

    NASA Astrophysics Data System (ADS)

    Shi, Guan-yong; Zhang, Ting-an; Dou, Zhi-he; Niu, Li-ping

    2016-09-01

    Electrical conductivity is one of the most important properties of molten slags. It has an important influence on process parameter selection of the electroslag remelting process. In the present work, a new model for estimating electrical conductivity of high-temperature slags has been proposed via calculating the conductivity by electrical conductivity of pure substances and interaction parameters between the different components in the slag has been proposed. In this model, the Arrhenius law is used to describe the relationship between electrical conductivity and temperature of slags. This model has been successfully applied to the CaF2-Al2O3, CaF2-CaO, and CaO-Al2O3, as well as CaF2-CaO-Al2O3 systems, and the calculated results are in good agreement with the measured values.

  11. Geological Sequestration of CO2 by Hydrous Carbonate Formation with Reclaimed Slag

    SciTech Connect

    Von L. Richards; Kent Peaslee; Jeffrey Smith

    2008-02-06

    The concept of this project is to develop a process that improves the kinetics of the hydrous carbonate formation reaction enabling steelmakers to directly remove CO2 from their furnace exhaust gas. It is proposed to bring the furnace exhaust stream containing CO2 in contact with reclaimed steelmaking slag in a reactor that has an environment near the unit activity of water resulting in the production of carbonates. The CO2 emissions from the plant would be reduced by the amount sequestered in the formation of carbonates. The main raw materials for the process are furnace exhaust gases and specially prepared slag.

  12. 44. DETAIL VIEW LOOKING EAST AT THE FOUNDATION FOR SLAG ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    44. DETAIL VIEW LOOKING EAST AT THE FOUNDATION FOR SLAG CRUSHER, A DEVICE USED TO REMOVE HARDENED SLAG FROM STEEL LADLES. - John A. Roebling's Sons Company, Kinkora Works, Support Systems, Roebling, Burlington County, NJ

  13. Predicting slag viscosity from coal ash composition

    SciTech Connect

    Laumb, J.; Benson, S.A.; Katrinak, K.A.; Schwalbe, R.; McCollor, D.P.

    1999-07-01

    Management of slag flow from cyclone-fired utility boilers requires accurate prediction of viscosity. Cyclones tend to build up slag when the cyclone combustion temperature is less than the temperature required to melt and tap the ash from the coal being fired. Cyclone-fired boilers designed for lignite are equipped with predry systems, which remove 6-9% of the moisture from the coal. Cyclones tend to slag when the as-received heating value of the fuel is less than 6350 Btu/lb and T250 (temperature where viscosity equals 250 poise) is greater than 2350 F. The T250 value, as well as the rest of the viscosity-temperature relationship, can be predicted using models based on coal ash composition. The focus of this work is to evaluate several models in terms of their agreement with measured viscosities. Viscosity measurements were made for ten samples, including nine lignite coals and one lignite-derived slag. Model performance is related to the SiO{sub 2}, CaO, and Fe{sub 2}O{sub 3} contents of the slag. The Sage and McIlroy and Kalmanovitch models worked best for high SiO{sub 2} and low Fe{sub 2}O{sub 3} fuels. The Senior model worked best when Fe{sub 2}O{sub 3} content was moderate to high.

  14. The improvement of slagging gasifier refractories

    SciTech Connect

    Kwong, K.-S.; Bennett, J.P.; Powell, C.A.; Krabbe, R.A.

    2006-03-01

    Refractories play a vital role in slagging gasifier on-line availability and profitability for the next clean power generation system. A recent survey of gasifier users by USDOE indicated that a longer service life of refractories is the highest need among gasifier operators. Currently, Cr2O3 based refractories, the best of commercially available materials for use in slagging gasifiers, last between 3 and 24 months. Researchers at Albany Research Center (ARC) have identified structural spalling, caused by slag penetration, as one of the major failure mechanisms of Cr2O3 refractories through postmortem analysis. New Cr2O3 refractories with phosphate additives have been developed by ARC to decrease slag penetration and thus structural spalling. Laboratory physical property tests indicated that ARC developed refractories are superior to other commercial bricks. One of the ARC developed phosphate containing refractories has been installed in a slagging gasifier. Preliminary results of the performance of this refractory in the gasifier will be reported along with research to develop non-chromia refractories.

  15. ENHANCEMENT OF STRUCTURAL FOAM MATERIALS BY INCORPORATION OF GASIFIER SLAG

    SciTech Connect

    Olin Perry Norton; Ronald A. Palmer; W. Gene Ramsey

    2006-03-15

    As advanced gasification technology is increasingly adopted as an energy source, disposal of the resulting slag will become a problem. We have shown that gasifier slag can be incorporated into foamed glass, which is currently being manufactured as an abrasive and as an insulating material. The slag we add to foamed glass does not simply act as filler, but improves the mechanical properties of the product. Incorporation of gasifier slag can make foamed glass stronger and more abrasion resistant.

  16. Immobilization of antimony waste slag by applying geopolymerization and stabilization/solidification technologies.

    PubMed

    Salihoglu, Güray

    2014-11-01

    During the processing of antimony ore by pyrometallurgical methods, a considerable amount of slag is formed. This antimony waste slag is listed by the European Union as absolutely hazardous waste with a European Waste Catalogue code of 10 08 08. Since the levels of antimony and arsenic in the leachate of the antimony waste slag are generally higher than the landfilling limits, it is necessary to treat the slag before landfilling. In this study, stabilization/solidification and geopolymerization technologies were both applied in order to limit the leaching potential of antimony and arsenic. Different combinations ofpastes by using Portland cement, fly ash, clay, gypsum, and blast furnace slag were prepared as stabilization/solidification or geopoljymer matrixes. Sodium silicate-sodium hydroxide solution and sodium hydroxide solution at 8 M were used as activators for geopolymer samples. Efficiencies of the combinations were evaluated in terms of leaching and unconfined compressive strength. None of the geopolymer samples prepared with the activators yielded arsenic and antimony leaching below the regulatory limit at the same time, although they yielded high unconfined compressive strength levels. On the other hand, the stabilization/solidification samples prepared by using water showed low leaching results meeting the landfilling criteria. Use of gypsum as an additive was found to be successful in immobilizing the arsenic and antimony.

  17. Performance evaluation for carbonation of steel-making slags in a slurry reactor.

    PubMed

    Chang, E-E; Chen, Chung-Hua; Chen, Yi-Hung; Pan, Shu-Yuan; Chiang, Pen-Chi

    2011-02-15

    CO(2) sequestration by the aqueous carbonation of steel-making slag under various operational conditions was investigated in this study. The effects of the operational conditions, including type of steel-making slag, reaction time, reaction temperature, and CO(2) flow rate, on the performance of the carbonation process were evaluated. The results indicated that the BOF slag had the highest carbonation conversion, approximately 72%, at a reaction time of 1h, an operating pressure of 101 kPa and a temperature of 60°C due to its higher BET surface area of BOF slag compared to UF, FA, and BHC slags. The major factors affecting the carbonation conversion are reaction time and temperature. The reaction kinetics of the carbonation conversion can be expressed by the shrinking-core model. The measurements of the carbonated material by the SEM and XRD instruments provide evidence indicating the suitability of using the shrinking-core model in this investigation. Comparison of the results with other studies suggests that aqueous carbonation by slurry reactor is viable due to its higher mass transfer rate.

  18. Pre-fired, refractory block slag dams for wet bottom furnace floors

    SciTech Connect

    Vihnicka, R.S.; Meskimen, R.L.

    1998-12-31

    Slagging (wet bottom), utility boilers count on a refractory coating over the furnace floor tube structure for protection from corrosion damage from both the harsh, hot gas atmosphere from the burning fuel and the acidic coal slag. To protect and extend the life of this protective refractory coating the boiler original equipment manufacturers (OEMs) utilized a water-cooled monkey ring or slag chill ring (typically a 6--8 inch high ring of small diameter tubes) surrounding the slag tap locations on most wet bottom furnace floors (both utility and package boilers). The old water-cooled tube ring was such a high maintenance item, however, that it`s use has been discontinued in all but the most extreme environments throughout both utility and industrial applications. Where the use of the ring was discontinued, there has been a corresponding shortening of life on the protective floor refractory coatings (high maintenance cost), further aggravated by recent OSHA restrictions limiting the use of chrome oxide refractory materials in these types of boilers. This paper describes the developmental process and the final resultant product (a non-watercooled, slag dam made from pre-fired refractory shapes), undertaken by the inventors. Derived operational benefits a concept 2 project, with NO{sub x} Title 4 and Title 1 significance (which is currently underway) will also be detailed.

  19. Characterization study of heavy metal-bearing phases in MSW slag.

    PubMed

    Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Motomura, Yoshinobu; Watanabe, Koichiro

    2009-05-30

    Slag products derived from the pyrolysis/melting and plasma/melting treatment of municipal solid waste (MSW) in Japan were examined for the characterization study of heavy metal-bearing phases using petrographic techniques. Detailed microscopic observations revealed that the shapes of heavy metal-rich inclusions are generally spherical to semi-spherical and their sizes range from submicron to scarcely large size spheres (over 100 microm). The experiments (both optical microscopy and electron probe microanalysis) indicated that Fe and Cu participate in mutual substitution and different proportions, and form mainly two-phase Fe-Cu alloys that bound in the silicate glass. This alloy characterizes the composition of more than 80% of the metal-rich inclusions. Other metals and non-metals (such as Pb, Ni, Sb, Sn, P, Si, Al and S) with variable amounts and uneven distributions are also incorporated in the Fe-Cu alloy. In average, the bulk concentration of heavy metals in samples from pyrolysis/melting type is almost six times greater than samples treated under plasma/arc processing. The observations also confirmed that slag from pyrolysis origin contains remarkably higher concentration of metallic inclusions than slag from plasma treatment. In the latter, the metallic compounds are separately tapped from molten slag during the melting treatment that might lead to the generation of safer slag product for end users from environmental viewpoint. PMID:18926624

  20. Mechanism of Phase Formation in the Batch Mixtures for Slag-Bearing Glass Ceramics - 12207

    SciTech Connect

    Stefanovsky, Sergey V.; Stefanovsky, Olga I.; Malinina, Galina A.

    2012-07-01

    Slag surrogate was produced from chemicals by heating to 900 deg. C and keeping at this temperature for 1 hr. The product obtained was intermixed with either sodium di-silicate (75 wt.% waste loading) or borax (85 wt.% slag loading). The mixtures were heat-treated within a temperature range of 25 to 1300 deg. C. The products were examined by X-ray diffraction and infrared spectroscopy. The products prepared at temperatures of up to 1000 deg. C contained both phase typical of the source slag and intermediate phases as well as phases typical of the materials melted at 1350 deg. C such as nepheline, britholite, magnetite and matrix vitreous phase. Vitrification process in batch mixtures consisting of slag surrogate and either sodium di-silicate or sodium tetraborate runs through formation of intermediate phases mainly silico-phosphates capable to incorporate Sm as trivalent actinides surrogate. Reactions in the batch mixtures are in the whole completed by ∼1000 deg. C but higher temperatures are required to homogenize the products. If in the borate-based system the mechanism is close to simple dissolution of slag constituents in the low viscous borate melt, then in the silicate-based system the mechanism was found to be much complicated and includes re-crystallization during melting with segregation of newly-formed nepheline type phase. (authors)

  1. Lignite air-steam gasification in the fluidized bed of iron-containing slag catalysts

    SciTech Connect

    Kuznetsov, B.N.; Shchipko, M.L.; Golovin, Yu.

    1995-12-01

    The influence of fluidized bed of iron-containing slag particles on air-steam gasification of powdered Kansk-Achinsk lignite in entrained flow was studied in pilot installation with productivity about 60 kg per hour. Slag of Martin process and boiler slag were used as catalytic active materials until their complete mechanical attrition. Two following methods of catalytic gasification of lignite were compared: the partial gasification in stationary fluidized bed of slag particles with degree of fuel conversion 40-70% and complete gasification in circulating bed of slag particles. In the first case only the most reactive part of fuel is gasified with the simultaneously formation of porous carbon residue with good sorption ability. It was found the catalytic fluidized bed improves heat transfer from combustion to reduction zone of gas-generator and increases the rate of fuel conversion at the temperature range 900-1000{degrees}C. At these temperatures the degree of conversion is depended considerably on the duration time of fuel particles in the catalytic fluidized bed. The influence of catalytic fluidized bed height and velocity of reaction mixture on the temperature profiles in the gas-generator was studied. The optimal relationship was found between the fluidized bed height and velocity of flow which makes possible to produce the gas with higher calorific value at maximum degree of fuel conversion.

  2. Thermal stabilization of chromium slag by sewage sludge: effects of sludge quantity and temperature.

    PubMed

    Wu, Changlin; Zhang, Hua; He, Pinjing; Shao, Liming

    2010-01-01

    To investigate the feasibility of detoxifying chromium slag by sewage sludge, synthetic chromium slag containing 3% of Cr(VI) was mixed with sewage sludge followed by thermal treatment in nitrogen gas for stabilizing chromium. The effects of slag to sludge ratio (0.5, 1 and 2) and temperature (200, 300, 500, 700 and 900 degrees C) on treatment efficiency were investigated. During the mixing process before thermal treatment, 59.8%-99.7% of Cr(VI) was reduced, but Cr could be easily leached from the reduction product. Increasing heating temperature and decreasing slag to sludge ratio strengthened the reduction and stabilization of Cr(VI). When the slag to sludge ratio was 0.5 and thermal treatment temperature was 300 degrees C, the total leached Cr and Cr(VI) declined to 0.55 mg/L and 0.17 mg/L respectively, and 45.5% of Cr in the thermally treated residue existed as residual fraction. A two-stage mechanism was proposed for the reduction and stabilization of Cr.

  3. Oxidation of 2,4-dinitrophenol by hydrogen peroxide in the presence of basic oxygen furnace slag.

    PubMed

    Li, Y S; You, Y H; Lien, E T

    1999-11-01

    A treatment process was developed when basic oxygen furnace slag (BOF slag) and hydrogen peroxide were used to oxidize 2, 4-dinitrophenol from an aqueous solution. BOF slag, final waste slurry from steel making plants, contains about 12.5% by weight of ferrous oxide. In an acid solution, BOF slag can be dissociated to produce ferrous ions and react with hydrogen peroxide to produce hydroxyl radicals and oxidize 2,4-dinitrophenol. The results of the research demonstrated that the process had a significant capacity for oxidation of 2,4-dinitrophenol from the aqueous phase. Various factors critical to the oxidation of 2,4-dinitrophenol were studied, including hydrogen peroxide concentration, concentration of BOF slag, initial concentration of 2,4-dinitrophenol, and pH value of solution. Experimental results proved that 100 mg/L 2, 4-dinitrophenol and its oxidation intermediate could be totally decomposed within 60 min by 10 g/L BOF slag, 0.18 g/L hydrogen peroxide and pH 2.8 +/- 0.2. The optimum hydrogen peroxide concentration for degradation of 100 mg/L of 2,4-dinitrophenol is between 0.09 g/L and 0.18 g/L as 10 g/L BOF slag in the solution of pH 2.8 +/- 0.2. A hydrogen peroxide concentration higher than 0.18 g/L is disadvantageous to the oxidation process. The oxidation efficiency increased with the increase of BOF slag concentration at 0.18 g/L hydrogen peroxide dose. The best pH value of the solution is in the vicinity of 2.8. An oxidation reaction mechanism was proposed for predicting the concentration changes of 2, 4-dinitrophenol, ferrous ion, and hydrogen peroxide.http://link. springer-ny.com/link/service/journals/00244/bibs/37n4p427.++ +html

  4. Characterization of Slag, Fly Ash and Portland Cement for Saltstone

    SciTech Connect

    Harbour, J

    2006-02-01

    Batch-to-batch variability in the chemical and physical properties of the fly ash, slag and portland cement (binders) will be an ongoing concern over the many years that salt waste from Tank 50 will be processed into grout at the Saltstone Processing Facility. This batch-to-batch variability in the properties of the binder materials translates to variability in the fresh and cured properties of Saltstone. Therefore, it is important to quantify the batch-to-batch variability of the binder materials and the resultant variation in grout properties. This report is the starting point for that process by providing the baseline (reference point) binder properties to which future batches of binder materials can be compared. For this characterization effort, properties of fly ash, slag and portland cement were obtained and documented in this report. These properties included particle size distribution by laser light scattering and dry sieving, particle size and morphology by scanning electron microscopy, true, aerated and tapped densities, chemical composition, rheological properties of the water based slurries made from individual binder material, and volatility through thermogravimetric analysis and differential thermal analysis. The properties presented in this report also provide a baseline data set to assist in problem solving efforts when or if unanticipated and/or unwanted processing events occur at the Saltstone Processing Facility.

  5. Marble-type glass based on blast furnace slag

    SciTech Connect

    Sarkisov, P.D.; Smirnov, V.G.; Trifonova, T.E.; Sergeev, Yu.N.

    1987-01-01

    This paper discusses the recovery and use of blast furnace wastes as coloring agents in the manufacture of imitation marble glass. The slags consist of a series of metal oxides each of which is tested for the color it generates when reacted and annealed with the molten glass. Comparative tests were also run against non-waste coloring agents and it was found that the waste-derived colorants were equal or superior both in process behavior and in generating the appropriate optical properties in the finished glass.

  6. Valorization of electric arc furnace primary steelmaking slags for cement applications.

    PubMed

    Kim, Hyung-Seok; Kim, Kee-Seok; Jung, Sung Suk; Hwang, Jin Ill; Choi, Jae-Seok; Sohn, Il

    2015-07-01

    To produce supplementary cementitious materials from electric arc furnace (EAF) slags, FeO was reduced using a two-stage reduction process that included an Al-dross reduction reaction followed by direct carbon reduction. A decrease in FeO was observed on tapping after the first-stage reduction, and further reduction with a stirred carbon rod in the second-stage reduction resulted in final FeO content below 5wt%, which is compatible with cement clinker applications. The reduced electric arc furnace slags (REAFS) mixed with cement at a unit ratio exhibited physical properties comparable to those of commercialized ground granulated blast furnace slags (GGBFS). Confocal laser scanning microscopy (CLSM) was used to obtain fundamental information on the cooling characteristics and conditions required to obtain amorphous REAFS. REAFS can be applied in cement mixtures to achieve the hydraulic properties needed for commercial use.

  7. Using a direct-current arc furnace to recover cobalt from slags

    NASA Astrophysics Data System (ADS)

    Jones, R. T.; Deneys, A. C.

    1998-10-01

    Cobalt can be recovered from a variety of slags by treatment with a carbonaceous reducing agent in a direct-current arc furnace at around 1,500°C. The principal materials suitable for treatment using this technology are primary smelter slags, which typically originate from the processing of sulfide concentrates. The technology has been tested using copper, nickel-copper, and lead smelting slags. In all cases studied, cobalt is recovered as a valuable by-product to help improve overall plant profitability. Pilot-plant tests have demonstrated a cobalt recovery of more than 80 percent at power levels up to 600 kW. Very high recoveries of other valuable elements, such as nickel and copper, have also been achieved.

  8. Refractory liner materials used in slagging gasifiers

    SciTech Connect

    Bennett, James P.

    2004-09-01

    Refractory liners are used on the working face of entrained flow slagging gasifiers that react coal, petroleum coke, or other carbon feedstock with oxygen and water. The refractory liners protect the gasifier shell from elevated temperatures, corrosive slags, and thermal cycling during gasification. Refractory failure is primarily by two means, corrosive dissolution and spalling. High chrome oxide refractory materials have evolved as the material of choice to line the hot face of gasifiers, yet the performance of these materials does not meet the service requirements of industry. A review of gasifier liner materials, their evolution, issues impacting their performance, and future research direction are discussed.

  9. Using ausmelt technology for the recovery of cobalt from smelter slags

    NASA Astrophysics Data System (ADS)

    Matusewicz, Robert; Mounsey, Ed

    1998-10-01

    The occurrence of cobalt with copper and nickel and the propensity for this material to report mainly to the final-process discard slag has provided a substantial resource in both current arisings and stockpiles in many copper and nickel smelting operations. Ausmelt has undertaken investigations for the recovery of cobalt from smelter slags using top-submerged lancing technology. These tests, conducted at both the laboratory and pilot-plant scales, have provided good evidence of the application of this proven technology to the recovery of cobalt from these sources.

  10. Simulation of slag control for the Plasma Hearth Project

    SciTech Connect

    Power, M.A.; Carney, K.P.; Peters. G.G.

    1996-12-31

    The goal of the Plasma Hearth Project is to stabilize alpha-emitting radionuclides in a vitreous slag and to reduce the effective storage volume of actinide-containing waste for long-term burial. The actinides have been shown to partition into the vitreous slag phase of the melt. The slag composition may be changed by adding glass-former elements to ensure that this removable slag has the most desired physical and chemical properties for long-term burial. A data acquisition and control system has been designed to regulate the composition of five elements in the slag.

  11. Limitation of Sulfide Capacity Concept for Molten Slags

    NASA Astrophysics Data System (ADS)

    Jung, In-Ho; Moosavi-Khoonsari, Elmira

    2016-04-01

    The sulfide capacity concept has been widely used in pyrometallurgy to define sulfur removal capacities of slags. Typically, the sulfide capacity is considered to be a unique slag property depending only on temperature regardless of partial pressures of oxygen and sulfur. In the present study, it is demonstrated that sulfide capacities of slags in particular those of Na2O-containing slags can vary with partial pressures of oxygen and sulfur due to large solubility of sulfide in Na2O-containing slag systems.

  12. Verification of Steelmaking Slags Iron Content Final Technical Progress Report

    SciTech Connect

    J.Y. Hwang

    2006-10-04

    The steel industry in the United States generates about 30 million tons of by-products each year, including 6 million tons of desulfurization and BOF/BOP slag. The recycling of BF (blast furnace) slag has made significant progress in past years with much of the material being utilized as construction aggregate and in cementitious applications. However, the recycling of desulfurization and BOF/BOP slags still faces many technical, economic, and environmental challenges. Previous efforts have focused on in-plant recycling of the by-products, achieving only limited success. As a result, large amounts of by-products of various qualities have been stockpiled at steel mills or disposed into landfills. After more than 50 years of stockpiling and landfilling, available mill site space has diminished and environmental constraints have increased. The prospect of conventionally landfilling of the material is a high cost option, a waste of true national resources, and an eternal material liability issue. The research effort has demonstrated that major inroads have been made in establishing the viability of recycling and reuse of the steelmaking slags. The research identified key components in the slags, developed technologies to separate the iron units and produce marketable products from the separation processes. Three products are generated from the technology developed in this research, including a high grade iron product containing about 90%Fe, a medium grade iron product containing about 60% Fe, and a low grade iron product containing less than 10% Fe. The high grade iron product contains primarily metallic iron and can be marketed as a replacement of pig iron or DRI (Direct Reduced Iron) for steel mills. The medium grade iron product contains both iron oxide and metallic iron and can be utilized as a substitute for the iron ore in the blast furnace. The low grade iron product is rich in calcium, magnesium and iron oxides and silicates. It has a sufficient lime value and

  13. Exploring the life cycle management of industrial solid waste in the case of copper slag.

    PubMed

    Song, Xiaolong; Yang, Jianxin; Lu, Bin; Li, Bo

    2013-06-01

    Industrial solid waste has potential impacts on soil, water and air quality, as well as human health, during its whole life stages. A framework for the life cycle management of industrial solid waste, which integrates the source reduction process, is presented and applied to copper slag management. Three management scenarios of copper slag are developed: (i) production of cement after electric furnace treatment, (ii) production of cement after flotation, and (iii) source reduction before the recycling process. A life cycle assessment is carried out to estimate the environmental burdens of these three scenarios. Life cycle assessment results showed that the environmental burdens of the three scenarios are 2710.09, 2061.19 and 2145.02 Pt respectively. In consideration of the closed-loop recycling process, the environmental performance of the flotation approach excelled that of the electric furnace approach. Additionally, although flash smelting promotes the source reduction of copper slag compared with bath smelting, it did not reduce the overall environmental burdens resulting from the complete copper slag management process. Moreover, it led to the shifting of environmental burdens from ecosystem quality damage and resources depletion to human health damage. The case study shows that it is necessary to integrate the generation process into the whole life cycle of industrial solid waste, and to make an integrated assessment for quantifying the contribution of source reduction, rather than to simply follow the priority of source reduction and the hierarchy of waste management.

  14. THERMOCHEMICAL MODELING OF REFRACTORY CORROSION IN SLAGGING COAL GASIFIERS

    SciTech Connect

    Besmann, Theodore M

    2008-01-01

    Slagging coal gasifiers suffer corrosive attack on the refractory liner and these interactions were thermochemically simulated. The slag is observed to penetrate the refractory, which complicates modeling the phase behavior of the slag-penetrated interior of the refractory. A simple strategy was adopted such that step-wise changes in composition with decreasing slag content were assumed to account for the compositional changes as slag penetrates the refractory. The thermochemical equilibrium calculations following this strategy typically yielded three solution phases as well as the stoichiometric crystalline phases AlPO4 and Ca3(PO4)2 depending on composition/penetration. Under some conditions a slag liquid miscibility gap exists such that two slag liquids co-exist.

  15. Experimental Studies on the Sulfide Capacities of CaO-SiO2-CrOx Slags

    NASA Astrophysics Data System (ADS)

    Wang, Lijun; Seetharaman, Seshadri

    2010-04-01

    To understand the desulfurization process during the refining of Cr-containing steel grades, this work was initiated to study the reactions between Cr-sulfur and chromium-containing slags. The sulfide capacities of CaO-SiO2-CrOx pseudo-ternary slags were measured using the traditional gas-slag equilibration technique between 1823 K and 1923 K. Sixteen different slag compositions were examined, and two different equilibrium oxygen partial pressures were used to understand the impact of the varying valence of Cr on the sulfide capacities. The results showed that log10 Cs varied linearly with the reciprocal T, and the slope was higher than the corresponding value reported for the binary CaO-SiO2 of corresponding composition. It was difficult to isolate the relative effects of the bi- and trivalent Cr in the slags because the Cr2+/Cr3+ ratio was influenced by the basicity of the slag. By using the equation developed by these authors earlier that related Cr2+/Cr3+ with basicity, oxygen partial pressure, and temperature, it was possible to obtain an approximate trend of the CrO effect on the sulfide capacities; viz. the sulfide shows a decreasing trend as Cr2+ replaces Ca2+ in the slag. With a continued increase of Cr2+ content, indications of the occurrence of a minimum point were observed; beyond which the sulfide capacities showed a slight increasing trend. The latter was attributed, based on slag-structure analysis by Gaskell et al., to the increasing extent of the polymerization reaction releasing oxygen ions for sulfide reactions.

  16. Utilization of lightweight materials made from coal gasification slags. Quarterly report, September 1, 1996--November 30, 1996

    SciTech Connect

    1997-04-01

    Integrated-gasification combined-cycle (IGCC) technology is an emerging technology that utilizes coal for power generation and production of chemical feedstocks. However, the process generates large amounts of solid waste, consisting of vitrified ash (slag) and some unconverted carbon. In previous projects, Praxis investigated the utilization of {open_quotes}as-generated{close_quotes} slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, we found that it would be extremely difficult for {open_quotes}as-generated{close_quotes} slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It was further determined that the unconverted carbon, or char, in the slag is detrimental to its utilization as sand or fine aggregate. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1400 and 1700{degrees}F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications.

  17. Removal of metallic iron on oxide slags

    SciTech Connect

    Shannon, G.N.; Fruehan, R.J.; Sridhar, S.

    2009-10-15

    It is possible, in some cases, for ground coal particles to react with gasifier gas during combustion, allowing the ash material in the coal to form phases besides the expected slag phase. One of these phases is metallic iron, because some gasifiers are designed to operate under a reducing atmosphere (pO{sub 2}) of approximately 10{sup -4} atm). Metallic iron can become entrained in the gas stream and deposit on, and foul, downstream equipment. To improve the understanding of the reaction between different metallic iron particles and gas, which eventually oxidizes them, and the slag that the resulting oxide dissolves in, the kinetics of iron reaction on slag were predicted using gas-phase mass-transfer limitations for the reaction and were compared with diffusion in the slag; the reaction itself was observed under confocal scanning laser microscopy. The expected rates for iron droplet removal are provided based on the size and effective partial pressure of oxygen, and it is found that decarburization occurs before iron reaction, leading to an extra 30- to 100-second delay for carbon-saturated particles vs pure iron particles. A pure metallic iron particle of 0.5 mg should be removed in about 220 seconds at 1400{sup o}C and in 160 seconds at 1600{sup o}C.

  18. MECHANISMS OF PYRITE OXIDATION TO NON-SLAGGING SPECIES

    SciTech Connect

    Professor Reginald E. Mitchell

    2002-09-01

    A project was undertaken to characterize the oxidation of iron pyrite to the non-slagging species magnetite during pulverized coal combustion. The work was aimed at defining the pyrite transformations responsible for the higher slagging propensity of staged, low-NO{sub x} pulverized coal combustor burners. With such burners, coal is injected into a reducing environment. Consequently, the products of pyrite combustion become shifted from non-depositing, oxidized species such as Fe{sub 3}O{sub 4} to highly-depositing, reduced species such as FeO and Fe{sub 1-x}S, where x ranges from 0 to 0.125. The propensity for slagging can be minimized by the judicious redistribution of furnace air to maximize the oxide formation rate. This must be accomplished with minimal degradation of other aspects of boiler performance. To effect this, an understanding of the rate-limiting mechanisms of pyrite oxidation is required. The overall objectives of this project were to characterize the various mechanisms that control overall pyrite combustion rates and to synthesize the mechanisms into a pyrite combustion model. These objectives were achieved. The model produced has the capability of being incorporated into numerical codes developed to predict phenomena occurring in coal-fired boilers and furnaces. Such comprehensive codes can be used to formulate and test strategies for enhancing pyrite transformation rates that involve the minor adjustment of firing conditions. Ultimately, the benefit of this research project is intended to be an increase in the range of coals compatible with staged, low-NO{sub x} combustor retrofits. Project activities were aimed at identifying the mechanisms of pyrite combustion and quantifying their effects on the overall oxidation rate in order to formulate a model for pyrite conversion during coal combustion. Chemical and physical processes requiring characterization included pyrite intraparticle kinetics and mass transfer, gas-phase kinetics and mass

  19. Integrated carbon dioxide/sludge gasification using waste heat from hot slags: syngas production and sulfur dioxide fixation.

    PubMed

    Sun, Yongqi; Zhang, Zuotai; Liu, Lili; Wang, Xidong

    2015-04-01

    The integrated CO2/sludge gasification using the waste heat in hot slags, was explored with the aim of syngas production, waste heat recovery and sewage sludge disposal. The results demonstrated that hot slags presented multiple roles on sludge gasification, i.e., not only a good heat carrier (500-950 °C) but also an effective desulfurizer (800-900 °C). The total gas yields increased from 0.022 kg/kgsludge at 500 °C to 0.422 kg/kgsludge at 900 °C; meanwhile, the SO2 concentration at 900 °C remarkably reduced from 164 ppm to 114 ppm by blast furnace slags (BFS) and 93 ppm by steel slags (SS), respectively. A three-stage reaction was clarified including volatile release, char transformation and fixed carbon using Gaussian fittings and the kinetic model was analyzed. Accordingly, a decline process using the integrated method was designed and the optimum slag/sludge ratio was deduced. These deciphered results appealed potential ways of reasonable disposal of sewage sludge and efficient recovery of waste heat from hot slags.

  20. Investigation of Bubble-Slag Layer Behaviors with Hybrid Eulerian-Lagrangian Modeling and Large Eddy Simulation

    NASA Astrophysics Data System (ADS)

    Li, Linmin; Li, Baokuan

    2016-08-01

    In ladle metallurgy, bubble-liquid interaction leads to complex phase structures. Gas bubble behavior, as well as the induced slag layer behavior, plays a significant role in the refining process and the steel quality. In the present work, a mathematical model using the large eddy simulation (LES) is developed to investigate the bubble transport and slag layer behavior in a water model of an argon-stirred ladle. The Eulerian volume of fluid model is adopted to track the liquid steel-slag-air free surfaces while the Lagrangian discrete phase model is used for tracking and handling the dynamics of discrete bubbles. The bubble coalescence is considered using O'Rourke's algorithm to solve the bubble diameter redistribution and bubbles are removed after leaving the air-liquid interface. The turbulent liquid flow that is induced by bubble-liquid interaction is solved by LES. The slag layer fluactuation, slag droplet entrainment and spout eye open-close phenomenon are well revealed. The bubble diameter distribution and the spout eye size are compared with the experiment. The results show that the hybrid Eulerian-Lagrangian-LES model provides a valid modeling framework to predict the unsteady gas bubble-slag layer coupled behaviors.

  1. Dissolution Behaviour of Hazardous Materials from Steel Slag with Wet Grinding Method

    NASA Astrophysics Data System (ADS)

    Hisyamudin Muhd Nor, Nik; Norhana Selamat, Siti; Hanif Abd Rashid, Muhammad; Fauzi Ahmad, Mohd; Jamian, Saifulnizan; Chee Kiong, Sia; Fahrul Hassan, Mohd; Mohamad, Fariza; Yokoyama, Seiji

    2016-06-01

    Steel slag is a by-product from steel industry and it contains variety of hazardous materials. In this study, the dissolution behaviour and removal potential of hazardous materials from steel slag with the wet grinding method was investigated. The slag was wet ground in the CO2 atmosphere and the slurry produced was filtered using centrifugal separator to separate the liquid and solid sediments. Then, the concentrations of dissolved metal elements in the liquid sediment were analyzed by ICP-MS. The changes of pH during the grinding were also investigated. It was found that the pHs were decreased immediately after the CO2 gas introduced into the vessel. The pHs were ranging from 6.8 to 7.6 at the end of grinding. The dissolved concentration of Zn and Cr were ranging from 5~45 [mg/dm3] and 0.2~2.5 [mg/dm3] respectively. The ratios of Zn removal for stainless steel oxidizing and reducing slag were very high, but those from normal steel oxidizing and reducing slag were very low. It is assumed that the Zn dissolved as ZnOH+ from Zn(OH)2 that formed due to the reaction between ZnO and water. Dissolution of Cr also occurred but in very low quantity compared to the dissolution of Zn. The dissolution of Cr occurred due to the grinding process and small amount of Cr(OH)3 was formed during the grinding. This small formation of Cr(OH)3 resulted to the low dissolved concentration of Cr in the form of Cr(OH)2+. According to the XRD analysis, the Cr mostly existed in the slags as Cr(IIl) in the form of MgCr2O4 and FeCr2O4.

  2. Selective Precipitation and Concentrating of Perovskite Crystals from Titanium-Bearing Slag Melt in Supergravity Field

    NASA Astrophysics Data System (ADS)

    Gao, Jintao; Zhong, Yiwei; Guo, Zhancheng

    2016-08-01

    Selective precipitation and concentrating of perovskite crystals from titanium-bearing slag melt in the supergravity field was investigated in this study. Since perovskite was the first precipitated phase from the slag melt during the cooling process, and a greater precipitation quantity and larger crystal sizes of perovskite were obtained at 1593 K to 1563 K (1320 °C to 1290 °C), concentrating of perovskite crystals from the slag melt was carried out at this temperature range in the supergravity field, at which the perovskite transforms into solid particles while the other minerals remain in the liquid melt. The layered structures appeared significantly in the sample obtained by supergravity treatment, and all the perovskite crystals moved along the supergravity direction and concentrated as the perovskite-rich phase in the bottom area, whereas the molten slag concentrated in the upper area along the opposite direction, in which it was impossible to find any perovskite crystals. With the gravity coefficient of G = 750, the mass fraction of TiO2 in the perovskite-rich phase was up to 34.65 wt pct, whereas that of the slag phase was decreased to 12.23 wt pct, and the recovery ratio of Ti in the perovskite-rich phase was up to 75.28 pct. On this basis, an amplification experimental centrifugal apparatus was exploited and the continuous experiment with larger scale was further carried out, the results confirming that selective precipitation and concentrating of perovskite crystals from the titanium-bearing slag melt by supergravity was a feasible method.

  3. A Model for Dissolution of Lime in Steelmaking Slags

    NASA Astrophysics Data System (ADS)

    Sarkar, Rahul; Roy, Ushasi; Ghosh, Dinabandhu

    2016-08-01

    In a previous study by Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015), a dynamic model of the LD steelmaking was developed. The prediction of the previous model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) for the bath (metal) composition matched well with the plant data (Cicutti et al. in Proceedings of 6th International Conference on Molten Slags, Fluxes and Salts, Stockholm City, 2000). However, with respect to the slag composition, the prediction was not satisfactory. The current study aims to improve upon the previous model Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015) by incorporating a lime dissolution submodel into the earlier one. From the industrial point of view, the understanding of the lime dissolution kinetics is important to meet the ever-increasing demand of producing low-P steel at a low basicity. In the current study, three-step kinetics for the lime dissolution is hypothesized on the assumption that a solid layer of 2CaO·SiO2 should form around the unreacted core of the lime. From the available experimental data, it seems improbable that the observed kinetics should be controlled singly by any one kinetic step. Accordingly, a general, mixed control model has been proposed to calculate the dissolution rate of the lime under varying slag compositions and temperatures. First, the rate equation for each of the three rate-controlling steps has been derived, for three different lime geometries. Next, the rate equation for the mixed control kinetics has been derived and solved to find the dissolution rate. The model predictions have been validated by means of the experimental data available in the literature. In addition, the effects of the process conditions on the dissolution rate have been studied, and compared with the experimental results wherever possible. Incorporation of this submodel into the earlier global model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) enables the prediction of the lime dissolution rate

  4. Quantification and Modelling of Fugitive Dust Emissions From Nickel Slag

    NASA Astrophysics Data System (ADS)

    Sanderson, R. S.; McKenna Neuman, C.

    2009-05-01

    Mining and smelting operations in Northern Ontario, and indeed worldwide, introduce a number of unique sources of fugitive dust and other aerosol pollutants into the surrounding environment from smokestacks, tailings, and slag dumps exposed to wind erosion. Fugitive dust represents a potential health hazard, and as such, mining companies are required to maintain inventories of dust emissions associated with their operations. The purpose of this study was to fully characterize the wind-induced fugitive dust emission rates of nickel slag collected from a slag dump at a smelting facility in Northern Ontario, as dependent on wind speed, surface roughness, duration of weathering, effects of mechanical disturbance, and exposure to rain. PM10 flux rates were measured through combined field monitoring and wind tunnel simulation. In both settings, airborne dust concentrations downwind of the source were measured using four vertically distributed DustTrak aerosol monitors. Wind speed was measured in the wind tunnel using a micro-pitot tube mounted on a programmable traversing slide, and in the field, using five vertically distributed cup anemometers mounted on a mast. The profiles of PM10 and wind speed were used to compute the vertical emission rate (Fv) using a finite difference method. The PM10 emission rates simulated in the laboratory were found to directly overlap those measured on site at the smelting facility over a range of wind speeds, suggesting that Fv values measured in wind tunnel simulations can be used in dispersion modelling with a reasonable degree of confidence. Although showing a strong positive correlation with wind speed, PM10 emissions from nickel slag were found to demonstrate an exponential, temporal decay immediately following any form of mechanical disturbance that resulted in exposure of the silt fraction of the material. Winnowing of this fraction left behind an armoured surface of coarse, non-erodible clasts. It was further determined that

  5. Investigation of Freeze-Linings in Copper-Containing Slag Systems: Part I. Preliminary Experiments

    NASA Astrophysics Data System (ADS)

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Jak, Evgueni

    2013-06-01

    Slag freeze-linings are increasingly used in industrial pyrometallurgical processes to insure that furnace integrity is maintained in aggressive high-temperature environments. Most previous studies of freeze-linings have analyzed the formation of slag deposits based solely on heat-transfer models. The focus of the present research is to determine the impact of slag chemistry and local process conditions on the microstructures, thickness, stability, and heat-transfer characteristics of the frozen deposit at steady-state conditions. The formation of the freeze-linings is studied under controlled laboratory conditions using an air-cooled "cold-finger" technique for Cu-Fe-Si-Al-O slag at equilibrium with metallic copper relevant to the industrial copper smelting processes. The phase assemblages and microstructures of the deposits formed in the cold-finger experiments differ significantly from those expected from phase equilibrium considerations. The freeze-lining deposits have been found, in general, to consist of several layers. Starting from the cold finger, these layers consist of glass; glass with microcrystalline precipitates; closed crystalline layer; and open crystalline layer. Even at steady-state conditions, there was no primary phase sealing layer of delafossite [Cu2O · (Al, Fe)2O3] present at the deposit/liquid interface—these observations differ markedly from those expected from phase equilibrium considerations. The findings have significant practical implications, and potential for the improved design and operation of industrial metallurgical furnaces.

  6. Recovering industrial sludge-derived slag as fine aggregate.

    PubMed

    Huang, Yi-Chin; Li, Kung-Cheh; Chiang, Hui-Hsien

    2005-01-01

    This study presents the result of using melting to recover both industrial sludge slag (the main constituent of which is calcium fluoride) and water works sludge slag as fine aggregate in cement. The main characteristics of both slag and cement mortars were measured to evaluate the feasibility of using slag as aggregate. In this study, the slag replacement ratios were 0, 10, 20, 30, 40, and 50% (w/w), and the curing periods were 7, 28, and 90 days. Slag quality was determined according to the standards of fine aggregates in the ASTM specifications, and cement mortars with various slag replacement ratios were evaluated based on their compressive strength, and Toxicity Characteristic Leaching Procedure (TCLP). The crushed slag produced in this study met the ASTM standards for fine aggregate, including gravity, unit weight, absorption, and grading, and the TCLP leached concentrations are far below existing limits, establishing the safety and suitability of slag as fine aggregate. The TCLP leached concentrations of slag and cement mortar were not significantly related to the replacement ratio, and declined with increasing curing period, revealing that the hydration strongly influenced metal leaching. The compressive strength test results of the cement mortars demonstrated that the optimal replacement ratio for maximizing compressive strength was 40%. This study also discussed the effects of replacement ratio and curing periods on cement mortars.

  7. Synthesis and heavy metal immobilization behaviors of slag based geopolymer.

    PubMed

    Yunsheng, Zhang; Wei, Sun; Qianli, Chen; Lin, Chen

    2007-05-01

    In this paper, two aspects of studies are carried out: (1) synthesis of geopolymer by using slag and metakaolin; (2) immobilization behaviors of slag based geopolymer in a presence of Pb and Cu ions. As for the synthesis of slag based geopolymer, four different slag content (10%, 30%, 50%, 70%) and three types of curing regimes (standard curing, steam curing and autoclave curing) are investigated to obtain the optimum synthesis condition based on the compressive and flexural strength. The testing results showed that geopolymer mortar containing 50% slag that is synthesized at steam curing (80 degrees C for 8h), exhibits higher mechanical strengths. The compressive and flexural strengths of slag based geopolymer mortar are 75.2 MPa and 10.1 MPa, respectively. Additionally, Infrared (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques are used to characterize the microstructure of the slag based geopolymer paste. IR spectra show that the absorptive band at 1086 cm(-1) shifts to lower wave number around 1007 cm(-1), and some six-coordinated Als transforms into four-coordination during the synthesis of slag based geopolymer paste. The resulting slag based geopolymeric products are X-ray amorphous materials. SEM observation shows that it is possible to have geopolymeric gel and calcium silicate hydrate (C-S-H) gel forming simultaneously within slag based geopolymer paste. As for immobilization of heavy metals, the leaching tests are employed to investigate the immobilization behaviors of the slag based geopolymer mortar synthesized under the above optimum condition. The leaching tests show that slag based geopolymer mortar can effectively immobilize Cu and Pb heavy metal ions, and the immobilization efficiency reach 98.5% greater when heavy metals are incorporated in the slag geopolymeric matrix in the range of 0.1-0.3%. The Pb exhibits better immobilization efficiency than the Cu in the case of large dosages of heavy metals.

  8. Distribution of Bi Between Slags and Liquid Copper

    NASA Astrophysics Data System (ADS)

    Chen, Chunlin; Wright, Steven

    2016-06-01

    The distribution of Bi between liquid copper and calcium ferrite slag containing 24 wt pct CaO, iron silicate slag with 25 wt pct SiO2, and calcium iron silicate slags was measured at 1573 K (1300 °C) under controlled CO-CO2 atmosphere. The experimental results showed that bismuth distribution is affected by the oxygen partial pressure, and bismuth is likely to exist in slags in the 2+ oxidation state, i.e., as BiO. The distribution ratio between calcium ferrite slag and metal was found to be close to that of iron silicate slag. The Bi distribution ratio was found to decrease with increasing SiO2 and Al2O3 content in slag. Increasing temperature was found to decrease the Bi distribution ratio between slag and metal. Using the measured equilibrium data on Bi content of the metal and slag and composition dependence of the activity of Bi in liquid copper, the activity and hence activity coefficient of BiO in the slag was calculated. The close value of activity coefficient of BiO in both slags at the same oxygen partial pressure indicates that the CaO-BiO and SiO2-BiO interactions are likely to be at the same level, or the FeO x -BiO interaction is the predominant interaction for BiO in the slag. Therefore at a constant FeO x content in the slag, the CaO-BiO and SiO2-BiO interactions doesn't affect γ_{{BiO}} significantly.

  9. Producing fired bricks using coal slag from a gasification plant in indiana

    USGS Publications Warehouse

    Chen, L.-M.; Chou, I.-Ming; Chou, S.-F.J.; Stucki, J.W.

    2009-01-01

    Integrated gasification combined cycle (IGCC) is a promising power generation technology which increases the efficiency of coal-to-power conversion and enhances carbon dioxide concentration in exhaust emissions for better greenhouse gas capture. Two major byproducts from IGCC plants are bottom slag and sulfur. The sulfur can be processed into commercially viable products, but high value applications need to be developed for the slag material in order to improve economics of the process. The purpose of this study was to evaluate the technical feasibility of incorporating coal slag generated by the Wabash River IGCC plant in Indiana as a raw material for the production of fired bricks. Full-size bricks containing up to 20 wt% of the coal slag were successfully produced at a bench-scale facility. These bricks have color and texture similar to those of regular fired bricks and their water absorption properties met the ASTM specifications for a severe weathering grade. Other engineering properties tests, including compressive strength tests, are in progress.

  10. Fluoride evaporation and crystallization behavior of CaF2-CaO-Al2O3-(TiO2) slag for electroslag remelting of Ti-containing steels

    NASA Astrophysics Data System (ADS)

    Shi, Cheng-bin; Cho, Jung-wook; Zheng, Ding-li; Li, Jing

    2016-06-01

    To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2-CaO-Al2O3-(TiO2) slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite (CaTiO3) crystals instead of CaO crystals in the slag. The crystallization of perovskite (CaTiO3) occurs by bulk nucleation and diffusion-controlled one-dimensional growth.

  11. Accelerated carbonation of steel slags in a landfill cover construction.

    PubMed

    Diener, S; Andreas, L; Herrmann, I; Ecke, H; Lagerkvist, A

    2010-01-01

    Steel slags from high-alloyed tool steel production were used in a full scale cover construction of a municipal solid waste (MSW) landfill. In order to study the long-term stability of the steel slags within the final cover, a laboratory experiment was performed. The effect on the ageing process, due to i.e. carbonation, exerted by five different factors resembling both the material characteristics and the environmental conditions is investigated. Leaching behaviour, acid neutralization capacity and mineralogy (evaluated by means of X-ray diffraction, XRD, and thermogravimetry/differential thermal analysis, TG/DTA) are tested after different periods of ageing under different conditions. Samples aged for 3 and 10 months were evaluated in this paper. Multivariate data analysis was used for data evaluation. The results indicate that among the investigated factors, ageing time and carbon dioxide content of the atmosphere were able to exert the most relevant effect. However, further investigations are required in order to clarify the role of the temperature. PMID:19836224

  12. Accelerated carbonation of steel slags in a landfill cover construction

    SciTech Connect

    Diener, S.; Andreas, L.; Herrmann, I.; Ecke, H.; Lagerkvist, A.

    2010-01-15

    Steel slags from high-alloyed tool steel production were used in a full scale cover construction of a municipal solid waste (MSW) landfill. In order to study the long-term stability of the steel slags within the final cover, a laboratory experiment was performed. The effect on the ageing process, due to i.e. carbonation, exerted by five different factors resembling both the material characteristics and the environmental conditions is investigated. Leaching behaviour, acid neutralization capacity and mineralogy (evaluated by means of X-ray diffraction, XRD, and thermogravimetry/differential thermal analysis, TG/DTA) are tested after different periods of ageing under different conditions. Samples aged for 3 and 10 months were evaluated in this paper. Multivariate data analysis was used for data evaluation. The results indicate that among the investigated factors, ageing time and carbon dioxide content of the atmosphere were able to exert the most relevant effect. However, further investigations are required in order to clarify the role of the temperature.

  13. Quantifying the Thermal Behavior of Slags (TRP 9903)

    SciTech Connect

    Alan W. Cramb

    2003-05-30

    Successful operation of a continuous caster is based upon control of heat transfer in the mold. The mold slag is a key component in the success of continuous casting; however, the phenomena that occur in the gap between the shell and the mold are largely unknown as until recently there have been no techniques that allowed visualization and quantification of the solidification behavior of liquid slags. This has lead to slag design being an empirical science or art. Recently a new experimental technique, called Double Hot Thermocouple Technique (DHTT), was developed at Carnegie Mellon University that allowed the solidification behavior of a slag to be observed and quantified under conditions that simulate the thermal conditions that occur in steelmaking environments. This technique allows ladle, tundish and mold slags to be characterized under extreme conditions including those found between the mold wall and the growing shell of a continuous caster. Thus, a program is initiated, under this grant, to quantify and describe the phenomena that occur during the solidification of a slag in a steel mill environment. This will allow slag design to become an engineering science rather than an empirical exercise. The project deliverables were as follows: (1) The further development of a tool that will have broad use in the quantification of slag melting and solidification behavior; and (2) The development of a set of meaningful design criteria for slag application in steel mill environments. The project was broken down into a number of objectives: (a) Develop a systematic understanding of the effect of cooling rate on slag solidification; (b) Develop a systematic understanding on the effect of slag chemistry changes on slag solidification behavior; (c) Develop a method to characterize slag melting; (d) Develop an understanding of the role of the environment on slag solidification and melting; (e) Develop the ability to understand slag solidification under the conditions that

  14. Reduction Kinetics of Electric Arc Furnace Oxidizing Slag by Al-Fe Alloy

    NASA Astrophysics Data System (ADS)

    Lee, Jaehong; Oh, Joon Seok; Lee, Joonho

    2016-07-01

    Effects of temperature and slag basicity on the reduction rate of iron oxide in molten synthetic electric arc furnace oxidizing slag by Al-40 wt.%Fe alloy was investigated. An alloy sample was dropped into molten slag in an MgO crucible. When the initial slag temperature was 1723 K, there was no reduction. However, when the initial slag temperature was 1773 K and the slag basicity was 1.1, the reduction was initiated and the temperature of the slag rapidly increased. When the slag basicity was 1.1, increasing the initial slag temperature from 1773 K to 1823 K increases the reaction rate. As the slag basicity increased from 1.1 to 1.4 at 1773 K, the reaction rate increased. From SEM analysis, it was found that an Al2O3 or a spinel phase at the slag-metal interface inhibited the reaction at a lower temperature and a lower slag basicity.

  15. Reduction Kinetics of Electric Arc Furnace Oxidizing Slag by Al-Fe Alloy

    NASA Astrophysics Data System (ADS)

    Lee, Jaehong; Oh, Joon Seok; Lee, Joonho

    2016-09-01

    Effects of temperature and slag basicity on the reduction rate of iron oxide in molten synthetic electric arc furnace oxidizing slag by Al-40 wt.%Fe alloy was investigated. An alloy sample was dropped into molten slag in an MgO crucible. When the initial slag temperature was 1723 K, there was no reduction. However, when the initial slag temperature was 1773 K and the slag basicity was 1.1, the reduction was initiated and the temperature of the slag rapidly increased. When the slag basicity was 1.1, increasing the initial slag temperature from 1773 K to 1823 K increases the reaction rate. As the slag basicity increased from 1.1 to 1.4 at 1773 K, the reaction rate increased. From SEM analysis, it was found that an Al2O3 or a spinel phase at the slag-metal interface inhibited the reaction at a lower temperature and a lower slag basicity.

  16. PENETRATION OF COAL SLAGS INTO HIGH-CHROMIA REFRACTORIES

    SciTech Connect

    Longanbach, Sara C.; Matyas, Josef; Sundaram, S. K.

    2009-10-05

    Slagging coal gasifiers are used for the production of electricity and synthetic gases, as well as chemicals. High temperatures in the reaction chamber, typically between 1250ºC and 1600ºC, high pressure, generally greater than 400 psi, and corrosive slag place severe demands on the refractory materials. Slag produced during the combustion of coal flows over the refractory surface and penetrates the porous material. Slag penetration is typically followed by spalling of a brick that significantly decreases the service life of gasifier refractories. Laboratory tests were conducted to determine the penetration depth of slags into high-chromia refractories as a function of time and temperature for various refractory-slag combinations.

  17. The Effects of Orbital Distribution from Solid Rocket Motor Slag

    NASA Astrophysics Data System (ADS)

    Peng, Keke; Pang, Baojun; Xiao, Weike

    2013-08-01

    Solid rocket motor (SRM) firings are an important source of space debris environment. The resulting by-products are generally divided into two categories: slag and dust. Dust will re-entry sharply and do not pose a significant hazard. Slag debris can achieve centimeter level, these particles have a serious effect on risk assessment and defend structural design of spacecraft. It is important to understand the size distribution and orbital behavior of slag in order to predict the hazard posed both currently and in the future. Utilizing previous researches on SRM slag and 8-year launch cycle, we have analyzed the orbital distribution of SRM slag. The results indicate that SRM slag is a crucial component of the space debris environment. In order to sustainable utilization outer space, human should forbid the use of SRM in the future, especially for the medium Earth orbit (MEO) and geosynchronous Earth orbit (GEO) regions.

  18. Investigation of the Freeze-Lining Formed in an Industrial Copper Converting Calcium Ferrite Slag

    NASA Astrophysics Data System (ADS)

    Fallah-Mehrjardi, Ata; Jansson, Jani; Taskinen, Pekka; Hayes, Peter C.; Jak, Evgueni

    2014-06-01

    Pyrometallurgical coppermaking processes are operated under intensive reaction conditions; high process temperatures and vigorous bath agitation is used to increase the kinetics of reactions and to achieve high smelter throughput. Slag freeze-lining reactor wall protection is a widely used technology in coppermaking processes, such as flash smelting and converting reactors. Freeze-linings mitigate and resist the effects of thermal and chemical attack by aggressive slags. In this laboratory-based study, a water-cooled probe "cold finger" technique has been used to investigate freeze-lining formation with calcium ferrite slags in equilibrium with metallic copper; the slag composition reflects that used in the industrial copper flash converting furnace of Rio Tinto—Kennecott Utah Copper. The effects of probe immersion times on the thickness and microstructures in the freeze-lining deposits have been investigated. A range of complex oxide solutions and copper-containing phases have been found in the deposits. The phase assemblages formed from the industrial calcium ferrite slag in the steady-state deposit are very complex and information on the phase equilibria of the multi-component systems with addition of minor elements may not be available. Subsolidus and subliquidus phase equilibria in the Cu-Ca-Fe-O system at metallic copper saturation along with interpolated temperature across the deposit, microstructural changes and compositional trends in the phases in the deposit have been used to understand the formation and characteristics of the phases in the steady-state freeze-lining. Also, it has been shown that under steady-state conditions a dense sealing layer consisting primarily of the spinel primary phase is formed at the deposit/liquid interface; however, the interface temperature is below the liquidus temperature. The findings of the study have potentially important implications for the operation of the converting furnace and the design of freeze linings in

  19. Ex Situ CO2 capture by carbonation of steelmaking slag coupled with metalworking wastewater in a rotating packed bed.

    PubMed

    Pan, Shu-Yuan; Chiang, Pen-Chi; Chen, Yi-Hung; Tan, Chung-Sung; Chang, E-E

    2013-04-01

    Both basic oxygen furnace (BOF) slag and cold-rolling wastewater (CRW) exhibiting highly alkaline characteristics require stabilization and neutralization prior to utilization and/or final disposal. Using CO2 from flue gases as the stabilizing and neutralizing agents could also diminish CO2 emissions. In this investigation, ex situ hot stove gas containing 30 vol% CO2 in the steelmaking process was captured by accelerated carbonation of BOF slag coupled with CRW in a rotating packed bed (RPB). The developed RPB process exhibits superior results, with significant CO2 removal efficiency (η) of 96-99% in flue gas achieved within a short reaction time of 1 min at 25 °C and 1 atm. Calcite (CaCO3) was identified as the main product according to XRD and SEM-XEDS observations. In addition, the elimination of lime and Ca(OH)2 in the BOF slag during carbonation is beneficial to its further use as construction material. Consequently, the developed RPB process could capture the CO2 from the flue gas, neutralize the CRW, and demonstrate the utilization potential for BOF slag. It was also concluded that carbonation of BOF slag coupled with CRW in an RPB is a viable method for CO2 capture due to its higher mass transfer rate and CO2 removal efficiency in a short reaction time. PMID:23458276

  20. Ex Situ CO2 capture by carbonation of steelmaking slag coupled with metalworking wastewater in a rotating packed bed.

    PubMed

    Pan, Shu-Yuan; Chiang, Pen-Chi; Chen, Yi-Hung; Tan, Chung-Sung; Chang, E-E

    2013-04-01

    Both basic oxygen furnace (BOF) slag and cold-rolling wastewater (CRW) exhibiting highly alkaline characteristics require stabilization and neutralization prior to utilization and/or final disposal. Using CO2 from flue gases as the stabilizing and neutralizing agents could also diminish CO2 emissions. In this investigation, ex situ hot stove gas containing 30 vol% CO2 in the steelmaking process was captured by accelerated carbonation of BOF slag coupled with CRW in a rotating packed bed (RPB). The developed RPB process exhibits superior results, with significant CO2 removal efficiency (η) of 96-99% in flue gas achieved within a short reaction time of 1 min at 25 °C and 1 atm. Calcite (CaCO3) was identified as the main product according to XRD and SEM-XEDS observations. In addition, the elimination of lime and Ca(OH)2 in the BOF slag during carbonation is beneficial to its further use as construction material. Consequently, the developed RPB process could capture the CO2 from the flue gas, neutralize the CRW, and demonstrate the utilization potential for BOF slag. It was also concluded that carbonation of BOF slag coupled with CRW in an RPB is a viable method for CO2 capture due to its higher mass transfer rate and CO2 removal efficiency in a short reaction time.

  1. Effect of the chemical composition of slag on its foamability in an electric arc furnace

    NASA Astrophysics Data System (ADS)

    Kozhukhov, A. A.

    2015-06-01

    The problems of foaming electric furnace slags are considered. The role of the physicochemical properties of slag during its foaming in electric arc furnaces is studied. The regions of slag foaming in an electric arc furnace are determined. Based on the derived relations between the chemical composition of slag and its foamability, one can choose a rational path of slag formation to ensure good slag foaming in the course of electrosmelting of steel.

  2. Thermochemistry of calcium oxide and calcium hydroxide in fluoride slags

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Mitchell, A.

    1990-08-01

    Calcium oxide activity in binary CaF2-CaO and ternary CaF2-CaO-Al2O3 and CaF2-CaO-SiO2 slags has been determined by CO2-slag equilibrium experiments at 1400 °C. The carbonate ca-pacity of these slags has also been computed and compared with sulfide capacity data available in the literature. The similarity in trends suggests the possibility of characterizing carbonate capacity as an alternative basicity index for fluoride-base slags. Slag-D2O equilibrium experi-ments are performed at 1400°C with different fluoride-base slags to determine water solubility at two different partial pressures of D2O, employing a new slag sampling technique. A novel isotope tracer detection technique is employed to analyze water in the slags. The water solubility data found show higher values than the previous literature data by an order of magnitude but show a linear relationship with the square root of water vapor partial pressure. The activity of hydroxide computed from the data is shown to be helpful in estimating water solubility in in-dustrial electroslag remelting (ESR) slags.

  3. Characteristics of bricks made from waste steel slag.

    PubMed

    Shih, Pai-Haung; Wu, Zong-Zheng; Chiang, Hung-Lung

    2004-01-01

    The characteristics of bricks made from steel slag were investigated in this research. Slag addition was shown to reduce the required firing temperature. When the firing temperature was greater than 1050 degrees C and the slag addition less than 10%, the bricks met ROC national standard CNS 3319 third-class brick for builders. The percentage of slag increased as the quartz and kaolin decreased in the sintered samples while the magnesium aluminum silicate and calcium silicate increased. There were no new crystal phases observed in these samples.

  4. Evaluation of copper slag blast media for railcar maintenance

    NASA Astrophysics Data System (ADS)

    Sagers, N. W.; Finlayson, Mack H.

    1989-06-01

    Copper slag was tested as a blasting substitute for zirconium silicate which is used to remove paint from railroad cars. The copper slag tested is less costly, strips paint faster, is produced near the point of need, provides a good bonding surface for paint, and permits the operator to work in a more comfortable position, i.e., standing nearly erect instead of having to crouch. Outdoor blasting with the tested Blackhawk (20 to 40 mesh) copper slag is also environmentally acceptable to the State of Utah. Results of tests for the surface erosion rate with copper slag blasting are included.

  5. Evaluation of copper slag blast media for railcar maintenance

    NASA Technical Reports Server (NTRS)

    Sagers, N. W.; Finlayson, Mack H.

    1989-01-01

    Copper slag was tested as a blasting substitute for zirconium silicate which is used to remove paint from railroad cars. The copper slag tested is less costly, strips paint faster, is produced near the point of need, provides a good bonding surface for paint, and permits the operator to work in a more comfortable position, i.e., standing nearly erect instead of having to crouch. Outdoor blasting with the tested Blackhawk (20 to 40 mesh) copper slag is also environmentally acceptable to the State of Utah. Results of tests for the surface erosion rate with copper slag blasting are included.

  6. Characteristics and environmental aspects of slag: a review

    USGS Publications Warehouse

    Piatak, Nadine M.; Parsons, Michael B.; Seal, Robert R., II

    2015-01-01

    The composition of ferrous slag is dominated by Ca and Si. Steel slag may contain significant Fe, whereas Mg and Al may be significant in Fe slag. Calcium-rich olivine-group silicates, melilite-group silicates that contain Al or Mg, Ca-rich glass, and oxides are the most commonly reported major phases in ferrous slag. Calcite and trace amounts of a variety of sulfides, intermetallic compounds, and pure metals are typically also present. The composition of non-ferrous slag, most commonly from base-metal production, is dominated by Fe and Si with significant but lesser amounts of Al and Ca. Silicates in the olivine, pyroxene, and melilite groups, as well as glass, spinels, and SiO2 (i.e., quartz and other polymorphs) are commonly found in non-ferrous slag. Sulfides and intermetallic compounds are less abundant than the silicates and oxides. The concentrations of some elements exceed generic USEPA soil screening levels for human contact based on multiple exposure pathways; these elements include Al, Cr, Cu, Fe, Mn, Pb, and Zn based on bulk chemical composition. Each slag type usually contains a specific suite of elements that may be of environmental concern. In general, non-ferrous slag may have a higher potential to negatively impact the environment compared to ferrous slag, and is thus a less attractive material for reuse, based on trace element chemistry, principally for base metals. However, the amount of elements released into the environment is not always consistent with bulk chemical composition. Many types of leaching tests have been used to help predict slag’s long-term environmental behavior. Overall, ferrous slags produce an alkaline leachate due to the dissolution of Ca oxides and silicates derived from compounds originally added as fluxing agents, such as lime. Ferrous slag leachate is commonly less metal-rich than leachate from non-ferrous slag generated during base metal extraction; the latter leachate may even be acidic due to the oxidation of

  7. Durability of Alkali Activated Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Ellis, K.; Alharbi, N.; Matheu, P. S.; Varela, B.; Hailstone, R.

    2015-11-01

    The alkali activation of blast furnace slag has the potential to reduce the environmental impact of cementitious materials and to be applied in geographic zones where weather is a factor that negatively affects performance of materials based on Ordinary Portland Cement. The scientific literature provides many examples of alkali activated slag with high compressive strengths; however research into the durability and resistance to aggressive environments is still necessary for applications in harsh weather conditions. In this study two design mixes of blast furnace slag with mine tailings were activated with a potassium based solution. The design mixes were characterized by scanning electron microscopy, BET analysis and compressive strength testing. Freeze-thaw testing up to 100 freeze-thaw cycles was performed in 10% road salt solution. Our findings included compressive strength of up to 100 MPa after 28 days of curing and 120 MPa after freeze-thaw testing. The relationship between pore size, compressive strength, and compressive strength after freeze-thaw was explored.

  8. Windblown fugitive dust emissions from smelter slag

    NASA Astrophysics Data System (ADS)

    Sanderson, R. Steven; McKenna Neuman, Cheryl; Boulton, J. Wayne

    2014-06-01

    The waste products of mining and smelter operations contain fine particles that, when stored in stockpiles and tailings ponds, are subject to aerodynamic forces that may result in their suspension and transport within boundary layer air flows. The accuracy of atmospheric dispersion models such as AERMOD depends strongly upon suitable inputs for the emission rate that generally must be either measured or estimated from suitable analogues. Measurements of the emission rate of PM10 from smelter slag, based on wind tunnel experiments using the control volume method, are reported in this study and compared with vertical flux values obtained using a finite difference approximation. As compared to natural soils, the dust coatings on slag fragments are rapidly depleted during wind events so that the temporal aspect is important to capture in any consideration of the emission rate. At low wind speeds, vertical flux measurements underestimate the emission rate, but otherwise the agreement is excellent. Comparison with field measurements obtained at the smelter site reveals a degree of overlap with the laboratory data. As a general rule, PM10 emission from smelter slag by aerodynamic entrainment alone is several orders of magnitude lower than published fluxes of total suspended particulate (TSP) emitted from natural soil surfaces for which saltation bombardment is recognized to play a key role in the ejection of dust.

  9. Assessment of hexavalent chromium release in Malaysian electric arc furnace steel slag for fertilizer usage

    NASA Astrophysics Data System (ADS)

    Bankole, L. K.; Rezan, S. A.; Sharif, N. M.

    2014-03-01

    This study investigates the leaching of hexavalent chromium (Cr (VI)) from electric arc furnace steel slag as Cr (VI) is classified as human carcinogen. Batch leaching tests were performed for 16 days. The lixiviants used were alkaline, de-ionized and rain water. After 16 days, Cr (VI) was found to be highest in alkaline water (0.03 mg/L) and lowest in de-ionized water (0.01 mg/L). Besides the lixiviants used, slag stirring speed and liquid to solid ratio also affect Cr (VI) released. The experimental work was complimented with slag characterization using XRF, XRD and SEM/EDX analysis. The leaching process was also simulated via Factsage software to calculate isothermal pourbaix diagrams. The Cr (VI) released was low and below the threshold of 0.1 mg/L set for public water systems. Recycle the slag as fertilizer should be considered safe as it does not exceed the safety limit set for Cr (VI) dissolution.

  10. Effects of thin-film accelerated carbonation on steel slag leaching.

    PubMed

    Baciocchi, R; Costa, G; Polettini, A; Pomi, R

    2015-04-01

    This paper discusses the effects of accelerated carbonation on the leaching behaviour of two types of stainless steel slags (electric arc furnace and argon oxygen decarburisation slag). The release of major elements and toxic metals both at the natural pH and at varying pH conditions was addressed. Geochemical modelling of the eluates was used to theoretically describe leaching and derive information about mineralogical changes induced by carbonation. Among the investigated elements, Ca and Si were most appreciably affected by carbonation. A very clear effect of carbonation on leaching was observed for silicate phases; geochemical modelling indicated that the Ca/Si ratio of Ca-controlling minerals shifted from ∼ 1 for the untreated slag to 0.5-0.67 for the carbonated samples, thus showing that the carbonation process left some residual Ca-depleted silicate phases while the extracted Ca precipitated in the form of carbonate minerals. For toxic metals the changes in leaching induced by carbonation appeared to be mainly related to the resulting pH changes, which were as high as ∼ 2 orders of magnitude upon carbonation. Depending on the specific shape of the respective solubility curves, the extent of leaching of toxic metals from the slag was differently affected by carbonation.

  11. Carbonation of steel slag for CO{sub 2} sequestration: leaching of products and reaction mechanisms

    SciTech Connect

    Wouter J.J. Huijgen; Rob N.J. Comans

    2006-04-15

    Carbonation of industrial alkaline residues can be used as a CO{sub 2} sequestration technology to reduce carbon dioxide emissions. In this study, steel slag samples were carbonated to a varying extent. Leaching experiments and geochemical modeling were used to identify solubility-controlling processes of major and trace elements, both with regard to carbonation mechanisms and the environmental properties of the (carbonated) steel slag. Carbonation was shown to reduce the leaching of alkaline earth metals (except Mg) by conversion of Ca-phases, such as portlandite, ettringite, and Ca-(Fe)-silicates into calcite, possibly containing traces of Ba and Sr. The leaching of vanadium increased substantially upon carbonation, probably due to the dissolution of a Ca-vanadate. The reactive surface area of Al- and Fe-(hydr)oxides increased with the carbonation degree, which tends to reduce the leaching of sorption-controlled trace elements. Sorption on Mn-(hydr)oxides was found to be required to adequately model the leaching of divalent cations, but was not influenced by carbonation. Consideration of these three distinct reactive surfaces and possible (surface) precipitation reactions resulted in adequate modeling predictions of oxyanion and trace metal leaching from (carbonated) steel slag. Hence, these surfaces exert a major influence on the environmental properties of both fresh and carbonated steel slag. 24 refs., 1 fig., 2 tabs.

  12. Effects of sintering atmosphere on the physical and mechanical properties of modified BOF slag glass

    NASA Astrophysics Data System (ADS)

    Dai, Wen-bin; Li, Yu; Cang, Da-qiang; Zhou, Yuan-yuan; Fan, Yong

    2014-05-01

    This study proposes an efficient way to utilize all the chemical components of the basic oxygen furnace (BOF) slag to prepare high value-added glass-ceramics. A molten modified BOF slag was converted from the melting BOF slag by reducing it and separating out iron component in it, and the modified BOF slag was then quenched in water to form glasses with different basicities. The glasses were subsequently sintered in the temperature range of 600-1000°C in air or nitrogen atmosphere for 1 h. The effects of different atmospheres on the physical and mechanical properties of sintered samples were studied by using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and by conducting experiment on evaluating the sintering shrinkage, water absorption and bulk density. It is found that the kinetics of the sintering process is significantly affected by sintering atmosphere. In particular, compared with sintering in air atmosphere, sintering in N2 atmosphere promotes the synergistic growth of pyroxene and melilite crystalline phases, which can contribute to better mechanical properties and denser microstructure.

  13. Carbonation of steel slag for CO2 sequestration: leaching of products and reaction mechanisms.

    PubMed

    Huijgen, Wouter J J; Comans, Rob N J

    2006-04-15

    Carbonation of industrial alkaline residues can be used as a CO2 sequestration technology to reduce carbon dioxide emissions. In this study, steel slag samples were carbonated to a varying extent. Leaching experiments and geochemical modeling were used to identify solubility-controlling processes of major and trace elements, both with regard to carbonation mechanisms and the environmental properties of the (carbonated) steel slag. Carbonation was shown to reduce the leaching of alkaline earth metals (except Mg) by conversion of Ca-phases, such as portlandite, ettringite, and Ca-(Fe)-silicates into calcite, possibly containing traces of Ba and Sr. The leaching of vanadium increased substantially upon carbonation, probably due to the dissolution of a Ca-vanadate. The reactive surface area of Al- and Fe-(hydr)oxides increased with the carbonation degree, which tends to reduce the leaching of sorption-controlled trace elements. Sorption on Mn- (hydr)oxides was found to be required to adequately model the leaching of divalent cations, but was not influenced by carbonation. Consideration of these three distinct reactive surfaces and possible (surface) precipitation reactions resulted in adequate modeling predictions of oxyanion and trace metal leaching from (carbonated) steel slag. Hence, these surfaces exert a major influence on the environmental properties of both fresh and carbonated steel slag.

  14. Phase Equilibria of ``Cu2O''-``FeO''-CaO-MgO-Al2O3 Slags at PO2 of 10-8.5 atm in Equilibrium with Metallic Copper for a Copper Slag Cleaning Production

    NASA Astrophysics Data System (ADS)

    Henao, Hector M.; Pizarro, Claudio; Font, Jonkion; Moyano, Alex; Hayes, Peter C.; Jak, Evgueni

    2010-12-01

    Limited data are available on phase equilibria of the multicomponent slag system at the oxygen partial pressures used in the copper smelting, converting, and slag-cleaning processes. Recently, experimental procedures have been developed and have been applied successfully to characterize several complex industrial slags. The experimental procedures involve high-temperature equilibration on a substrate and quenching followed by electron probe X-ray microanalysis. This technique has been used to construct the liquidus for the “Cu2O”-“FeO”-SiO2-based slags with 2 wt pct of CaO, 0.5 wt pct of MgO, and 4.0 wt pct of Al2O3 at controlled oxygen partial pressures in equilibrium with metallic copper. The selected ranges of compositions and temperatures are directly relevant to the copper slag-cleaning processes. The new experimental equilibrium results are presented in the form of ternary sections and as a liquidus temperature vs Fe/SiO2 weight ratio diagram. The experimental results are compared with the FactSage thermodynamic model calculations.

  15. Dissolution Behavior of Rhodium in the Na2O-SiO2 and CaO-SiO2 Slags

    NASA Astrophysics Data System (ADS)

    Wiraseranee, Chompunoot; Okabe, Toru H.; Morita, Kazuki

    2013-06-01

    To understand the behavior of rhodium during its recovery process, the dissolution behaviors of rhodium in Na2O-SiO2 and in CaO-SiO2 slags at temperatures ranging from 1423 K to 1623 K (from 1150 °C to 1350 °C) and from 1773 K to 1873 K (from 1500 °C to 1600 °C), respectively, in an oxidizing atmosphere were investigated. The solubility of rhodium in the slags was found to increase with increasing oxygen partial pressure, temperature, and the basic oxide content. The correlation between the solubility of rhodium and the oxygen partial pressure suggested that rhodium dissolved into the slags as RhO1.5. The dissolution of rhodium was slightly endothermic: the enthalpy change of the dissolution of solid rhodium was determined to be 50 ± 10 kJ/mol for the 50(mass pct)Na2O-50SiO2; and 188 ± 94 kJ/mol for the 56(mass pct)CaO-44SiO2 slag systems. The increase in the solubility of rhodium with the basic oxide content indicated that rhodium exhibits acidic behavior in slags. The correlation between the solubility of rhodium and the sulfide capacity of the slags suggested that the ionic species of rhodium in slags is the rhodate ion, RhO{2/-}. The rhodate capacity of the slags was defined, and its application to estimate the possible rhodium content in various slag systems was proposed.

  16. Stabilization of residues obtained from the treatment of laboratory waste: Part 2--transformation of plasma vitrified slag into composites.

    PubMed

    Kuo, Yi-Ming; Tseng, Ho-Jung; Chang, Juu-En; Chao, Chih-C; Wang, Chih-Ta; Chang-Chien, Guo-Ping; Wang, Jian-Wen

    2011-01-01

    The Sustainable Environment Research Center of National Cheng Kung University in Taiwan has set up a treatment plant to dispose of laboratory waste. In the treatment process, the residue from the incineration system and the physical and chemical system is vitrified by a plasma melting system. Part 1 of this study described the treatment path of metals during vitrification. In Part 2, plasma vitrified slag is reused by using a molding technology. Unsaturated polyester resin and glass fiber were used as the molding material and additive, respectively, in the molding process. With an appropriate mixing ratio of unsaturated polyester resin, glass fiber, and slag, the physical properties of composites improved, and the ultimate tensile strength reached 17.6 MPa. However, an excess amount of slag reduced the strength and even retarded the production of composites. Differential thermal analysis and the water bathing test results show that the composite decomposed at 80 degrees C and that it vaporized at 187 degrees C. Although the unsaturated polyester resin decomposed, the metal encapsulated in the slag did not leach out. The results show that the reuse of slag using molding technology should be taken into consideration. PMID:21305891

  17. Mineral CO2 sequestration by steel slag carbonation.

    PubMed

    Huijgen, Wouter J J; Witkamp, Geert-Jan; Comans, Rob N J

    2005-12-15

    Mineral CO2 sequestration, i.e., carbonation of alkaline silicate Ca/Mg minerals, analogous to natural weathering processes, is a possible technology for the reduction of carbon dioxide emissions to the atmosphere. In this paper, alkaline Ca-rich industrial residues are presented as a possible feedstock for mineral CO2 sequestration. These materials are cheap, available near large point sources of CO2, and tend to react relatively rapidly with CO2 due to their chemical instability. Ground steel slag was carbonated in aqueous suspensions to study its reaction mechanisms. Process variables, such as particle size, temperature, carbon dioxide pressure, and reaction time, were systematically varied, and their influence on the carbonation rate was investigated. The maximum carbonation degree reached was 74% of the Ca content in 30 min at 19 bar CO2 pressure, 100 degrees C, and a particle size of <38 microm. The two most important factors determining the reaction rate are particle size (<2 mm to <38 microm) and reaction temperature (25-225 degrees C). The carbonation reaction was found to occur in two steps: (1) leaching of calcium from the steel slag particles into the solution; (2) precipitation of calcite on the surface of these particles. The first step and, more in particular, the diffusion of calcium through the solid matrix toward the surface appeared to be the rate-determining reaction step. The Ca diffusion was found to be hindered by the formation of a CaCO3-coating and a Ca-depleted silicate zone during the carbonation process. Research on further enhancement of the reaction rate, which would contribute to the development of a cost-effective CO2-sequestration process, should focus particularly on this mechanism.

  18. Process for improving metal production in steelmaking processes

    DOEpatents

    Pal, Uday B.; Gazula, Gopala K. M.; Hasham, Ali

    1996-01-01

    A process and apparatus for improving metal production in ironmaking and steelmaking processes is disclosed. The use of an inert metallic conductor in the slag containing crucible and the addition of a transition metal oxide to the slag are the disclosed process improvements.

  19. Process for improving metal production in steelmaking processes

    DOEpatents

    Pal, U.B.; Gazula, G.K.M.; Hasham, A.

    1996-06-18

    A process and apparatus for improving metal production in ironmaking and steelmaking processes is disclosed. The use of an inert metallic conductor in the slag containing crucible and the addition of a transition metal oxide to the slag are the disclosed process improvements. 6 figs.

  20. Foamability of stainless steelmaking slags in an EAF

    NASA Astrophysics Data System (ADS)

    Kerr, James John

    Foaming in electric furnace steelmaking is desirable to allow for a longer arc and subsequently higher power operation in order to reduce the tap to tap time and consequently increase productivity. Stainless steelmaking slags do not foam as well as carbon steelmaking slags. To produce foam, the foamability or foam index of a slag and the gas generation rate must be adequate. The possible causes for the poor foamability of stainless steelmaking slags were examined in this research. Specifically the foam index of a simulated stainless steelmaking slag containing chrome oxide was measured and the rate at which carbon reacts with Cr2O3, CrO, and FeO was also measured. The experimental results show that the foam index of stainless steelmaking slags is comparable to carbon steelmaking slags provided that the amount of solid chrome oxide particles or complexes is not excessive. This indicates the low foamability is not due to a poor foam index. Gas is normally generated by cycling carbon into the slag, which produces CO by reducing oxides in the slag. The experimental results demonstrate that the reaction rate of carbon with CrO dissolved in the slag and hence the generation of CO is significantly slower than for the reaction rate of carbon with FeO dissolved in slags. Therefore, the lack of FeO or other reducible oxides in stainless steelmaking slags is a primary reason for the poor foamability. Experimental results indicate that limestone, nickel oxide, calcium nitrate, and waste oxide briquettes generate gas at sufficient rates to induce foaming when added to the stainless steelmaking slag. Heat transfer most likely controls the rate of CO2 generated by limestone and NiO reduction is controlled by mass transfer of NiO to the carbon in the slag. WOBs generate gas very rapidly due to intimate mixing of the carbon and iron oxides at unit activity. Calcium nitrate generates gas by dissociation and heat transfer likely controls the dissociation rate. Simple models are

  1. Investigation of Copper Ammonia Leaching from Smelter Slags: Characterization, Leaching and Kinetics

    NASA Astrophysics Data System (ADS)

    Bidari, Ehsan; Aghazadeh, Valeh

    2015-10-01

    Although ammonia leaching of copper from slags has been reported generally as a part of copper slag utilization methods, but no detailed studies have been reported in the literature. In this research, we tried to investigate the effect of different parameters on ammonia leaching of copper from copper smelting slag by identifying different copper-bearing phases and following them during leaching time. Mineralogical characterization of the smelting slag (1.7 pct Cu) was done using X-ray fluorescence, X-ray diffraction, optical microscopy, diagnostic leaching tests, and scanning electron microscopy. The characterization studies indicated that main copper-bearing species are soluble copper oxides and chalcocite along with minor amount of covellite, bornite, blister copper particles, and chalcopyrite. It was also found that only approximately 0.2 pct Cu was present in the insoluble bulk silicate phases. These results suggest that approximately 88 pct of the total copper of slag could be extracted by ammonia sulfide leaching. Leaching tests were carried out and the effects of various parameters, namely pH, ammonia concentration, temperature, presence of oxygen, stirring speed, and pulp density were examined on copper leaching. The temperature and stirring speed had the most pronounced effect on the copper leaching, whereas ammonia affected the leaching yield at low concentrations of ammonia. It was found that 78 pct of Cu could be extracted within 4 hours and under optimum conditions: T = 343 K (70 °C), 2M ammonia, pH 10.5, stirring speed = 900 rpm, pulp density = 10 pct ( w s/ v). The kinetic data were analyzed with the shrinking core models, and it was found that the leaching process is controlled by both the interfacial transfer and diffusion across the product layer and the activation energy is calculated to be 49.4 kJ mol-1.

  2. Thin-film versus slurry-phase carbonation of steel slag: CO₂ uptake and effects on mineralogy.

    PubMed

    Baciocchi, R; Costa, G; Di Gianfilippo, M; Polettini, A; Pomi, R; Stramazzo, A

    2015-01-01

    The results of direct aqueous accelerated carbonation of three types of steel manufacturing residues, including an electric arc furnace (EAF) slag and two basic oxygen furnace (BOF) slags, are reported. Batch accelerated carbonation tests were conducted at different temperatures and CO2 pressures applying the thin-film route (liquid to solid, L/S, ratio=0.3L/kg) or the slurry-phase route (L/S ratio=5L/kg). The CO2 uptake strongly depended on both the slag characteristics and the process route; maximum yields of 280 (EAF), 325 (BOF1) and 403 (BOF2) gCO2/kg slag were achieved in slurry phase at T=100°C and pCO2=10 bar. Differently from previous studies, additional carbonates (other than Ca-based phases) were retrieved in the carbonated BOF slags, indicating that also Mg-, Fe- and Mn-containing phases partially reacted with CO2 under the tested conditions. The results hence show that the effects of accelerated carbonation in terms of CO2 uptake capacity, yield of mineral conversion into carbonates and mineralogy of the treated product, strongly rely on several factors. These include, above all, the mineralogy of the original material and the operating conditions adopted, which thus need specific case-by-case optimization to maximize the CO2 sequestration yield.

  3. Phase analytical studies of industrial copper smelting slags. Part I: Silicate slags

    NASA Astrophysics Data System (ADS)

    Rüffler, R.; Dávalos, J.

    1998-12-01

    The pyrometallurgical extraction of copper from sulfide ore concentrates is determined by the behaviour of the associated iron during smelting. Hence, 57Fe Mössbauer spectroscopy is an attractive tool for studying the phases in silicate slags from German and Chilean smelting plants. Other methods used were ore microscopy, electron microprobe analysis, and X-ray powder diffraction.

  4. Measurement of Moisture Content in Sand, Slag, and Crucible Materials

    SciTech Connect

    Gray, J.H.

    1999-09-20

    The deinventory process at Rocky Flats (RFETS) has included moisture content measurements of sand, slag, and crucible (SSC) materials by performing weight loss measurements at 210 degrees - 220 degrees Celsius on representative samples prior to packaging for shipment. Shipping requirements include knowledge of the moisture content. Work at the Savannah River Technology Center (SRTC) showed that the measurement at 210 degrees - 220 degrees Celsius did not account for all of the moisture. The objective of the work in this report was to determine if the measurement at 210 degrees - 220 degrees Celsius at RFETS could be used to set upper bounds on moisture content and therefore, eliminate the need for RFETS to unpack, reanalyze and repack the material.

  5. Mechanisms of hydrogen sulfide removal with steel making slag.

    PubMed

    Kim, Kyunghoi; Asaoka, Satoshi; Yamamoto, Tamiji; Hayakawa, Shinjiro; Takeda, Kazuhiko; Katayama, Misaki; Onoue, Takasumi

    2012-09-18

    In the present study, we experimentally investigated the removal of hydrogen sulfide using steel-making slag (SMS) and clarified the mechanism of hydrogen sulfide removal with the SMS. The results proved that SMS is able to remove hydrogen sulfide dissolved in water, and the maximum removal amount of hydrogen sulfide per unit weight of the SMS for 8 days was estimated to be 37.5 mg S/g. The removal processes of hydrogen sulfide were not only adsorption onto the SMS, but oxidation and precipitation as sulfur. The chemical forms of sulfide adsorbed onto the SMS were estimated to be sulfur and manganese sulfide in the ratio of 81% and 19%, respectively. It is demonstrated here that the SMS is a promising material to remediate organically enriched coastal sediments in terms of removal of hydrogen sulfide. Furthermore, using SMS is expected to contribute to development of a recycling-oriented society.

  6. Sulfide capacity of high alumina blast furnace slags

    NASA Astrophysics Data System (ADS)

    Shankar, Amitabh; Görnerup, Märten; Seetharaman, S.; Lahiri, A. K.

    2006-12-01

    Sulfide capacities of high alumina blast furnace slags were experimentally determined using the gas-slag equilibration technique. Two different slag systems were considered for the current study, namely, CaO-SiO2-MgO-Al2O3 quaternary and CaO-SiO2-MgO-Al2O3-TiO2 quinary system. The liquid slag was equilibrated with the Ar-CO-CO2-SO2 gas mixture. Experiments were conducted in the temperature range of 1773 to 1873 K. The effects of temperature, basicity, and the MgO and TiO2 contents of slags on sulfide capacity were studied. As expected, sulfide capacity was found to increase with the increase in temperature and basicity. At the higher experimental temperature, titania decreases the sulfide capacity of slag. However, at the lower temperature, there was no significant effect of titania on the sulfide capacity of slag. Sulfide capacity increases with the increase in MgO content of slag if the MgO content is more than 5 pct.

  7. Crystallization of Synthetic Blast Furnace Slags Pertaining to Heat Recovery

    NASA Astrophysics Data System (ADS)

    Esfahani, Shaghayegh

    Heat recovery from blast furnace slags is often contradicted by another requirement, to generate amorphous slag for its use in cement production. As both the rate and extent of heat recovery and slag structure are determined by its cooling rate, a relation between the crystallization kinetics and the cooling conditions is highly desired. In this study, CaO-SiO2-Al2O3-MgO (CSAM) slags with different basicities were studied by Single Hot Thermocouple Technique (SHTT) during isothermal treatment and non-isothermal cooling. Their time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams were plotted and compared with each other. Furthermore, kinetic parameters such as the Avrami exponent (n), rate coefficient (K) and effective activation energy of crystallization (EA) were found by analysis of data obtained from in-situ observation of glassy to crystalline transformation and image analysis. Also, the dependence of nucleation and growth rates of crystalline phases were quantified as a function of time, temperature, and slag basicity. Together with the observations of crystallization front, they facilitated establishing the dominant mechanisms of crystallization. In addition to the experimental work, a mathematical model was developed and validated that predicts the amount of crystallization during cooling. A second mathematical model that calculates temperature history of slag during its cooling was coupled with the above model, to allow studying the effect of parameters such as the slag/air ratio and granule size on the heat recovery and glass content of slag.

  8. Interactions of Refractory Materials with Molten Gasifier Slags

    SciTech Connect

    Nakano, Jimichiro; Sridhar, Seetharaman; Kwong, Kye-Sing; Bennett, James; Moss, Tyler

    2011-04-01

    The current study focuses on the analysis of sessile-drop interfacial reactions between two synthetic slags (based on average ash chemistries of coal and petcoke feedstock) and two refractory materials (90 wt% Cr{sub 2}O{sub 3}–10 wt% Al{sub 2}O{sub 3} and 100 wt% Al{sub 2}O{sub 3}), using a Confocal Scanning Laser Microscope (CSLM). Ground slag samples (less than 325 mesh) were placed at specific microstructure locations on refractory substrates and heated to 1500 °C in an atmosphere of CO/CO{sub 2} gas mixture (volume ratio = 1.8), using a gold-image heating chamber. Cross-sections of the slag/refractory interface indicated unique slag penetration into preferred areas of the refractory and grain dissolution into the slag which promoted spalling of the refractory. Initially, the slag attacked both grain boundaries and fine microstructure areas, freeing alumina grains into the slag. The formation of VO{sub x}-based crystalline material in the petcoke slag was found to alter the liquid composition. Chemical spalling of Cr-containing crystal layer also facilitated degradation of the refractory.

  9. Micronutrient availability from steel slag amendment in pine bark substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Steel slag is a byproduct of the steel industry that can be used as a liming agent, but also has a high mineral nutrient content. While micronutrients are present in steel slag, it is not known if the mineral form of the micronutrients would render them available for plant uptake. The objective of...

  10. A ceramographic evaluation of chromia refractories corroded by slag

    SciTech Connect

    Hunt, Alton H.; Chinn, Richard E.

    2001-01-01

    This paper describes the ceramographic preparation of Cr{sub 2}O{sub 3}-Al{sub 2}O{sub 3} refractory bricks and subsequent microstructural analysis to determine the corrosive effects of molten slag. The porous and friable nature of the brick, especially after exposure to the slag or its individual components, presented some problems in the preparation.

  11. Thermodynamics Behavior of Germanium During Equilibrium Reactions between FeOx-CaO-SiO2-MgO Slag and Molten Copper

    NASA Astrophysics Data System (ADS)

    Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S.; Reuter, M. A.

    2016-10-01

    The distribution ratio of germanium (Ge), L_{{Ge}}^{s/m} during equilibrium reactions between magnesia-saturated FeOx-CaO-SiO2 (FCS) slag and molten copper has been measured under oxygen partial pressures from 10-10 to 10-7 atm and at temperatures 1473 to 1623 K (1200 to 1350 °C). It was observed that the Ge distribution ratio increases with increasing oxygen partial pressure, and with decreasing temperature. It was also observed that the distribution ratio is strongly dependent on slag basicity. The distribution ratio was observed to increase with increasing optical basicity. At fixed CaO concentration in the slag, the distribution ratio was found to increase with increasing Fe/SiO2 ratio, tending to a plateau at L_{{Ge}}^{s/m} = 0.8. This behavior is consistent with the assessment of ionic bond fraction carried out in this study, and suggested the acidic nature of germanium oxide (GeO2) in the slag system studied. The characterisation results of the quenched slag suggested that Ge is present in the FeOx-CaO-SiO2-MgO slag predominantly as GeO2. At 1573 K (1300 °C) and p_{{{{O}}2 }} = 10-8 atm, the activity coefficient of GeO2 in the slag was calculated to be in the range of 0.24 to 1.50. The results from the current study suggested that less-basic slag, high operating temperature, and low oxygen partial pressure promote a low Ge distribution ratio. These conditions are desired for maximizing Ge recovery, for example, during pyrometallurgical processing of Ge-containing e-waste through secondary copper smelting. Overall, the thermodynamics data generated from this study can be used for process modeling purposes for improving recovery of Ge in primary and secondary copper smelting processes.

  12. Refractory-Slag-Metal-Inclusion Multiphase Reactions Modeling Using Computational Thermodynamics: Kinetic Model for Prediction of Inclusion Evolution in Molten Steel

    NASA Astrophysics Data System (ADS)

    Shuva, M. A. H.; Rhamdhani, M. A.; Brooks, G. A.; Masood, S.; Reuter, M. A.

    2016-07-01

    The distribution ratio of germanium (Ge), L_{{Ge}}^{s/m} during equilibrium reactions between magnesia-saturated FeOx-CaO-SiO2 (FCS) slag and molten copper has been measured under oxygen partial pressures from 10-10 to 10-7 atm and at temperatures 1473 to 1623 K (1200 to 1350 °C). It was observed that the Ge distribution ratio increases with increasing oxygen partial pressure, and with decreasing temperature. It was also observed that the distribution ratio is strongly dependent on slag basicity. The distribution ratio was observed to increase with increasing optical basicity. At fixed CaO concentration in the slag, the distribution ratio was found to increase with increasing Fe/SiO2 ratio, tending to a plateau at L_{{Ge}}^{s/m} = 0.8. This behavior is consistent with the assessment of ionic bond fraction carried out in this study, and suggested the acidic nature of germanium oxide (GeO2) in the slag system studied. The characterisation results of the quenched slag suggested that Ge is present in the FeOx-CaO-SiO2-MgO slag predominantly as GeO2. At 1573 K (1300 °C) and p_{{{{O}}2 }} = 10-8 atm, the activity coefficient of GeO2 in the slag was calculated to be in the range of 0.24 to 1.50. The results from the current study suggested that less-basic slag, high operating temperature, and low oxygen partial pressure promote a low Ge distribution ratio. These conditions are desired for maximizing Ge recovery, for example, during pyrometallurgical processing of Ge-containing e-waste through secondary copper smelting. Overall, the thermodynamics data generated from this study can be used for process modeling purposes for improving recovery of Ge in primary and secondary copper smelting processes.

  13. Improved refractories for slagging gasifiers in IGCC power systems

    SciTech Connect

    Bennett, James P.; Kwong, Kyei-Sing; Powell, Cynthia A.; Chinn, Richard E.

    2004-01-01

    Most gasifiers are operated for refining, chemical production, and power generation. They are also considered a possible future source of H2 for future power systems under consideration. A gasifier fulfills these roles by acting as a containment vessel to react carbon-containing raw materials with oxygen and water using fluidized-bed, moving-bed, or entrained-flow systems to produce CO and H2, along with other gaseous by-products including CO2, CH4, SOx, HS, and/or NOx. The gasification process provides the opportunity to produce energy more efficiently and with less environmental impact than more conventional combustion processes. Because of these advantages, gasification is viewed as one of the key processes in the U.S. Department of Energy?s vision of an advanced power system for the 21st Century. However, issues with both the reliability and the economics of gasifier operation will have to be resolved before gasification will be widely adopted by the power industry. Central to both enhanced reliability and economics is the development of materials with longer service lives in gasifier systems that can provide extended periods of continuous, trouble-free gasifier operation. The focus of the Advanced Refractories for Gasification project at the Albany Research Center (ARC) is to develop improved refractory liner materials capable of withstanding the harsh, high-temperature environment created by the gasification reaction. Current generation refractory liners in slagging gasifiers are typically replaced every 3 to 18 months at costs ranging up to $1,000,000 or more, depending upon the size of the gasification vessel. Compounding materials and installation costs are the lost-opportunity costs for the time that the gasifier is off-line for refractory repair/exchange. The goal of this project is to develop new refractory materials or to extend the service life of refractory liner materials currently used to at least 3 years. Post-mortem analyses of refractory brick

  14. [Bioregeneration of the solutions obtained during the leaching of nonferrous metals from waste slag by acidophilic microorganisms].

    PubMed

    Fomchenko, N V; Murav'ev, M I; Kondrat'eva, T F

    2014-01-01

    The bioregeneration of the solutions obtained after the leaching of copper and zinc from waste slag by sulfuric solutions of ferric sulfate is examined. For bioregeneration, associations of mesophilic and moderately thermqophilic acidophilic chemolithotrophic microorganisms were made. It has been shown that the complete oxidation of iron ions in solutions obtained after the leaching of nonferrous metals from waste slag is possible at a dilution of the pregnant solution with a nutrient medium. It has been found that the maximal rate of oxidation of iron ions is observed at the use of a mesophilic association of microorganisms at a threefold dilution of the pregnant solution with a nutrient medium. The application ofbioregeneration during the production of nonferrous metals from both waste and converter slags would make it possible to approach the technology of their processing using the closed cycle of workflows.

  15. Utilisation of IGCC slag and clay steriles in soft mud bricks (by pressing) for use in building bricks manufacturing.

    PubMed

    Acosta, A; Iglesias, I; Aineto, M; Romero, M; Rincón, J Ma

    2002-01-01

    The subject of this study is the application to the construction of soft mud bricks (also known as pressed bricks), both green and heat-treated bodies, built from raw materials from Santa Cruz de Mudela, Ciudad Real, and IGCC slag from the power central of Puertollano (Ciudad Real, Spain). For this purpose, industrial level tests have been performed: the production of these kind of bricks from mixes of waste from ores of construction clays and to significant fraction of different ratios and clay granulometries mixed with IGCC slag. The results of this experimentation suggests that not only can IGCC slag be applied to a ceramic process, but also its use gives several advantages, as water and energy savings, as well as improvements on the final properties of products.

  16. Mechanisms of pyrite oxidation to non-slagging species. Quarterly report, January 1, 1995--March 31, 1995

    SciTech Connect

    Akan-Etuk, A.E.J.; Mitchell, R.E.

    1995-08-01

    This document is the third quarterly status report on a project conducted at the High Temperature Gasdynamics Laboratory at Stanford University, Stanford, California and concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO{sub x} pulverized coal (P.C.) combustion. The research project is intended to advance PETC`s efforts to improve our technical understanding of the high-temperature chemical and physical processes involved in the utilization of coal. The work focuses on the mechanistic description and rate quantification of the effects of fuel properties and combustion environment on the oxidation of iron pyrite to form the non-slagging species magnetite. The knowledge gained from this work is intended to be incorporated into numerical codes that can be used to formulate anti-slagging strategies involving minimal disturbance of coal combustor performance.

  17. Cu-Zn Slags from R⊘ros (Norway): A Case Study of Rapid Cooling and Crystal Nucleation

    NASA Astrophysics Data System (ADS)

    Warchulski, Rafał; Szopa, Krzysztof

    2014-09-01

    The mining town of R⊘ros located in central Norway was established in 1644 and it is known of historical mining industry related to copper. R⊘ros was designated as an UNESCO World Heritage Site in 1980 on the base of mining culture represented by, e.g., unique wooden architecture. Slag pieces are composed of three parts differing in glass to crystallites ratio. R⊘ros slags are composed of olivine- and pyroxene- group minerals accompanied by sulphides, with glass in the interstices. Temperature gradient and volatiles content were determined as the main factor influencing crystallization process in this material.

  18. Cu-Zn slags from Røros (Norway): a case study of rapid cooling and crystal nucleation

    NASA Astrophysics Data System (ADS)

    Warchulski, Rafał; Szopa, Krzysztof

    2014-09-01

    The mining town of Røros located in central Norway was established in 1644 and it is known of historical mining industry related to copper. Røros was designated as an UNESCO World Heritage Site in 1980 on the base of mining culture represented by, e.g., unique wooden architecture. Slag pieces are composed of three parts differing in glass to crystallites ratio. Røros slags are composed of olivine- and pyroxene- group minerals accompanied by sulphides, with glass in the interstices. Temperature gradient and volatiles content were determined as the main factor influencing crystallization process in this material

  19. Large Eddy Simulation of Bubbly Flow and Slag Layer Behavior in Ladle with Discrete Phase Model (DPM)-Volume of Fluid (VOF) Coupled Model

    NASA Astrophysics Data System (ADS)

    Li, Linmin; Liu, Zhongqiu; Cao, Maoxue; Li, Baokuan

    2015-07-01

    In the ladle metallurgy process, the bubble movement and slag layer behavior is very important to the refining process and steel quality. For the bubble-liquid flow, bubble movement plays a significant role in the phase structure and causes the unsteady complex turbulent flow pattern. This is one of the most crucial shortcomings of the current two-fluid models. In the current work, a one-third scale water model is established to investigate the bubble movement and the slag open-eye formation. A new mathematical model using the large eddy simulation (LES) is developed for the bubble-liquid-slag-air four-phase flow in the ladle. The Eulerian volume of fluid (VOF) model is used for tracking the liquid-slag-air free surfaces and the Lagrangian discrete phase model (DPM) is used for describing the bubble movement. The turbulent liquid flow is induced by bubble-liquid interactions and is solved by LES. The procedure of bubble coming out of the liquid and getting into the air is modeled using a user-defined function. The results show that the present LES-DPM-VOF coupled model is good at predicting the unsteady bubble movement, slag eye formation, interface fluctuation, and slag entrainment.

  20. Enhanced humification by carbonated basic oxygen furnace steel slag--I. Characterization of humic-like acids produced from humic precursors.

    PubMed

    Qi, Guangxia; Yue, Dongbei; Fukushima, Masami; Fukuchi, Shigeki; Nie, Yongfeng

    2012-01-01

    Carbonated basic oxygen furnace steel slag (hereinafter referred to as "steel slag") is generated during iron and steel manufacturing and is often classified as waste. The effect of steel slag on humification process was investigated. Catechol, glycine and glucose were used as model humic precursors from degraded biowastes. To verify that humification occurred in the system, humic-like acids (HLAs) were isolated and characterized structurally by elemental analysis, FTIR spectra, solid-state CP-MAS (13)C NMR spectra, and TMAH-Py-GC/MS. Characteristics of the steel slag-HLA were compared with those of HLAs formed in the presence of zeolite and birnessite, and with that of mature compost humic acid. The results showed that steel slag-HLA, like zeolite- and birnessite-HLA, is complex organic material containing prominent aromatic structures. Steel slag substantially accelerated the humification process, which would be highly significant for accelerating the stabilization of biowastes during composting (e.g. municipal solid waste, sewage sludge, and food waste).

  1. [Leaching of nonferrous metals from copper-smelting slag with acidophilic microorganisms].

    PubMed

    2013-01-01

    The leaching process of copper and zinc from copper converter slag with sulphuric solutions of trivalent iron sulphate obtained using the association of acidophilic chemolithotrophic microorganisms was investigated. The best parameters of chemical leaching (temperature 70 degrees C, an initial concentration of trivalent iron in the leaching solution of 10.1 g/L, and a solid-phase content in the suspension of 10%) were selected. Carrying out the process under these parameters resulted in the recovery of 89.4% of copper and 39.3% of zinc in the solution. The possibility of the bioregeneration of trivalent iron in the solution obtained after the chemical leaching of slag by iron-oxidizingacidophilic chemolithotrophic microorganisms without inhibiting their activity was demonstrated.

  2. Adsorption of superplasticizer admixtures on alkali-activated slag pastes

    SciTech Connect

    Palacios, M. Houst, Y.F.; Bowen, P.; Puertas, F.

    2009-08-15

    Alkali-activated slag (AAS) binders are obtained by a manufacturing process less energy-intensive than ordinary Portland cement (OPC) and involves lower greenhouse gasses emission. These alkaline cements allow the production of high mechanical strength and durable concretes. In the present work, the adsorption of different superplasticizer admixtures (naphthalene-based, melamine-based and a vinyl copolymer) on the slag particles in AAS pastes using alkaline solutions with different pH values have been studied in detail. The effect of the superplasticizers on the yield stress and plastic viscosity of the AAS and OPC pastes have been also evaluated. The results obtained allowed us to conclude that the adsorption of the superplasticizers on AAS pastes is independent of the pH of the alkaline solutions used and lower than on OPC pastes. However, the effect of the admixtures on the rheological parameters depends directly on the type and dosage of the superplasticizer as well as of the binder used and, in the case of the AAS, on the pH of the alkaline activator solution. In 11.7-pH NaOH-AAS pastes the dosages of the superplasticizers required to attain similar reduction in the yield stress are ten-fold lower than for Portland cement. In this case the superplasticizers studied show a fluidizing effect considerably higher in 11.7-pH NaOH-AAS pastes than in OPC pastes. In 13.6-pH NaOH-AAS pastes, the only admixture observed to affect the rheological parameters is the naphthalene-based admixture due to its higher chemical stability in such extremely alkaline media.

  3. Production of Welding Fluxes Using Waste Slag Formed in Silicomanganese Smelting

    NASA Astrophysics Data System (ADS)

    Kozyrev, N. A.; Kryukov, R. E.; Kozyreva, O. E.; Lipatova, U. I.; Filonov, A. V.

    2016-04-01

    The possibility in principle of using slag, which is formed in the silicon-manganese smelting process, in producing welding fluxes is shown. The composition of and technology used for a new fused flux has been designed. A comparative evaluation of the new flux and the widely used AN-348 type flux was done. It has been proved that the new flux has high strength properties.

  4. Dissolution Kinetics of SiO2 into CaO-Fe2O3-SiO2 Slag

    NASA Astrophysics Data System (ADS)

    Yu, Bin; Lv, Xuewei; Xiang, Shenglin; Xu, Jian

    2016-06-01

    High-basicity sinter is the predominant Fe-bearing material used in blast furnace process in East Asia. The dissolution of SiO2 into molten calcium ferrite influences the assimilation process. In this study, a rotating cylinder method was used to explore the dissolution kinetics of SiO2 into CaO-Fe2O3-SiO2 slag. The influencing factors, including temperature, rotating time and speed, and initial composition of the slag, were considered. Results showed that the dissolution rate increased with increasing rotation speed and temperature, whereas the increase in ω(SiO2) or ω(Fe2O3)/ ω(CaO) ratio in the initial slag composition decreased the dissolution rate. The diffusion coefficient and activation energy of SiO2 during the dissolution process ranged from 2.09 × 10-6 to 6.40 × 10-6 cm2 s-1 and 106.62 to 248.20 kJ mol-1, respectively. Concentration difference between the boundary layer and bulk phase was the primary driving force of the dissolution process; however, this process was also influenced by the slag viscosity and ion diffusivity.

  5. Crystallization of synthetic coal-petcoke slag mixtures simulating those encountered in entrained bed slagging gasifiers

    SciTech Connect

    Jinichiro Nakano; Seetharaman Sridhar; Tyler Moss; James Bennett; Kyei-Sing Kwong

    2009-09-15

    Commercial entrained bed slagging gasifiers use a carbon feedstock of coal, petcoke, or combinations of them to produce CO and H{sub 2}. These carbon sources contain mineral impurities that liquefy during gasification and flow down the gasification sidewall, interacting with the refractory linear and solidifying in the cooler zones of the gasifier. Proper slag flow is critical to good gasifier operation. A hot-stage confocal scanning laser microscope (CSLM) was used to analyze the kinetic behavior of slag crystallization for a range of synthetic coal-petcoke mixtures. On the basis of the observed precipitation during cool down studies in the 1200-1700{sup o}C temperature range, a time-temperature-transformation (TTT) diagram was created. The crystallization studies were conducted with a CO/CO{sub 2} (=1.8) corresponding to a gasification PO{sub 2} of approximately 10-8 atm at 1500{sup o}C. Ash chemistries were chosen such that they correspond to coal-petcoke feedstock mixtures with coal ash amounts of 0, 10, 30, 50, 70, and 100% (by weight), with the balance being petcoke ash. The TTT diagram exhibited two crystallization areas, one above and one below 1350{sup o}C. At the nose of the higher temperature curves, karelianite (V{sub 2}O{sub 3}) crystallization occurred and was fastest for a 30% coal-petcoke ash mixture. The second nose was located below 1350{sup o}C and had spinel-type phases that formed at 1200{sup o}C, in which preferred atomic occupation at the octahedral and tetrahedral sites varied depending upon the ash composition. At 1200{sup o}C, an Al-rich spinel formed for 100% coal slag and a Fe-rich spinel formed in petcoke-enriched slags. The addition of petcoke ash to coal ash promoted crystallization in the slag, with additional crystalline phases, such as V-rich spinel, forming at the lower temperatures. These phases were not predicted using commercially available databases. 30 refs., 18 figs.

  6. Slags and ashes from municipal waste incineration in Poland - mineralogical and chemical composition

    NASA Astrophysics Data System (ADS)

    Kowalski, Piotr; Michalik, Marek

    2013-04-01

    In the next few years there will be a large change in the waste management system in Poland. Its primary aim will be reduction of the amount of landfilled waste by enhancing level of recycling, waste segregation, composting of biomass and incineration. The biggest investment during this transformation is construction of nine incinerators with assumed slags production around 200 thousand tons per year. Slag production is accompanied by fly ash generating. This ash can be a valuable raw material as fly ash from the power industry. Waste management system transformation will cause big increase in slag production in comparison to the present amount and will require taking necessary steps to ensure environmental safety. For this purpose, studies of slags and fly ashes in terms of environmental risk and potential impact on human health are significant. The object of the study are fly ashes and slags produced in the biggest municipal waste incineration power plant in Poland. Two series of samples obtained in municipal waste incineration process were studied in order to characterize mineralogical and chemical composition and to determine the concentrations of heavy metals and their possible negative environmental impact. Characteristics of these materials will be the basis for determining their value in application, for example in building industry. Mineralogical characteristic of slags was based on X-ray diffraction. Characteristic of structures and forms of occurrence of mineral phases was based on the optical microscopy and SEM imaging coupled with EDS analysis. Chemical analysis were performed using ICP-MS/ICP-AES methods. They allowed to follow variability between studied samples and gave basic information about metals. Metals in samples of slag and ashes are present as component of mineral phases and in the form of metallic inclusions in glass or minerals. Potentially hazardous concentrations for environment are observed for copper (330-4900ppm), zinc (1500-8100ppm

  7. Leaching of cadmium, chromium, copper, lead, and zinc from two slag dumps with different environmental exposure periods under dynamic acidic condition.

    PubMed

    Jin, Zhisheng; Liu, Taoze; Yang, Yuangen; Jackson, Daniel

    2014-06-01

    Over the past few decades, zinc smelting activities in Guizhou, China have produced numerous slag dumps, which are often dispersed on roadsides and hill slopes throughout the region. During periods of acid rain, these exposed slags release heavy metals into surface water bodies. A column leaching study was designed to test the potential release of the heavy metals cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) under simulated acid rain events. Two slags with varying environmental exposure periods were packed in columns and subjected to leaching solutions of pH 3.5, 5.5, or DI H2O at intervals of 1, 7, 14, 28, 56d. Pulse concentrations of Cd in leachate were found above 5μg/L, Cr, Pb, and Zn >10μg/L, whereas, Cu reached 10μg/L. After five leaching events, the leachability (percentage of cumulative heavy metal leached after five leaching events as in its respective total concentration in slags) of Cd was 0.05 percent and 0.035 percent from the old and young slag, respectively. Cr (0.035 percent and 0.05 percent) was greater than Cu (0.002 percent and 0.005 percent) and Zn (0.006 percent and 0.003 percent), while the lowest leachability was observed for Pb (0.0005 percent and 0.0002 percent) from the old and young slags, respectively. Reaction rates (release amount of heavy metals in certain period of leaching) of heavy metals in the leachates demonstrated the sequence of Zn>Cr>Cd, Cu>Pb. Leaching release of heavy metals was jointly affected by the pH of leaching solution and mineral composition of slags (including chemical forms of Cd, Cr, Cu, Pb, and Zn). Environmental exposure period of slags, resulting in the alteration of minerals, could affect the release process of heavy metals in leaching as well. PMID:24632122

  8. Leaching of cadmium, chromium, copper, lead, and zinc from two slag dumps with different environmental exposure periods under dynamic acidic condition.

    PubMed

    Jin, Zhisheng; Liu, Taoze; Yang, Yuangen; Jackson, Daniel

    2014-06-01

    Over the past few decades, zinc smelting activities in Guizhou, China have produced numerous slag dumps, which are often dispersed on roadsides and hill slopes throughout the region. During periods of acid rain, these exposed slags release heavy metals into surface water bodies. A column leaching study was designed to test the potential release of the heavy metals cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) under simulated acid rain events. Two slags with varying environmental exposure periods were packed in columns and subjected to leaching solutions of pH 3.5, 5.5, or DI H2O at intervals of 1, 7, 14, 28, 56d. Pulse concentrations of Cd in leachate were found above 5μg/L, Cr, Pb, and Zn >10μg/L, whereas, Cu reached 10μg/L. After five leaching events, the leachability (percentage of cumulative heavy metal leached after five leaching events as in its respective total concentration in slags) of Cd was 0.05 percent and 0.035 percent from the old and young slag, respectively. Cr (0.035 percent and 0.05 percent) was greater than Cu (0.002 percent and 0.005 percent) and Zn (0.006 percent and 0.003 percent), while the lowest leachability was observed for Pb (0.0005 percent and 0.0002 percent) from the old and young slags, respectively. Reaction rates (release amount of heavy metals in certain period of leaching) of heavy metals in the leachates demonstrated the sequence of Zn>Cr>Cd, Cu>Pb. Leaching release of heavy metals was jointly affected by the pH of leaching solution and mineral composition of slags (including chemical forms of Cd, Cr, Cu, Pb, and Zn). Environmental exposure period of slags, resulting in the alteration of minerals, could affect the release process of heavy metals in leaching as well.

  9. Analysis of coal slag for naturally occurring radioactive material.

    PubMed

    Spitz, H B; Rajaretnam, G

    1998-07-01

    Samples of aerosolized coal slag were collected during an abrasive blasting operation to determine the concentration of naturally occurring radioactive materials (NORM) in the respirable and nonrespirable fractions. Each slag fraction was analyzed using alpha and gamma spectrometry. Since the slag is insoluble, it was necessary to dissolve samples completely by fusion with potassium fluoride and, after additional transposing and separation, mount the precipitate containing radium (Ra), the main radioactive component in NORM, on a membrane filter for alpha counting. The concentration of 226Ra in coal slag was independent of the particle size fraction and equal to 2.28 picocuries/gram (pCi/g) +/- 0.43 pCi/g, which is approximately twice the typical concentration of NORM in uncontaminated soil. Analysis of NORM by gamma spectrometry identified low concentrations of uranium, thorium, and potassium, all primordial radioactive materials that are commonly encountered in normal background soil. Integral exposure to workers from inhalation of NORM during abrasive blasting with coal slag is extremely low and could be essentially eliminated by use of appropriate respiratory protection. External radiation exposure to workers handling large quantities of NORM-contaminated coal slag during shipping or storage is also low, but would vary depending on the concentration of NORM in the slag.

  10. On the Dissolution Behavior of Sulfur in Ternary Silicate Slags

    NASA Astrophysics Data System (ADS)

    Kang, Youn-Bae; Park, Joo Hyun

    2011-12-01

    Sulfur dissolution behavior, in terms of sulfide capacity ( C S), in ternary silicate slags (molten oxide slags composed of MO - NO - SiO2, where M and N are Ca, Mn, Fe, and Mg), is discussed based on available experimental data. Composition dependence of the sulfur dissolution, at least in the dilute region of sulfur, may be explained by taking into account the cation-anion first-nearest-neighbor (FNN) interaction (stability of sulfide) and the cation-cation second-nearest-neighbor (SNN) interaction over O anion (oxygen proportions in silicate slags). When the Gibbs energy of a reciprocal reaction MO + NS = MS + NO is positive, the sulfide capacity of slags with virtually no SiO2 or low SiO2 concentration decreases as the concentration of MO increases. However, in some slags, as SiO2 concentration increases, replacing NO by MO at a constant SiO2 concentration may increase sulfide capacity when the basicity of NO is less than that of MO. This phenomenon is observed as rotation of iso- C S lines in ternary silicate slags, and it is explained by simultaneous consideration of the stability of sulfide and oxygen proportions in the silicate slags. It is suggested that a solution model for the prediction of sulfide capacity should be based on the actual dissolution mechanism of sulfur rather than on the simple empirical correlation.

  11. Steel Reoxidation by Gunning Mass and Tundish Slag

    NASA Astrophysics Data System (ADS)

    Yan, Pengcheng; Arnout, Sander; Van Ende, Marie-Aline; Zinngrebe, Enno; Jones, Tom; Blanpain, Bart; Guo, Muxing

    2015-01-01

    Steel reoxidation in the tundish has a significant influence on the steel cleanliness and therefore on the mechanical properties of the final product. In the present work, the steel reoxidation by two types of gunning mass (GM), viz. magnesia- and alumina-based GM, and two types of tundish slag, viz. lime-alumina-silica and lime-alumina slags, has been investigated. The evolution of the steel composition during the test was analyzed and predicted based on thermodynamic and kinetic considerations. The calculated steel composition agrees well with measured values, when assuming the mass transfer in slag phase limits the reoxidation reactions. The oxidation capacity of the gunning mass and tundish slag is quantified by calculating the oxygen amount supplied from the GM and the slag to the steel phase. It was found that compared to alumina GM, magnesia GM exhibits a stronger oxidation capacity due to its higher content of reducible oxides (10 wt pct SiO2 + 6 wt pct FeO). Compared to lime-alumina-silica tundish slag, lime-alumina slag (with more FeO + MnO contents) provides more oxygen to the molten steel in the present experimental conditions and consequently shows a stronger oxidation capacity.

  12. Calibration-free electrical conductivity measurements for highly conductive slags

    SciTech Connect

    MACDONALD,CHRISTOPHER J.; GAO,HUANG; PAL,UDAY B.; VAN DEN AVYLE,JAMES A.; MELGAARD,DAVID K.

    2000-05-01

    This research involves the measurement of the electrical conductivity (K) for the ESR (electroslag remelting) slag (60 wt.% CaF{sub 2} - 20 wt.% CaO - 20 wt.% Al{sub 2}O{sub 3}) used in the decontamination of radioactive stainless steel. The electrical conductivity is measured with an improved high-accuracy-height-differential technique that requires no calibration. This method consists of making continuous AC impedance measurements over several successive depth increments of the coaxial cylindrical electrodes in the ESR slag. The electrical conductivity is then calculated from the slope of the plot of inverse impedance versus the depth of the electrodes in the slag. The improvements on the existing technique include an increased electrochemical cell geometry and the capability of measuring high precision depth increments and the associated impedances. These improvements allow this technique to be used for measuring the electrical conductivity of highly conductive slags such as the ESR slag. The volatilization rate and the volatile species of the ESR slag measured through thermogravimetric (TG) and mass spectroscopy analysis, respectively, reveal that the ESR slag composition essentially remains the same throughout the electrical conductivity experiments.

  13. Vanadium bioavailability in soils amended with blast furnace slag.

    PubMed

    Larsson, Maja A; Baken, Stijn; Smolders, Erik; Cubadda, Francesco; Gustafsson, Jon Petter

    2015-10-15

    Blast furnace (BF) slags are commonly applied as soil amendments and in road fill material. In Sweden they are also naturally high in vanadium. The aim of this study was to assess the vanadium bioavailability in BF slags when applied to soil. Two soils were amended with up to 29% BF slag (containing 800 mg V kg(-1)) and equilibrated outdoors for 10 months before conducting a barley shoot growth assay. Additional soil samples were spiked with dissolved vanadate(V) for which assays were conducted two weeks (freshly spiked) and 10 months (aged) after spiking. The BF slag vanadium was dominated by vanadium(III) as shown by V K-edge XANES spectroscopy. In contrast, results obtained by HPLC-ICP-MS showed that vanadium(V), the most toxic vanadium species, was predominant in the soil solution. Barley shoot growth was not affected by the BF slag additions. This was likely due to limited dissolution of vanadium from the BF slag, preventing an increase of dissolved vanadium above toxic thresholds. The difference in vanadium bioavailability among treatments was explained by the vanadium concentration in the soil solution. It was concluded that the vanadium in BF slag is sparingly available. These findings should be of importance in environmental risk assessment.

  14. Phosphorus removal by electric arc furnace steel slag and serpentinite.

    PubMed

    Drizo, Aleksandra; Forget, Christiane; Chapuis, Robert P; Comeau, Yves

    2006-05-01

    Electric arc furnace (EAF) steel slag and serpentinite were tested in columns either alone or mixed with limestone to determine their capacity to remove phosphorus (P) from a solution containing initially 20mg P/L (for 114 days) than 400mg P/L (for 21 days). EAF steel slag was nearly 100% efficient due to specific P adsorption onto metal hydroxides and precipitation of hydroxyapatite. Serpentinite also showed a good performance that decreased with time, adsorption appearing to be the dominant mechanism for P removal. Mixing limestone with these two materials did not improve their performance and in the case of serpentinite, it actually even decreased it. In 114 days of experimentation, serpentinite alone and the mixture of serpentinite and limestone removed 1.0mg P/g while in 180 days of experimentation, EAF steel slag and the mixture of slag and limestone removed an average of 2.2mg P/g, without attaining their maximum P removal potential. The void hydraulic retention time (HRTv) was a key factor for growing hydroxyapatite crystals and had a significant effect on P removal efficiency by EAF steel slag. A temporary increase in HRTv caused by clogging resulted in an increase in EAF steel slag efficiency (from 80% to almost 100%) towards the end of investigation. Results from this study indicate that the use of EAF steel slag in constructed wetlands or filter beds is a promising solution for P removal via adsorption and precipitation mechanisms.

  15. Slag/mud mixtures improve cementing operations in China

    SciTech Connect

    Wu, D.; Peiyan; Huang, B.

    1996-12-23

    The use of blast furnace slag, which is inexpensive and widely available throughout China, can with proper activators and retarders, solidify mud into an excellent cementing material. The use of slag-mix has been somewhat controversial. Some experts claim slag-mix is the most important progress to date in mud-to-cement conversion and has become another choice for cementing practices.They also believed there were no fundamental limitations to its application downhole, and conceivably the material could be used for any well cemented. Other experts have different points of view and thought it might have limits for oil field use. In their studies, the basic mud had to be diluted by 60% or more with water before the blast furnace slag (BFS) was added. Their slag slurries showed a high incidence of cracking and apparent brittle nature, bad settling stability, and volume shrinkage. To date, the Chinese National petroleum Corp. (CNPC) has used mud solidification by slag successfully on 22 cementing jobs in the Sichun, Changqing, Jidong, and Shengli oil fields.The major purpose of these investigations was to determine the application of slag-mix technology to various cementing operations.

  16. Vaporization Rate of Cesium from Molten Slag in a Plasma Melting Furnace for the Treatment of Simulated Low-Level Radioactive Wastes

    SciTech Connect

    Yasui, Shinji; Amakawa, Tadashi

    2003-02-15

    The vaporization phenomena of cesium (Cs) from molten slag have been investigated in a plasma melting process for simulated radioactive waste materials. A direct current transfer-type plasma with a maximum output of 50 kW was used to melt carbon steel and granular oxide mixtures (Fe{sub 2}O{sub 3}, Al{sub 2}O{sub 3}, SiO{sub 2}, CaO, and MgO) containing nonradioactive cesium nitrate, to measure Cs vaporization. These materials are the main components of low-level miscellaneous solid wastes. The vaporization rate of Cs from the molten slag during the plasma melting was observed and was compared with the vaporization rate obtained in an electric resistance furnace. The apparent vaporization rate of Cs was found to follow the first-order rate equation with respect to the molten slag's Cs content, and its rate constant values varied (3.5 to 21.0) x 10{sup -6} m/s varying with the chemical composition of the miscellaneous solid wastes. These rate constants were about one order larger than those obtained in the electric resistant furnace and also the diffusion coefficients of basic elements in the molten slag. These results suggest that the vaporization rate of Cs is controlled by the vaporization step from the free molten slag furnace to the gas phase and depends predominantly on the thermodynamic properties of the molten slag.

  17. Estimating phosphorus removal by steel slag in a flume experiment: effects of P concentrations and subsurface hydrological conditions

    NASA Astrophysics Data System (ADS)

    Chagas, I. S. P.; Huang, C. H.; Bowling, L. C.; Smith, D. R.

    2015-12-01

    Managing excessive phosphorus (P) is essential to reduce the incidence of environmental quality issues, such as eutrophication and harmful algal blooms. One potential strategy that have been developed with this purpose is the use of P sorption materials (PSMs) to sequester P from water systems, which is the objective of this study. We evaluated the performance of steel slag, an industrial by-product with high P sorption potential, through a flume experiment under two different subsurface hydrological conditions, drainage and saturation, and two input P concentrations, 1 and 5 ppm. The 10-m flume configuration, designed to simulate processes occurring in a drainage ditch, is comprised of four 2.5-m sequential segments: a sediment bed, a slag bed over sediment, a slag dam built over a slag bed, and another sediment bed. In the experiments, all four segments of the flume were set to either saturation or with a constant drainage (percolation) of 0.1 L/min for each segment. The experiment was conducted with a constant flow of elevated P water at 7.3 L/min for 4 hrs (adsorption run) and followed 24 hrs later by a 4-hr run of deionized water (desorption run) at the same inflow rate. The adsorption-desorption cycle was repeated three times with the same sediment and slag materials, to allow testing of the resilience of P sorption under different PSM placement, subsurface hydrologic and P loading conditions. Preliminary results from the first adsorption and desorption cycle show that the flow-through slag section sequestered the most P during the adsorption runs. By comparing the different P inflow concentrations analysis, it is clear that the removal process is concentration driven: 83% of the injected P was removed in the 5 ppm as compared to 46% in the 1 ppm saturation run. Because of the higher P removal at 5 ppm P inflow, slightly higher release was also observed during the desorption run. Analyses of the persistence of steel slag as PSM under repeated adsorption and

  18. Fixation and partitioning of heavy metals in slag after incineration of sewage sludge

    SciTech Connect

    Chen Tao; Yan Bo

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer The contents and partitioning of HMs in slag of sludge incineration were examined. Black-Right-Pointing-Pointer The fixation rate decreases with residential time and finally keeps a constant. Black-Right-Pointing-Pointer Water mass fraction of 55% is optimal for the sediment for Ni, Mn, Zn, Cu and Cr. Black-Right-Pointing-Pointer Water mass fraction of 75% is optimal for the sediment for Pb. Black-Right-Pointing-Pointer We found higher temperature versus lower non-residual fraction except that of Pb. - Abstract: Fixation of heavy metals in the slag produced during incineration of sewage sludge will reduce emission of the metals to the atmosphere and make the incineration process more environmentally friendly. The effects of incineration conditions (incineration temperature 500-1100 Degree-Sign C, furnace residence time 0-60 min, mass fraction of water in the sludge 0-75%) on the fixation rates and species partitioning of Cd, Pb, Cr, Cu, Zn, Mn and Ni in slag were investigated. When the incineration temperature was increased from 500 to 1100 Degree-Sign C, the fixation rate of Cd decreased from 87% to 49%, while the fixation rates of Cu and Mn were stable. The maximum fixation rates for Pb and Zn and for Ni and Cr were reached at 900 and 1100 Degree-Sign C, respectively. The fixation rates of Cu, Ni, Cd, Cr and Zn decreased as the residence time increased. With a 20 min residence time, the fixation rates of Pb and Mn were low. The maximum fixation rates of Ni, Mn, Zn, Cu and Cr were achieved when the mass fraction of water in the sludge was 55%. The fixation rate of Cd decreased as the water mass fraction increased, while the fixation rate of Pb increased. Partitioning analysis of the metals contained in the slag showed that increasing the incineration temperature and residence time promoted complete oxidation of the metals. This reduced the non-residual fractions of the metals, which would lower the bioavailability of the

  19. Reaction between Steel-Making Slag and Carbonaceous Materials While Mixing with High Density Polyethylene

    NASA Astrophysics Data System (ADS)

    Hong, Lan; Sahajwalla, Veena

    2016-01-01

    Since the beginning of the extensive applications in numerous high temperature processes such as iron- and steel-making, coke-making etc. partly in the place of coke, the investigation into the reaction mechanism of waste plastics has become increasingly necessary. In this paper a fundamental study on the behavior of a typical component of waste plastics, high density polyethylene (HDPE), in a mixture with coke at a 1:1 ratio in mass base was conducted during the reaction with iron oxide in steel-making slag at 1823 K and was compared with coke and graphite. The reaction mechanism of carbonaceous materials was analyzed based on the contents of CO and CO2 in the off-gas monitored by an infrared (IR) gas analyzer. It is clear from the results that the reaction of HDPE and coke mixture with steel-making slag approached equilibrium of the Boudouard reaction more quickly and closely than coke or graphite.

  20. The efficiency of quartz addition on electric arc furnace (EAF) carbon steel slag stability.

    PubMed

    Mombelli, D; Mapelli, C; Barella, S; Gruttadauria, A; Le Saout, G; Garcia-Diaz, E

    2014-08-30

    Electric arc furnace slag (EAF) has the potential to be re-utilized as an alternative to stone material, however, only if it remains chemically stable on contact with water. The presence of hydraulic phases such as larnite (2CaO SiO2) could cause dangerous elements to be released into the environment, i.e. Ba, V, Cr. Chemical treatment appears to be the only way to guarantee a completely stable structure, especially for long-term applications. This study presents the efficiency of silica addition during the deslagging period. Microstructural characterization of modified slag was performed by SEM and XRD analysis. Elution tests were performed according to the EN 12457-2 standard, with the addition of silica and without, and the obtained results were compared. These results demonstrate the efficiency of the inertization process: the added silica induces the formation of gehlenite, which, even in caustic environments, does not exhibit hydraulic behaviour. PMID:25113518

  1. Hydration mechanism of a cementitious material prepared with Si-Mn slag

    NASA Astrophysics Data System (ADS)

    Zhang, Xu-Fang; Ni, Wen; Wu, Jun-Yu; Zhu, Li-Ping

    2011-04-01

    A cementitious material was prepared by mixing 80wt% Si-Mn slag powder, 10wt% lime, and 10wt% anhydrite. The compressive strength of mortar samples reaches 51.48 MPa after 28 d curing. The analyses of X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that much ettringite is formed in the sample cured for 3 d, and C-S-H gel increases rapidly during subsequent curing. Nuclear magnetic resonance (NMR) analysis of 29Si and 27Al and infrared spectroscopy (IR) analysis show that aluminum decomposition from tetrahedral network of the slag glass and its subsequent migration and re-combination play an important role in the process of hydration and strength development of the samples.

  2. The efficiency of quartz addition on electric arc furnace (EAF) carbon steel slag stability.

    PubMed

    Mombelli, D; Mapelli, C; Barella, S; Gruttadauria, A; Le Saout, G; Garcia-Diaz, E

    2014-08-30

    Electric arc furnace slag (EAF) has the potential to be re-utilized as an alternative to stone material, however, only if it remains chemically stable on contact with water. The presence of hydraulic phases such as larnite (2CaO SiO2) could cause dangerous elements to be released into the environment, i.e. Ba, V, Cr. Chemical treatment appears to be the only way to guarantee a completely stable structure, especially for long-term applications. This study presents the efficiency of silica addition during the deslagging period. Microstructural characterization of modified slag was performed by SEM and XRD analysis. Elution tests were performed according to the EN 12457-2 standard, with the addition of silica and without, and the obtained results were compared. These results demonstrate the efficiency of the inertization process: the added silica induces the formation of gehlenite, which, even in caustic environments, does not exhibit hydraulic behaviour.

  3. Study on Apparent Viscosity and Structure of Foaming Slag

    NASA Astrophysics Data System (ADS)

    Martinsson, Johan; Glaser, Björn; Sichen, Du

    2016-07-01

    Foaming slag was generated using induction heating. The foam was found non-Newtonian having much higher apparent viscosity compared to the dynamic viscosity of pure slag. Quenched foam was examined. The appearance of the foaming slag was very different from silicone oil-gas foam. The size of gas bubbles ranged from 0.1 to 4 mm (while in the case of silicone oil, 1 to 2 mm). The gas fraction in the foam was considerably lower than in the case of silicone oil.

  4. Study on Apparent Viscosity and Structure of Foaming Slag

    NASA Astrophysics Data System (ADS)

    Martinsson, Johan; Glaser, Björn; Sichen, Du

    2016-10-01

    Foaming slag was generated using induction heating. The foam was found non-Newtonian having much higher apparent viscosity compared to the dynamic viscosity of pure slag. Quenched foam was examined. The appearance of the foaming slag was very different from silicone oil-gas foam. The size of gas bubbles ranged from 0.1 to 4 mm (while in the case of silicone oil, 1 to 2 mm). The gas fraction in the foam was considerably lower than in the case of silicone oil.

  5. The recovery of Zn and Pb and the manufacture of lightweight bricks from zinc smelting slag and clay.

    PubMed

    Hu, Huiping; Deng, Qiufeng; Li, Chao; Xie, Yue; Dong, Zeqin; Zhang, Wei

    2014-04-30

    Novel lightweight bricks have been produced by sintering mixes of zinc smelting slag and clay. A two-stage sintered process has been proposed to recovery of Zn and Pb and reutilization of the zinc smelting slag. In the first stage of the process, called reduction and volatilization procedure, zinc and lead were reduced by the carbon contained in the zinc smelting slag and volatilized into the dust, and the dust can be used as a secondary zinc resource. In the second stage of the process, called oxidation sintering procedure, a lightweight brick was produced. Samples containing up to 60 wt.% zinc smelting slag and 40 wt.% kaolin clay were reduced at 1050°C for 6h, and then sintered at 1050°C for 4h. The recoveries of Zn and Pb from the brick are 94.5 ± 0.6% and 97.6 ± 0.2%, respectively. Low bulk density (1.42 g cm(-3)) and relatively high compressive strength (2 2MPa) sintered bricks were produced, and the leaching toxicity of the sintered bricks was below the regulatory thresholds of Chinese National Standards.

  6. The recovery of Zn and Pb and the manufacture of lightweight bricks from zinc smelting slag and clay.

    PubMed

    Hu, Huiping; Deng, Qiufeng; Li, Chao; Xie, Yue; Dong, Zeqin; Zhang, Wei

    2014-04-30

    Novel lightweight bricks have been produced by sintering mixes of zinc smelting slag and clay. A two-stage sintered process has been proposed to recovery of Zn and Pb and reutilization of the zinc smelting slag. In the first stage of the process, called reduction and volatilization procedure, zinc and lead were reduced by the carbon contained in the zinc smelting slag and volatilized into the dust, and the dust can be used as a secondary zinc resource. In the second stage of the process, called oxidation sintering procedure, a lightweight brick was produced. Samples containing up to 60 wt.% zinc smelting slag and 40 wt.% kaolin clay were reduced at 1050°C for 6h, and then sintered at 1050°C for 4h. The recoveries of Zn and Pb from the brick are 94.5 ± 0.6% and 97.6 ± 0.2%, respectively. Low bulk density (1.42 g cm(-3)) and relatively high compressive strength (2 2MPa) sintered bricks were produced, and the leaching toxicity of the sintered bricks was below the regulatory thresholds of Chinese National Standards. PMID:24637448

  7. Improved Refractories for Slagging Gasifiers in IGCC Power Systems

    SciTech Connect

    Dogan, Cynthia P.; Kwong, Kyei-Sing; Bennett, James P.; Chinn, Richard E.

    2003-04-24

    The gasification of coal and other carbon-containing fuels provides the opportunity to produce energy more efficiently, and with significantly less environmental impact, than more-conventional combustion-based processes. In addition, the synthesis gas that is the product of the gasification process offers the option of ''polygeneration,'' i.e., the production of alternative products instead of power should it be economically favorable to do so. Because of these advantages, gasification is viewed as one of the key processes in the U.S. Department of Energy's Vision 21 power system. However, issues with both the reliability and the economics of gasifier operation will have to be resolved before gasification will be widely adopted by the power industry. Central to both enhanced reliability and economics is the development of materials with longer service lives in gasifier systems that can provide extended periods of continuous, trouble-free gasifier operation. The focus of the Advanced Refractories for Gasification project at the Albany Research Center is to develop improved refractory materials capable of withstanding the harsh, high-temperature environment created by the gasification reaction, and includes both the refractory lining that protects and insulates the slagging gasifier, as well as the thermocouple assemblies that are utilized to monitor gasifier operating temperatures. Current generation refractory liners in slagging gasifiers are typically replaced every four to 18 months, at costs ranging up to $2,000,000, depending upon the size of the gasification vessel. Compounding materials and installation costs are the lost-opportunity costs for the time that the gasifier is off-line for the refractory exchange. Current generation thermocouple devices rarely survive the gasifier start-up process, leaving the operator with no real means of temperature measurement during routine operation. Reliable, efficient, and economical gasifier operation that includes the

  8. INTERIOR VIEW OF BLAST FURNACE NO. 3 LOOKING EAST, SLAG ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF BLAST FURNACE NO. 3 LOOKING EAST, SLAG RUNNERS & GATES IN FOREGROUND. - Pittsburgh Steel Company, Monessen Works, Blast Furnace No. 3, Donner Avenue, Monessen, Westmoreland County, PA

  9. 180. Jet Lowe, Photographer July 1978. VIEW FROM SLAG DUMP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    180. Jet Lowe, Photographer July 1978. VIEW FROM SLAG DUMP OF (LEFT TO RIGHT) RAILROAD WAREHOUSE (1901); BRIQUETTING PLANT (1906); CUPOLA BUILDING (1898) AND MACHINE SHOP (1907). - Quincy Mining Company, Hancock, Houghton County, MI

  10. Structural characteristics and hydration kinetics of modified steel slag

    SciTech Connect

    Li Jianxin; Yu Qijun; Wei Jiangxiong Zhang Tongsheng

    2011-03-15

    This study investigates the structural characteristics and hydration kinetics of modified basic oxygen furnace steel slag. The basic oxygen furnace steel slag (BOFS) was mixed with electric arc furnace steel slag (EAFS) in appropriate ratios and heated again at high temperature in the laboratory. The mineralogical and structural characteristics of both BOFS and modified steel slag (MSS) were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, Raman and Fourier transform infrared spectroscopies. The results show that modification increases alite content in MSS and decreases alite crystal size with the formation of C{sub 6}AF{sub 2}. One more obvious heat evolution peak appears in MSS's heat-flow rate curves in comparison to BOFS, becoming similar to that of typical Portland cement paste. As a result, its cementitious activity is much improved.

  11. WORKER REMOVING SLAG FROM THE MOLTEN METAL BATH IN THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    WORKER REMOVING SLAG FROM THE MOLTEN METAL BATH IN THE ELECTRIC FURNACE AFTER ADDING A CHEMICAL COAGULANT TO FORCE IT TO THE SURFACE. - Southern Ductile Casting Company, Melting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  12. Desulfurization ability of refining slag with medium basicity

    NASA Astrophysics Data System (ADS)

    Yu, Hui-xiang; Wang, Xin-hua; Wang, Mao; Wang, Wan-jun

    2014-12-01

    The desulfurization ability of refining slag with relative lower basicity ( B) and Al2O3 content ( B = 3.5-5.0; 20wt%-25wt% Al2O3) was studied. Firstly, the component activities and sulfide capacity ( C S) of the slag were calculated. Then slag-metal equilibrium experiments were carried out to measure the equilibrium sulfur distribution ( L S). Based on the laboratorial experiments, slag composition was optimized for a better desulfurization ability, which was verified by industrial trials in a steel plant. The obtained results indicated that an MgO-saturated CaO-Al2O3-SiO2-MgO system with the basicity of about 3.5-5.0 and the Al2O3 content in the range of 20wt%-25wt% has high activity of CaO ( a CaO), with no deterioration of C S compared with conventional desulfurization slag. The measured L S between high-strength low-alloyed (HSLA) steel and slag with a basicity of about 3.5 and an Al2O3 content of about 20wt% and between HSLA steel and slag with a basicity of about 5.0 and an Al2O3 content of about 25wt% is 350 and 275, respectively. The new slag with a basicity of about 3.5-5.0 and an Al2O3 content of about 20wt% has strong desulfurization ability. In particular, the key for high-efficiency desulfurization is to keep oxygen potential in the reaction system as low as possible, which was also verified by industrial trials.

  13. UTILIZATION OF LIGHTWEIGHT MATERIALS MADE FROM COAL GASIFICATION SLAGS

    SciTech Connect

    Unknown

    1999-07-01

    The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of lightweight aggregates (LWA) and ultra-lightweight aggregates (ULWA) from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase I, comprising the production of LWA and ULWA from slag at the large pilot scale, and Phase II, which involves commercial evaluation of these aggregates in a number of applications.

  14. Study of Chromium Oxide Activities in EAF Slags

    NASA Astrophysics Data System (ADS)

    Yan, Baijun; Li, Fan; Wang, Hui; Sichen, Du

    2016-02-01

    The activity coefficients of chromium in Cu-Cr melts were determined by equilibrating liquid copper with solid Cr2O3 in CO-CO2 atmosphere. The temperature dependence of the activity coefficients of chromium in Cu-Cr melts could be expressed as lg γ_{Cr}(s)^{0} = { 3 2 5 9( ± 1 8 6} )/T - 0. 5 9( { ± 0. 1} ). Based on the above results, the activities of bivalent and trivalent chromium oxide in some slags at 1873 K (1600 °C) were measured. The slags were equilibrated with Cu-Cr melts under two oxygen partial pressures ( {p_{O}_{ 2} }} } = 6.9 × 10-4 and 1.8 × 10-6 Pa, respectively). The morphology of the quenched slags and the solubility of chromium oxide in the melts were investigated by EPMA, SEM, and XRD. Under both oxygen partial pressures, the slags were saturated by the solid solution MgAl2- x Cr x O4- δ . At the low oxygen partial pressure (1.8 × 10-6 Pa), the content of Cr in the liquid phase varied from 0.4 to 1.6 mass pct with the total Cr content in the slags increasing from 1.3 to 10.8 mass pct. At the high oxygen partial pressure (6.9 × 10-4 Pa), the content of Cr in the liquid phase decreased to the level of 0.2 to 0.6 mass pct. Both the activities of CrO and Cr2O3 in slag were found to increase approximately linearly with the increase of the total Cr content in slag. While the oxygen partial pressure had minor effect on the activity of Cr2O3 in the slag, it had significant effect on the activity of CrO.

  15. Preparation of High-Grade Titania Slag from Ilmenite-Bearing High Ca and Mg by Vacuum Smelting Method

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Lv, Xuewei; Huang, Run; Song, Bing; Xi, Fei

    2014-06-01

    Ilmenite produced from the Panxi area in China has high impurities such as Ca and Mg. High-grade titanium (Ti) slag can be obtained by the electric arc furnace process, a traditional method of treating ilmenite. Thus, Ti slag prepared from the Panxi ilmenite contains high CaO and MgO, exceeding 5 pct of the slag content. This high CaO and MgO content confers considerable difficulty in producing titania (TiO2) white using fluidizing chlorination. In this study, a new process named vacuum separation was found to produce high-grade TiO2 materials. The effects of separation temperature and time on the TiO2 grade were studied. The high-grade TiO2 slag, which has 93 pct TiO2, <0.1 pct MgO, <1.2 pct SiO2, and <0.5 pct CaO, can be produced at 1823 K (1550 °C) in 45 minutes through the proposed method.

  16. Dusts, scale, slags, sludges... Not wastes, but sources of profits

    NASA Astrophysics Data System (ADS)

    Koros, Peter J.

    2003-12-01

    Historically, the steel industry has focused on the need for and the many benefits of recycling steel that is discarded either in its own or in its customers’ manufacturing processes, as well as in recovery and reuse of steel scrap that arises after the product has served its intended purpose. In fact, modern steelmaking relies on the use of recycled iron units for at least half of its production. The other side of the story is the fate of the non-steel by-products (e.g., oxide dusts, sludges, scales, slags, spent refractories and the contained “low grade” energy units that are generated as natural adjuncts to iron and steelmaking processes). These valuable by-products often are classified as “wastes” and are discarded to landfills, at significant cost, although in reality they offer significant potential for cost savings or profit if reintroduced into the industrial arena via well planned programs. Examples of such instances will be presented, including energy credit issues, in the hope of pointing the way for future expansion of benefits from these opportunities. Preparing for a challenge and honor such as the Howe Memorial Lecture, one has to stand in awe of the accomplishments of the predecessor we honor in this forum. He worked in the early days of our industry without the benefits of the many technological improvements he and his successors brought to play as the years went by. John Stubbles, in his Howe Memorial Lecture in 1997,[1] presented a masterful and entertaining biography of Howe and his very active and prolific life. Perhaps the most telling quotation he attributed to Howe is very pertinent to the topic we will address presently: “Metallurgy lives by profit, not logic,” to which I would like to add a comment that bears on the topic of this lecture from the 1991 Howe lecturer, my friend and mentor Bill Dennis, “Where there is muck, there is money.” There are numerous examples of “one hand washes the other” in this business; that

  17. CO2 sequestration through aqueous accelerated carbonation of BOF slag: A factorial study of parameters effects.

    PubMed

    Polettini, Alessandra; Pomi, Raffaella; Stramazzo, Alessio

    2016-02-01

    A factorial study was conducted on basic oxygen furnace slag from a steelmaking industry with the aim of systematically identifying the individual and joint effects of the operating parameters (total pressure, CO2 concentration in the gas phase and temperature) on the CO2 sequestration yield of a direct aqueous carbonation process. Each operating parameter was varied over a range of three levels according to a 3(3) factorial design, resulting in 27 carbonation experiments. The carbonation performance and the changes in particle size and mineralogical characteristics of the slag were investigated in detail. The analysis of the experimental results indicated large effects of the operating factors on CO2 uptake, which was observed to span the range 6.7-53.6 g CO2/100 g slag. The best carbonation performance achieved was particularly significant compared to previous studies, even more considering the relative mild operating conditions adopted (P = 5 bar, C = 40% vol. CO2, T = 50 °C, t = 4 h). The analysis of the solid and liquid phases at the end of the carbonation treatment evidenced significant changes in the physical, chemical and mineralogical composition of the material. In particular, evidence was gained of other elements (Mg, Fe, Mn, Zn) in addition to Ca being intensively involved in the carbonation reactions, with a variety of carbonate phases being produced in addition to calcium carbonate forms. PMID:26686071

  18. Synthetic lightweight aggregate from cool water slag: Bench-scale confirmation tests

    SciTech Connect

    Choudhry, V.; Hadley, S.R. )

    1990-05-01

    This report analyzes the potential for production of synthetic lightweight aggregate (SLA) from a Texaco coal gasification solid residue. The objective of the project was to develop a replacement for conventional lightweight aggregates typically derived from expanded clays and shales or natural lightweight aggregates. The sequence of tests performed to develop SLA from slag began with the crushing of samples of slag, followed by either extrusion or pelletization. The level of clay binder required for sufficient aggregate strength was evaluated. Using a tube furnace, expansion characteristics were studied as a function of temperature and residence time. Next, a large batch of SLA was produced in a muffle furnace and used to form concrete test cylinders. The unit weight of the resultant concrete was 105 lb/ft{sup 3}, with a compressive strength of 3100 psi, which meets the requirements specified in ASTM C 330 for lightweight aggregate of a comparable density. When the same sequence of tests was performed using a slag from which the bulk of the char had been removed, the concrete test cylinders showed an improved relationship between strength and density. Based on the results of bench-scale tests and the similarity to conventional LWA production, the conceptual design of an SLA processing plant was formulated. A comparative estimate of operating costs was prepared by analyzing data from plants using clays and shales to produce lightweight aggregates. 24 refs., 15 figs., 17 tabs.

  19. Glassy slags as novel waste forms for remediating mixed wastes with high metal contents

    SciTech Connect

    Feng, X.; Wronkiewicz, D.J.; Bates, J.K.; Brown, N.R.; Buck, E.C.; Gong, M.; Ebert, W.L.

    1994-03-01

    Argonne National Laboratory (ANL) is developing a glassy slag final waste form for the remediation of low-level radioactive and mixed wastes with high metal contents. This waste form is composed of various crystalline and metal oxide phases embedded in a silicate glass phase. This work indicates that glassy slag shows promise as final waste form because (1) it has similar or better chemical durability than high-level nuclear waste (HLW) glasses, (2) it can incorporate large amounts of metal wastes, (3) it can incorporate waste streams having low contents of flux components (boron and alkalis), (4) it has less stringent processing requirements (e.g., viscosity and electric conductivity) than glass waste forms, (5) its production can require little or no purchased additives, which can result in greater reduction in waste volume and overall treatment costs. By using glassy slag waste forms, minimum additive waste stabilization approach can be applied to a much wider range of waste streams than those amenable only to glass waste forms.

  20. CO2 sequestration through aqueous accelerated carbonation of BOF slag: A factorial study of parameters effects.

    PubMed

    Polettini, Alessandra; Pomi, Raffaella; Stramazzo, Alessio

    2016-02-01

    A factorial study was conducted on basic oxygen furnace slag from a steelmaking industry with the aim of systematically identifying the individual and joint effects of the operating parameters (total pressure, CO2 concentration in the gas phase and temperature) on the CO2 sequestration yield of a direct aqueous carbonation process. Each operating parameter was varied over a range of three levels according to a 3(3) factorial design, resulting in 27 carbonation experiments. The carbonation performance and the changes in particle size and mineralogical characteristics of the slag were investigated in detail. The analysis of the experimental results indicated large effects of the operating factors on CO2 uptake, which was observed to span the range 6.7-53.6 g CO2/100 g slag. The best carbonation performance achieved was particularly significant compared to previous studies, even more considering the relative mild operating conditions adopted (P = 5 bar, C = 40% vol. CO2, T = 50 °C, t = 4 h). The analysis of the solid and liquid phases at the end of the carbonation treatment evidenced significant changes in the physical, chemical and mineralogical composition of the material. In particular, evidence was gained of other elements (Mg, Fe, Mn, Zn) in addition to Ca being intensively involved in the carbonation reactions, with a variety of carbonate phases being produced in addition to calcium carbonate forms.

  1. Reuse of steel slag in bituminous paving mixtures.

    PubMed

    Sorlini, Sabrina; Sanzeni, Alex; Rondi, Luca

    2012-03-30

    This paper presents a comprehensive study to evaluate the mechanical properties and environmental suitability of electric arc furnace (EAF) steel slag in bituminous paving mixtures. A variety of tests were executed on samples of EAF slag to characterize the physical, geometrical, mechanical and chemical properties as required by UNI EN specifications, focusing additionally on the volumetric expansion associated with hydration of free CaO and MgO. Five bituminous mixtures of aggregates for flexible road pavement were designed containing up to 40% of EAF slag and were tested to determine Marshall stability and indirect tensile strength. The leaching behaviour of slag samples and bituminous mixtures was evaluated according to the UNI EN leaching test. The tested slag showed satisfactory physical and mechanical properties and a release of pollutants generally below the limits set by the Italian code. Tests on volume stability of fresh materials confirmed that a period of 2-3 months is necessary to reduce effects of oxides hydration. The results of tests performed on bituminous mixtures with EAF slag were comparable with the performance of mixtures containing natural aggregates and the leaching tests provided satisfactory results.

  2. Uranium distribution in pseudowollastonite slag from a phosphorus furnace

    USGS Publications Warehouse

    Young, Edward; Altschuler, Zalman S.

    1956-01-01

    Silicate slag from the Victor Chemical Company phosphorus furnace at Tarpon Springs, Fla., has been found to consist essentially of pseudowollastonite, α-CaSiO3. The first-formed crystals are euhedral laths which form a mesh making up most of the slag. As the slag continues to solidify, its composition changes slightly and more equant, subhedral crystals of pseudowollastonite are deposited within the framework of the earlier material. Finally, anherdral masses of fibrous, poorly crystallized material are deposited in the remaining pore spaces which are not always completely filled. Spherules of iron phosphide, Fe2P, occur very sparsely in the slag as inclusions from the immiscible iron phosphide melt. Uranium content increases in the later crystal products of the slag, and by heavy-liquid fractionation it has been possible to segregate partially the phases and to obtain a fourfold concentration of uranium in 5 percent of the material and a twofold concentration in 30 percent of the material. Nuclear-emulsion studies indicate that the last phases of the silicate slag are actually eight times as radioactive as the early phases. In addition, the iron phosphide spherules are comparably enriches in uranium.

  3. The effects of atmosphere and additives of coal slag viscosity

    SciTech Connect

    Hurley, J.P.; Watne, T.M.; Nowok, J.W.

    1996-12-31

    The viscosities of a Powder River Basin slag were measured in air, air + 10% water vapor, and a reducing atmosphere. The temperature of critical viscosity (T), below which the viscosity increases dramatically, was approximately 1250{degrees}C in air and air + water vapor, but dropped to 1180{degrees}C when measured in the reducing atmosphere. Since the corrosivity of the slag is much higher when its viscosity is low, the slag will be highly corrosive at the substantially lower temperature in reducing gas. The addition of alumina increased viscosity and T{sub c} making the slag less corrosive, while magnesia additions dropped viscosity but increased T{sub c}. These changes imply that magnesia additions will make the slag slightly more corrosive in its liquid range, but that the slag will harden and become less corrosive at a higher temperature than without the magnesia addition. The changes in T{sub c} were more substantial when measured in the presence of water vapor in the case of alumina additions, but less substantial in the case of magnesia additions.

  4. Recovery of copper and cobalt from ancient slag.

    PubMed

    Bulut, Gülay

    2006-04-01

    About 2.5 million tonnes of copper smelter slag are available in Küre, northern part of Turkey. This slag contains large amounts of metallic values such as copper and cobalt. A representative slag sample containing 0.98% Cu, 0.49% Co and 51.47% Fe was used in the experimental studies. Two different methods, direct acid leaching and acid baking followed by hot water leaching were used for recovering Cu and Co from the slag. The effects of leaching time, temperature and acid concentration on Cu- and Co-dissolving efficiencies were investigated in the direct acid leaching tests. The optimum leaching conditions were found to be a leaching time of 2 h, acid concentration of 120 g L(-1), and temperature of 60 degrees C. Under these conditions, 78% Cu and 90% Co were extracted. In the acid baking + hot water leaching tests, 74% Co was dissolved after 1 h of roasting at 200 degrees C using a 3:1 acid:slag ratio, whereas the Cu-dissolving efficiency was 79% and the total slag weight loss was approximately 50%. PMID:16634226

  5. Reuse of steel slag in bituminous paving mixtures.

    PubMed

    Sorlini, Sabrina; Sanzeni, Alex; Rondi, Luca

    2012-03-30

    This paper presents a comprehensive study to evaluate the mechanical properties and environmental suitability of electric arc furnace (EAF) steel slag in bituminous paving mixtures. A variety of tests were executed on samples of EAF slag to characterize the physical, geometrical, mechanical and chemical properties as required by UNI EN specifications, focusing additionally on the volumetric expansion associated with hydration of free CaO and MgO. Five bituminous mixtures of aggregates for flexible road pavement were designed containing up to 40% of EAF slag and were tested to determine Marshall stability and indirect tensile strength. The leaching behaviour of slag samples and bituminous mixtures was evaluated according to the UNI EN leaching test. The tested slag showed satisfactory physical and mechanical properties and a release of pollutants generally below the limits set by the Italian code. Tests on volume stability of fresh materials confirmed that a period of 2-3 months is necessary to reduce effects of oxides hydration. The results of tests performed on bituminous mixtures with EAF slag were comparable with the performance of mixtures containing natural aggregates and the leaching tests provided satisfactory results. PMID:22305201

  6. Stabilization of Black Cotton Soil Using Micro-fine Slag

    NASA Astrophysics Data System (ADS)

    Shukla, Rajesh Prasad; Parihar, Niraj Singh

    2016-08-01

    This work presents the results of laboratory tests conducted on black cotton soil mixed with micro-fine slag. Different proportions of micro-fine slag, i.e., 3, 6, 9, 12 and 15 % were mixed with the black cotton soil to improve soil characteristics. The improvement in the characteristics of stabilized soil was assessed by evaluating the changes in the physical and strength parameters of the soil, namely, the Atterberg limits, free swell, the California Bearing Ratio (CBR), compaction parameters and Unconfined Compressive Strength (UCS). The mixing of micro-fine slag decreases the liquid limit, plasticity index and Optimum Moisture Contents (OMC) of the soil. Micro-fine slag significantly increases the plastic limit, UCS and CBR of the soil up to 6-7 % mixing, but mixing of more slag led to decrease in the UCS and CBR of the soil. The unsoaked CBR increased by a substantial amount unlike soaked CBR value. The swell potential of the soil is reduced from medium to very low. The optimum amount of micro-fine slag is found to be approximately 6-7 % by the weight of the soil.

  7. Recycling of ladle slag in cement composites: Environmental impacts.

    PubMed

    Serjun, Vesna Zalar; Mladenovič, Ana; Mirtič, Breda; Meden, Anton; Ščančar, Janez; Milačič, Radmila

    2015-09-01

    In the present work compact and ground cement composites in which 30% of cement by mass was replaced by ladle slag were investigated for their chemical and physico-mechanical properties. To evaluate long-term environmental impacts, leachability test based on diffusion, which combined both, diffusion and dissolution of contaminants, was performed in water and saline water. Total element concentrations and Cr(VI) were determined in leachates over a time period of 180days. At the end of the experiment, the mineralogical composition and the physico-mechanical stability of cement composites was also assessed. The results revealed that Cr(III) and Cr(VI) were immobilized by the hydration products formed in the cement composites with the addition of ladle slag. Cr(VI) content originating from the cement was also appreciably reduced by Fe(II) from minerals present in the added ladle slag, which thus had significant positive environmental effects. Among metals, only Mo and Ba were leached in elevated concentrations, but solely in ground cement composites with the addition of ladle slag. Lower V concentrations were observed in leachates of ground than compact composite. It was demonstrated that the presence of ladle slag in cement composites can even contribute to improved mortar resistance. The investigated ladle slag can be successfully implemented in cement composites as supplementary cementitious material.

  8. Applicability of Carbonated Electric Arc Furnace Slag to Mortar

    NASA Astrophysics Data System (ADS)

    Yokoyama, S.; Arisawa, R.; Hisyamudin, M. N. N.; Murakami, K.; Maegawa, A.; Izaki, M.

    2012-03-01

    Authors have been studying the absorption of CO2 in the steelmaking slag. In this study, an application of the electric arc furnace slag after the carbonation to admixture of mortar was investigated with the JIS (A6206-1997) method for ground granulated blast-furnace slag for concrete. The percent flows for the test mortar were smaller than that for the standard mortar. The percent flow of the carbonated slag whose average particle size of more than approximately 4 μm increased with an increase in the average size of the particles. Because the compressive strengths of the test mortar cured for 91 days were almost the same as those cured 28 days, the slag after the carbonation was thought not to have self-hardening property for a medium and long term. The compressive strength for the test mortar was almost unchanged within a range of approximately 2 to 7 μm of the average particle size, and it in this range was highest. The activity indexes for the test mortar prepared with the slag after the carbonation ranged from approximately 40 to 60 %.

  9. Stabilization of Black Cotton Soil Using Micro-fine Slag

    NASA Astrophysics Data System (ADS)

    Shukla, Rajesh Prasad; Parihar, Niraj Singh

    2016-09-01

    This work presents the results of laboratory tests conducted on black cotton soil mixed with micro-fine slag. Different proportions of micro-fine slag, i.e., 3, 6, 9, 12 and 15 % were mixed with the black cotton soil to improve soil characteristics. The improvement in the characteristics of stabilized soil was assessed by evaluating the changes in the physical and strength parameters of the soil, namely, the Atterberg limits, free swell, the California Bearing Ratio (CBR), compaction parameters and Unconfined Compressive Strength (UCS). The mixing of micro-fine slag decreases the liquid limit, plasticity index and Optimum Moisture Contents (OMC) of the soil. Micro-fine slag significantly increases the plastic limit, UCS and CBR of the soil up to 6-7 % mixing, but mixing of more slag led to decrease in the UCS and CBR of the soil. The unsoaked CBR increased by a substantial amount unlike soaked CBR value. The swell potential of the soil is reduced from medium to very low. The optimum amount of micro-fine slag is found to be approximately 6-7 % by the weight of the soil.

  10. Effects of Slag Ejection on Solid Rocket Motor Performance

    NASA Technical Reports Server (NTRS)

    Whitesides, R. Harold; Purinton, David C.; Hengel, John E.; Skelley, Stephen E.

    1995-01-01

    In past firings of the Reusable Solid Rocket Motor (RSRM) both static test and flight motors have shown small pressure perturbations occurring primarily between 65 and 80 seconds. A joint NASA/Thiokol team investigation concluded that the cause of the pressure perturbations was the periodic ingestion and ejection of molten aluminum oxide slag from the cavity around the submerged nozzle nose which tends to trap and collect individual aluminum oxide droplets from the approach flow. The conclusions of the team were supported by numerous data and observations from special tests including high speed photographic films, real time radiography, plume calorimeters, accelerometers, strain gauges, nozzle TVC system force gauges, and motor pressure and thrust data. A simplistic slag ballistics model was formulated to relate a given pressure perturbation to a required slag quantity. Also, a cold flow model using air and water was developed to provide data on the relationship between the slag flow rate and the chamber pressure increase. Both the motor and the cold flow model exhibited low frequency oscillations in conjunction with periods of slag ejection. Motor and model frequencies were related to scaling parameters. The data indicate that there is a periodicity to the slag entrainment and ejection phenomena which is possibly related to organized oscillations from instabilities in the dividing streamline shear layer which impinges on the underneath surface of the nozzle.

  11. Growth promotion effect of steelmaking slag on Spirulina platensis

    NASA Astrophysics Data System (ADS)

    Nogami, R.; Tam, L. T.; Anh, H. T. L.; Quynh, H. T. H.; Thom, L. T.; Nhat, P. V.; Thu, N. T. H.; Hong, D. D.; Wakisaka, M.

    2016-04-01

    A growth promotion effect of steelmaking slag on Spirulina platensis M135 was investigated. The growth promotion effect was obtained that was 1.27 times greater than that obtained by the control by adding 500 mg L‑1 of steelmaking slag and culturing for 60 days. The lipid content decreased in a concentration-dependent manner with steelmaking slag, whereas the carbohydrate content remained constant. The protein content of S. platensis M135 increased in a concentration-dependent manner with steelmaking slag when cultured at day 45. The superoxide dismutase activity of S. platensis M135 exhibited a decreasing trend in a time-dependent manner and an increasing trend in the control. The superoxide dismutase activity was lower than that of the control at day 1 but was higher at day 30. No genetic damage was observed up to 500 mg L‑1 of steelmaking slag at 30 days of culture. Recovery from genetic damage was observed at 1,000 mg L‑1 of steelmaking slag but not at higher concentrations.

  12. The optimisation of the viscosity of lubricating slags used in the continuous casting of steel

    NASA Astrophysics Data System (ADS)

    Gheorghiu, Csaba Attila; Hepuť, Teodor; Popa, Erika

    2016-06-01

    In the steel continuous casting process, the mould lubrication has a very important technological role, with direct effects on the continuous cast blank quality. The lubrication process is directly influenced by the synthetic flux viscosity (slag thickness), which is determined on its turn by the chemical composition and the temperature. The researches made aimed to establish some correlation relationships between the viscosity, chemical composition and temperature, analytically and graphically expressed, by processing the data in the Matlab program. Based on these correlations the best chemical compositions of the lubrication fluxes are established.

  13. Mass Transfer Behavior of Phosphorus from the Liquid Slag Phase to Solid 2CaO·SiO2 in the Multiphase Dephosphorization Slag

    NASA Astrophysics Data System (ADS)

    Xie, Senlin; Wang, Wanlin; Luo, Zhican; Huang, Daoyuan

    2016-06-01

    The mass transfer behavior of phosphorus in the multiphase dephosphorization slag at 1623 K (1350 °C) is investigated in this article by adding the reagent P2O5 powders into the CaO-FeOt-SiO2 slag saturated with a directly precipitated 2CaO·SiO2 phase. The results show that the phosphorus was first quickly dissolved and transferred from the liquid slag to the precipitated solid 2CaO·SiO2 particle; then it reacted with the solid 2CaO·SiO2 particle to form (2CaO·SiO2-3CaO·P2O5) solid solution at the edge of a large solid particle. The further diffusion of phosphorus from the formed (2CaO·SiO2-3CaO·P2O5) solid solution reaction layer into the core of the 2CaO·SiO2 particle is the limiting step during the enrichment-phosphorus process. It is observed that the enrichment-phosphorus process is changed when the amount of added P2O5 content is increased and the formed solid solution phase is torn and peeled off from the surface of the 2CaO·SiO2 particle. In addition, the study shows that the solid solution structure is changed and becomes more compacted with the addition of P2O5 content, leading to the increment of solid solution density.

  14. SEM evaluation of advanced refractory failures in slagging gasifiers

    SciTech Connect

    Collins, W.Keith; Dahlin, Cheryl L.; Bennett, James P.; Kwong, Kyei-Sing; Rawers, James C.

    2005-08-01

    The SEM is an invaluable tool in the evaluation of advanced refractories and their failure. A reaction vessel?s refractory liner, at minimum, must protect the reaction vessel from elevated temperatures, corrosive slag and thermal cycling. To understand the failure mechanisms ARC staff had first to determine how an advanced chrome rich refractory was attacked by various components that make up a slag. Refractory cups were made from the refractory of interest and various compounds that can be found in a slag such as CaO, SiO2, Fe2O3, NaCl were placed into the test cups and fired for 24 hours at the required temperature with the desired atmosphere. The cups are prepared for examination by embedding in epoxy and cross sectioning. SEM examination revealed how various slag compositions attacked and penetrated the refractory. The slag could corrode, free refractory grains or react with the refractory and from a new compound. It was found that the only way to measure slag component penetration was with multiple elemental X-ray maps. SiO2 penetrated deeply and in many instances moved through the cup. The knowledge of slag refractory interactions gather during cup testing was applied to actual spent refractory from reaction vessels. Obtaining samples from the reaction vessel itself proved difficult due to time constraints imposed in relining. Samples were selected based on spent brick shape, color or location in the heap of spent refractory. Sample preparation affected the results dry, water or oil coolant during cutting may dissolve reaction products. The complex reactions between the slag and refractory made for very interesting and time consuming evaluation. Elemental X-ray maps at low and high magnification combined with point analysis aided in locating regions of interest. Crystals were found growing in voids and appear to be from vapor deposition. Other crystal structures are from the slag refractory interaction. Knowledge gathered from this and other supporting

  15. Can iron-making and steelmaking slag products be used to sequester CO2? Passive weathering and active carbonation experiments.

    NASA Astrophysics Data System (ADS)

    Worrall, Fred; Dobrzański, Andrew

    2015-04-01

    The high calcium content of iron and steel-making slags has been highlighted as providing a suitable feedstock material and medium with which to sequester CO2 into geologically stable carbonate phases. Optimisation of the natural carbonation process provides the potential for increasing the degree of carbonation above that possible via passive weathering. This study has assessed the baseline passive carbonation potential of several different slag products (graded steel slag aggregate, pellite, GBFS) within the climate of the northern UK. This baseline was then used as a comparison to the carbonation values achieved by the same products when actively reacted in a CO2-rich environment. The active carbonation phase of the project involved a factorial experimental study of materials reacted at 1MPa/10MPa CO2 pressure and 25˚C/125˚C. This study has shown: 1) That active carbonation of these products can successfully sequester additional CO2. 2) Carbonation potential in general is highly dependent upon grain size within material types, 3) There is a material-dependant cost-benefit issue when using different active carbonation conditions as well as the choice to use active vs. passive carbonation. The median sequestration potential of the slag products in this study is equivalent to the total emissions from 910 people from the UK; the CO2 emissions from 10000 tonnes of cement production; or 340000 tonnes of steel production.

  16. LWA demonstration applications using Illinois coal gasification slag: Phase 2. Technical report, September 1--November 30, 1993

    SciTech Connect

    Choudhry, V.; Steck, P.

    1993-12-31

    The objectives of this program are to demonstrate the feasibility of producing ultra-lightweight aggregates (ULWA) from solid residues (slag) generated during the gasification of Illinois coals, and to test the products as substitutes for conventional aggregates produced by pyroprocessing of perlite ores. In Phase 1 of this project, Praxis developed a pilotscale production technique and produced a large batch of expanded aggregates from an Illinois coal slag feed. The Phase 2 work focuses on characterization and applications-oriented testing of the expanded slag products as substitutes for conventional ULWAs. Target applications include high-volume uses such as loose fill insulation, insulating concrete, lightweight precast products (blocks), waterproof wallboard, rooftiles, and filtration media. The precast products will be subjected to performance and characterization testing in conjunction with a commercial manufacturer of such products in order to obtain input from a potential user. The production of value-added products from slag will eliminate a solid waste and possibly enhance the overall gasification process economics, especially when the avoided costs of disposal are taken into consideration.

  17. Mineral precipitation and dissolution at two slag-disposal sites in northwestern Indiana, USA

    USGS Publications Warehouse

    Bayless, E.R.; Schulz, M.S.

    2003-01-01

    Slag is a ubiquitous byproduct of the iron- and steel-refining industries. In northwestern Indiana and northeastern Illinois, slag has been deposited over more than 52 km2 of land surface. Despite the widespread use of slag for fill and construction purposes, little is known about its chemical effects on the environment. Two slagdisposal sites were examined in northwestern Indiana where slag was deposited over the native glacial deposits. At a third site, where slag was not present, background conditions were defined. Samples were collected from cores and drill cuttings and described with scanning electron microscopy and electron microprobe analysis. Ground-water samples were collected and used to assess thermodynamic equilibria between authigenic minerals and existing conditions. Differences in the mineralogy at background and slag-affected sites were apparent. Calcite, dolomite, gypsum, iron oxides, and clay minerals were abundant in native sediments immediately beneath the slag. Mineral features indicated that these minerals precipitated rapidly from slag drainage and co-precipitated minor amounts of non-calcium metals and trace elements. Quartz fragments immediately beneath the slag showed extensive pitting that was not apparent in sediments from the background site, indicating chemical weathering by the hyperalkaline slag drainage. The environmental impacts of slag-related mineral precipitation include disruption of natural ground-water flow patterns and bed-sediment armoring in adjacent surface-water systems. Dissolution of native quartz by the hyperalkaline drainage may cause instability in structures situated over slag fill or in roadways comprised of slag aggregates.

  18. Comparison of different digestive tract models for estimating bioaccessibility of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) from red slag 'Kieselrot'.

    PubMed

    Wittsiepe, J; Schrey, P; Hack, A; Selenka, F; Wilhelm, M

    2001-03-01

    'Kieselrot' (red slag), a highly PCDD/F-contaminated leaching residue from a copper production process, has been used as surface layer for more than 1,000 sports fields, playgrounds and pavements in Germany and neighbouring countries. Children can ingest this material directly by hand-to-mouth activities or soil-pica behaviour. Furthermore secondary contamination of farm land or kitchen gardens by drift of red slag dust may lead to an enrichment of PCDD/F within the food-chain. PCDD/F can be mobilized from contaminated materials by digestive juices and thus become bioaccessible for intestinal absorption. Two different digestive tract models were used to estimate the bioaccessibility of PCDD/F from red slag and to study the influence of food material on the mobilization of the contaminants. The bioaccessibility of PCDD/F from red slag depends on the charge of red slag material used, the bile content of the intestinal juice and on the presence of lipophilic foodstuffs. A low bioaccessibility of less than 5% was found when using a digestive tract model with a low bile content and in absence of food material. The bioaccessibility was estimated to be more than 60% when using a model with a higher bile content and in the presence of whole milk powder. A low bioaccessibility of PCDD/F from red slag in general--as assumed until now and mentioned in legal provision--was not confirmed by our study. Considering observations for the different homologue groups it is obvious that bioaccessibility is the first of several important steps to estimate human health risks arising from contaminated materials. In case red slag contaminated with PCDD/F their absorption rate in the digestive tract and/or metabolism might be at least just like important.

  19. Application of Two-Phase CFD to the Design and Analysis of a Subscale Motor Experiment to Evaluate Propellant Slag Production

    NASA Technical Reports Server (NTRS)

    Whitesides, R. Harold; Dill, Richard A.

    1996-01-01

    The redesigned solid rocket motor (RSRM) Pressure Perturbation Investigation Team concluded that the cause of recent pressure spikes during both static and flight motor burns was the expulsion of molten aluminum oxide slag from a pool which collects in the aft end of the motor around the submerged nozzle nose during the last half of motor operation. It is suspected that some motors produce more slag than others due to differences in aluminum oxide agglomerate particle sizes which may relate to subtle differences in propellant ingredient characteristics such as particle size distribution, contaminants, or processing variations. In order to determine the effect of suspect propellant ingredient characteristics on the propensity for slag production in a real motor environment, a subscale motor experiment was designed. An existing 5 inch ballistic test motor was selected as the basic test vehicle due to low cost and quick turn around times. The standard converging/diverging nozzle was replaced with a submerged nozzle nose design to provide a positive trap for the slag which would increase both the quantity and repeatability of measured slag weights. Computational fluid dynamics (CFD) was used to assess a variety of submerged nose configurations to identify the design which possessed the best capability to reliably collect slag. CFD also was used to assure that the final selected nozzle design would result in flow field characteristics such as dividing streamline location, nose attach point, and separated flow structure which would have similtude with the RSRM submerged nozzle nose flow field. It also was decided to spin the 5 inch motor about its longitudinal axis to further enhance slag collection quantities. Again, CFD was used to select an appropriate spin rate along with other considerations, including the avoidance of burn rate enhancement from radial acceleration effects.

  20. Environmental impact of ferrochrome slag in road construction.

    PubMed

    Lind, B B; Fällman, A M; Larsson, L B

    2001-01-01

    Vargon Alloys in Western Sweden is one of the largest producers of ferrochrome slag in Europe. Ferrochrome slag is a by-product from the production of ferrochrome, an essential component in stainless steel. Extensive tests have been carried out on the physical properties of the ferrochrome slag from Vargon Alloys and it was found to be highly suitable as road construction material. The composition and leaching tests of the ferrochrome slag show that the chromium content is high, 1-3%, although leaching under normal conditions is very low. With the exception of potassium (K), which had a potential leaching capacity (availability test) of around 16%, the leaching of chromium, nickel, zinc and other elements was just a few per cent. However, all these tests were conducted in the laboratory. What happens out in the field, under the influence of acid rain and biological activity, and how does this compare with the laboratory results? To answer this question an investigation was carried out to study the environmental impact of ferrochrome slag in roads that were built in 1994. The investigation includes soil sampling (total content and leachable amounts of metals) and groundwater analysis (filtered and non-filtered samples). In addition, a new method involving the bio-uptake of chromium and other metals by the roots of the dandelion (Taraxacum officinale) was tested. The results show that there was a low migration of particles from the slag to the underlying soil and that the leaching into the groundwater was also low for all the elements analysed. However, there seemed to be a significant uptake of Cr by plants growing with their roots in the slag. An investigation of plant uptake was an important complement to laboratory leaching tests on alternative materials.

  1. Slag columns for upgrading phosphorus removal from constructed wetland effluents.

    PubMed

    Chazarenc, F; Brisson, J; Comeau, Y

    2007-01-01

    The current best option to upgrade constructed wetlands (CWs) for phosphorus (P) retention, in terms of efficiency, cost and simplicity, consists in using media having a strong P affinity. The media can be used either in the planted beds or in a filtration system downstream of the beds. The use of slag filters was shown to be efficient for removing P from wastewater as it represented a slow release source of calcium and hydroxide, favouring the formation of hydroxyapatite. Our study aimed at maximising the P retention capacity of slag filters located at the outlet of CWs since electric arc furnace slag has been shown to inhibit the growth of macrophytes when used in the filtration matrix. Bench-scale columns (Vtot = 6.2 L) filled with various combinations of filter media (slag, granite, limestone) of different sizes (2-5, 5-10, 10-20 mm) were fed on-site during four months with a CW effluent (in mg/L: 30 COD, 30 TSS, 10 Pt). Results showed that the best media combination enabling the maximum o-PO4 retention (more than 80% removal without clogging) consisted in a series of a ternary mix column (slag 5-10 mm, granite 2-5 mm, limestone 5-10 mm) followed by a slag column (slag 5-10 mm). Pilot scale columns (Vtot = 300 L), filled with the best media combination, were installed at the outlet of a 28 m2 CW. These columns showed more than 75% removal efficiency during one year and were designed to be easily replaced each year.

  2. Slagging and fluidity behavior of coal ash under gasifier environment

    SciTech Connect

    Kim, H.T.; Bae, H.J.; Lee, S.H.; Park, J.S.; Yun, Y.S.; Chung, S.W.

    1997-12-31

    The objective of this study is to predict the slagging and fluidity behavior of coal ashes from the physical/chemical properties of parent coals to determine the optimum operating parameter of a slagging-type coal gasifier. Three types of coal samples, such as Alaska Usibelli, China Datong and Posco (blended coal), are analyzed for their ash composition and ash fusion temperature. To investigate the effect of flux addition on ash slagging behavior, optimum quantity of CaO addition is evaluated with considering negative effect of CaO addition on gasification reaction. The effect of blending of Posco coal with Alaska and Datong coal on ash slagging is also investigated to expand the variety and performance of coal types in slagging-type entrained-bed gasifier. The results of the experiment shows that the optimum CaO fluxing quantity is 10%, 20% on Alaska and Dating coal, respectively. However, optimum blending ratio for ash slagging is not found when mixing Posco coal with Alaska or Datong coals. Melting and slagging characteristics of coal ash samples with changing temperature are examined in detail by DTA. ASTM ash melting temperatures as well as critical viscosity temperature are compared with TGA and DTA profiles. DTA experiments illustrate that coal ash starts to melt before the IDT (initial deformation temperature) and that theoretical T{sub CV} is well correlated with DTA profile. Experiment of ash fluidity are also carried on with the Alaska and Datong coal ashes using a high temperature viscometer. The experimental viscosity data is compared with the calculated viscosity and results show good correlation. As a result, viscosity of coal ash could be calculated with the Watt and Fereday equation in the high temperature range. The experimental results from this investigation will be used as reference data for determining optimum operating condition of 3t/d bench scale unit gasifier which is located in Ajou University, Suwon, Korea.

  3. Separation of Iron Phase and P-Bearing Slag Phase from Gaseous-Reduced, High-Phosphorous Oolitic Iron Ore at 1473 K (1200 °C) by Super Gravity

    NASA Astrophysics Data System (ADS)

    Gao, Jintao; Zhong, Yiwei; Guo, Lei; Guo, Zhancheng

    2016-04-01

    In situ observation on the morphology evolution and phosphorous migration of gaseous-reduced, high-phosphorous oolitic iron ore during the melting process was carried out with a high-temperature confocal scanning laser microscope. The results showed that 1473 K (1200 °C) was a critical temperature at which the gangue minerals started to form into the slag phase while the iron grains remained in a solid state; in addition, the phosphorus remained in the slag phase. Since the separation of iron grains and P-bearing slag was not achieved at the low temperature under the conventional conditions, separate experiments of the iron phase and the P-bearing slag phase from gaseous-reduced, high-phosphorous oolitic iron ore at 1473 K (1200 °C) by super gravity were carried out in this study. Based on the iron-slag separation by super gravity, phosphorus was removed effectively from the iron phase at the temperature below the melting point of iron. Iron grains moved along the super-gravity direction, joined, and concentrated as the iron phase on the filter, whereas the slag phase containing apatite crystals broke through the barriers of the iron grains and went through the filter. Consequently, increasing the gravity coefficient was definitely beneficial for the separation of the P-bearing slag phase from the iron phase. With the gravity coefficient of G = 1200, the mass fractions of separated slag and iron phases were close to their respective theoretical values, and the mass fraction of MFe in the separated iron phase was up to 98.09 wt pct and that of P was decreased to 0.083 wt pct. The recovery of MFe in the iron phase and that of P in the slag phase were up to 99.19 and 95.83 pct, respectively.

  4. Geochemical and mineralogical controls on trace element release from the Penn Mine base-metal slag dump, California

    USGS Publications Warehouse

    Parsons, M.B.; Bird, D.K.; Einaudi, M.T.; Alpers, C.N.

    2001-01-01

    Base-metal slag deposits at the Penn Mine in Calaveras County, California, are a source of environmental contamination through leaching of potentially toxic elements. Historical Cu smelting at Penn Mine (1865-1919) generated approximately 200,000 m3 of slag. The slag deposits, which are flooded annually by a reservoir used for drinking water and irrigation, also may be in contact with acidic ground waters (pH < 4) from the adjacent mine area. Slags vary from grey to black, are glassy to crystalline, and range in size from coarse sand to large (0.6 ?? 0.7 ?? 1.5 m), tub-shaped casts. Metals are hosted by a variety of minerals and two glass phases. On the basis of mineralogy, slags are characterized by 4 main types: fayalite-rich, glassy, willemite-rich, and sulfide-rich. The ranges in metal and metalloid concentrations of 17 slag samples are: As, 0.0004-0.92; Ba, 0.13-2.9; Cd, 0.0014-1.4; Cu, 0.18-6.4; Pb, 0.02-11; and Zn, 3.2-28 wt.%. Leachates from Toxicity Characteristic Leaching Procedure tests (acetic acid buffered at pH 4.93) on two wiltemite-rich slags contained Cd and Pb concentrations (up to 2.5 and 30 mg/l, respectively) in excess of US Environmental Protection Agency (USEPA) regulatory limits. Analyses of filtered (0.45 ??m) water, collected within the flooded slag dump during reservoir drawdown, reveal concentrations of Cd (1.7 ??g/l), Cu (35 ??g/l), and Zn (250 ??g/l) that exceed USEPA chronic toxicity guidelines for the protection of aquatic life. Data from field and laboratory studies were used to develop geochemical models with the program EQ3/6 that simulate irreversible mass-transfer between slag deposits and reservoir waters. These models include kinetic rate laws for abiotic sulfide oxidation and surface-controlled dissolution of silicates, oxides, and glass. Calculations demonstrate that the main processes controlling dissolved metal concentrations are (1) dissolution of fayalite, willemite, and glass; (2) sulfide oxidation; and (3) secondary

  5. Influence of Basicity and MgO on Fluidity and Desulfurization Ability of High Aluminum Slag

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Meng, Qing-min; Long, Hong-ming; Li, Jia-xin

    2016-08-01

    The viscosity of experimental slag, which was mixed based on the composition of a practical blast furnace slag, was measured in this paper. The influence of Al2O3 and MgO content, basicity R2 = w(CaO)/w(SiO2) on the fluidity of slag was studied. The stepwise regression analysis in SPSS was used to reveal the relationship between sulfur distribution coefficient LS and slag composition as well as furnace temperature. The results show that increasing of MgO up to 12% can decrease the slag viscosity. The w(MgO) should be controlled below 8% when there is 20% Al2O3 in the slag. Temperature of hot metal and content of CaO in slag are the two dominant factors on the desulfurization capacity of slag.

  6. New laser technology helps reduce coal-slagging headaches

    SciTech Connect

    Neville, A.

    2009-02-15

    Laser-induced breakdown spectroscopy (LIBS) is starting to light the way for power plant operators who want to reduce coal ash deposition in their boilers. The method was developed by Lehigh University's Energy Research Centre and the Energy Research Co. The LIBS system analyzes the chemical properties of coal using a pulsating laser with two frequencies, one infrared and one visible light. The laser vaporizes a sample, resulting in a distinct elemental signature. From these data, a newly developed software package containing artificial neural network (ANN) models estimates ash fusion temperature and predicts coal slagging potential. LIBS is the size of a table top, safe to use and provides instantaneous data without interrupting the process. The performance of the LIBS system was verified in lab experiments and then the system was set up at Dominion's Brayton Point Power Station, a 1,150-MW coal-fired power plant in Somerset, MA. The project demonstrated the merit of the LIBS system that produces coal elemental analysis and estimated fusion temperatures. Further development is needed to equip a LIBS system with an automatic online coal-sampling attachment and to achieve higher accuracy and repeatability. The researchers have been awarded a second DOE grant to fund development of a commercial prototype of the LIBS system. 2 figs., 2 photos.

  7. Effect of TiO2 Content on the Crystallization Behavior of Titanium-Bearing Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Hu, Meilong; Wei, Ruirui; Yin, Fangqing; Liu, Lu; Deng, Qingyu

    2016-09-01

    The content of TiO2 has an important influence on both the basic structure and the crystallization behavior of titanium-bearing blast furnace (BF) slag. The results of thermodynamic calculations show that, when the mass content of TiO2 is smaller than 25%, CaTiO3 increases as the content of TiO2 increases. However, when the TiO2 content is more than 25%, the CaTiO3 content decreases and TiO2 gradually increases. The results of a confocal laser scanning microscopy (CLSM) experiment show that, when the TiO2 mass content is 10%, Ca2MgSi2O7 and Ca2Al2SiO7 are the main crystallized phases resulting from the molten slag. Furthermore, when the TiO2 mass content is 20%, CaMgSi2O6, Ca(Ti,Mg,Al)(Si,Al)2O7 and dendrite CaTiO3 are the crystallized phases, while when the TiO2 mass content increases to 30%, CaTiO3 is the sole phase. The discrepancy between the CLSM results and the thermodynamic calculations occurs mainly due to the high melting point of the titanium-bearing BF slag. During the cooling process for the molten slag, CaTiO3 is crystallized first, due to its high crystallization temperature. Furthermore, the molten slag is solidified in its entirety before the other phases crystallize.

  8. Effect of TiO2 Content on the Crystallization Behavior of Titanium-Bearing Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Hu, Meilong; Wei, Ruirui; Yin, Fangqing; Liu, Lu; Deng, Qingyu

    2016-07-01

    The content of TiO2 has an important influence on both the basic structure and the crystallization behavior of titanium-bearing blast furnace (BF) slag. The results of thermodynamic calculations show that, when the mass content of TiO2 is smaller than 25%, CaTiO3 increases as the content of TiO2 increases. However, when the TiO2 content is more than 25%, the CaTiO3 content decreases and TiO2 gradually increases. The results of a confocal laser scanning microscopy (CLSM) experiment show that, when the TiO2 mass content is 10%, Ca2MgSi2O7 and Ca2Al2SiO7 are the main crystallized phases resulting from the molten slag. Furthermore, when the TiO2 mass content is 20%, CaMgSi2O6, Ca(Ti,Mg,Al)(Si,Al)2O7 and dendrite CaTiO3 are the crystallized phases, while when the TiO2 mass content increases to 30%, CaTiO3 is the sole phase. The discrepancy between the CLSM results and the thermodynamic calculations occurs mainly due to the high melting point of the titanium-bearing BF slag. During the cooling process for the molten slag, CaTiO3 is crystallized first, due to its high crystallization temperature. Furthermore, the molten slag is solidified in its entirety before the other phases crystallize.

  9. Preparation of calcium silicate absorbent from iron blast furnace slag.

    PubMed

    Brodnax, L F; Rochelle, G T

    2000-09-01

    Calcium silicate hydrate (CSH) solids were prepared from hydrated lime and iron blast furnace slag in an aqueous agitated slurry at 92 degrees C. While it was hoped a minimal lime/slag ratio could be used to create near-amorphous CSH, the surface area of the product improved by increasing the lime/slag weight ratio to 2. The addition of gypsum to the lime/slag system dramatically improved the formation of surface area, creating solids with 139 m2/g after 30 hr of reaction when only a minimal amount of lime was present. The SO2 reactivity of solids prepared with gypsum greatly exceeded that of hydrated lime, achieving greater than 70-80% conversion of the alkalinity after 1 hr of reaction with SO2. The use of CaCl2 as an additive to the lime/slag system, in lieu of gypsum, also produced high-surface-area solids, 115 m2/g after 21 hr of reaction. However, the SO2 reactivity of these sorbents was relatively low given the high surface area. This emphasized that the correlation between surface area and SO2 reactivity was highly dependent on the solid phase, which was subsequently dependent on slurry composition. PMID:11055162

  10. Investigation of High-Temperature Slag/Copper/Spinel Interactions

    NASA Astrophysics Data System (ADS)

    De Wilde, Evelien; Bellemans, Inge; Campforts, Mieke; Guo, Muxing; Blanpain, Bart; Moelans, Nele; Verbeken, Kim

    2016-09-01

    An important cause for the mechanical entrainment of copper droplets in slags during primary and secondary copper production is their interaction with solid spinel particles, hindering the sedimentation of the copper droplets. In the present study, the interactions between the three phases involved (slag-Cu droplets-spinel solids) were investigated using an adapted sessile drop experiment, combined with detailed microstructural investigation of the interaction zone. An industrially relevant synthetic PbO-CaO-SiO2-Cu2O-Al2O3-FeO-ZnO slag system, a MgAl2O4 spinel particle, and pure copper were examined with electron microscopy after their brief interaction at 1523 K (1250 °C). Based on the experimental results, a mechanism depending on the interlinked dissolved Cu and oxygen contents within the slag is proposed to describe the origin of the phenomenon of sticking Cu alloy droplets. In addition, the oxygen potential gradient across the phases (i.e., liquid Cu, slag, and spinel) appears to affect the Cu entrainment, as deduced from a microstructural analysis.

  11. Effect of slag on shear strength of calcium bentonite

    SciTech Connect

    Khera, R.P.; So, L.T.

    1997-12-31

    To prevent lateral migration of liquid pollutants in groundwater, relatively impervious vertical barriers are built around waste disposal sites. The slurry trench technique is the most commonly used construction method. The two common types of slurry walls are soil bentonite (SB) and cement bentonite (CB) walls. This study was undertaken to determine the strength of calcium bentonite as affected by cement and slag. Test specimens were prepared with 15% calcium bentonite, 5% to 15% cement, and 7.5% to 10% slag. Undrained triaxial compression tests and unconfined compression tests were performed on different mixes. These test results show that regardless of the proportion of cement and slag, the peak strength occurred at strain equal to or less than 1%. The strength essentially reached its ultimate value at about 2% strain and there was little change in strength beyond this point. The strength of specimens increased as the proportion of slag to cement increased. Pore water pressure at peak strength was positive. With increasing strain and increasing proportion of slag the pore water pressure reduced in magnitude. Specimens which were not subjected to vacuum during preparation showed extremely high negative pore pressures and higher strength.

  12. Preparation of calcium silicate absorbent from iron blast furnace slag.

    PubMed

    Brodnax, L F; Rochelle, G T

    2000-09-01

    Calcium silicate hydrate (CSH) solids were prepared from hydrated lime and iron blast furnace slag in an aqueous agitated slurry at 92 degrees C. While it was hoped a minimal lime/slag ratio could be used to create near-amorphous CSH, the surface area of the product improved by increasing the lime/slag weight ratio to 2. The addition of gypsum to the lime/slag system dramatically improved the formation of surface area, creating solids with 139 m2/g after 30 hr of reaction when only a minimal amount of lime was present. The SO2 reactivity of solids prepared with gypsum greatly exceeded that of hydrated lime, achieving greater than 70-80% conversion of the alkalinity after 1 hr of reaction with SO2. The use of CaCl2 as an additive to the lime/slag system, in lieu of gypsum, also produced high-surface-area solids, 115 m2/g after 21 hr of reaction. However, the SO2 reactivity of these sorbents was relatively low given the high surface area. This emphasized that the correlation between surface area and SO2 reactivity was highly dependent on the solid phase, which was subsequently dependent on slurry composition.

  13. Investigation of Freeze-Linings in a Nonferrous Industrial Slag

    NASA Astrophysics Data System (ADS)

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Vervynckt, Stephanie; Jak, Evgueni

    2014-06-01

    Slag freeze-lining reactor wall protection is a widely used technology in high temperature reaction systems. An air-cooled probe technique was used to investigate the formation of the freeze-linings in an industrial blast furnace slag. The compositions of the phases and the microstructures within the deposits have been characterized. It has been demonstrated that an industrial air-cooled probe can be used to take bath samples from actual smelter operations. In addition, a laboratory-scale experiment was undertaken to investigate the formation, stability, and bath/deposit interface temperature at steady-state conditions. Importantly, the current study has shown that stable steady-state freeze-linings can be obtained in metallurgical reactors operating below the slag liquidus temperature. In spite of the fact that solids are present in the bulk slag, the deposit thickness remains unaltered due to the dynamic conditions present at the deposit/bath interface. The results are consistent with findings obtained on a number of other different slag systems and the proposed dynamic mechanism of deposit stabilization. The findings demonstrate the basis for, and potential benefits that may follow from, operating the high temperature reactors at temperatures below the liquidus temperature, i.e., with solids present, without a catastrophic build-up of solids. This change in design concept could result in significant decreases in operating temperature, energy, and operating cost savings.

  14. Petrogenetic characteristics of molten slag from the pyrolysis/melting treatment of MSW.

    PubMed

    Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Motomura, Yoshinobu; Watanabe, Koichiro

    2009-03-01

    MSW slag materials derived from four pyrolysis melting plants in Japan were studied from the viewpoint of petrology in order to discriminate the glass and mineral phases and to propose a petrogenetic model for the formation process of molten slag. Slag material is composed of two major components: melt and refractory products. The melt products that formed during the melting process comprise silicate glass, and a suite of minerals as major constituents. The silicate glass is essentially composed of low and high silica glass members (typically 30% and 50% of SiO(2), respectively), from which minerals such as spinels, melilite, pseudowollastonite, and metallic inclusions have been precipitated. The refractory products consist mainly of pieces of metals, minerals and lithic fragments that survived through the melting process. Investigations demonstrated that the low silica melts (higher Ca and Al contents) were produced at upper levels of high temperature combustion chamber HTCC, at narrower temperature ranges (1250-1350 degrees C), while the high silica melts formed at broader temperature ranges (1250-1450 degrees C), at the lower levels of HTCC. The recent temperature ranges were estimated by using CaOAl(2)O(3)SiO(2) (CAS) ternary liquidus diagram that are reasonably consistent with those reported for a typical combustor. It was also understood that the samples with a higher CaO/SiO(2) ratio (>0.74-0.75) have undergone improved melting, incipient crystallization of minerals, and extensive homogenization. The combined mineralogical and geochemical examinations provided evidence to accept the concept of stepwise generation of different melt phases within the HTCC. The petrogenesis of the melt products may therefore be described as a two-phase melt system with immiscible characteristics that have been successively generated during the melting process of MSW. PMID:18922688

  15. A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate.

    PubMed

    Sekaran, Alan; Palaniswamy, Murthi; Balaraju, Sivagnanaprakash

    2015-01-01

    Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i) Mix A, conventional concrete mix with no material substitution, (ii) Mix B, 30% replacement of cement with fly ash, and (iii) Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C) had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications.

  16. A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate

    PubMed Central

    Sekaran, Alan; Palaniswamy, Murthi; Balaraju, Sivagnanaprakash

    2015-01-01

    Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i) Mix A, conventional concrete mix with no material substitution, (ii) Mix B, 30% replacement of cement with fly ash, and (iii) Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C) had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications. PMID:26421315

  17. Synthesis of highly efficient CaO-based, self-stabilizing CO2 sorbents via structure-reforming of steel slag.

    PubMed

    Tian, Sicong; Jiang, Jianguo; Yan, Feng; Li, Kaimin; Chen, Xuejing

    2015-06-16

    Capturing anthropogenic CO2 in a cost-effective and highly efficient manner is one of the most challenging issues faced by scientists today. Herein, we report a novel structure-reforming approach to convert steel slag, a cheap, abundant, and nontoxic calcium-rich industrial waste, as the only feedstock into superior CaO-based, self-stabilizing CO2 sorbents. The CO2 capture capacity of all the steel slag-derived sorbents was improved more than 10-fold compared to the raw slag, with the maximum uptake of CO2 achieving at 0.50 gCO2 gsorbent(-1). Additionally, the initial steel slag-derived sorbent could retain 0.25 gCO2 gsorbent(-1), that is, a decay rate of only 12% over 30 carbonation-calcination cycles, the excellent self-stabilizing property allowed it to significantly outperform conventional CaO, and match with most of the existing synthetic CaO-based sorbents. A synergistic effect that facilitated CO2 capture by CaO-based sorbents was clearly recognized when Mg and Al, the most common elements in steel slag, coexisted with CaO in the forms of MgO and Al2O3, respectively. During the calcium looping process, MgO served as a well spacer to increase the porosity of sorbents together with Al2O3 serving as a durable stabilizer to coresist the sintering of CaCO3 grains at high temperatures.

  18. Role of prereduced pellets in the slag foaming in modern EAFs

    NASA Astrophysics Data System (ADS)

    Kozhukhov, A. A.

    2013-06-01

    The problems of electric arc furnace slags are considered, and the role of prereduced pellets in the slag foaming in electric arc furnaces is studied. The optimum rate of loading of prereduced pellets into a furnace that ensures effective steelmaking slag foaming is determined as a function of the degree of pellet prereduction.

  19. An analysis of slag stratification in nickel laterite smelting furnaces due to composition and temperature gradients

    NASA Astrophysics Data System (ADS)

    Utigard, T.

    1994-08-01

    The density of FeO-MgO-SiO2 and FeO-Fe2O3-SiO2 based slags has been analyzed in terms of smelting of lateritic ores for the production of ferronickel. The density of these slags decreases with increasing MgO, SiO2, and Fe2O3 contents as well as with increasing temperature. During the electric furnace smelting of calcined and prereduced garnieritic ores, the slag temperature decreases from the upper layer down toward the slag/metal interface. Together with precipitation of either olivine or silica, this leads to the formation of a dense and stagnant slag layer at the slag/metal interface. For limonitic ores, the use of deep electrode immersion and high currents leads to slag reduction and increased slag temperatures toward the bottom part of the slag layer. The reduction of Fe2O3 to FeO increases the slag density. In this manner, it may be possible to maintain a hot slag layer in the region of the slag/metal interface, without buoyancy-induced flow.

  20. Field Trial Results of an Improved Refractory Material for Slagging Gasifiers

    SciTech Connect

    Bennett, J.P.; Kwong, K.-S.; Powell, C.P.; Petty, A.V., Jr.; Thomas, H.; Prior, H.D.; Schnake, M.

    2006-09-01

    Gasifiers are used commercially to react a carbon feedstock with water and oxygen under reducing conditions; producing chemicals used as feedstock for other processes, fuel for power plants, and/or steam used in other processes. A gasifier acts as a high temperature, high pressure reaction chamber, typically operating between 1250-1575°C, and with pressures between 300-1000 psi. Ash that originates from mineral impurities in the carbon feedstock becomes a by-product of gasification. In a slagging gasifier it melts, forming a liquid which flows down the gasifier sidewall; penetrating and wearing away the refractory liner by corrosive dissolution, abrasive wear, or by other processes such as spalling. The refractory liner must withstand the severe service environment, protecting the steel shell against corrosive gases, temperature, and material wear. Users have identified refractory service life as the most important limitation to sustained on-line availability of gasifiers, limiting gasifier acceptance and use by industry. The National Energy Technology Laboratory in Albany, OR, has developed and patented (US Patent # 6,815,386) a phosphate containing high chrome oxide refractory for use in slagging gasifiers. In cooperation with ANH Refractories Company, this refractory material has been commercially produced and is undergoing field tests in commercial gasifiers. An analysis of data from these field tests indicates that the phosphate containing refractory results in an improved service life over other refractory materials currently used as gasifier liners. Results from the post-mortem analysis of the field trial in relation to the failure mechanisms in a slagging gasifier will be presented.

  1. Computer modeling brings slag control into the 21st century

    SciTech Connect

    Smyrniotis, C.

    2005-10-01

    Many power plants have switched from bituminous coals to Powder River Basin coals to comply with lower SOx emissions limits. Although this has been a successful strategy, increased slagging has led many plants to seek coals with lower sodium content. But the increased demand for these coals has raised their prices. Can anything else be done to simultaneously widen fuel options, control costs, and keep the slag devil at bay? Targeted In-Furnace Injection (TIFI), which uses CFD modeling and virtual reality visualization techniques can address all three issues. The modelling program targets areas of the radiant and convection sections of a boiler with chemicals to reduce or eliminate slagging and fouling. The article describes the two different forms of CFD modelling and the virtual reality engine used in TIFI technology. The technology has been successfully used with the same chemical attitude for three years at Hugo Station in Fort Towson, OK. 3 figs.

  2. A clean coal combustion technology-slagging combustors

    SciTech Connect

    Chang, S. L.; Berry, G. F.

    1989-03-01

    Slagging combustion is an advanced clean coal technology technique characterized by low NOx and SOx emission, high combustion efficiency, high ash removal, simple design and compact size. The design of slagging combustors has operational flexibility for a wide range of applications, including retrofitting boilers, magnetohydrodynamic combustors, coal-fired gas turbines, gasifiers and hazardous waste incinerators. In recent years, developers of slagging combustors have achieved encouraging progress toward the commercialization of this technology. Although there is a diversity of technical approaches among the developers, they all aim for a compact design of pulverized coal combustion with high heat release and sub-stoichiometric combustion regimes of operation to suppress NOx formation, and most aim to capture sulfur by using sorbent injection in the combustor. If the present pace toward commercialization continues, retrofitting boilers of sizes ranging from 20 to 250 MMBtu/hr (5.9 to 73 MWt) may be available for commercial use in the 1990's. 18 refs., 2 figs.

  3. Structure and Vibrational Spectra of Slags Produced from Radioactive Waste

    NASA Astrophysics Data System (ADS)

    Malinina, G. A.; Stefanovsky, S. V.

    2014-05-01

    The structure of the anionic motif of aluminosilicate and aluminoborosilicate glasses containing simulated slags from a solid radioactive waste incinerator was studied by IR and Raman spectroscopy. Spectra of melted slag were consistent with Si-O tetrahedra with various numbers of bridging O ions and Al-O tetrahedra embedded in the Si-O network in the slag vitreous and crystalline phases (nepheline, nagelschmidtite). Vibrations of doubly and triply bound Si-O tetrahedra and Al-O tetrahedra embedded between them were mainly responsible for the spectra as the content of sodium disilicate fl ux and the glass fraction in the materials increased. Addition of sodium tetraborate fl ux caused the appearance of B-O vibrations of predominantly three-coordinate B and a tendency toward chemical differentiation preceding phase separation.

  4. Pyrochemical recovery of plutonium from calcium fluoride reduction slag

    DOEpatents

    Christensen, D.C.

    A pyrochemical method of recovering finely dispersed plutonium metal from calcium fluoride reduction slag is claimed. The plutonium-bearing slag is crushed and melted in the presence of at least an equimolar amount of calcium chloride and a few percent metallic calcium. The calcium chloride reduces the melting point and thereby decreases the viscosity of the molten mixture. The calcium reduces any oxidized plutonium in the mixture and also causes the dispersed plutonium metal to coalesce and settle out as a separate metallic phase at the bottom of the reaction vessel. Upon cooling the mixture to room temperature, the solid plutonium can be cleanly separated from the overlying solid slag, with an average recovery yield on the order of 96 percent.

  5. Archaeo-metallurgical studies of tuyeres and smelting slags found at Tharros (north-western Sardinia, Italy)

    NASA Astrophysics Data System (ADS)

    de Caro, T.; Riccucci, C.; Parisi, E. I.; Renzulli, A.; Del Moro, S.; Santi, P.; Faraldi, F.

    2013-12-01

    A large number of pyrometallurgical materials such as tuyeres, slags and refractory tools likely associated with metal extraction processes have been found at Tharros (north-western Sardinia, Italy) during archaeological excavations stratigraphically related to the Phoenician-Punic period (VI-III centuries BC). Micro-chemical, micro-structural and mineralogical studies have been carried out by means of the combined use of X-ray diffraction (XRD), selected-area X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) in order to identify pyrometallurgical processes and main relevant technological parameters. The results reveal that tuyeres, slags and refractory tools can be associated with an iron ore smelting process to extract the metal by slagging the unwanted by-products. Moreover, temperature and duration of the smelting process have been estimated through mineralogical studies and by a comparative analysis between the micro-chemical and structural features of thermally treated refractory materials and tuyeres. The results disclose the high level of technological competence of the ancient metallurgists able to carry out complex high-temperature processes to extract iron from ores by separating the metal from unwanted siliceous species.

  6. Synthetic Coal Slag Infiltration into Varying Refractory Materials

    SciTech Connect

    Kaneko, Tetsuya K; Thomas, Hugh; Bennett, James P; Sridhar, Seetharaman

    2012-10-01

    The infiltrations of synthetic coal slag into 99%Al{sub 2}O{sub 3}, 85%Al{sub 2}O{sub 3}–15%SiO{sub 2}, and 90%Cr{sub 2}O{sub 3}–10%Al{sub 2}O{sub 3} refractories with a temperature gradient induced along the penetration direction were compared to one another. The infiltrating slag was synthesized with a composition that is representative of an average of the ash contents from U S coal feedstock. Experiments were conducted with a hot-face temperature of 1450°C in a CO/CO{sub 2} atmosphere. Minimal penetration was observed in the 90%Cr{sub 2}O{sub 3}–10%Al{sub 2}O{sub 3} material because interactions between the refractory and the slag produced a protective layer of FeCr{sub 2}O{sub 4}, which impeded slag flow into the bulk of the refractory. After 5 h, the 99%Al{sub 2}O{sub 3} sample exhibited an average penetration of 12.7 mm whereas the 85%Al{sub 2}O{sub 3}–15%SiO{sub 2} sample showed 3.8 mm. Slag infiltrated into the 99%Al{sub 2}O{sub 3} and 85%Al{sub 2}O{sub 3}–15%SiO{sub 2} refractory systems by dissolving the respective refractories' matrix materials, which consist of fine Al{sub 2}O{sub 3} particles and an amorphous alumino-silicate phase. Due to enrichment in SiO{sub 2}, a network-former, infiltration into the 85%Al{sub 2}O{sub 3}–15%SiO{sub 2} system yielded a higher viscosity slag and hence, a shallower penetration depth. The results suggest that slag infiltration can be limited by interactions with the refractory through the formation of either a solid layer that physically impedes fluid flow or a more viscous slag that retards infiltration.

  7. Crystallization Behavior of Perovskite in the Synthesized High-Titanium-Bearing Blast Furnace Slag Using Confocal Scanning Laser Microscope

    NASA Astrophysics Data System (ADS)

    Hu, Meilong; Liu, Lu; Lv, Xuewei; Bai, Chenguang; Zhang, Shengfu

    2013-10-01

    The isothermal phase composition of high-titanium-bearing slag (23 mass pct TiO2) under an argon atmosphere during cooling process from 1723 K (1450 °C) was calculated by FactSage.6.3 (CRCT-ThermFact Inc., Montréal, Canada). Three main phases, which were perovskite, titania spinel, and clinopyroxene, could form during the cooling process and they precipitated at 1713 K, 1603 K, and 1498 K (1440 °C, 1330 °C, and 1225 °C), respectively. The nonisothermal crystallization process of perovskite in synthesized high-titanium-bearing slag was studied in situ by a confocal scanning laser microscope (CSLM) with cooling rate of 30 K/min. The results showed that the primary phase was perovskite that precipitated at 1703 K (1430 °C). The whole precipitation and growth process of perovskite was obtained, whereas other phases formed as glass under the current experimental conditions. Perovskite grew along a specific growth track and finally appeared with snowflake morphology. The growing kinetics of perovskite formation from molten slag were also mentioned.

  8. Utilization of flotation wastes of copper slag as raw material in cement production.

    PubMed

    Alp, I; Deveci, H; Süngün, H

    2008-11-30

    Copper slag wastes, even if treated via processes such as flotation for metal recovery, still contain heavy metals with hazardous properties posing environmental risks for disposal. This study reports the potential use of flotation waste of a copper slag (FWCS) as iron source in the production of Portland cement clinker. The FWCS appears a suitable raw material as iron source containing >59% Fe(2)O(3) mainly in the form of fayalite (Fe(2)SiO(4)) and magnetite (Fe(3)O(4)). The clinker products obtained using the FWCS from the industrial scale trial operations over a 4-month period were characterised for the conformity of its chemical composition and the physico-mechanical performance of the resultant cement products was evaluated. The data collected for the clinker products produced using an iron ore, which is currently used as the cement raw material were also included for comparison. The results have shown that the chemical compositions of all the clinker products including those of FWCS are typical of a Portland cement clinker. The mechanical performance of the standard mortars prepared from the FWCS clinkers were found to be similar to those from the iron ore clinkers with the desired specifications for the industrial cements e.g. CEM I type cements. Furthermore, the leachability tests (TCLP and SPLP) have revealed that the mortar samples obtained from the FWCS clinkers present no environmental problems while the FWCS could act as the potential source of heavy metal contamination. These findings suggest that flotation wastes of copper slag (FWCS) can be readily utilised as cement raw material due to its availability in large quantities at low cost with the further significant benefits for waste management/environmental practices of the FWCS and the reduced production and processing costs for cement raw materials.

  9. Controlling chromium slag pollution utilising scavengers: a case of Shandong Province, China.

    PubMed

    Liu, Changhao; Côté, Raymond P

    2015-04-01

    The problem of chromium slag pollution is a great challenge for China. It is now an urgent task for China to take effective measures to eliminate chromium slag pollution. This article examines the case of the treatment of chromium slag in Shandong Province and explores how chromium slag pollution can be eliminated in Shandong Province. It shows that the chromium slag stockpiled by the chemical plants was successfully utilised by local steel companies, who act as 'scavenger companies'. The driving mechanism, seeking a potential 'scavenger company' within the local region and the role of the local government on the case of Shandong Province are discussed. This article concludes that local steel companies can be utilised to effectively and efficiently treat the chromium slag while benefiting the steel companies. The local governments need to play multiple roles in solving the problem of chromium slag pollution. Seeking and identifying 'scavenger companies' within a region could be an important approach to reducing pollution within the region.

  10. Interaction of CaO-FeO-SiO[sub 2] slags with partially stabilized zirconia

    SciTech Connect

    Chung, Yau Don; Schlesinger, M.E. . Dept. of Metallurgical Engineering)

    1994-03-01

    Calcia- and magnesia-partially-stabilized zirconia samples were corroded under static and dynamic conditions in three slags from the CaO-FeO-SiO[sub 2] system. Low-basicity and high-FeO slags corroded the samples by leaching magnesia from the cubic phase in the specimen, causing its destabilization and ultimate dissolution. However, a higher-basicity slag which proved the most corrosive of the three promoted bulk dissolution of the cubic phase instead, the rate of which was controlled by the thickness of the adjacent slag boundary layer. The levels of sample corrosion both at and below the slag line are used to illustrate the effects of experimental variables, including slag composition, specimen density, and slag motion.

  11. Monitoring of stainless-steel slag carbonation using X-ray computed microtomography.

    PubMed

    Boone, Marijn A; Nielsen, Peter; De Kock, Tim; Boone, Matthieu N; Quaghebeur, Mieke; Cnudde, Veerle

    2014-01-01

    Steel production is one of the largest contributors to industrial CO2 emissions. This industry also generates large amounts of solid byproducts, such as slag and sludge. In this study, fine grained stainless-steel slag (SSS) is valorized to produce compacts with high compressive strength without the use of a hydraulic binder. This carbonation process is investigated on a pore-scale level to identify how the mineral phases in the SSS react with CO2, where carbonates are formed, and what the impact of these changes is on the pore network of the carbonated SSS compact. In addition to conventional research techniques, high-resolution X-ray computed tomography (HRXCT) is applied to visualize and quantify the changes in situ during the carbonation process. The results show that carbonates mainly precipitate at grain contacts and in capillary pores and this precipitation has little effect on the connectivity of the pore space. This paper also demonstrates the use of a custom-designed polymer reaction cell that allows in situ HRXCT analysis of the carbonation process. This shows the distribution and influence of water and CO2 in the pore network on the carbonate precipitation and, thus, the influence on the compressive strength development of the waste material.

  12. Monitoring the condition of the slag crust in blast furnaces

    SciTech Connect

    Chernov, N.N.; Marder, B.F.; Demidenko, T.V.; Riznitskii, I.G.; Safina, L.A.; Dyshlevich, I.I.; Tkach, A.Ya.

    1988-05-01

    Studies conducted at the Krivorozhstal' combine blast furnaces have shown that fusion of the crust can be established from the change in the total content of alkali metals in the slag. After the furnaces were blown out for repairs the remaining lining and crust were inspected. It was found that the lining of the uncooled part of the stock remained in relatively good shape with the greatest amount of lining wear seen between the second row of stack coolers and bosh coolers. The composition and structure of the slag crust for different regions of the furnaces were analyzed and various physicochemical properties leading to crust formation and behavior were assessed. It was concluded that the systematic determination of the fraction of K/sub 2/O in the alkali compounds in the furnace slag will permit monitoring of the conditions of the slag crust in the furnace and, in the event of the onset of its collapse, will enable measures to be taken to stabilize the heating of the furnace.

  13. Steel slag raises pH of greenhouse substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dolomitic lime (DL) is the primary liming agent used for increasing pH in peatmoss-based substrates. Steel slag (SS) is a byproduct of the steel manufacturing industry that has been used to elevate field soil pH. The objective of this research was to determine the pH response of a peatmoss-based g...

  14. Dephosphorization of Steelmaking Slag by Leaching with Acidic Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Qiao, Yong; Diao, Jiang; Liu, Xuan; Li, Xiaosa; Zhang, Tao; Xie, Bing

    2015-12-01

    In the present paper, dephosphorization of steelmaking slag by leaching with acidic aqueous solution composed of citric acid, sodium hydroxide, hydrochloric acid and ion-exchanged water was investigated. The buffer solution of C6H8O7-NaOH-HCl system prevented changes in the pH values. Kinetic parameters including leaching temperature, slag particle size and pH values of the solution were optimized. The results showed that temperature has no obvious effect on the dissolution ratio of phosphorus. However, it has a significant effect on the dissolution ratio of iron. The dephosphorization rate increases with the decrease of slag particle size and the pH value of the solution. Over 90% of the phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30% below the optimal condition. Leaching kinetics of dephosphorization follow the unreacted shrinking core model with a rate controlled step by the solid diffusion layer, the corresponding apparent activation energy being 1.233 kJ mol-1. A semiempirical kinetic equation was established. After leaching, most of the nC2S-C3P solid solution in the steelmaking slag was selectively dissolved in the aqueous solution and the iron content in the solid residue was correspondingly enriched.

  15. Micronutrient availability from steel slag amendment in peatmoss substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to determine the suitability of a steel slag product for supplying micronutrients to container-grown floriculture crops. Geranium (Pelargonium xhortorum 'Maverick Red') and tomato (Solanum lycopersicon 'Megabite') were grown in 11.4 cm containers with a substrate ...

  16. Dephosphorization of Steelmaking Slag by Leaching with Acidic Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Qiao, Yong; Diao, Jiang; Liu, Xuan; Li, Xiaosa; Zhang, Tao; Xie, Bing

    2016-09-01

    In the present paper, dephosphorization of steelmaking slag by leaching with acidic aqueous solution composed of citric acid, sodium hydroxide, hydrochloric acid and ion-exchanged water was investigated. The buffer solution of C6H8O7-NaOH-HCl system prevented changes in the pH values. Kinetic parameters including leaching temperature, slag particle size and pH values of the solution were optimized. The results showed that temperature has no obvious effect on the dissolution ratio of phosphorus. However, it has a significant effect on the dissolution ratio of iron. The dephosphorization rate increases with the decrease of slag particle size and the pH value of the solution. Over 90% of the phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30% below the optimal condition. Leaching kinetics of dephosphorization follow the unreacted shrinking core model with a rate controlled step by the solid diffusion layer, the corresponding apparent activation energy being 1.233 kJ mol-1. A semiempirical kinetic equation was established. After leaching, most of the nC2S-C3P solid solution in the steelmaking slag was selectively dissolved in the aqueous solution and the iron content in the solid residue was correspondingly enriched.

  17. An Analysis of the Orbital Distribution of Solid Rocket Motor Slag

    NASA Technical Reports Server (NTRS)

    Horstman, Matthew F.; Mulrooney, Mark

    2007-01-01

    The contribution made by orbiting solid rocket motors (SRMs) to the orbital debris environment is both potentially significant and insufficiently studied. A combination of rocket motor design and the mechanisms of the combustion process can lead to the emission of sufficiently large and numerous by-products to warrant assessment of their contribution to the orbital debris environment. These particles are formed during SRM tail-off, or the termination of burn, by the rapid expansion, dissemination, and solidification of the molten Al2O3 slag pool accumulated during the main burn phase of SRMs utilizing immersion-type nozzles. Though the usage of SRMs is low compared to the usage of liquid fueled motors, the propensity of SRMs to generate particles in the 100 m and larger size regime has caused concern regarding their contributing to the debris environment. Particle sizes as large as 1 cm have been witnessed in ground tests conducted under vacuum conditions and comparable sizes have been estimated via ground-based telescopic and in-situ observations of sub-orbital SRM tail-off events. Using sub-orbital and post recovery observations, a simplistic number-size-velocity distribution of slag from on-orbit SRM firings was postulated. In this paper we have developed more elaborate distributions and emission scenarios and modeled the resultant orbital population and its time evolution by incorporating a historical database of SRM launches, propellant masses, and likely location and time of particulate deposition. From this analysis a more comprehensive understanding has been obtained of the role of SRM ejecta in the orbital debris environment, indicating that SRM slag is a significant component of the current and future population.

  18. Mineral Liberation of Magnetite-Precipitated Copper Slag Obtained via Molten Oxidation by Using High-Voltage Electrical Pulses

    NASA Astrophysics Data System (ADS)

    Fan, Yong; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

    2016-10-01

    Our proposed method, i.e., a controlled molten oxidation process under 1 vol pct oxygen, leads to selective precipitation of magnetite in a copper smelter slag for downstream iron separation. In the present study, the preroasted magnetite precipitated copper slag was treated via magnetite liberation, which was realized by using high-voltage electrical pulses. The mineral distribution was determined by using a laser microscope and its image analysis; and it revealed that the 100- µm under-sieve product contains approximately 70 pct of liberated mineral particles. The study affirms the positive outcome of using this new technology for comminution to obtain micrometer-scale particles that yield monominerals via selective liberation. Using magnetic separation, iron was capable of finally separating into high- and low-iron-bearing concentrate and tailing that can be used in specific applications.

  19. Mineral Liberation of Magnetite-Precipitated Copper Slag Obtained via Molten Oxidation by Using High-Voltage Electrical Pulses

    NASA Astrophysics Data System (ADS)

    Fan, Yong; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

    2016-08-01

    Our proposed method, i.e., a controlled molten oxidation process under 1 vol pct oxygen, leads to selective precipitation of magnetite in a copper smelter slag for downstream iron separation. In the present study, the preroasted magnetite precipitated copper slag was treated via magnetite liberation, which was realized by using high-voltage electrical pulses. The mineral distribution was determined by using a laser microscope and its image analysis; and it revealed that the 100-µm under-sieve product contains approximately 70 pct of liberated mineral particles. The study affirms the positive outcome of using this new technology for comminution to obtain micrometer-scale particles that yield monominerals via selective liberation. Using magnetic separation, iron was capable of finally separating into high- and low-iron-bearing concentrate and tailing that can be used in specific applications.

  20. Analysis of slags using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Sanghapi, Hervé K.; Ayyalasomayajula, Krishna K.; Yueh, Fang Y.; Singh, Jagdish P.; McIntyre, Dustin L.; Jain, Jinesh C.; Nakano, Jinichiro

    2016-01-01

    The feasibility of laser-induced breakdown spectroscopy (LIBS) for the analysis of gasification slags was investigated by comparing LIBS results to the results of an ICP-OES analyzer. A small amount of slag sample was placed on a piece of double sided adhesive tape attached to a glass microscope slide and analyzed for Al, Ca, Fe, Si, and V which are major elements found in slags. The partial least squares regression (PLS-R) and univariate simple linear regression (SLR) calibration methods indicated that apart from V (accuracy up to + 20%) the accuracy of analysis varies within 0.35-6.5% for SLR and 0.06-10% for PLS-R. A paired-sample t-test within the 95% confidence level yielded p-values greater than 0.05, meaning no appreciable statistical difference was observed between the univariate SLR with internal standardization and the multivariate PLS-R for most of the analytes. From the results obtained in this work, LIBS response varies depending on the element and the technique used for quantitative analysis. Simultaneous use of the univariate calibration curves with internal standard (intensity ratio) and PLS regression in multi-elemental analysis can help reduce the matrix effect of slags associated to their high variation in concentration. Overall, these results demonstrate the capability of LIBS as an alternative technique for analyzing gasification slags. Estimated limits of detection for Al, Ca, Fe, Si and V were 0.167, 0.78, 0.171, 0.243 and 0.01 wt.%, respectively.

  1. Field investigation of the temperature distribution in a commercial hazardous waste slagging rotary kiln

    SciTech Connect

    Veranth, J.M.; Gao, D.; Silcox, G.D.

    1996-10-01

    Gas and bed temperatures were studied in a 4.4 m by 12 m, co-current flow, slagging rotary kiln at a commercial hazardous waste incinerator. The visual observations used by the kiln operators to control the process are described. These observations were quantified using thermocouples, radiation pyrometers, and phase-change indicators. The objectives were to estimate the peak bed temperature and compare this to measurements at the kiln exit. The maximum bed temperature occurs toward the middle of this type of kiln and not at the discharge. The slag melting temperature and test pellets with known melting points indicate that the peak bed temperature can be 100-300 K higher than the kiln exit temperature reported by the permanent instruments at this facility. Both broad-band radiation pyrometers and thermocouples give a qualitative temperature indication that can be used for process control, but the readings depend on the sensor locations relative to the incompletely mixed air and combustion products. Two-color radiation pyrometer measurements of surface temperature near the kiln exit are higher than the actual temperature due to reflected radiation. 7 refs., 5 figs., 5 tabs.

  2. ISACONVERT™—Continuous converting of nickel/PGM matte with calcium ferrite slag

    NASA Astrophysics Data System (ADS)

    Bakker, M. L.; Nikolic, S.; Alvear, G. R. F.

    2011-05-01

    The ISASMELT™ process is a top submerged lance (TSL) bath smelting technology which has been developed and optimized over the last 25 years. By the end of 2011, the total installed capacity of the ISASMELT technology will exceed 9,000,000 tonnes per year of feed materials in copper and lead smelters around the world. Commercial plants, operating in Belgium and Germany, are also batch converting copper materials in ISASMELT furnaces. This TSL technology is equally effective for continuous converting processes, whereupon it is called ISACONVERT™. Xstrata Technology (XT) has recently patented a new ISACONVERT process for the continuous converting of nickel/platinum group metal (PGM) mattes using the calcium ferrite slag system. This paper outlines the development of this new process and presents a conceptual flowsheet for how it can be integrated into an existing nickel/PGM smelter.

  3. Rheological behavior and constitutive equations of heterogeneous titanium-bearing molten slag

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Liao, De-ming; Zhou, Mi; Zhang, Qiao-yi; Yue, Hong-rui; Yang, Song-tao; Duan, Pei-ning; Xue, Xiang-xin

    2015-08-01

    Experimental studies on the rheological properties of a CaO-SiO2-Al2O3-MgO-TiO2-(TiC) blast furnace (BF) slag system were conducted using a high-temperature rheometer to reveal the non-Newtonian behavior of heterogeneous titanium-bearing molten slag. By measuring the relationships among the viscosity, the shear stress and the shear rate of molten slags with different TiC contents at different temperatures, the rheological constitutive equations were established along with the rheological parameters; in addition, the non-Newtonian fluid types of the molten slags were determined. The results indicated that, with increasing TiC content, the viscosity of the molten slag tended to increase. If the TiC content was less than 2wt%, the molten slag exhibited the Newtonian fluid behavior when the temperature was higher than the critical viscosity temperature of the molten slag. In contrast, the molten slag exhibited the non-Newtonian pseudoplastic fluid characteristic and the shear thinning behavior when the temperature was less than the critical viscosity temperature. However, if the TiC content exceeded 4wt%, the molten slag produced the yield stress and exhibited the Bingham and plastic pseudoplastic fluid behaviors when the temperature was higher and lower than the critical viscosity temperature, respectively. When the TiC content increased further, the yield stress of the molten slag increased and the shear thinning phenomenon became more obvious.

  4. Steel slag filters to upgrade phosphorus removal in constructed wetlands: two years of field experiments.

    PubMed

    Barca, Cristian; Troesch, Stéphane; Meyer, Daniel; Drissen, Peter; Andrès, Yves; Chazarenc, Florent

    2013-01-01

    Electric arc furnace steel slag (EAF-slag) and basic oxygen furnace steel slag (BOF-slag) were used as filter substrates in two horizontal subsurface flow filters (6 m(3) each) designed to remove phosphorus (P) from the effluent of a constructed wetland. The influences of slag composition, void hydraulic retention time (HRTv), temperature, and wastewater quality on treatment performances were studied. Over a period of almost two years of operation, the filter filled with EAF-slag removed 37% of the inlet total P, whereas the filter filled with BOF-slag removed 62% of the inlet total P. P removal occurred predominantly via CaO-slag dissolution followed by Ca phosphate precipitation. P removal efficiencies improved with increasing temperature and HRTv, most probably because this affected the rates of CaO-slag dissolution and Ca phosphate precipitation. It was observed that long HRTv (>3 days) can cause high pH in the effluents (>9) as a result of excessive CaO-slag dissolution. However, at shorter HRTv (1-2 days), pH values were elevated only during the first five weeks and then stabilized below a pH of 9. The kinetics of P removal were investigated employing a first-order equation, and a model for filter design was proposed.

  5. Characterisation of the sintering behaviour of Waelz slag from electric arc furnace (EAF) dust recycling for use in the clay ceramics industry.

    PubMed

    Quijorna, N; de Pedro, M; Romero, M; Andrés, A

    2014-01-01

    Waelz slag is an industrial by-product from the recovery of electric arc furnace (EAF) dust which is mainly sent to landfills. Despite the different chemical and mineralogical compositions of Waelz slag compared to traditional clays, previous experiments have demonstrated its potential use as a clay substitute in ceramic processes. Indeed, clayey products containing Waelz slag could improve mechanical and environmental performance, fixing most of the metallic species and moreover decreasing the release of some potential pollutants during firing. However, a deeper understanding of the complex phase transformations during its thermal treatment and the connection of this behaviour with the end properties is desirable in order to explain the role that is played by the Waelz slag and its potential contribution to the ceramic process. For this purpose, in the present study, the chemical, mineralogical, thermal and environmental behaviour of both (i) unfired powdered samples, and (ii) pressed specimen of Waelz slag fired up to different temperatures within the typical range of clay based ceramic production, has been studied. The effect of the heating temperature on the end properties of the fired samples has been assessed. In general, an increase of the firing temperature promotes sintering and densification of the products and decreases the open porosity and water absorption which also contributes to the fixation of heavy metals. On the contrary, an increase in the leaching of Pb, Cr and Mo from the fired specimens is observed. This can be attributed to the creation of Fe and Ca molybdates and chromates that are weakly retained in the alkali matrix. On the other side, at temperature above 950 °C a weight gain related to the emission of evolved gases is observed. In conclusion, the firing temperature of the ceramic process is a key parameter that affects not only the technical properties but also strongly affects the leaching behaviour and the process emissions.

  6. Mechanisms of pyrite oxidation to non-slagging species. Quarterly report, April 1, 1995--June 30, 1995

    SciTech Connect

    Akan-Etuk, A.E.J.; Mitchell, R.E.

    1995-12-01

    This document is the fourth quarterly status report on a project that is conducted at the High Temperature Gasdynamics Laboratory at Stanford University, Stanford, California and is concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO{sub x} pulverized coal (P.C.) combustion. The research project is intended to advance PETC`s efforts to improve our technical understanding of the high-temperature chemical and physical processes involved in the utilization of coal. The work focuses on the mechanistic description and rate quantification of the effects of fuel properties and combustion environment on the oxidation of iron pyrite to form the non-slagging species magnetite. The knowledge gained from this work is intended to be incorporated into numerical codes that can be used to formulate anti-slagging strategies involving minimal disturbance of coal combustor performance. This project is to be performed over the three-year period from September 1994 to August 1997. The project aims to identify the mechanisms of pyrite combustion and to quantify their effects, in order to formulate a general rate expression for the combustion of pyrite that accounts for coal properties as well as furnace conditions.

  7. Immobilisation of lead smelting slag within spent aluminate-fly ash based geopolymers.

    PubMed

    Ogundiran, M B; Nugteren, H W; Witkamp, G J

    2013-03-15

    This study presents the solidification/stabilisation and immobilisation of lead smelting slag (LSS) by its incorporation in coal fly ash - blast furnace slag based geopolymers. It also explores the use of a spent aluminium etching solution (AES) as geopolymer activator instead of the commonly used silicate solutions. The compressive strength of the geopolymers produced with the AES was lower than when applying a K-silicate solution as activator (100MPa versus 80MPa after 28 days). Compressive strength was not affected when up to 10% of the FA was replaced by LSS. NEN 12457-4, TCLP, SPLP and NEN 7375 leaching tests indicated that mobile Pb from LSS was highly immobilised. The diffusion leaching test NEN 7375 revealed exceeding of the Dutch Soil Quality Regulation threshold limits only for Se and Sb. On the condition that the remaining excess leaching can be reduced by further refinement of the mixture recipes, the proposed process will have the potential of producing waste-based construction materials that may be applied under controlled conditions in specific situations.

  8. Sulphate removal over barium-modified blast-furnace-slag geopolymer.

    PubMed

    Runtti, Hanna; Luukkonen, Tero; Niskanen, Mikko; Tuomikoski, Sari; Kangas, Teija; Tynjälä, Pekka; Tolonen, Emma-Tuulia; Sarkkinen, Minna; Kemppainen, Kimmo; Rämö, Jaakko; Lassi, Ulla

    2016-11-01

    Blast-furnace slag and metakaolin were geopolymerised, modified with barium or treated with a combination of these methods in order to obtain an efficient SO4(2-) sorbent for mine water treatment. Of prepared materials, barium-modified blast-furnace slag geopolymer (Ba-BFS-GP) exhibited the highest SO4(2-) maximum sorption capacity (up to 119mgg(-1)) and it compared also favourably to materials reported in the literature. Therefore, Ba-BFS-GP was selected for further studies and the factors affecting to the sorption efficiency were assessed. Several isotherms were applied to describe the experimental results of Ba-BFS-GP and the Sips model showed the best fit. Kinetic studies showed that the sorption process follows the pseudo-second-order kinetics. In the dynamic removal experiments with columns, total SO4(2-) removal was observed initially when treating mine effluent. The novel modification method of geopolymer material proved to be technically suitable in achieving extremely low concentrations of SO4(2-) (<2mgL(-1)) in mine effluents.

  9. Immobilisation of lead smelting slag within spent aluminate-fly ash based geopolymers.

    PubMed

    Ogundiran, M B; Nugteren, H W; Witkamp, G J

    2013-03-15

    This study presents the solidification/stabilisation and immobilisation of lead smelting slag (LSS) by its incorporation in coal fly ash - blast furnace slag based geopolymers. It also explores the use of a spent aluminium etching solution (AES) as geopolymer activator instead of the commonly used silicate solutions. The compressive strength of the geopolymers produced with the AES was lower than when applying a K-silicate solution as activator (100MPa versus 80MPa after 28 days). Compressive strength was not affected when up to 10% of the FA was replaced by LSS. NEN 12457-4, TCLP, SPLP and NEN 7375 leaching tests indicated that mobile Pb from LSS was highly immobilised. The diffusion leaching test NEN 7375 revealed exceeding of the Dutch Soil Quality Regulation threshold limits only for Se and Sb. On the condition that the remaining excess leaching can be reduced by further refinement of the mixture recipes, the proposed process will have the potential of producing waste-based construction materials that may be applied under controlled conditions in specific situations. PMID:23339881

  10. Sulphate removal over barium-modified blast-furnace-slag geopolymer.

    PubMed

    Runtti, Hanna; Luukkonen, Tero; Niskanen, Mikko; Tuomikoski, Sari; Kangas, Teija; Tynjälä, Pekka; Tolonen, Emma-Tuulia; Sarkkinen, Minna; Kemppainen, Kimmo; Rämö, Jaakko; Lassi, Ulla

    2016-11-01

    Blast-furnace slag and metakaolin were geopolymerised, modified with barium or treated with a combination of these methods in order to obtain an efficient SO4(2-) sorbent for mine water treatment. Of prepared materials, barium-modified blast-furnace slag geopolymer (Ba-BFS-GP) exhibited the highest SO4(2-) maximum sorption capacity (up to 119mgg(-1)) and it compared also favourably to materials reported in the literature. Therefore, Ba-BFS-GP was selected for further studies and the factors affecting to the sorption efficiency were assessed. Several isotherms were applied to describe the experimental results of Ba-BFS-GP and the Sips model showed the best fit. Kinetic studies showed that the sorption process follows the pseudo-second-order kinetics. In the dynamic removal experiments with columns, total SO4(2-) removal was observed initially when treating mine effluent. The novel modification method of geopolymer material proved to be technically suitable in achieving extremely low concentrations of SO4(2-) (<2mgL(-1)) in mine effluents. PMID:27318734

  11. Utilization of ferrochrome wastes such as ferrochrome ash and ferrochrome slag in concrete manufacturing.

    PubMed

    Acharya, Prasanna K; Patro, Sanjaya K

    2016-08-01

    Solid waste management is one of the subjects essentially addressing the current interest today. Due to the scarcity of land filling area, utilization of wastes in the construction sector has become an attractive proposition for disposal. Ferrochrome ash (FA) is a dust obtained as a waste material from the gas cleaning plant of Ferro alloy industries. It possesses the chemical requirements of granulated slag material used for the manufacture of Portland cement. Ferrochrome slag (FS) is another residue that is obtained as a solid waste by the smelting process during the production of stainless steel in Ferroalloy industries. FS possesses the required engineering properties of coarse aggregates. The possibility of using FA with lime for partial replacement of ordinary Portland cement (OPC) and FS for total replacement of natural coarse aggregates is explored in this research. The combined effect of FA with lime and FS-addition on the properties of concrete, such as workability, compressive strength, flexural strength, splitting tensile strength and sorptivity, were studied. Results of investigation revealed improvement in strength and durability properties of concrete on inclusion of FA and FS. Concrete mix containing 40% FA with 7% lime (replacing 47% OPC) and100% of FS (replacing 100% natural coarse aggregate) achieved the properties of normal concrete or even better properties at all ages. The results were confirmed by microscopic study such as X-ray diffraction and petrography examination. Environmental compatibility of concrete containing FA and FS was verified by the toxicity characteristic leaching procedure test.

  12. Mechanisms of pyrite oxidation to non-slagging species. Quarterly report, January 1--March 31, 1997

    SciTech Connect

    Akan-Etuk, A.E.J.; Mitchell, R.E.

    1997-12-31

    This document is the eleventh quarterly status report on a project that is concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO{sub x} pulverized coal (P.C.) combustion. The research project is intended to advance PETC`s efforts to improve the technical understanding of the high-temperature chemical and physical processes involved in the utilization of coal. The work focuses on the mechanistic description and rate quantification of the effects of fuel properties and combustion environment on the oxidation of iron pyrite to form the non-slagging species magnetite. Activities during this report period were associated with the numerical encoding of the pyrite combustion model. The computer program resulting from the efforts put forth is intended to provide predictive capabilities with respect to pyrite composition during pulverized coal firing. The subroutines that have been written to track the fate of a pyrite particle of specified size and composition flowing in a gaseous environment of specified oxygen concentration, temperature, and velocity are being debugged and tested.

  13. Mechanisms of pyrite oxidation to non-slagging species. Quarterly report, October 1--December 31, 1996

    SciTech Connect

    Akan-Etuk, A.E.J.; Mitchell, R.E.

    1997-12-31

    This document is the tenth quarterly status report on a project that is concerned with enhancing the transformation of iron pyrite to non-slagging species during staged, low-NO{sub x} pulverized coal (P.C.) combustion. The research project is intended to advance PETC`s efforts to improve the technical understanding of the high-temperature chemical and physical processes involved in the utilization of coal. The work focuses on the mechanistic description and rate quantification of the effects of fuel properties and combustion environment on the oxidation of iron pyrite to form the non-slagging species magnetite. During this report period numerical encoding of a pyrite combustion model was embarked upon. The effort was intended to lead to predictive capabilities with respect to pyrite composition during pulverized coal firing. Many subroutines were written of a FORTRAN computer program to track the fate of a pyrite particle by integrating time-dependent differential equations for species, momentum, and energy conservation. Inputs to the program include fuel-related properties such as particle size and composition, as well as properties of the reactor environment such as oxygen level, temperature, gas velocity, and a set of initial and final positions.

  14. Utilization of ferrochrome wastes such as ferrochrome ash and ferrochrome slag in concrete manufacturing.

    PubMed

    Acharya, Prasanna K; Patro, Sanjaya K

    2016-08-01

    Solid waste management is one of the subjects essentially addressing the current interest today. Due to the scarcity of land filling area, utilization of wastes in the construction sector has become an attractive proposition for disposal. Ferrochrome ash (FA) is a dust obtained as a waste material from the gas cleaning plant of Ferro alloy industries. It possesses the chemical requirements of granulated slag material used for the manufacture of Portland cement. Ferrochrome slag (FS) is another residue that is obtained as a solid waste by the smelting process during the production of stainless steel in Ferroalloy industries. FS possesses the required engineering properties of coarse aggregates. The possibility of using FA with lime for partial replacement of ordinary Portland cement (OPC) and FS for total replacement of natural coarse aggregates is explored in this research. The combined effect of FA with lime and FS-addition on the properties of concrete, such as workability, compressive strength, flexural strength, splitting tensile strength and sorptivity, were studied. Results of investigation revealed improvement in strength and durability properties of concrete on inclusion of FA and FS. Concrete mix containing 40% FA with 7% lime (replacing 47% OPC) and100% of FS (replacing 100% natural coarse aggregate) achieved the properties of normal concrete or even better properties at all ages. The results were confirmed by microscopic study such as X-ray diffraction and petrography examination. Environmental compatibility of concrete containing FA and FS was verified by the toxicity characteristic leaching procedure test. PMID:27357563

  15. Two-stage high temperature sludge gasification using the waste heat from hot blast furnace slags.

    PubMed

    Sun, Yongqi; Zhang, Zuotai; Liu, Lili; Wang, Xidong

    2015-12-01

    Nowadays, disposal of sewage sludge from wastewater treatment plants and recovery of waste heat from steel industry, become two important environmental issues and to integrate these two problems, a two-stage high temperature sludge gasification approach was investigated using the waste heat in hot slags herein. The whole process was divided into two stages, i.e., the low temperature sludge pyrolysis at ⩽ 900°C in argon agent and the high temperature char gasification at ⩾ 900°C in CO2 agent, during which the heat required was supplied by hot slags in different temperature ranges. Both the thermodynamic and kinetic mechanisms were identified and it was indicated that an Avrami-Erofeev model could best interpret the stage of char gasification. Furthermore, a schematic concept of this strategy was portrayed, based on which the potential CO yield and CO2 emission reduction achieved in China could be ∼1.92∗10(9)m(3) and 1.93∗10(6)t, respectively.

  16. Velocity and temperature distributions of coal-slag layers on magnetohydrodynamic generators walls

    NASA Technical Reports Server (NTRS)

    Pian, C. C. P.; Smith, J. M.

    1977-01-01

    Approximate analytical expressions are derived for the velocity and temperature distributions in steady state coal slag deposits flowing over MHD generator walls. Effects of slag condensation and Joule heating are included in the analysis. The transport conditions and the slag temperature at the slag-gas interface are taken to be known parameters in the formulation. They are assumed to have been predetermined either experimentally or from the slag properties and the gas dynamic calculations of the free stream flow. The analysis assumes a power law velocity profile for the slag and accounts for the coupling between the energy and momentum conservation equations. Comparisons are made with the more exact numerical solutions to verify the accuracy of the results.

  17. Properties of blast-furnace slags containing high amounts of manganese

    SciTech Connect

    Pera, J.; Ambroise, J.; Chabannet, M.

    1999-02-01

    This paper presents results of tests performed to characterize the physical and chemical properties of five blast-furnace slags having MnO content up to 21%. The interactions between ordinary Portland cement or calcium oxide and each slag were investigated by X-ray diffraction, scanning electron microscopy, and thermoanalysis. Mortars and concretes using these slags were cast. When ground to a Blaine surface area of 300 m{sup 2}/kg, the slags were utilized in road binders in combination with calcium oxide or Portland cement. When ground to a Blaine surface area of 600 m{sup 2}/kg, the slags were introduced into the composition of different concretes instead of fly ash or silica fume. Based on the resulting high strengths, fine grinding of manganese-rich slag for use in concrete appears to be a good way of beneficiation.

  18. Influence of Partial Pressure of Sulfur and Oxygen on Distribution of Fe and Mn between Liquid Fe-Mn Oxysulfide and Molten Slag

    NASA Astrophysics Data System (ADS)

    Kim, Sun-Joong; Shibata, Hiroyuki; Takekawa, Jun; Kitamura, Shin-Ya; Yamaguchi, Katsunori; Kang, Youn-Bae

    2012-10-01

    The authors proposed an innovative process for recovering Mn from steelmaking slag. The process starts with the sulfurization of steelmaking slag to separate P from Mn by the formation of a liquid sulfide phase (matte). Then, the obtained matte is weakly oxidized to make a Mn-rich oxide phase without P. High-purity Fe-Mn alloys can therefore be produced by the reduction of the Mn-rich oxide phase. However, to the authors' knowledge, the sulfurization of molten slag containing P and Mn has not been sufficiently investigated. It was recently found that P was not distributed to the matte in equilibrium with the molten slag. To gain knowledge of the process's development, it is important to investigate the influence of the partial pressures of sulfur and oxygen on the equilibrium distribution of Mn and Fe between the matte and the molten slag. In the current work, a mineralogical microstructure analysis of the matte revealed that the existence of the oxysulfide and metal phases was dependent on the partial pressure of sulfur and oxygen. The Mn content of the matte increased with partial pressure of sulfur while the O content of the matte decreased. In contrast, the ratio of Mn/Fe in the matte was constant when the metal phase of the matte was observed at a log P_{{{{O}}2 }} below -11. These results also corresponded to the relationship between the activity coefficient ratio of MnS/FeS and the mole fraction of MnS/FeS in the matte. The γ MnS/ γ FeS value decreased exponentially as the mole fraction of MnS/FeS increased.

  19. Effects of slag-based silicon fertilizer on rice growth and brown-spot resistance.

    PubMed

    Ning, Dongfeng; Song, Alin; Fan, Fenliang; Li, Zhaojun; Liang, Yongchao

    2014-01-01

    It is well documented that slag-based silicon fertilizers have beneficial effects on the growth and disease resistance of rice. However, their effects vary greatly with sources of slag and are closely related to availability of silicon (Si) in these materials. To date, few researches have been done to compare the differences in plant performance and disease resistance between different slag-based silicon fertilizers applied at the same rate of plant-available Si. In the present study both steel and iron slags were chosen to investigate their effects on rice growth and disease resistance under greenhouse conditions. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the effects of slags on ultrastructural changes in leaves of rice naturally infected by Bipolaris oryaze, the causal agent of brown spot. The results showed that both slag-based Si fertilizers tested significantly increased rice growth and yield, but decreased brown spot incidence, with steel slag showing a stronger effect than iron slag. The results of SEM analysis showed that application of slags led to more pronounced cell silicification in rice leaves, more silica cells, and more pronounced and larger papilla as well. The results of TEM analysis showed that mesophyll cells of slag-untreated rice leaf were disorganized, with colonization of the fungus (Bipolaris oryzae), including chloroplast degradation and cell wall alterations. The application of slag maintained mesophyll cells relatively intact and increased the thickness of silicon layer. It can be concluded that applying slag-based fertilizer to Si-deficient paddy soil is necessary for improving both rice productivity and brown spot resistance. The immobile silicon deposited in host cell walls and papillae sites is the first physical barrier for fungal penetration, while the soluble Si in the cytoplasm enhances physiological or induced resistance to fungal colonization.

  20. Effects of Slag-Based Silicon Fertilizer on Rice Growth and Brown-Spot Resistance

    PubMed Central

    Ning, Dongfeng; Song, Alin; Fan, Fenliang; Li, Zhaojun; Liang, Yongchao

    2014-01-01

    It is well documented that slag-based silicon fertilizers have beneficial effects on the growth and disease resistance of rice. However, their effects vary greatly with sources of slag and are closely related to availability of silicon (Si) in these materials. To date, few researches have been done to compare the differences in plant performance and disease resistance between different slag-based silicon fertilizers applied at the same rate of plant-available Si. In the present study both steel and iron slags were chosen to investigate their effects on rice growth and disease resistance under greenhouse conditions. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the effects of slags on ultrastructural changes in leaves of rice naturally infected by Bipolaris oryaze, the causal agent of brown spot. The results showed that both slag-based Si fertilizers tested significantly increased rice growth and yield, but decreased brown spot incidence, with steel slag showing a stronger effect than iron slag. The results of SEM analysis showed that application of slags led to more pronounced cell silicification in rice leaves, more silica cells, and more pronounced and larger papilla as well. The results of TEM analysis showed that mesophyll cells of slag-untreated rice leaf were disorganized, with colonization of the fungus (Bipolaris oryzae), including chloroplast degradation and cell wall alterations. The application of slag maintained mesophyll cells relatively intact and increased the thickness of silicon layer. It can be concluded that applying slag-based fertilizer to Si-deficient paddy soil is necessary for improving both rice productivity and brown spot resistance. The immobile silicon deposited in host cell walls and papillae sites is the first physical barrier for fungal penetration, while the soluble Si in the cytoplasm enhances physiological or induced resistance to fungal colonization. PMID:25036893

  1. Slag breaker of pressure-type coal gasifier

    SciTech Connect

    Starke, J.; Exner, R.; Girodi, E.; Jakubik, A.; Strudinger, M.

    1984-02-21

    A slag breaker of a pressure-type coal gasifier having a rotary grate with a plurality of grate segments, a generator bottom and an ash separator, has an inclined breaking plate arranged to be located immediately below the grate segment and prior to the ash separator and provided with a plurality of breaking projections, and a wear sheet arranged to be located on the generator bottom and provided with a plurality of breaking webs.

  2. Low-Chrome/Chrome Free Refractories for Slagging Gasifiers

    SciTech Connect

    Bennett, J.P.; Kwong, K.-S.; Powell, C.P.; Thomas, H.; Petty, A.V., Jr.

    2007-01-01

    Gasifiers are containment vessels used to react carbon-containing materials with oxygen and water, producing syngas (CO and H2) that is used in chemical and power production. It is also a potential source of H2 in a future hydrogen economy. Air cooled slagging gasifiers are one type of gasifier, operating at temperatures from 1275-1575º C and at pressures of 400 psi or higher. They typically use coal or petroleum coke as the carbon source, materials which contain ash impurities that liquefy at the gasification temperatures, producing liquid slag in quantities of 100 or more tons/day, depending on the carbon fed rate and the percent ash present in the feedstock. The molten slag is corrosive to refractory linings, causing chemical dissolution and spalling. The refractory lining is composed of chrome oxide, alumina, and zirconia; and is replaced every 3-24 months. Gasifier users would like greater on-line availability and reliability of gasifier liners, something that has impacted gasifier acceptance by industry. Research is underway at NETL to improve refractory service life and to develop a no-chrome or low-chrome oxide alternative refractory liner. Over 250 samples of no- or low-chrome oxide compositions have been evaluated for slag interactions by cup testing; with potential candidates for further studies including those with ZrO2, Al2O3, and MgO materials. The development of improved liner materials is necessary if technologies such as IGCC and DOE’s Near Zero Emissions Advanced Fossil Fuel Power Plant are to be successful and move forward in the marketplace.

  3. Slag Characterization and Removal Using Pulse Detonation for Coal Gasification.

    SciTech Connect

    Hugue, Z; Mei, D.; Biney, P.O.; Zhou, J.; Ali, M.R.

    1997-09-25

    The research activities performed in this quarter (reporting period: 07/01/97- 09/30/97) are summarized as follows: The research activities concentrated on (1) Design, development, and fabrication of a 9 positions (3x3 matrix form) fixture (2) Preparation of the test parameters (3) Multi-cycle detonation wave slag removal test (4) Partial analysis of the test results and (5) Interpretation and discussion of the test results.

  4. Environmental impacts of asphalt mixes with electric arc furnace steel slag.

    PubMed

    Milačič, Radmila; Zuliani, Tea; Oblak, Tina; Mladenovič, Ana; Ančar, Janez Šč

    2011-01-01

    Electric arc furnace (EAF) steel slag can be used as an alternative high-quality material in road construction. Although asphalts with slag aggregates have been recognized as environmentally acceptable, there is a lack of data concerning the potential leaching of toxic Cr(VI) due to the highly alkaline media of EAF slag. Leaching of selected water extractable metals from slag indicated elevated concentrations of total chromium and Cr(VI). To estimate the environmental impacts of asphalt mixes with slag, leachability tests based on diffusion were performed using pure water and salt water as leaching agents. Compact and ground asphalt composites with natural aggregates, and asphalt composites in which the natural aggregates were completely replaced by slag were prepared. The concentrations of total chromium and Cr(VI) were determined in leachates over a time period of 6 mo. After 1 and 6 mo, the concentrations of some other metals were also determined in the leachates. The results indicated that chromium in leachates from asphalt composites with the addition of slag was present almost solely in its hexavalent form. However, the concentrations were very low (below 25 μg L) and did not represent an environmental burden. The leaching of other metals from asphalt composites with the addition of slag was negligible. Therefore, the investigated EAF slag can be considered as environmentally safe substitute for natural aggregates in asphalt mixes.

  5. Use of ancient copper slags in Portland cement and alkali activated cement matrices.

    PubMed

    Nazer, Amin; Payá, Jordi; Borrachero, María Victoria; Monzó, José

    2016-02-01

    Some Chilean copper slag dumps from the nineteenth century still remain, without a proposed use that encourages recycling and reduces environmental impact. In this paper, the copper slag abandoned in landfills is proposed as a new building material. The slags studied were taken from Playa Negra and Púquios dumps, both located in the region of Atacama in northern Chile. Pozzolanic activity in lime and Portland cement systems, as well as the alkali activation in pastes with copper slag cured at different temperatures, was studied. The reactivity of the slag was measured using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical conductivity and pH in aqueous suspension and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, copper slag-Portland cement mortars with the substitution of 25% (by weight) of cement by copper slag and alkali-activated slag mortars cured at 20 and 65 °C were made, to determine the compressive strength. The results indicate that the ancient copper slags studied have interesting binding properties for the construction sector.

  6. Phosphate removal from synthetic and real wastewater using steel slags produced in Europe.

    PubMed

    Barca, Cristian; Gérente, Claire; Meyer, Daniel; Chazarenc, Florent; Andrès, Yves

    2012-05-01

    Electric arc furnace steel slags (EAF-slags) and basic oxygen furnace steel slags (BOF-slags) were used to remove phosphate from synthetic solutions and real wastewater. The main objective of this study was to establish an overview of the phosphate removal capacities of steel slags produced in Europe. The influences of parameters, including pH, and initial phosphate and calcium concentrations, on phosphate removal were studied in a series of batch experiments. Phosphate removal mechanisms were also investigated via an in-depth study. The maximum capacities of phosphate removal from synthetic solutions ranged from 0.13 to 0.28 mg P/g using EAF-slags and from 1.14 to 2.49 mg P/g using BOF-slags. Phosphate removal occurred predominantly via the precipitation of Ca-phosphate complexes (most probably hydroxyapatite) according to two consecutive reactive phases: first, dissolution of CaO-slag produced an increase in Ca(2+) and OH(-) ion concentrations; then the Ca(2+) and OH(-) ions reacted with the phosphates to form hydroxyapatite. It was found that the release of Ca(2+) from slag was not always enough to enable hydroxyapatite precipitation. However, our results indicated that the Ca(2+) content of wastewater represented a further source of Ca(2+) ions that were available for hydroxyapatite precipitation, thus leading to an increase in phosphate removal efficiencies.

  7. SLAG CHARACTERIZATION AND REMOVAL USING PULSE DETONATION TECHNOLOGY DURING COAL GASIFICATION

    SciTech Connect

    DR. DANIEL MEI; DR. JIANREN ZHOU; DR. PAUL O. BINEY; DR. ZIAUL HUQUE

    1998-07-30

    Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. Conventional slag removal methods including soot blowers and water lances have great difficulties in removing slags especially from the down stream areas of utility power plant boilers. The detonation wave technique, based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. A slight increase in the boiler efficiency, due to more effective ash/deposit removal and corresponding reduction in plant maintenance downtime and increased heat transfer efficiency, will save millions of dollars in operational costs. Reductions in toxic emissions will also be accomplished due to reduction in coal usage. Detonation waves have been demonstrated experimentally to have exceptionally high shearing capability, important to the task of removing slag and fouling deposits. The experimental results describe the parametric study of the input parameters in removing the different types of slag and operating condition. The experimental results show that both the single and multi shot detonation waves have high potential in effectively removing slag deposit from boiler heat transfer surfaces. The results obtained are encouraging and satisfactory. A good indication has also been obtained from the agreement with the preliminary computational fluid dynamics analysis that the wave impacts are more effective in removing slag deposits from tube bundles rather than single tube. This report presents results obtained in effectively removing three different types of slag (economizer, reheater, and air-heater) t a distance of up to 20 cm from the exit of the detonation tube. The experimental results show that the softer slags can be removed more easily. Also closer the slag to the exit of

  8. Pozzolanic reactivity of the synthetic slag from municipal solid waste incinerator cyclone ash and scrubber ash.

    PubMed

    Lin, Kae-Long; Lin, Deng-Fong

    2006-05-01

    This study investigates the pozzolanic reactions and compressive strength of the blended cement manufactured using synthetic slag obtained from municipal solid waste incinerator (MSWI) cyclone ash and scrubber ash as partial replacement of portland cement. The synthetic slag was made by co-melting the MSWI scrubber ash and cyclone ash mixtures at 1400 degrees C for 30 min. Following pulverization, the different types of slag were blended with cement as cement replacement at ratios ranging from 10 to 40 wt %. The synthetic slag thus obtained was quantified, and the characteristics of the slag-blended cement pastes were examined. These characteristics included the pozzolanic activity, compressive strength, hydration activity, crystal phases, species, and microstructure at various ages. The 90-day compressive strength developed by slag-blended cement pastes with 10 and 20 wt % of the cement replaced by the synthetic slag outperformed ordinary portland cement by 1-7 MPa. X-ray diffraction species analyses indicated that the hydrates in the slag-blended cement pastes were mainly portlandite, the calcium silicate hydrate gels, and calcium aluminate hydrate salts, similar to those found in ordinary portland cement paste. Differential thermal and thermogravimetric analysis also indicated that the slag reacted with portlandite to form calcium silicate hydrate gels.

  9. Use of ancient copper slags in Portland cement and alkali activated cement matrices.

    PubMed

    Nazer, Amin; Payá, Jordi; Borrachero, María Victoria; Monzó, José

    2016-02-01

    Some Chilean copper slag dumps from the nineteenth century still remain, without a proposed use that encourages recycling and reduces environmental impact. In this paper, the copper slag abandoned in landfills is proposed as a new building material. The slags studied were taken from Playa Negra and Púquios dumps, both located in the region of Atacama in northern Chile. Pozzolanic activity in lime and Portland cement systems, as well as the alkali activation in pastes with copper slag cured at different temperatures, was studied. The reactivity of the slag was measured using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical conductivity and pH in aqueous suspension and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, copper slag-Portland cement mortars with the substitution of 25% (by weight) of cement by copper slag and alkali-activated slag mortars cured at 20 and 65 °C were made, to determine the compressive strength. The results indicate that the ancient copper slags studied have interesting binding properties for the construction sector. PMID:26615227

  10. Speciation of copper in the thermally stabilized slag

    NASA Astrophysics Data System (ADS)

    Tuan, Y.-J.; Paul Wang, H.; Chang, J.-E.; Chao, C.-C.; Tsai, C.-K.

    2010-07-01

    The Taiwan universities laboratory hazardous wastes have been treated by incineration at the temperature range of 1173-1273 K. By X-ray absorption near edge structure (XANES) spectroscopy, mainly CuO and CuSO 4 are found in the incineration bottom and fly ashes. The incineration fly ash can be stabilized thermally at 1773 K in the plasma melting reaction chamber (integrated with the incinerator), and converted to slag. The concentration of leachable copper in the slag is reduced significantly mainly due to the fact that copper is encapsulated in the SiO 2 matrix. In addition, the refined extended X-ray adsorption fine structure (EXAFS) spectra of copper also indicate formation of the Cu-O-Si species in the slag as the bond distances of 1.95 Å for Cu-O and 2.67 Å for O-Si are observed. This work exemplifies utilization of the synchrotron X-ray absorption spectroscopy to facilitate the thermal stabilization treatments of the fly ash hazardous waste using the plasma melting method.

  11. Recycling ferrous-nickel slag in blast cleaning.

    PubMed

    Katsikaris, K; Voutsas, E; Magoulas, K; Andronikos, G; Stamataki, S

    2002-06-01

    The aim of this study is the development of a procedure for the recycling of the ferrous-nickel slag that is widely used in open dry blast cleaning operations in Greek shipyards thus annually generating thousands of tons of blast cleaning waste. Laboratory tests were carried out, based on the reclamation of the material fraction with size a distribution within the range -1,400 + 150 microm, in order to determine the number of the effective uses (life cycles) of the abrasive material. It is demonstrated that the reclamation yield in the first three life cycles is more than 80%. Laboratory tests also proved that the recycled ferrous-nickel slag has properties comparable to the fresh material's ones in terms of particle size distribution, consumption and other physical-chemical properties. A semi-industrial recycling unit of used ferrous-nickel slag was also designed and installed in a Greek shipyard (Neorion New SA of Syros Shipyards). The operation of the semi-industrial recycling unit verified the conclusions resulting from the laboratory tests, and most important, it was proved profitable for the ship-

  12. Simulation of past exposure in slag wool production.

    PubMed

    Fallentin, B; Kamstrup, O

    1993-08-01

    A survey of the working conditions at a Danish slag wool production factory during the early technological phase in the 1940s is presented. No exposure data, however, are available for that period. So, a full-scale simulation of the past production of slag wool has been performed. Air monitoring was carried out in the working area around the cupola furnace. The aim was to measure exposure to air pollutants other than fibres. Such exposure might have confounded a possible association between lung cancer and exposure to fibres, in the early technological phase of slag wool production. The simulation experiment demonstrated exposure to PAH, a known lung carcinogen. The effect of other concurrent exposures is difficult to assess. Time-weighted average concentrations of particulate material ranged between 12.9 and 49.1 mg m-3 at the upper decks around the cupola. Corresponding concentrations of the dominant metals zinc and lead were 4.4-22.7 mg Zn m-3 and 0.9-4.7 mg Pb m-3. Significant concentrations of PAH up to 269 micrograms PAH m-3 (4 micrograms BaP m-3) occurred during ignition of the cupola furnace. The carbon monoxide level reached 270 ppm also during ignition.

  13. Sulfide Capacity in Ladle Slag at Steelmaking Temperatures

    NASA Astrophysics Data System (ADS)

    Allertz, Carl; Sichen, Du

    2015-12-01

    Sulfide capacity measurements were conducted at 1823 K and 1873 K (1550 °C and 1600 °C) for the quaternary Al2O3-CaO-MgO-SiO2 system, for typical compositions used in the ladle in steelmaking. A copper-slag equilibrium was used under controlled oxygen and sulfur potentials. The sulfide capacity is strongly dependent on the composition and it was found to increase with the basic oxides, while it decreases with increase of the acidic components. It was found that CaO is more effective in holding sulfur in the slag compared to MgO when replacing SiO2. For the present slag compositions, Al2O3 and SiO2 behaved similar with respect to sulfur, and no considerable effect could be recorded when replacing one for the other. The sulfide capacity was also found to be strongly dependent on the temperature, increasing with temperature. The present results were compared with industrial data from the ladle, after vacuum treatment, and they were in good agreement.

  14. Corrosion performance of ceramic materials in slagging environments

    SciTech Connect

    Natesan, K.

    1996-10-01

    Conceptual designs of advanced combustion systems that use coal as feedstock require high-temperature furnaces and heat transfer surfaces that can operate at temperatures much higher than in current coal-fired power plants. Combination of elevated temperatures and hostile combustion environments requires advanced ceramics. Objectives of this program are to evaluate the (a) chemistry of gaseous and condensed products arising during coal combustion, (b) corrosion behavior of candidate materials in air, slag, and salt environments, and (c)residual mechanical properties of the materials after corrosion. Temperatures in the range of 1000-1400 C for ceramics and 600-1000 C for metallic alloys are emphasized. Coal/ash chemistries developed on the basis of thermodynamic/kinetic calculations, together with slags from actual combustors, are used. Materials being evaluated include monolithic Si carbides from several sources: Si nitride, Si carbide in alumina composites, Si carbide fibers in a Si carbide-matrix composite, and some advanced Ni-base alloys. This paper presents results from an ongoing program on corrosion performance of candidate ceramic materials exposed to air, salt, and slag environments and their effect on flexural strength and energy absorbed during fracture of these materials. 10 figs, 4 tabs, 8 refs.

  15. Selective Sulfidation of Lead Smelter Slag with Sulfur

    NASA Astrophysics Data System (ADS)

    Han, Junwei; Liu, Wei; Wang, Dawei; Jiao, Fen; Qin, Wenqing

    2016-02-01

    The selective sulfidation of lead smelter slag with sulfur was studied. The effects of temperature, sulfur dosage, carbon, and Na salts additions were investigated based on thermodynamic calculation. The results indicated that more than 96 pct of zinc in the slag could be converted into sulfides. Increasing temperature, sulfur dosage, or Na salts dosage was conducive to the sulfidation of the zinc oxides in the slag. High temperature and excess Na salts would result in the more consumption of carbon and sulfur. Carbon addition not only promoted the selective sulfidation but reduced the sulfur dosage and eliminated the generation of SO2. Iron oxides had a buffering role on the sulfur efficient utilization. The transformation of sphalerite to wurtzite was feasible under reducing condition at high temperature, especially above 1273 K (1000 °C). The growth of ZnS particles largely depended upon the roasting temperature. They were significantly increased when the temperature was above 1273 K (1000 °C), which was attributed to the formation of a liquid phase.

  16. Development of improved performance refractory liner materials for slagging gasifiers

    SciTech Connect

    Kwong, Kyei-Sing; Bennett, James P.; Powell, Cynthia; Thomas, Hugh; Krabbe, Rick

    2005-01-01

    Refractory liners for slagging gasifiers used in power generation, chemical production, or as a possible future source of hydrogen for a hydrogen based economy, suffer from a short service life. These liner materials are made of high Cr2O3 and lower levels of Al2O3 and/or ZrO2. As a working face lining in the gasifier, refractories are exposed to molten slags at elevated temperature that originate from ash in the carbon feedstock, including coal and/or petroleum coke. The molten slag causes refractory failure by corrosion dissolution and by spalling. The Albany Research Center is working to improve the performance of Cr2O3 refractories and to develop refractories without Cr2O3 or with Cr2O3 content under 30 wt pct. Research on high Cr2O3 materials has resulted in an improved refractory with phosphate additions that is undergoing field testing. Results to date of field trials, along with research direction on refractories with no or low Cr2O3, will be discussed.

  17. Recycling ferrous-nickel slag in blast cleaning.

    PubMed

    Katsikaris, K; Voutsas, E; Magoulas, K; Andronikos, G; Stamataki, S

    2002-06-01

    The aim of this study is the development of a procedure for the recycling of the ferrous-nickel slag that is widely used in open dry blast cleaning operations in Greek shipyards thus annually generating thousands of tons of blast cleaning waste. Laboratory tests were carried out, based on the reclamation of the material fraction with size a distribution within the range -1,400 + 150 microm, in order to determine the number of the effective uses (life cycles) of the abrasive material. It is demonstrated that the reclamation yield in the first three life cycles is more than 80%. Laboratory tests also proved that the recycled ferrous-nickel slag has properties comparable to the fresh material's ones in terms of particle size distribution, consumption and other physical-chemical properties. A semi-industrial recycling unit of used ferrous-nickel slag was also designed and installed in a Greek shipyard (Neorion New SA of Syros Shipyards). The operation of the semi-industrial recycling unit verified the conclusions resulting from the laboratory tests, and most important, it was proved profitable for the ship- PMID:12152895

  18. AISI/DOE Technology Roadmap Program: Removal of Residual Elements in The Steel Ladle by a Combination of Top Slag and Deep Injection Practice

    SciTech Connect

    S. Street; K.S. Coley; G.A. Iron

    2001-08-31

    The objective of this work was to determine if tin could be removed from liquid steel by a combination of deep injection of calcium and a reducing top-slag practice. The work was carried out in three stages: injection of Ca wire into 35 Kg heats in an induction furnace under laboratory condition; a fundamental study of the solubility of Sn in the slag as a function of oxygen potential, temperature and slag composition; and, two full-scale plant trials. During the first stage, it was found that 7 to 50% of the Sn was removed from initial Sn contents of 0.1%, using 8 to 16 Kg of calcium per tonne of steel. The Sn solubility study suggested that low oxygen potential, high basicity of the slag and lower temperature would aid Sn removal by deep injection of Ca in the bath. However, two full-scale trials at the LMF station in Dofasco's plant showed virtually no Sn removal, mainly because of very low Ca consumption rates used (0.5 to 1.1 Kg/tonne vs. 8 to 16 Kg/tonne used during the induction furnace study in the laboratory). Based on the current price of Ca, addition of 8 to 16 Kg/tonne of steel to remove Sn is too cost prohibitive, and therefore, it is not worthwhile to pursue this process further, even though it may be technically feasible.

  19. Slag characterization and removal using pulse detonation for coal gasification. Quarterly research report, July 1--September 31, 1996

    SciTech Connect

    Huque, Z.; Mei, D.; Biney, P.O.; Zhou, J.; Ali, M.R.

    1996-10-25

    Boiler slagging and fouling as a result of inorganic impurities in combustion gases being deposited on heat transfer tubes have caused severe problems in coal-fired power plant operation. These problems are fuel, system design, and operating condition dependent. Conventional slag and ash removal methods include the use of in situ blowing or jet-type devices such as air or steam soot blowers and water lances. Pulse detonation technology for the purpose of removing slag and fouling deposits in coal-fired utility power plant boilers offers great potential. The detonation wave technique based on high impact velocity with sufficient energy and thermal shock on the slag deposited on gas contact surfaces offers a convenient, inexpensive, yet efficient and effective way to supplement existing slag removal methods. These detonation waves have been demonstrated experimentally to have exceptionally high shearing capability important to the task of removing slag and fouling deposits. Several tests have been performed with single shot detonation wave at University of Texas at Arlington to remove the slag deposit. To hold the slag deposit samples at the exit of detonation tube, two types of fixture was designed and fabricated. They are axial arrangement and triangular arrangement. The slag deposits from the utility boilers have been used to prepare the slag samples for the test. The experimental results show that the single shot detonation wave is capable of removing the entire slag (types of slag deposited on economizer, and air-heater, i.e., relatively softer slags) and 30% of the reheater slag (which is harder) even at a distance of 6 in. from the exit of a detonation engine tube. Wave strength and slag orientation also have different effects on the chipping off of the slag. The annual report discusses about the results obtained in effectively removing the slag.

  20. Cr(VI) reduction in aqueous solutions by using copper smelter slag

    SciTech Connect

    Kiyak, B.; Oezer, A.; Altundogan, H.S.; Erdem, M.; Tuemen, F.

    1999-11-01

    The ability of Copper Smelter Slag (CSS) to reduce Cr(VI) in aqueous solutions has been investigated. The extent of reduction if dependent on the amounts of acid and reductant, contact time, Cr(VI) concentration, temperature of the solution and particle size of CSS. The amount of acid is the most important variable affecting the reduction process. When twice the amount of acid required with respect to Cr(VI) was used, Cr(VI) in 100 ml solution (100 mg/l) was completely reduced in a contact period less than 5 min by a 10 g/l dosage of CSS. Reduction efficiency increased with increase in temperature of solution, showing that the process is endothermic. Reduced chromium, and iron and other metals dissolved from CSS were effectively precipitated by using NaOH or calcinated carbonation sludge from sugar plant.

  1. Cr(VI) reduction in aqueous solutions by using copper smelter slag

    SciTech Connect

    Kiyak, B.; Oezer, A.; Altundogan, H.S.; Erdem, M.; Tuemen, F. )

    1999-01-01

    The ability of Copper Smelter Slag (CSS) to reduce Cr(VI) in aqueous solutions has been investigated. The extent of reduction if dependent on the amounts of acid and reductant, contact time, Cr(VI) concentration, temperature of the solution and particle size of CSS. The amount of acid is the most important variable affecting the reduction process. When twice the amount of acid required with respect to Cr(VI) was used, Cr(VI) in 100 ml solution (100 mg/l) was completely reduced in a contact period less than 5 min by a 10 g/l dosage of CSS. Reduction efficiency increased with increase in temperature of solution, showing that the process is endothermic. Reduced chromium, and iron and other metals dissolved from CSS were effectively precipitated by using NaOH or calcinated carbonation sludge from sugar plant.

  2. Advanced Characterization of Slags and Refractory Bricks Using Electron Backscatter Diffraction

    SciTech Connect

    John Kay; Kurt Eylands

    2007-09-30

    Numerous studies have been conducted to determine changes that occur in slag that cause a rapid change in viscosity, but these studies have been limited by the inability to characterize/identify the phases present in the slag. Rapid freezing of slag in entrained gasifiers and slagging combustion systems can cause a shutdown of the system. The reactions occurring in slag that result in rapid freezing of slags are not well understood. It is believed that electron backscatter diffraction (EBSD) can be used to analyze slags and aid in their characterization although its use has not been found in literature. The EBSD technique allows particle-by-particle mineralogy based on diffraction patterns generated by the electron beam when the sample is tilted to a high angle. The diffraction pattern (Kikuchi bands) can only come from crystalline phases, which makes this technique ideally suited to study crystal formation in slags where oftentimes the crystals are very small and a reasonable chemical analysis cannot be made by conventional energy-dispersive spectrometry (EDS) methods in the scanning electron microscope. The ability to have mineralogical data based on the crystalline structure of a phase rather than a chemical analysis by EDS allows much better interpretation of the temperature regimes in which specific phases tend to form. Knowing the type and relative amounts of a phase crystallizing in a slag is critical in predicting the viscosity of a slag at a given temperature. Six slag samples were selected based on the parent coal. Unfortunately, none of the slags appeared to have any crystalline material associated with them. The funding for this project was not adequate for generating more slags from the various coal types. For this reason, sample archives were searched for those containing slags that were not rapidly quenched. A slag from a bituminous coal was found to contain several dendritic crystals (10 {mu}m to 50 {mu}m in size) that formed near the edges of the

  3. New evidence for rejuvenation of phosphorus retention capacity in EAF steel slag.

    PubMed

    Drizo, Aleksandra; Cummings, John; Weber, David; Twohig, Eamon; Druschel, Greg; Bourke, Bill

    2008-08-15

    The purpose of this research was to investigate phosphorus (P) retention capacity and rejuvenation potential of electric arc furnace (EAF) steel slag from Quebec and New Zealand (NZ) iron melter slag (IMS). Columns filled with slag materials were fed with dairy effluent and subjected to two feeding and one resting cycle(s). P retention capacities and rejuvenation potentials were determined after each feeding cycle. Elemental composition and mineralogical analysis were performed on IMS samples. Finally, chemical fractionation analysis was conducted on both NZ IMS and Quebec EAF steel slags. The results revealed that initiating a resting period in EAF steel slag filters prior to reaching their P saturation point increased the overall filter P retention capacity by 49.5 and 42.4% compared to 28% in a filter which had its resting period initiated after reaching P saturation. The rejuvenation property could play a significant role in full-scale applications by prolonging life expectancy and increasing cost efficiency. P retention and rejuvenation by NZ slag materials was negligible relative to EAF steel slag material from Quebec. Chemical fractionation analysis revealed differences between materials, indicating that the highest quantities of P were bound to Ca and Fe in EAF steel slag and to Ca and Al fractions in iron melter slag. This study also demonstrates that slag's performance is dependent on the source of the material and the steel making practices. Therefore, testing of the P adsorptive capability and, if relevant, the rejuvenation potential of individual steel mill slags, should be a prerequisite prior to their use in field applications.

  4. Laser-induced breakdown spectroscopy for 24/7 automatic liquid slag analysis at a steel works.

    PubMed

    Sturm, Volker; Fleige, Rüdiger; de Kanter, Martinus; Leitner, Richard; Pilz, Karl; Fischer, Daniel; Hubmer, Gerhard; Noll, Reinhard

    2014-10-01

    Laser-induced breakdown spectroscopy (LIBS) is applied for the inline analysis of liquid slag at a steel works. The slag in the ladle of a slag transporter is measured at a distance of several meters during a short stop of the transporter. The slag surface with temperatures from ≈600 to ≈1400 °C consists of liquid slag and solidified slag parts. Automatic measurements at varying filling levels of the ladle are realized, and the duration amounts to 2 min including data transmission to the host computer. Analytical results of the major components such as CaO, Fe, SiO2, MgO, Mn, and Al2O3 are compared with reference values from the steel works laboratory for solid pressed slag samples as well as for samples from the liquid slag. Stable 24/7 operation during the first three-month test run was achieved.

  5. A Kinetic Ladle Furnace Process Simulation Model: Effective Equilibrium Reaction Zone Model Using FactSage Macro Processing

    NASA Astrophysics Data System (ADS)

    Van Ende, Marie-Aline; Jung, In-Ho

    2016-05-01

    The ladle furnace (LF) is widely used in the secondary steelmaking process in particular for the de-sulfurization, alloying, and reheating of liquid steel prior to the casting process. The Effective Equilibrium Reaction Zone model using the FactSage macro processing code was applied to develop a kinetic LF process model. The slag/metal interactions, flux additions to slag, various metallic additions to steel, and arcing in the LF process were taken into account to describe the variations of chemistry and temperature of steel and slag. The LF operation data for several steel grades from different plants were accurately described using the present kinetic model.

  6. The pH-dependent contaminant leaching from the copper smelter fly ash and slag

    NASA Astrophysics Data System (ADS)

    Jarosikova, Alice; Ettler, Vojtech; Mihaljevic, Martin; Penizek, Vit

    2014-05-01

    Metallurgical wastes produced during smelting processes represent a potential risk of environmental contamination, depending particularly on the content and mobility of the elements contained. Due to leaching, serious environmental impact especially in contaminated soil systems in the vicinity of the smelting plants may occur. In this respect two potentially hazardous metallurgical wastes from the copper smelter Tsumeb (Namibia, Africa) were investigated by laboratory leaching experiments. The leaching behaviours of (i) Ausmelt slag from Cu smelting (9500 ppm As, 24000 ppm Cu, 10200 ppm Pb, 24500 ppm Zn; mineralogy: glass, fayalite, spinel, metallic/sulphide droplets) and (ii) fly ash from Cu smelter bag house filters (43.7 wt% As, 13000 ppm Cu, 39700 ppm Pb, 20000 ppm Zn; mineralogy: arsenolite, galena, gypsum, litharge, anglesite) were studied using a 48-h pH-static leaching test (CEN/TS 14997). The release of metals/metalloids at a range of pH 3-12, investigation of changes in mineralogical composition and PHREEQC speciation-solubility modelling were used to understand processes governing the contaminant leaching from these waste materials. It was observed that the contaminant leaching was highly pH-dependent. The release of metals from slag corresponded to "L-type" leaching curve with Cu being the key contaminant leached (up to 1780 mg/kg). In contrast, As was highly leached also in alkaline conditions (31-173 mg/kg) and significantly exceeded the limit value for hazardous waste materials in all cases (25 mg/kg). Fly ash was found to be extremely reactive in terms of the As release with a "J-type" leaching curve indicating the highest leaching at pH of 11 and 12 (up to 314 g/kg). Arsenic was considered to be the most important contaminant for both waste materials and its release can represent a risk for the environment, especially in case, where the fly ash- or slag-derived particulates are deposited into the soil systems. This study was supported by the Czech

  7. Thermodynamics of Iron Oxidation in Metallurgical Slags

    NASA Astrophysics Data System (ADS)

    Matousek, Jan

    2012-11-01

    The state of oxidation of a pyrometallurgical process, given by the partial pressure of oxygen and the temperature, is one of the important properties monitored and controlled in the smelting and refining of iron and the nonferrous metals. This article reviews the thermodynamic background for this quantity and examines some empirical methods for its estimation and use. The emphasis is on copper smelting, but the same principles apply to iron, nickel, lead, and zinc processes.

  8. Two-zone countercurrent smelter system and process

    DOEpatents

    Cox, James H.; Fruehan, Richard J.; Elliott, deceased, John F.

    1995-01-01

    A process for continuously smelting iron ore by use of coal to yield molten iron or semi-steel is disclosed. The process comprises the steps of establishing a melt covered by slag; inducing the slag and the molten iron to flow countercurrently to one another, toward opposite ends of the smelter; maintaining iron oxide-reducing conditions in that zone of the smelter towards which the slag flows; maintaining carbon-oxidizing conditions in that zone of the smelter towards which the molten iron flows; continuously or semicontinuously tapping the slag from the reducing zone end of the smelter; continuously or semicontinuously tapping the molten iron from the oxidizing zone end of the smelter; and adding to both zones iron ore, coal, oxygen, and flux at addition rates sufficient to keep the molten iron in the reducing zone substantially saturated with carbon, maintain in the slag being tapped an FeO content of about 5 weight percent or less, and maintain in the molten iron being tapped a carbon content of about 0.5 to 5 weight percent. A slag dam preferably is included in the smelter, to impede the backflow of the slag from the reducing zone to the oxidizing zone. A metal bath dam with one or more flow-through portals also is preferably used, submerged below the slag dam, to impede the backflow of the hot metal.

  9. Two-zone countercurrent smelter system and process

    DOEpatents

    Cox, J.H.; Fruehan, R.J.; Elliott, J.F.

    1995-01-03

    A process for continuously smelting iron ore by use of coal to yield molten iron or semi-steel is disclosed. The process comprises the steps of establishing a melt covered by slag; inducing the slag and the molten iron to flow countercurrently to one another, toward opposite ends of the smelter; maintaining iron oxide-reducing conditions in that zone of the smelter towards which the slag flows; maintaining carbon-oxidizing conditions in that zone of the smelter towards which the molten iron flows; continuously or semicontinuously tapping the slag from the reducing zone end of the smelter; continuously or semicontinuously tapping the molten iron from the oxidizing zone end of the smelter; and adding to both zones iron ore, coal, oxygen, and flux at addition rates sufficient to keep the molten iron in the reducing zone substantially saturated with carbon, maintain in the slag being tapped an FeO content of about 5 weight percent or less, and maintain in the molten iron being tapped a carbon content of about 0.5 to 5 weight percent. A slag dam preferably is included in the smelter, to impede the backflow of the slag from the reducing zone to the oxidizing zone. A metal bath dam with one or more flow-through portals also is preferably used, submerged below the slag dam, to impede the backflow of the hot metal. 8 figures.

  10. Kinetics of Hydrochloric Acid Leaching of Titanium from Titanium-Bearing Electric Furnace Slag

    NASA Astrophysics Data System (ADS)

    Zheng, Fuqiang; Chen, Feng; Guo, Yufeng; Jiang, Tao; Travyanov, Andrew Yakovlevich; Qiu, Guanzhou

    2016-05-01

    The hydrochloric acid leaching of titanium from titanium-bearing electric furnace slag was investigated under different experimental conditions. The results indicate that particle size, hydrochloric acid concentration and reaction temperature were of significance to the leaching kinetics. Specifically, reaction temperature was the most important factor followed by hydrochloric acid concentration and particle size. The shrinking core model was used to describe the leaching process which was controlled by surface chemical reaction. The kinetic equation was obtained and the activation energy was found to be 43.16 kJ/mol. Iron and calcium species were almost completely dissolved in the acid when the extraction degree of titanium reached 99.84%. MgO (19.34 wt.%) and Al2O3 (32.45 wt.%) in the spinel were still in the leaching residue and SiO2 (43.53 wt.%) in the form of quartz remained in the leaching residue.

  11. Study of Phase Relations of ZnO-Containing Fayalite Slag Under Fe Saturation

    NASA Astrophysics Data System (ADS)

    Shi, Huayue; Chen, Liugang; Malfliet, Annelies; Jones, Peter Tom; Blanpain, Bart; Guo, Muxing

    2016-10-01

    A ZnO-containing fayalite-based slag can be formed in copper smelting from secondary raw materials and its high viscosity is a common issue that hinders slag tapping. In this work, the crystallization behavior of the industrial slag was observed in situ by confocal laser scanning microscopy. Solid precipitation was found to be the major cause of the poor slag fluidity. The phase relations in the industrial slag system ZnO-"FeO"-SiO2-Al2O3-CaO (CaO/SiO2 = 0.05, Al2O3/SiO2 = 0.15) were investigated by quenching the samples after reaching equilibrium at 1423 K (1150 °C) under iron saturation. The equilibrium composition of the phases was determined with electron probe micro-analysis. The effect of individual components, such as FeO, ZnO, and CaO on the phase equilibrium of the slag system has been quantitatively studied. The relation between the solid-phase fraction and the chemical composition of the slag has been revealed. Suggestions to modify the slag composition toward low viscosity are provided.

  12. Physico-chemical characterization of steel slag. Study of its behavior under simulated environmental conditions.

    PubMed

    Navarro, Carla; Díaz, Mario; Villa-García, María A

    2010-07-15

    The chemical and mineralogical composition of steel slag produced in two ArcelorMittal steel plants located in the North of Spain, as well as the study of the influence of simulated environmental conditions on the properties of the slag stored in disposal areas, was carried out by elemental chemical analysis, XRF, X-ray diffraction, thermal analysis, and scanning electron microscopy with EDS analyzer. Spectroscopic characterization of the slag was also performed by using FTIR spectroscopy. Due to the potential uses of the slag as low cost adsorbent for water treatment and pollutants removal, its detailed textural characterization was carried out by nitrogen adsorption-desorption at 77 K and mercury intrusion porosimetry. The results show that the slag is a crystalline heterogeneous material whose main components are iron oxides, calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate), elemental iron, and quartz. The slags are porous materials with specific surface area of 11 m(2)g(-1), containing both mesopores and macropores. Slag exposure to simulated environmental conditions lead to the formation of carbonate phases. Carbonation reduces the leaching of alkaline earth elements as well as the release of the harmful trace elements Cr (VI) and V. Steel slags with high contents of portlandite and calcium silicates are potential raw materials for CO(2) long-term storage. PMID:20568743

  13. Study of Phase Relations of ZnO-Containing Fayalite Slag Under Fe Saturation

    NASA Astrophysics Data System (ADS)

    Shi, Huayue; Chen, Liugang; Malfliet, Annelies; Jones, Peter Tom; Blanpain, Bart; Guo, Muxing

    2016-06-01

    A ZnO-containing fayalite-based slag can be formed in copper smelting from secondary raw materials and its high viscosity is a common issue that hinders slag tapping. In this work, the crystallization behavior of the industrial slag was observed in situ by confocal laser scanning microscopy. Solid precipitation was found to be the major cause of the poor slag fluidity. The phase relations in the industrial slag system ZnO-"FeO"-SiO2-Al2O3-CaO (CaO/SiO2 = 0.05, Al2O3/SiO2 = 0.15) were investigated by quenching the samples after reaching equilibrium at 1423 K (1150 °C) under iron saturation. The equilibrium composition of the phases was determined with electron probe micro-analysis. The effect of individual components, such as FeO, ZnO, and CaO on the phase equilibrium of the slag system has been quantitatively studied. The relation between the solid-phase fraction and the chemical composition of the slag has been revealed. Suggestions to modify the slag composition toward low viscosity are provided.

  14. 54. View from southeast of KinneyOsborne slag granulator at right ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. View from southeast of Kinney-Osborne slag granulator at right and stack at left that vented steam generated when water was sprayed on hot slag to solidify and fracture it. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

  15. Heavy metal adsorption changes of EAF steel slag after phosphorus adsorption.

    PubMed

    Song, Guanling; Cao, Lijing; Chen, Xiao; Hou, Wenhua; Wang, Qunhui

    2012-01-01

    A kind of electric arc furnace (EAF) steel slag was phosphated, and its isothermal and dynamic adsorptions of copper, cadmium, and lead ions were measured to determine if heavy metal adsorption changes after phosphorus adsorption. The surface area increased greatly after the slag was phosphated. Isothermal adsorption experiments showed that the theoretical Q(max) of the EAF steel slag on Cu(2+), Cd(2+), and Pb(2+) improved 59, 50, and 89% respectively after it was phosphated. Dynamic adsorption results showed that the greatest adsorption capacities of unit volume of Cu(2+), Cd(2+), and Pb(2+) were 2.2, 1.8, and 1.8 times that of the column packed with original EAF steel slag when the column was packed with phosphate EAF steel slag at the same heavy metal ion concentration. The breakthrough time, the exhaustion time and elution efficiency of the column also increased when the column was packed with phosphated EAF steel slag compared with that packed with original EAF steel slag. Phosphorus adsorption could further improve the heavy metal ion adsorption of the EAF steel slag.

  16. Substrate pH and butterfly bush response to dolomitic lime or steel slag amendment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Steel slag is a fertilizer amendment with a high concentration of calcium oxide, and thus capable of raising substrate pH similar to dolomitic lime. Steel slag, however, contains higher concentrations of some nutrients, such as iron, manganese, and silicon, compared to dolomitic lime. The objectiv...

  17. Physico-chemical characterization of steel slag. Study of its behavior under simulated environmental conditions.

    PubMed

    Navarro, Carla; Díaz, Mario; Villa-García, María A

    2010-07-15

    The chemical and mineralogical composition of steel slag produced in two ArcelorMittal steel plants located in the North of Spain, as well as the study of the influence of simulated environmental conditions on the properties of the slag stored in disposal areas, was carried out by elemental chemical analysis, XRF, X-ray diffraction, thermal analysis, and scanning electron microscopy with EDS analyzer. Spectroscopic characterization of the slag was also performed by using FTIR spectroscopy. Due to the potential uses of the slag as low cost adsorbent for water treatment and pollutants removal, its detailed textural characterization was carried out by nitrogen adsorption-desorption at 77 K and mercury intrusion porosimetry. The results show that the slag is a crystalline heterogeneous material whose main components are iron oxides, calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate), elemental iron, and quartz. The slags are porous materials with specific surface area of 11 m(2)g(-1), containing both mesopores and macropores. Slag exposure to simulated environmental conditions lead to the formation of carbonate phases. Carbonation reduces the leaching of alkaline earth elements as well as the release of the harmful trace elements Cr (VI) and V. Steel slags with high contents of portlandite and calcium silicates are potential raw materials for CO(2) long-term storage.

  18. The Effect of Solid Constituent Particle Size Distributions on TP-H1148 Propellant Slag

    NASA Technical Reports Server (NTRS)

    May, Douglas H.; Miles, William L.; Taylor, David S.; Rackham, Jon L.

    1997-01-01

    Special aluminum and ammonium perchlorate (AP) particle size distributions were prepared for a matrix of five-inch diameter, center-perforated (CP) motor tests to measure the aluminum oxide slag response in Space Shuttle Reusable Solid Rocket Motor (RSRM) propellant. Previous tests of TP-H1148 propellant in five-inch CP spin motors have shown a correlation between aluminum particle size and generated slag. The motors for this study were cast from thirteen five-gallon propellant mixes which used five particle size levels of aluminum powder, five of unground AP and three of ground AP. Aluminum had the greatest effect on slag formation, the more coarse fractions causing greater slag quantities and larger slag particles. Unground AP had about half the effect of aluminum with the coarser fractions again producing more and larger sized slag particles. The variation in ground AP did not have a significant effect on slag formation. Quench bomb tests showed the same trends as the spin motors, that is, larger aluminum and AP particle size distributions generated larger slag particles leaving the propellant surface. Cured propellant mechanical properties were also impacted by particle size variation.

  19. A multiphase fluid mechanics approach to gas holdup in bath smelting processes

    SciTech Connect

    Gou, H.; Irons, G.A.; Lu, W.K.

    1996-04-01

    In several new smelting-reduction processes for iron-making, coal and partially prereduced iron ore are added to a slag phase. In slag-based, smelting-reduction processes, the overflow of slag from the vessel is considered a major limitation to productivity; this phenomenon is commonly called slag foaming. While much has been learned from laboratory-scale studies of foaming, the superficial gas velocities are well below those encountered in production (centimeters per second compared to meters per second). A multiphase fluid dynamic model was developed to determine the relationship between gas velocity and void fraction (holdup) at industrial production rates. In the model, the drag between the gas and slag is balanced against the weight of the slag. Within the framework of the model, the only unknown quantity is a drag factor which can be extracted from experimental data. Values of this factor from water models, smelting-reduction converters, and other slag systems fall in a narrow range. The model can be used to estimate slag height in smelting-reduction vessels. The behavior of slags at high rates of gas injection is markedly different from foaming observed at low flow rates.

  20. Effect of Slag on Titanium, Silicon, and Aluminum Contents in Superalloy During Electroslag Remelting

    NASA Astrophysics Data System (ADS)

    Jiang, Zhou-Hua; Hou, Dong; Dong, Yan-Wu; Cao, Yu-Long; Cao, Hai-Bo; Gong, Wei

    2016-04-01

    Many factors influence the chemical composition in electroslag remelting (ESR) steel, including atmosphere in crucible, melting rate, slag composition, deoxidation, and so on. Fluoride-based slag, which is exposed to liquid metal directly, influences the chemical composition of ESR ingots to a large extent. The present paper focuses on the effect of slag on the titanium, silicon, and aluminum contents in ingots based on the interaction of the slag and metal. In present work, superalloy of GH8825 and several slags containing different CaO contents have been employed for investigating the effect of slag on titanium, silicon, and aluminum contents in an electrical resistance furnace under argon atmosphere. Results indicate that the higher CaO content in slag has better capacity for avoiding loss of titanium caused by the reaction of titanium with silica in slag, especially in case of remelting superalloy with high titanium and low silicon content. The CaO has a great effect on the activities of TiO2, SiO2, and Al2O3. Thermodynamic analysis is applied to investigate the CaO behavior. Based on the ion and molecule coexistence theory of slag, activity model is established to calculate the activities of components containing titanium, silicon, and aluminum elements in a six-component slag consisting of CaO-CaF2-Al2O3-SiO2-TiO2-MgO. The components containing titanium, silicon, and aluminum in slag are mainly CaO·TiO2, 2CaO·SiO2, CaO·SiO2, CaO·Al2O3, and MgO·Al2O3. With the increase of CaO mass fraction in slag, the activity coefficient of SiO2 decreases significantly, whereas slightly change happens for Al2O3. As a result, the lg ({{γ_{{{{SiO}}2 }} } {/ {{{γ_{{{{SiO}}2 }} } {γ_{{{{TiO}}2 }} }}} {γ_{{{{TiO}}2 }} }}) decreases with increasing CaO content, which is better for preventing loss of titanium caused by the reaction of titanium with silica in slag. The slag with high CaO and appropriate TiO2 content is suitable for electroslag remelting of GH8825.

  1. Biomass fuel leaching for the control of fouling, slagging, and agglomeration in biomass power generation

    NASA Astrophysics Data System (ADS)

    Bakker, Robert Reurd

    The use of straws and other herbaceous biomass as boiler fuel is limited because of rapid formation of boiler deposits (i.e. fouling and slagging), which results in high boiler operating costs. The removal of troublesome elements in biomass that lead to slagging and fouling was tested by washing (leaching) biomass fuels in water. Potassium, sodium, and chlorine are easily removed from rice straw and other biomass in both tap and distilled water. Simple water leaching leads to considerable changes in combustion properties and ash transformation in biomass. In general, leaching elevates the sintering and melting temperatures, improves ash fusibility, and reduces the volatilization of inorganic species. Leaching leads to a notable decline in the alkali index, a broad indicator of the fouling potential of a biomass fuel. Bench-scale combustion tests at 800-1000°C furnace gas temperatures confirm that leaching dramatically changes the combustion behavior of rice straw. Full-scale combustion tests indicate that leached rice straw is technically suitable under normal boiler operating conditions. Two potential strategies to accomplish leaching of rice straw include leaching under controlled circumstances, and leaching by natural precipitation. Under controlled conditions, substantial amounts of K and Cl can be leached from rice straw with water at ambient temperatures, and without extensive particle size reduction. Leaching straw in a full-scale process is estimated to add approximately $15 to 18 Mg-1 to the fuel costs of a combustion facility. Leaving rice straw in the field and exposed to rainy weather leads to similar improvements in combustion behavior as observed with biomass that is leached under controlled circumstances. Collection of naturally leached rice straw in the Sacramento Valley through delayed harvesting is technically feasible, however its commercial implementation is dependent on harvest practices, rainfall distribution, and field-specific factors. The

  2. Characterization of Precious Metal Resources in Copper Slag and Their Implications in Beneficiation

    NASA Astrophysics Data System (ADS)

    Rao, D. S.; Angadi, S.; Reddy, P. S. R.

    2015-04-01

    Studies have been carried out on precious metal association, on a typical Indian copper slag sample using SEM-EDS. The studies revealed the presence of platinum as well as gold, reported here for the first time, in the copper metal as well as different types of metallic sulphides phases of the copper slag. These phases are either entrapped in the silicate minerals or are present as free liberated grains within the slag sample. The platinum content varies in the range of 1.24-1.95 wt% whereas gold values range from 2.41 to 5.90 wt% in some phases. The phases of copper slag, which contain gold and platinum are present in very less quantity with respect to volume percentage. The major phases, in the copper slag are fayalite and magnetite while spinel, ulvospinel, metallic iron, calcium oxide and barium sulphide are minor phases and all these are devoid of gold or platinum.

  3. Distinctive microstructural features of aged sodium silicate-activated slag concretes

    SciTech Connect

    San Nicolas, Rackel; Bernal, Susan A.; Mejía de Gutiérrez, Ruby; Deventer, Jannie S.J. van; Provis, John L.

    2014-11-15

    Electron microscopic characterisation of 7-year old alkali-activated blast-furnace slag concretes enabled the identification of distinct microstructural features, providing insight into the mechanisms by which these materials evolve over time. Backscattered electron images show the formation of Liesegang-type ring formations, suggesting that the reaction at advanced age is likely to follow an Oswald supersaturation–nucleation–depletion cycle. Segregation of Ca-rich veins, related to the formation of Ca(OH){sub 2}, is observed in microcracked regions due to the ongoing reaction between the pore solution and available calcium from remnant slag grains. A highly dense and uniform interfacial transition zone is identified between siliceous aggregate particles and the alkali activated slag binders, across the concretes assessed. Alkali-activated slag concretes retain a highly dense and stable microstructure at advanced ages, where any microcracks induced at early ages seem to be partially closing, and the remnant slag grains continue reacting.

  4. The Effect of Oxygen Potential on the Sulfide Capacity for Slags Containing Multivalent Species

    NASA Astrophysics Data System (ADS)

    Allertz, Carl; Selleby, Malin; Sichen, Du

    2016-10-01

    The dependence of sulfide capacity on the oxygen partial pressure for slags containing multivalent species was investigated experimentally using a slag containing vanadium oxide. Copper-slag equilibration experiments were carried out at 1873 K (1600 °C) in the approximate oxygen partial pressure range 10-15.4 to 10-9 atm. The sulfide capacity was found to be strongly dependent on the oxygen potential in this slag system, increasing with the oxygen partial pressure. The sulfide capacity changed by more than two orders of magnitude over the oxygen partial pressure range. The effect of changing oxygen partial pressure was found to be much greater than the effect of changing slag composition at a fixed oxygen partial pressure.

  5. Sulfide capacities of MnO-SiO2 slags

    NASA Astrophysics Data System (ADS)

    Reddy, Ramana G.; Blander, Milton

    1989-04-01

    Sulfide capacities of binary MnO-SiO2 slags at 1773 and 1923 K were calculated thermodynamically. Only known data, such as the standard free energy of formation of MnO and MnS and activities of MnO in the melt, are used in making calculations based on fundamental concepts. Excellent agreement is found between our calculations and published experimental data. Correlations of sulfide capacities, based on optical basicity using Pauling electronegativities or empirically deduced optical basicities, differ from the experimental data in both magnitude and concentration dependence. Our method provides useful predictions of sulfide capacities a priori.

  6. Workability and mechanical properties of alkali activated slag concrete

    SciTech Connect

    Collins, F.G.; Sanjayan, J.G.

    1999-03-01

    This paper reports the results of an investigation on concrete containing alkali activated slag (AAS) as the binder, with emphasis on achievement of reasonable workability and equivalent one-day strength to portland cement concrete at normal curing temperatures. Two types of activators were used: sodium hydroxide in combination with sodium carbonate and sodium silicate in combination with hydrated lime. The fresh concrete properties reported include slump and slump loss, air content, and bleed. Mechanical properties of AAS concrete, including compressive strength, elastic modulus, flexural strength, drying shrinkage, and creep are contrasted with those of portland cement concrete.

  7. An annular-furnace boiler for the 660-MW power unit for ultrasupercritical parameters intended for firing brown slagging coals

    NASA Astrophysics Data System (ADS)

    Serant, F. A.; Belorutskii, I. Yu.; Ershov, Yu. A.; Gordeev, V. V.; Stavskaya, O. I.; Katsel, T. V.

    2013-12-01

    We present the main technical solutions adopted in designing annular-furnace boilers intended for operation on brown coals of the prospective Maikubensk open-cast mine in Kazakhstan as part of 660-MW power units for ultrasupercritical steam conditions. Results from 3D modeling of combustion processes are presented, which clearly show the advantages furnaces of this kind have over a traditional furnace in burning heavily slagging brown coals. The layout of the main and boiler auxiliary equipment in the existing boiler cell of the 500-MW power unit at the Ekibastuz GRES-1 district power station is shown. Appropriate attention is paid to matters concerned with decreasing harmful emissions.

  8. Influence of slag chemistry on the hydration of alkali-activated blast-furnace slag - Part I: Effect of MgO

    SciTech Connect

    Ben Haha, M.; Lothenbach, B. Le Saout, G.; Winnefeld, F.

    2011-09-15

    The hydration and the microstructure of three alkali activated slags (AAS) with MgO contents between 8 and 13 wt.% are investigated. The slags were hydrated in the presence of two different alkaline activators, NaOH and Na{sub 2}SiO{sub 3}.5H{sub 2}O (WG). Higher MgO content of the slag resulted in a faster reaction and higher compressive strengths during the first days. The formation of C(- A)-S-H and of a hydrotalcite-like phase was observed in all samples by X-ray diffraction (XRD), thermal analysis (TGA) and scanning electron microscopy (SEM) techniques. Increasing the MgO content of the slag from 8 to 13% increased the amount of hydrotalcite and lowered the Al uptake by C-S-H resulting in 9% higher volume of the hydrates and a 50 to 80% increase of the compressive strength after 28 days and longer for WG activated slag pastes. For NaOH activated slags only a slight increase of the compressive strength was measured.

  9. Development of Low-Fluoride Slag for Electroslag Remelting: Role of Li2O on the Viscosity and Structure of the Slag

    NASA Astrophysics Data System (ADS)

    Shi, Cheng-Bin; Shin, Seung-Ho; Zheng, Ding-Li; Cho, Jung-Wook; Li, Jing

    2016-10-01

    The effect of the substitution of CaF2 with Li2O on the viscosity and structure of low-fluoride CaF2-CaO-Al2O3-MgO slag was studied with an aim to develop low-fluoride slag for electroslag remelting. Increasing Li2O addition up to 4.5 mass pct was observed to significantly reduce the slag viscosity monotonically. Increasing temperature significantly lowered the viscosity of slag, whereas this influence is less effective with increasing Li2O content especially above 3.5 mass pct. The activation energy for viscous flow decreases with increasing Li2O content. The polymerization degree of aluminate networks decreased with increasing Li2O content, as demonstrated by Raman analysis. The dominant structural unit in [AlO4]5--tetrahedral network is Q_{Al}4 . The amount of symmetric Al-O0 stretching vibrations significantly decreased with increasing Li2O content. The relative fraction of Q_{Al}4 in the [AlO4]5--tetrahedral units shows a decreasing trend, whereas Q_{Al}2 increases with the increase in Li2O content accordingly. The change in slag viscosity with chemistry variation agrees well with the changes in slag structural units.

  10. CO2 sequestration utilizing basic-oxygen furnace slag: Controlling factors, reaction mechanisms and V-Cr concerns.

    PubMed

    Su, Tung-Hsin; Yang, Huai-Jen; Shau, Yen-Hong; Takazawa, Eiichi; Lee, Yu-Chen

    2016-03-01

    Basic-oxygen furnace slag (BOF-slag) contains >35% CaO, a potential component for CO2 sequestration. In this study, slag-water-CO2 reaction experiments were conducted with the longest reaction duration extending to 96hr under high CO2 pressures of 100-300kg/cm(2) to optimize BOF-slag carbonation conditions, to address carbonation mechanisms, and to evaluate the extents of V and Cr release from slag carbonation. The slag carbonation degree generally reached the maximum values after 24hr slag-water-CO2 reaction and was controlled by slag particle size and reaction temperature. The maximum carbonation degree of 71% was produced from the experiment using fine slag of ≤0.5mm under 100°C and a CO2 pressure of 250kg/cm(2) with a water/slag ratio of 5. Vanadium release from the slag to water was significantly enhanced (generally >2 orders) by slag carbonation. In contrast, slag carbonation did not promote chromium release until the reaction duration exceeded 24hr. However, the water chromium content was generally at least an order lower than the vanadium concentration, which decreased when the reaction duration exceeded 24hr. Therefore, long reaction durations of 48-96hr are proposed to reduce environmental impacts while keeping high carbonation degrees. Mineral textures and water compositions indicated that Mg-wüstite, in addition to CaO-containing minerals, can also be carbonated. Consequently, the conventional expression that only considered carbonation of the CaO-containing minerals undervalued the CO2 sequestration capability of the BOF-slag by ~20%. Therefore, the BOF-slag is a better CO2 storage medium than that previously recognized.

  11. Mechanical and leaching behaviour of slag-cement and lime-activated slag stabilised/solidified contaminated soil.

    PubMed

    Kogbara, Reginald B; Al-Tabbaa, Abir

    2011-05-01

    Stabilisation/solidification (S/S) is an effective technique for reducing the leachability of contaminants in soils. Very few studies have investigated the use of ground granulated blast furnace slag (GGBS) for S/S treatment of contaminated soils, although it has been shown to be effective in ground improvement. This study sought to investigate the potential of GGBS activated by cement and lime for S/S treatment of a mixed contaminated soil. A sandy soil spiked with 3000mg/kg each of a cocktail of heavy metals (Cd, Ni, Zn, Cu and Pb) and 10,000mg/kg of diesel was treated with binder blends of one part hydrated lime to four parts GGBS (lime-slag), and one part cement to nine parts GGBS (slag-cement). Three binder dosages, 5, 10 and 20% (m/m) were used and contaminated soil-cement samples were compacted to their optimum water contents. The effectiveness of the treatment was assessed using unconfined compressive strength (UCS), permeability and acid neutralisation capacity (ANC) tests with determination of contaminant leachability at the different acid additions. UCS values of up to 800kPa were recorded at 28days. The lowest coefficient of permeability recorded was 5×10(-9)m/s. With up to 20% binder dosage, the leachability of the contaminants was reduced to meet relevant environmental quality standards and landfill waste acceptance criteria. The pH-dependent leachability of the metals decreased over time. The results show that GGBS activated by cement and lime would be effective in reducing the leachability of contaminants in contaminated soils. PMID:21420148

  12. Mechanical and leaching behaviour of slag-cement and lime-activated slag stabilised/solidified contaminated soil.

    PubMed

    Kogbara, Reginald B; Al-Tabbaa, Abir

    2011-05-01

    Stabilisation/solidification (S/S) is an effective technique for reducing the leachability of contaminants in soils. Very few studies have investigated the use of ground granulated blast furnace slag (GGBS) for S/S treatment of contaminated soils, although it has been shown to be effective in ground improvement. This study sought to investigate the potential of GGBS activated by cement and lime for S/S treatment of a mixed contaminated soil. A sandy soil spiked with 3000mg/kg each of a cocktail of heavy metals (Cd, Ni, Zn, Cu and Pb) and 10,000mg/kg of diesel was treated with binder blends of one part hydrated lime to four parts GGBS (lime-slag), and one part cement to nine parts GGBS (slag-cement). Three binder dosages, 5, 10 and 20% (m/m) were used and contaminated soil-cement samples were compacted to their optimum water contents. The effectiveness of the treatment was assessed using unconfined compressive strength (UCS), permeability and acid neutralisation capacity (ANC) tests with determination of contaminant leachability at the different acid additions. UCS values of up to 800kPa were recorded at 28days. The lowest coefficient of permeability recorded was 5×10(-9)m/s. With up to 20% binder dosage, the leachability of the contaminants was reduced to meet relevant environmental quality standards and landfill waste acceptance criteria. The pH-dependent leachability of the metals decreased over time. The results show that GGBS activated by cement and lime would be effective in reducing the leachability of contaminants in contaminated soils.

  13. Carbothermic Reduction of Titanium-Bearing Blast Furnace Slag

    NASA Astrophysics Data System (ADS)

    Zhen, Yu-Lan; Zhang, Guo-Hua; Chou, Kuo-Chih

    2016-03-01

    The carbothermic reduction experiments were carried out for titanium-bearing blast furnace slag in Panzhihua Iron and Steel Company in argon atmosphere at high temperatures. The effects of reduction temperature, isothermal treatment time and carbon content on the formation of TiC were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD pattern results showed that MgAl2O4 phase disappeared and the main phase of the reduced sample was TiC when the reduction temperature was higher than 1,773 K. The SEM pictures showed that the reduction rate of the titanium-bearing blast furnace slag could be increased by enhancing the temperature and the C content (carbon ratio ≤1.0). Furthermore, it was also found that TiC had the tendency of concentrating around the iron. The effects of additives such as Fe and CaCl2 on the formation of TiC were also studied in the present study.

  14. Buffering of alkaline steel slag leachate across a natural wetland.

    PubMed

    Mayes, William M; Younger, Paul L; Aumônier, Jonathan

    2006-02-15

    Buffering of high-pH (>12) steel slag leachate is documented across a small, natural calcareous wetland. The alkaline leachate is supersaturated with respect to calcite upstream of the wetland (Sl(calcite) values +2.3) and becomes less saturated with progress across the wetland, to Sl(calcite) values of +0.27 at the wetland outlet. Reduction in pH across the wetland (to around pH 8 at the wetland outlet) was observed to be more pronounced over summer months, possibly due to increased microbial activity, possibly further assisted by greater flow baffling by emergent vegetation. Calculated calcite precipitation rates downstream of the leachate source, estimated from hydrochemical data, flow, and surface area, were on the order of 0.4-15 g m(-2) day(-1), while direct measurements (using immersed limestone blocks) showed calcite precipitation values in the range 3-10 g m(-2) day(-1). Precipitation rate was highest in the pH range where the carbonate ion is a dominant constituent of sample alkalinity (pH 9.5-11) and at the locations where wetland biota became established downstream of the leachate emergence. These data provide valuable insights into the potential for using constructed wetlands for the passive treatment of high pH steel slag leachates.

  15. A Comparison Study of the Oxygen-Rich Side Blow Furnace and the Oxygen-Rich Bottom Blow Furnace for Liquid High Lead Slag Reduction

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Hao, Zhandong; Yang, Tianzu; Liu, Weifeng; Zhang, Duchao; Zhang, Li; Bin, Shu; Bin, Wanda

    2015-05-01

    This work investigates the characteristics of the oxygen-rich side blow furnace (OSBF) and the oxygen-rich bottom blow furnace (OBBF) as the reductive smelting reactor for molten high lead slag. The slags were collected from different sampling points of these furnaces during a regular high lead slag reduction process and analyzed. It is disclosed that lead content of the melt in the OSBF shows dramatic fluctuations, while melt from different sampling points of the furnace behave similarly, exhibiting the characteristics of batch reactor. An obvious axial lead content gradient is detected in the OBBF, showing the characteristics of a plug flow reactor. The industrial performances of these furnaces are also compared. The results indicate that 1.38% higher lead recovery can be achieved by using the OSBF instead of the OBBF. Unit energy consumptions of the OBBF-OSBF and OBBF-OBBF processes can be reduced to 230 kgce/ t crude lead, which is 70 kgce/ t crude lead less than that of the tradition Shuikoushan (SKS) process.

  16. Survey and conceptual flow sheets for coal conversion plant handling-preparation and ash/slag removal operations

    SciTech Connect

    Zapp, F.C.; Thomas, O.W.; Silverman, M.D.; Dyslin, D.A.; Holmes, J.M.

    1980-03-01

    This study was undertaken at the request of the Fossil Fuel Processing Division of the Department of Energy. The report includes a compilation of conceptual flow sheets, including major equipment lists, and the results of an availability survey of potential suppliers of equipment associated with the coal and ash/slag operations that will be required by future large coal conversion plant complexes. Conversion plant flow sheet operations and related equipment requirements were based on two representative bituminous coals - Pittsburgh and Kentucky No. 9 - and on nine coal conversion processes. It appears that almost all coal handling and preparation and ash/slag removal equipment covered by this survey, with the exception of some coal comminution equipment, either is on hand or can readily be fabricated to meet coal conversion plant capacity requirements of up to 50,000 short tons per day. Equipment capable of handling even larger capacities can be developed. This approach appears to be unjustified, however, because in many cases a reasonable or optimum number of trains of equipment must be considered when designing a conversion plant complex. The actual number of trains of equipment selected will be influenced by the total requied capacity of the complex, the minimum on-line capacity that can be tolerated in case of equipment failure, reliability of specific equipment types, and the number of reactors and related feed injection stations needed for the specific conversion process.

  17. Effect of electric arc furnace slag on growth and physiology of maize (Zea mays L.).

    PubMed

    Radić, Sandra; Crnojević, Helena; Sandev, Dubravka; Jelić, Sonja; Sedlar, Zorana; Glavaš, Katarina; Pevalek-Kozlina, Branka

    2013-12-01

    Basic slag, used in this study as a potential source of certain nutrients, is a byproduct of the production of steel in electric arc furnace (EAF). A pot experiment with two nutrient-poor substrates was conducted to investigate to compare the effect of EAF steel slag and fertilizers NPK + F e on growth and availability of specific nutrients to maize. Mineral content of both substrate and plant leaves, growth, chlorophyll fluorescence and photosynthetic pigments were measured following six weeks of cultivation. As steel slag also contains trace amounts of heavy metals, certain oxidative parameters (antioxidative enzyme activities and lipid peroxidation) were evaluated as well. The steel slag improved soil mineral composition, increased above ground maize biomass by providing Fe, Mn, Mg, K and partly P and improved photosynthetic parameters. The potential phytotoxicity of EAF slag containing substrates was not determined as evaluated by MDA (malondialdehyde), GR (glutathione reductase) and APX (ascorbate peroxidase) levels. The obtained results show that EAF steel slag is comparable to NPK + F e in supplying nutrients for maize growth, indicating the potential of EAF steel slag as an inexpensive and non-phytotoxic nutrient supplier especially in poor soils.

  18. A Proposal for a Novel Method to Measure the Diffusivity of Species in Slag

    NASA Astrophysics Data System (ADS)

    Muhmood, Luckman; Viswanathan, Nurni Neelakantan; Seetharaman, Seshadri

    2011-04-01

    The rate of reactions involved in steel-refining operations largely depend on the transport of species through the slag or metal phase at steel refining temperatures; the intrinsic reaction rates are expected to be high. Therefore, the study of diffusivity of species in slag is of great importance. The present work proposes a new methodology, in which experiments can be designed to determine the diffusivity of species in liquid slag. In this article, a mathematical description for the methodology is formulated and subsequently solved using numerical methods. This exercise will help in identifying appropriate bounds for experimental parameters for a desired accuracy. The proposed methodology is generic for any species in the liquid slag phase. However, diffusion of sulfur through slag has been illustrated as a case study. The order of magnitude for the diffusion coefficient for sulfur was taken from the classic works of Saito and Kawai, the sulfide capacity and sulfur partition ratio were retrieved from the works of Taniguchi et al., and the slag density was retrieved from earlier experimental results of the present authors. The slag density was obtained from earlier experimental results from the present group. The Henrian activity coefficients were retrieved from literature. Subsequent to the present work, the design of experiments and measurements carried out using the proposed methodology and the results obtained are presented as the second article on this subject.

  19. Feasibility study of using brick made from municipal solid waste incinerator fly ash slag.

    PubMed

    Lin, Kae Long

    2006-10-11

    This study deals with the effect of MSWI slag on fired clay bricks. Brick samples were heated to temperatures which varied from 800 to 1,000 degrees C for 6h, with a heating rate of 10 degrees C/min. The material properties of the resultant material then determined, including speciation variation, loss on ignition, shrinkage, bulk density, 24-h absorption rate and compressive strength. Toxicity Characteristic Leaching Procedure tests were also conducted. The results indicate that the heavy metal concentrations in the leachates met the current regulatory thresholds. Increasing the amount of MSWI slag resulted in a decrease in the water absorption rate and an increase in the compressive strength of the MSWI-slag bricks. The 24-h absorption rate and compressive strength of the MSWI-slag brick made from samples containing slag sintered at 1,000 degrees C all met the Chinese National Standard (CNS) building requirements for second-class brick. The addition of MSWI slag to the mixture reduced the degree of firing shrinkage. This indicates that MSWI slag is indeed suitable for the partial replacement of clay in bricks.

  20. Utilization of lightweight materials made from coal gasification slags. Quarterly report, March 1--May 31, 1998

    SciTech Connect

    1998-09-01

    The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of lightweight aggregates (LWA) and ultra-lightweight aggregates (ULWA) from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase 1, comprising the production of LWA and ULWA from slag at the large pilot scale, and Phase 2, which involves commercial evaluation of these aggregates in a number of applications. In the current reporting period, test work focused on Slag III lightweight aggregates. The following was accomplished during this reporting period: (1) Laboratory testing of expanded Slag III for the lightweight block application was completed satisfactorily. The block production run has been scheduled for 11 June 1998. (2) Testing of expanded Slag III made from 50/50 Slag III/clay for the roof tile application was completed satisfactorily. Specimens with a strength of over 5,600 psi were produced. (3) Commercial production and economic evaluation of the expanded slag in panel application was initiated per user request. (4) Additional batch testing for nursery applications has been initiated.

  1. Effect of electric arc furnace slag on growth and physiology of maize (Zea mays L.).

    PubMed

    Radić, Sandra; Crnojević, Helena; Sandev, Dubravka; Jelić, Sonja; Sedlar, Zorana; Glavaš, Katarina; Pevalek-Kozlina, Branka

    2013-12-01

    Basic slag, used in this study as a potential source of certain nutrients, is a byproduct of the production of steel in electric arc furnace (EAF). A pot experiment with two nutrient-poor substrates was conducted to investigate to compare the effect of EAF steel slag and fertilizers NPK + F e on growth and availability of specific nutrients to maize. Mineral content of both substrate and plant leaves, growth, chlorophyll fluorescence and photosynthetic pigments were measured following six weeks of cultivation. As steel slag also contains trace amounts of heavy metals, certain oxidative parameters (antioxidative enzyme activities and lipid peroxidation) were evaluated as well. The steel slag improved soil mineral composition, increased above ground maize biomass by providing Fe, Mn, Mg, K and partly P and improved photosynthetic parameters. The potential phytotoxicity of EAF slag containing substrates was not determined as evaluated by MDA (malondialdehyde), GR (glutathione reductase) and APX (ascorbate peroxidase) levels. The obtained results show that EAF steel slag is comparable to NPK + F e in supplying nutrients for maize growth, indicating the potential of EAF steel slag as an inexpensive and non-phytotoxic nutrient supplier especially in poor soils. PMID:24275594

  2. Effects of Some Additives on Copper Losses to Matte Smelting Slag

    NASA Astrophysics Data System (ADS)

    Rusen, Aydin; Geveci, Ahmet; Topkaya, Yavuz Ali; Derin, Bora

    2016-09-01

    Copper is lost to slag between 0.7 and 2.3 wt.% during the industrial copper matte smelting stage. In the present study, the aim was to minimize these losses in the slag phase by adding some fluxing agents like CaO, B2O3 and calcium borate (namely colemanite—2CaO·3B2O3·5H2O). Eti Copper Inc. (EBI) flash furnace smelter slag containing 0.88 wt.%Cu and matte with the addition each of CaO, B2O3 and colemanite up to 10 wt.% of the total charge were melted in a silica crucible placed in a vertical tube furnace at 1250°C under nitrogen atmosphere for 2 h. The experimental results of matte-slag-flux mixtures showed that the addition of all additives up to 4 wt.% led to a gradual decrease of the copper content in the final slags. Beyond this value, the copper losses to slag increased markedly with the increasing CaO and B2O3 additions. On the other hand, the colemanite addition of more than 4 wt.% did not substantially affect the copper losses to slag.

  3. Transient Thermo-fluid Model of Meniscus Behavior and Slag Consumption in Steel Continuous Casting

    NASA Astrophysics Data System (ADS)

    Jonayat, A. S. M.; Thomas, Brian G.

    2014-10-01

    The behavior of the slag layer between the oscillating mold wall, the slag rim, the slag/liquid steel interface, and the solidifying steel shell, is of immense importance for the surface quality of continuous-cast steel. A computational model of the meniscus region has been developed, that includes transient heat transfer, multi-phase fluid flow, solidification of the slag, and movement of the mold during an oscillation cycle. First, the model is applied to a lab experiment done with a "mold simulator" to verify the transient temperature-field predictions. Next, the model is verified by matching with available literature and plant measurements of slag consumption. A reasonable agreement has been observed for both temperature and flow-field. The predictions show that transient temperature behavior depends on the location of the thermocouple during the oscillation relative to the meniscus. During an oscillation cycle, heat transfer variations in a laboratory frame of reference are more severe than experienced by the moving mold thermocouples, and the local heat transfer rate is increased greatly when steel overflows the meniscus. Finally, the model is applied to conduct a parametric study on the effect of casting speed, stroke, frequency, and modification ratio on slag consumption. Slag consumption per unit area increases with increase of stroke and modification ratio, and decreases with increase of casting speed while the relation with frequency is not straightforward. The match between model predictions and literature trends suggests that this methodology can be used for further investigations.

  4. Submerged-arc welding slags: characterization and leaching strategies for the removal of aluminum and titanium.

    PubMed

    Annoni, Raquel; Souza, Poliana Santos; Petrániková, Martina; Miskufova, Andrea; Havlík, Tomáš; Mansur, Marcelo Borges

    2013-01-15

    In the present study, submerged-arc welding slags were characterized by applying a variety of methods, including X-ray fluorescence, X-ray diffraction, particle size, Raman spectroscopy, and scanning electron microscope with energy dispersive X-ray analysis. The content of Al proved to be quite similar within neutral and acid slags (10-14%), while that of Ti proved to be much higher in acid slags (approximately 10%) than in neutral slags (<1%). The presence of spinel structures associated with Al species could also be identified in the analyzed samples. This characterization study was accompanied by leaching tests performed under changing operating conditions in an attempt to evaluate to what extent the Al and Ti bearing components could be removed from the slags. The leaching work involved three distinct strategies: (i) NaOH leaching followed by H(2)SO(4) leaching, (ii) acid leaching (HCl and H(2)SO(4)) using oxidizing/reducing agents, and (iii) slag calcination followed by H(2)SO(4) leaching. In the best result, 80% of Al was extracted in one single leaching stage after calcination of the acid slag with NaCl+C at 900 °C. By contrast, the removal of Ti proved to be unsatisfactory. PMID:23274794

  5. Environmental impact and potential utilization of historical Cu-Fe-Co slags.

    PubMed

    Veselská, Veronika; Majzlan, Juraj

    2016-04-01

    Historical slags from the past Fe and Cu-Co production were investigated in order to evaluate either their potential for utilization or their long-term environmental risk for unsupervised old smelting areas. Here, we studied ferrous slags produced during the recovery of Fe from siderite-Cu ores in Slovakia and two different types of non-ferrous slags produced during the recovery of Cu and Co from Kupferschiefer ores in Germany. The glassy character, rare occurrence of primary silicate phases, and the lack of secondary phases in Cu slags indicate their stability for a prolonged period of time. Electron microprobe analytical work showed that the metals and metalloids (Cu, Co, Fe, Zn, Pb, As) are largely encased in droplets of matte and metal alloys and remain protected by the glassy matrix with its low weathering rate. Fe and Co slags are composed of high-temperature silicates such as wollastonite, cristobalite, as well as olivine, feldspar, quartz, leucite, pyroxene, and pyroxenoids. The presence of secondary phases attests to a certain degree metal release owing to weathering. Assuming minimal contents of metals in slags after a treatment with dilute H2SO4, slags could be used as pozzolanas for addition to cement. PMID:26681328

  6. Converter slag-coal cinder columns for the removal of phosphorous and other pollutants.

    PubMed

    Yang, Jian; Wang, Su; Lu, Zhibo; Yang, Jian; Lou, Shanjie

    2009-08-30

    A mixture of converter slag and coal cinder as adsorbent for the removal of phosphorous and other pollutants was studied in the paper. The maximum P adsorption capacity, pH of solution, contact time and initial phosphate concentration were evaluated in batch experiments for the two materials firstly. The data of P sorption were best fitted to Langumir equation, and the maximum adsorption capacities of converter slag and coal cinder were 2.417 and 0.398 mg P/g, respectively. The pH of solutions with converter slag and coal cinder changed dramatically with time and closed to 8 in 8h, and the influence of initial pH on phosphate removal by coal cinder was more significant than by converter slag. Phosphate removal rate by converter slag decreased with increase of initial phosphate concentrations. Subsequently, two flow-through columns (Column 1#, V(converter slag):V(coal cinder)=1:5; Column 2#, V(converter slag):V(coal cinder)=1:3) were operated for the removal of phosphorous and other pollutants from the effluents of a vermifilter for nearly eleven months. Results indicated the average removal efficiency of total phosphorus, dissolved phosphorus, COD and NH(4)(+)-N by Column 1# were 44%, 56%, 31% and 67%, and by Column 2# were 42%, 54%, 24% and 57%, respectively. Column 1# had higher removal efficiency for P and other pollutants.

  7. Other Oxides Pre-removed from Bangka Tin Slag to Produce a High Grade Tantalum and Niobium Oxides Concentrate

    NASA Astrophysics Data System (ADS)

    Permana, S.; Soedarsono, J. W.; Rustandi, A.; Maksum, A.

    2016-05-01

    Indonesia, as the second largest tin producer in the world, has a byproduct from the production of tin. This byproduct is in the forms of tin slag containing tantalum pentoxide (Ta2O5) and niobium pentoxide (Nb2O5). This study focuses on the recovery of tantalum pentoxide and niobium pentoxide from the tin slag. In the process, one part of the tin slag sample was sieved only (BTS), and the other was roasted at 900°C, water quenched and then sieved (BTS-RQS). Samples BTS and BTS-RQS were characterized by thermo gravimetric analysis (TGA) and X-ray flourence (XRF). One part of BTS-RQS sample was dissolved in hydrofluoric acid (HF) and the other was dissolved in hydrochloric acid (HCl), washed with distilled water, then dissolved into sodium hydroxide (NaOH). Each sample was characterized by using XRF. The BTS sample produced the highest recovery of 0.3807 and 0.6978% for Ta2O5 and Nb2O5, respectively, from the particle size of -1.00+0.71 and a fraction of 47.29%, while BTS-RQS produced the highest recovery of 0.3931 and 0.8994% for Ta2O5 and Nb2O5, respectively, on the particle size of -0.71+0350 and a fraction of 21%. BTS-RQS, dissolved with 8% hydro fluoride acid, yields tantalum pentoxide and niobium pentoxide with a ratio of 2.01 and 2.09, respectively. For the sample BTS-RQS dissolve first with 6M hydrochloric acid, washed with distilled water, then dissolved with sodium hydroxide 10M, the yield ratios are 1.60 and 1.84 for tantalum pentoxide and niobium pentoxide, respectively. In this study, it is found that the dissolution by using hydrofluoric acid 8% yields the best ratio.

  8. Increase in the efficiency of electric melting of pellets in an arc furnace with allowance for the energy effect of afterburning of carbon oxide in slag using fuel-oxygen burners

    NASA Astrophysics Data System (ADS)

    Stepanov, V. A.; Krakht, L. N.; Merker, E. E.; Sazonov, A. V.; Chermenev, E. A.

    2015-12-01

    The problems of increasing the efficiency of electric steelmaking using fuel-oxygen burners to supply oxygen for the afterburning of effluent gases in an arc furnace are considered. The application of a new energy-saving regime based on a proposed technology of electric melting is shown to intensify the processes of slag formation, heating, and metal decarburization.

  9. Optimizing Technological Parameters of the Reduction Processes in Treating Steels in a Ladle Furnace

    NASA Astrophysics Data System (ADS)

    Gizatulin, R. A.; Valuev, D. V.; Valueva, A. V.; Serikbol, A.; Borovikov, I. F.

    2015-09-01

    This work reports the possible development of reduction processes when treating the molten metal and slag using a ladle furnace under conditions of intensive stirring with an inert gas. The industrial data have been received, confirming the possibility of decreasing the concentration of ferrous and manganese oxides in the slag and stabilizing the contents of manganese and silicon in the metal.

  10. Infiltration of Slag Film into the Grooves on a Continuous Casting Mold

    NASA Astrophysics Data System (ADS)

    Cho, Jung-Wook; Jeong, Hee-Tae

    2013-02-01

    An analytical model is developed to clarify the slag film infiltration into grooves on a copper mold during the continuous casting of steel slabs. A grooved-type casting mold was applied to investigate the infiltration of slag film into the grooves of a pitch of 0.8 mm, width of 0.7 mm, and depth of 0.6 mm at the vicinity of a meniscus. The plant trial tests were carried out at a casting speed of 5.5 m min-1. The slag film captured at a commercial thin slab casting plant showed that both the overall and the liquid film thickness were decreased exponentially as the distance from the meniscus increases. In contrast, the infiltration of slag film into the grooves had been increased with increasing distance from the meniscus. A theoretic model has been derived based on the measured profile of slag film thickness to calculate the infiltration of slag film into the grooves. It successfully reproduces the empirical observation that infiltration ratio increased sharply along casting direction, about 80 pct at 50 mm and 95 pct at 150 mm below the meniscus. In the model calculation, the infiltration of slag film increases with increasing groove width and/or surface tension of the slag. The effect of groove depth is negligible when the width to depth ratio of the groove is larger than unity. It is expected that the developed model for slag film infiltration in this study will be widely utilized to optimize the design of groove dimensions in continuous casting molds.

  11. Study on Control of Inclusion Compositions in Tire Cord Steel by Low Basicity Top Slag

    NASA Astrophysics Data System (ADS)

    Xin, Cai-ping; Yue, Feng; Jiang, Chen-xu; Wu, Qi-fan

    2016-01-01

    Top slag melting experiment was conducted in a silicon molybdenum furnace with tire cord steel billet. The influence of top slag composition on the plasticity of CaO-Al2O3-SiO2-MgO inclusion and inclusion plasticization conditions was calculated by thermodynamic software FactSage. Use the thermodynamic calculation to guide the laboratory experiments to study slag compositions influence inclusions composition. Then industrial experiments were conducted based on the theoretical calculation and results of laboratory experiments. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to determine the morphology and composition of inclusions in steel. All studies show that in the CaO-Al2O3-SiO2-10% MgO diagram, when CaO = 8-48%, SiO2 = 35-75%, Al2O3 = 0-32%, inclusions are in the plastic area. When basicity of top slag is certain, Al2O3 content in inclusions increases with the increase of Al2O3 content in the slag, and the distribution of inclusions becomes scattered with the increase of Al2O3 content in slag. Inclusion plasticization can be achieved when the binary basicities of top slag are 0.6, 0.8-1.2, 1.4 and corresponding w(Al2O3)s are 2-15%, 2-10%, <2%. According to industrial experimental results, when top slag basicity decreases from 1.5 to 0.67-0.9 and Al2O3 content decreases below 10 wt%, the inclusion falls into plastic area. It is feasible in practice to control the CaO-Al2O3-SiO2-MgO inclusions plastic through adjusting Al2O3 content in slag.

  12. Model Study of the Effect of Slag Layer on the Swirl Motion of Molten Steel Jet

    NASA Astrophysics Data System (ADS)

    Iguchi, Daisuke; Hiratsuka, Akira; Ohmi, Tatsuya; Tsujino, Ryoji; Sasaki, Yasushi; Iguchi, Manabu

    Efficient agitation of molten steel and slag is requested in the steelmaking industry. The conventional agitation methods are mainly classified into Ar gas injection and electromagnetic stirring. These methods are very expensive and use much energy, and accordingly, we have proposed an alternative, cheap and effective mixing method using a swirl motion. This method does not need any driving devices in the reactor. In this study, low-density liquids and low-density particles are used as models for slag. The effects of the upper slag layer on the occurrence region and the amplitude of a swirl motion of a molten steel jet are investigated.

  13. Optical Measurements on Solid Specimens of Solid Rocket Motor Exhaust and Solid Rocket Motor Slag

    NASA Technical Reports Server (NTRS)

    Roberts, F. E., III

    1991-01-01

    Samples of aluminum slag were investigated to aid the Earth Science and Applications Division at the Marshall Space Flight Center (MSFC). Alumina from space motor propellant exhaust and space motor propellant slag was examined as a component of space refuse. Thermal emittance and solar absorptivity measurements were taken to support their comparison with reflectance measurements derived from actual debris. To determine the similarity between the samples and space motor exhaust or space motor slag, emittance and absorbance results were correlated with an examination of specimen morphology.

  14. Synthesis of TiO2 visible light catalysts with controllable crystalline phase and morphology from Ti-bearing electric arc furnace molten slag.

    PubMed

    Li, Yang; Liu, Lulu; Guo, Min; Zhang, Mei

    2016-09-01

    TiO2 visible light catalysts with different crystalline phases and morphologies were synthesized from titanium-bearing electric arc furnace molten slag (Ti-bearing EAF slag) by using a simple acidolysis process. The effects of the pH of the HCl solution, liquid to solid ratio (RL/S, HCl solution to the residue ratio, mL/g) and acidolysis time on the micro-morphology and crystalline phase of as-prepared TiO2 photocatalysts were systematically investigated. The results indicated that with decreasing pH in the HCl solution and increasing RL/S, the crystalline phase and micro-morphology of the obtained TiO2 nanostructures tended to transform from anatase type TiO2 with spherical nanoparticle structures to rutile type TiO2 with needle-like nanorod structures. The acidolysis time had little influence on the crystalline phase but great impact on the size of the obtained TiO2. The growth mechanism of TiO2 from Ti-bearing EAF slag during the acidolysis process was also discussed. In addition, the influence of RL/S on the photocatalytic properties of the synthesized nanostructured TiO2 was studied. The results showed that the photodegradation efficiency for Rhodamine B solution could reach 91.00% in 120min when the RL/S was controlled at 50:1.

  15. Synthesis of TiO2 visible light catalysts with controllable crystalline phase and morphology from Ti-bearing electric arc furnace molten slag.

    PubMed

    Li, Yang; Liu, Lulu; Guo, Min; Zhang, Mei

    2016-09-01

    TiO2 visible light catalysts with different crystalline phases and morphologies were synthesized from titanium-bearing electric arc furnace molten slag (Ti-bearing EAF slag) by using a simple acidolysis process. The effects of the pH of the HCl solution, liquid to solid ratio (RL/S, HCl solution to the residue ratio, mL/g) and acidolysis time on the micro-morphology and crystalline phase of as-prepared TiO2 photocatalysts were systematically investigated. The results indicated that with decreasing pH in the HCl solution and increasing RL/S, the crystalline phase and micro-morphology of the obtained TiO2 nanostructures tended to transform from anatase type TiO2 with spherical nanoparticle structures to rutile type TiO2 with needle-like nanorod structures. The acidolysis time had little influence on the crystalline phase but great impact on the size of the obtained TiO2. The growth mechanism of TiO2 from Ti-bearing EAF slag during the acidolysis process was also discussed. In addition, the influence of RL/S on the photocatalytic properties of the synthesized nanostructured TiO2 was studied. The results showed that the photodegradation efficiency for Rhodamine B solution could reach 91.00% in 120min when the RL/S was controlled at 50:1. PMID:27593268

  16. Multiphase Modeling of Bottom-Stirred Ladle for Prediction of Slag-Steel Interface and Estimation of Desulfurization Behavior

    NASA Astrophysics Data System (ADS)

    Singh, Umesh; Anapagaddi, Ravikiran; Mangal, Saurabh; Padmanabhan, Kuppuswamy Anantha; Singh, Amarendra Kumar

    2016-06-01

    Ladle furnace is a key unit in which various phenomena such as deoxidation, desulfurization, inclusion removal, and homogenization of alloy composition and temperature take place. Therefore, the processes present in the ladle play an important role in determining the quality of steel. Prediction of flow behavior of the phases present in the ladle furnace is needed to understand the phenomena that take place there and accordingly control the process parameters. In this study, first a mathematical model is developed to analyze the transient three-phase flow present. Argon gas bottom-stirred ladle with off-centered plugs has been used in this study. Volume of fluid method is used in a computational fluid dynamics (CFD) model to capture the behavior of slag, steel, and argon interfaces. The results are validated with data from literature. Eye opening and slag-steel interfacial area are calculated for different operating conditions and are compared with experimental and simulated results cited in literature. Desulfurization rate is then predicted using chemical kinetic equations, interfacial area, calculated from CFD model, and thermodynamic data, obtained from the Thermo-Calc software. Using the model, it is demonstrated that the double plug purging is more suitable than the single plug purging for the same level of total flow. The advantage is more distinct at higher flow rates as it leads higher interfacial area, needed for desulfurization and smaller eye openings (lower oxygen/nitrogen pickup).

  17. Simulation of Flow Fluid in the BOF Steelmaking Process

    NASA Astrophysics Data System (ADS)

    Lv, Ming; Zhu, Rong; Guo, Ya-Guang; Wang, Yong-Wei

    2013-12-01

    The basic oxygen furnace (BOF) smelting process consists of different chemical reactions among oxygen, slag, and molten steel, which engenders a vigorous stirring process to promote slagging, dephosphorization, decarbonization, heating of molten steel, and homogenization of steel composition and temperature. Therefore, the oxygen flow rate, lance height, and slag thickness vary during the smelting process. This simulation demonstrated a three-dimensional mathematical model for a 100 t converter applying four-hole supersonic oxygen lance and simulated the effect of oxygen flow rate, lance height, and slag thickness on the flow of molten bath. It is found that as the oxygen flow rate increases, the impact area and depth increases, which increases the flow speed in the molten bath and decreases the area of dead zone. Low oxygen lance height benefits the increase of impact depth and accelerates the flow speed of liquid steel on the surface of the bath, while high oxygen lance height benefits the increase of impact area, thereafter enhances the uniform distribution of radial velocity in the molten steel and increases the flow velocity of molten steel at the bottom of furnace hearth. As the slag thickness increases, the diameter of impinging cavity on the slag and steel surface decreases. The radial velocity of liquid steel in the molten bath is well distributed when the jet flow impact on the slag layer increases.

  18. Influence of slag chemistry on the hydration of alkali-activated blast-furnace slag - Part II: Effect of Al{sub 2}O{sub 3}

    SciTech Connect

    Ben Haha, M.; Lothenbach, B. Le Saout, G.; Winnefeld, F.

    2012-01-15

    The hydration and microstructural evolution of three alkali activated slags (AAS) with Al{sub 2}O{sub 3} contents between 7 and 17% wt.% have been investigated. The slags were hydrated in the presence of two different alkaline activators, NaOH and Na{sub 2}SiO{sub 3}{center_dot}5H{sub 2}O. The formation of C(-A)-S-H and hydrotalcite was observed in all samples by X-ray diffraction, thermal analysis and scanning electron microscopy. Higher Al{sub 2}O{sub 3} content of the slag decreased the Mg/Al ratio of hydrotalcite, increased the Al incorporation in the C(-A)-S-H and led to the formation of straetlingite. Increasing Al{sub 2}O{sub 3} content of the slag slowed down the early hydration and a lower compressive strength during the first days was observed. At 28 days and longer, no significant effects of slag Al{sub 2}O{sub 3} content on the degree of hydration, the volume of the hydrates, the coarse porosity or on the compressive strengths were observed.

  19. Greener durable concretes through geopolymerisation of blast furnace slag

    NASA Astrophysics Data System (ADS)

    Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

    2015-05-01

    The eco-friendliness of concrete is quantified by parameters such as ‘embodied energy’ (EE) and ‘embodied CO2 emission’ (ECO2e), besides duration of designed ‘service life’. It may be noted that ECO2e is also referred as carbon footprint (CF) in the literature. Geopolymer (GP) is an inorganic polymeric gel, a type of amorphous alumino-silicate product, which can be synthesised by polycondensation reactions. The concrete reported in this paper was prepared using industrial wastes in the form of blast furnace slag, fly ash as geopolymeric source materials and sodium silicate and sodium hydroxide as activators. Many mechanical properties such as compressive strength, chloride diffusion, steel corrosion, rapid chloride permeability test and rapid migration test are compared with Portland cement.

  20. Structural evolution of an alkali sulfate activated slag cement

    NASA Astrophysics Data System (ADS)

    Mobasher, Neda; Bernal, Susan A.; Provis, John L.

    2016-01-01

    In this study, the effect of sodium sulfate content and curing duration (from fresh paste up to 18 months) on the binder structure of sodium sulfate activated slag cements was evaluated. Isothermal calorimetry results showed an induction period spanning the first three days after mixing, followed by an acceleration-deceleration peak corresponding to the formation of bulk reaction products. Ettringite, a calcium aluminium silicate hydrate (C-A-S-H) phase, and a hydrotalcite-like Mg-Al layered double hydroxide have been identified as the main reaction products, independent of the Na2SO4 dose. No changes in the phase assemblage were detected in the samples with curing from 1 month up to 18 months, indicating a stable binder structure. The most significant changes upon curing at advanced ages observed were growth of the AFt phase and an increase in silicate chain length in the C-A-S-H, resulting in higher strength.

  1. Deoxidation Limits of Titanium Alloys during Pressure Electro Slag Remelting

    NASA Astrophysics Data System (ADS)

    Bartosinski, M.; Hassan-Pour, S.; Friedrich, B.; Ratiev, S.; Ryabtsev, A.

    2016-07-01

    This paper focuses on deoxidation of titanium alloys produced by aluminothermic reduction (ATR) and subsequent homogenizing and alloying by vacuum induction melting (VIM). The main goal of the performed research work is to outline the deoxidation limit during pressure electro slag remelting (PESR) of the described material. To obtain electrodes for deoxidation, a Ti-24Al-16V masteralloy was produced by ATR and afterwards melted in a 0.5 litre calcium- zirconate (lab scale) or 14 litres high purity calcia (pilot scale) crucibles with continuous addition of Ti-sponge after reaching liquid state in order to obtain a final Ti-6Al-4V alloy. During melting, in both cases evaporation of calcium was noticed. The cast ingots were analysed for oxygen using inert gas fusion method, matrix and alloying elements were analysed by XRF. Results show oxygen levels between 0.5 and 0.95 wt.-% for the ingots which were melted in calcium-zirconate crucibles and approx. 1 - 1.2 wt.-% for the material produced by utilization of calcia crucibles. The subsequent deoxidation was carried out in lab and pilot scale electroslag remelting furnaces using a commercially pure calcium fluoride slag and metallic calcium as deoxidation agent. It could be shown, that deoxidation of the highly contaminated material is possible applying this method to a certain limit. Pilot scale trials showed a reduction of oxygen contents by 1500 - 3500 ppm. Oxygen levels in lab scale trials showed weaker deoxidation effects. In order to describe the achieved deoxidation effects in a quantitative way, the analyzed oxygen contents of the obtained ingots are compared with calculated data resulting from a mathematical kinetic model. The modelled datasets are in good agreement with experimental oxygen values.

  2. Effect of the cooling rate on the phase composition and structure of copper matte converting slags

    NASA Astrophysics Data System (ADS)

    Selivanov, E. N.; Gulyaeva, R. I.; Udoeva, L. Yu.; Belyaev, V. V.; Pankratov, A. A.

    2009-08-01

    The effect of the cooling rate on the phase composition and microstructure of copper matte converting slags is studied by X-ray diffraction, combined thermogravimetry and calorimetry, mineragraphy, and electron-probe microanalysis. The compositions of oxide and sulfide phases are determined, and the forms of nonferrous metals in slags cooled at a rate of 0.3 and 900°C/s are revealed. At high cooling rates of the slags, iron silicate glass is shown to form apart from sulfide phases. Repeated heating of the slags leads to the development of devitrification, “cold” crystallization, and melting. A decrease in the cooling rate favors an increase in the grain sizes in oxides (magnetite, iron silicates) and sulfides (bornite-, sphalerite, and galena-based solid solutions).

  3. Characterization Report on Sand, Slag, and Crucible Residues and on Fluoride Residues

    SciTech Connect

    Murray, A.M.

    1999-02-10

    This paper reports on the chemical characterization of the sand, slag, and crucible (SS and C) residues and the fluoride residues that may be shipped from the Rocky Flats Environmental Technology Site (RFETS) to Savannah River Site (SRS).

  4. Phosphorus removal from slow-cooled steelmaking slags: Grain size determination and liberation studies

    SciTech Connect

    Fregeau-Wu, E.; Iwasaki, I.

    1995-07-01

    The major obstacle in recycling steelmaking slags to the blast furnace is their phosphorus content. Removal of the phosphorus, which is primarily associated with the silicate and phosphate phases, would allow for greater recycle of these slags for their iron, manganese, and lime contents. Calculations show that separation of the silicates from the oxide phases would remove nearly 90% of the phosphorus from the slag. The variable grain size of the as-received slag made liberation by fine grinding difficult. Therefore, slow-cooling experiments were undertaken to improve the grain size distribution. The grain size distributions were determined using in-situ image analysis. The samples were ground to their apparent liberation size and high gradient magnetic separation was used to separate the magnetic oxides from the nonmagnetic silicates and phosphates. Liberation analysis and modeling was performed on selected separation products for discussion of benefication characteristics.

  5. Improving the behavior of body roads by the use of gravel-slag mixture

    NASA Astrophysics Data System (ADS)

    Hadinane, Hocine; Oucief, Hocine; Merzoud, Mouloud

    2016-07-01

    The accumulation of wastes industrial stemming of the iron and steel industry has influenced negatively the environment. The adopted policy had for mission to eliminate these undesirable wastes by recycling them by their utilization in adequate areas. The objective of this work is to study the mechanical behavior of a gravel-slag based on crystallized and granulated slag, activated by lime. One will be interested in the study of resistance to punching and the bearing ratio of this slag through Proctor tests, CBR and by compression, tensile tests, for use in the layers of pavement (Foundation and base layers). The obtained result on gravel-slag show considerable performances, compared with natural aggregates point of resistance and thickness of the layers. Its utilization in the road area has allowed therefore the recycling these industrial wastes, to decrease the pollution, to use a minimum noble product requiring important exploitation energy and an economy on layers of surface realized with costly materials (bituminous concrete).

  6. Investigations on phosphorus recovery and reuse as soil amendment from electric arc furnace slag filters.

    PubMed

    Bird, Simon C; Drizo, Aleksandra

    2009-11-01

    Electric arc furnace (EAF) steel slag has been identified as an effective filter material for the removal of phosphorus (P) from both point and non-point sources. To determine the feasibility of land-applying P saturated EAF steel slag this study was undertaken to investigate (i) saturated EAF steel slag material's potential as a P fertilizer or soil amendment and (ii) P desorption and metals leachate from saturated EAF steel slag material to surface runoff. Medicago sativa (alfalfa) was planted in a nutrient depleted washed sand media. Phosphorus was added either as saturated EAF steel slag or as a standard commercial phosphate fertilizer in order to assess the plant availability of the P from saturated EAF steel slag. Four different P application levels were tested: a low (20 lbs acre furrow slice(-1) (5.5 g P m(-3))) two medium (40 and 60 lbs. acre f.s.(-1) (11 and 16.5 g P m(-3))) and a high (120 lbs. acre f.s.(-1) (33 g P m(-3))). The above-ground biomass of half of the plants was harvested after 5 weeks and the second half at 10 weeks. All treatments regardless of the P source used showed high rates of germination. At the first harvest period (5 weeks) significantly higher above-ground biomass (p < 0.01) was seen at the 3 highest P amendment rates in treatments with triple super phosphate fertilizer (TSP) than with EAF steel slag. However, by the second harvest (10 weeks) only the highest amendment rate of TSP showed a significantly higher amount of biomass (p < 0.01), suggesting that EAF steel slag might be an effective slow release P source. In a second experiment, a rain simulator was used to assess desorption of DRP, TP and metals from a saturated and semi-saturated EAF steel slag. The results revealed that the total amounts of DRP and TP released to surface runoff from EAF steel slag were negligible when compared to the total quantities of P retained by this material. Overall the results from this study demonstrated that once the EAF steel slag filter

  7. Investigations on phosphorus recovery and reuse as soil amendment from electric arc furnace slag filters.

    PubMed

    Bird, Simon C; Drizo, Aleksandra

    2009-11-01

    Electric arc furnace (EAF) steel slag has been identified as an effective filter material for the removal of phosphorus (P) from both point and non-point sources. To determine the feasibility of land-applying P saturated EAF steel slag this study was undertaken to investigate (i) saturated EAF steel slag material's potential as a P fertilizer or soil amendment and (ii) P desorption and metals leachate from saturated EAF steel slag material to surface runoff. Medicago sativa (alfalfa) was planted in a nutrient depleted washed sand media. Phosphorus was added either as saturated EAF steel slag or as a standard commercial phosphate fertilizer in order to assess the plant availability of the P from saturated EAF steel slag. Four different P application levels were tested: a low (20 lbs acre furrow slice(-1) (5.5 g P m(-3))) two medium (40 and 60 lbs. acre f.s.(-1) (11 and 16.5 g P m(-3))) and a high (120 lbs. acre f.s.(-1) (33 g P m(-3))). The above-ground biomass of half of the plants was harvested after 5 weeks and the second half at 10 weeks. All treatments regardless of the P source used showed high rates of germination. At the first harvest period (5 weeks) significantly higher above-ground biomass (p < 0.01) was seen at the 3 highest P amendment rates in treatments with triple super phosphate fertilizer (TSP) than with EAF steel slag. However, by the second harvest (10 weeks) only the highest amendment rate of TSP showed a significantly higher amount of biomass (p < 0.01), suggesting that EAF steel slag might be an effective slow release P source. In a second experiment, a rain simulator was used to assess desorption of DRP, TP and metals from a saturated and semi-saturated EAF steel slag. The results revealed that the total amounts of DRP and TP released to surface runoff from EAF steel slag were negligible when compared to the total quantities of P retained by this material. Overall the results from this study demonstrated that once the EAF steel slag filter

  8. Influence of the Mold Current on the Electroslag Remelting Process

    NASA Astrophysics Data System (ADS)

    Hugo, Mathilde; Dussoubs, Bernard; Jardy, Alain; Escaffre, Jessica; Poisson, Henri

    2016-08-01

    The electroslag remelting process is widely used to produce high value-added alloys. The use of numerical simulation has proven to be a valuable way to improve its understanding. In collaboration with Aubert & Duval, the Institute Jean Lamour has developed a numerical transient model of the process. The consumable electrode is remelted within a mold assumed to be electrically insulated by the solidified slag skin. However, this assumption has been challenged by some recent studies: the solidified slag skin may actually allow a part of the melting current to reach the mold. In this paper, the evolution of our model, in order to take into account this possibility, is presented and discussed. Numerical results are compared with experimental data, while several sensitivity studies show the influence of some slag properties and operating parameters on the quality of the ingot. Even, a weakly conductive solidified slag skin at the inner surface of the mold may be responsible for a non-negligible amount of current circulating between the slag and crucible, which in turn modifies the fluid flow and heat transfer in the slag and ingot liquid pool. The fraction of current concerned depends mainly on the electrical conductivities of both the liquid and solidified slag.

  9. Process for removing technetium from iron and other metals

    DOEpatents

    Leitnaker, James M.; Trowbridge, Lee D.

    1999-01-01

    A process for removing technetium from iron and other metals comprises the steps of converting the molten, alloyed technetium to a sulfide dissolved in manganese sulfide, and removing the sulfide from the molten metal as a slag.

  10. Process for removing technetium from iron and other metals

    DOEpatents

    Leitnaker, J.M.; Trowbridge, L.D.

    1999-03-23

    A process for removing technetium from iron and other metals comprises the steps of converting the molten, alloyed technetium to a sulfide dissolved in manganese sulfide, and removing the sulfide from the molten metal as a slag. 4 figs.

  11. Use of Phosphates to Reduce Slag Penetration in CR203-Based Refractories

    SciTech Connect

    Kwong, Kyei-Sing; Dogan, Cynthia P.; Bennett, James P.; Chinn, Richard E.; Petty, Arthur V.

    2004-11-09

    A high-chromium refractory material that provides improved resistance to coal slag penetration is presented. The refractory mixture comprises a blend of chromium oxide, aluminum oxide and phosphates. The refractory mixture may be blended with an aggregate and cured. In addition a phosphorus oxide may be blended with chromium oxide and aluminum oxide and additionally an aggregate. The refractory mixture reduces the rate of coal slag penetration into the surface of the cured refractory.

  12. Evaluation on chemical stability of lead blast furnace (LBF) and imperial smelting furnace (ISF) slags.

    PubMed

    Yin, Nang-Htay; Sivry, Yann; Guyot, François; Lens, Piet N L; van Hullebusch, Eric D

    2016-09-15

    The leaching behavior of Pb and Zn from lead blast furnace (LBF) and imperial smelting furnace (ISF) slags sampled in the North of France was studied as a function of pHs and under two atmospheres (open air and nitrogen). The leaching of major elements from the slags was monitored as a function of pH (4, 5.5, 7, 8.5 and 10) under both atmospheres for different slag-water interaction times (1 day and 9 days). The leaching results were coupled with a geochemical model; Visual MINTEQ version 3.0, and a detailed morphological and mineralogical analysis was performed on the leached slags by scanning and transmission electron microscopy (SEM and TEM). Significant amounts of Ca, Fe and Zn were released under acidic conditions (pH 4) with a decrease towards the neutral to alkaline conditions (pH 7 and 10) for both LBF and ISF slags. On the other hand, Fe leachability was limited at neutral to alkaline pH for both slags. The concentrations of all elements increased gradually after 216 h compared to initial 24 h of leaching period. The presence of oxygen under open-air atmosphere not only enhanced oxidative weathering but also encouraged formation of secondary oxide and carbonate phases. Formation of carbonates and clay minerals was suggested by Visual MINTEQ which was further confirmed by SEM & TEM. The hydration and partial dissolution of hardystonite, as well as the destabilization of amorphous glassy matrix mainly contributed to the release of major elements, whereas the spinel related oxides were resistant against pH changes and atmospheres within the time frame concerned for both LBF and ISF slags. The total amount of Pb leached out at pH 7 under both atmospheres suggested that both LBF and ISF slags are prone to weathering even at neutral environmental conditions.

  13. Use of phosphates to reduce slag penetration in Cr2O3-based refractories

    DOEpatents

    Kwong, Kyei-Sing; Dogan, Cynthia P.; Bennett, James P.; Chinn, Richard E.; Petty, Arthur V.

    2004-11-09

    A high-chromium refractory material that provides improved resistance to coal slag penetration is presented. The refractory mixture comprises a blend of chromium oxide, aluminum oxide and phosphates. The refractory mixture may be blended with an aggregate and cured. In addition a phosphorous oxide may be blended with chromium oxide and aluminum oxide and additionally an aggregate. The refractory mixture reduces the rate of coal slag penetration into the surface of the cured refractory.

  14. Evaluation on chemical stability of lead blast furnace (LBF) and imperial smelting furnace (ISF) slags.

    PubMed

    Yin, Nang-Htay; Sivry, Yann; Guyot, François; Lens, Piet N L; van Hullebusch, Eric D

    2016-09-15

    The leaching behavior of Pb and Zn from lead blast furnace (LBF) and imperial smelting furnace (ISF) slags sampled in the North of France was studied as a function of pHs and under two atmospheres (open air and nitrogen). The leaching of major elements from the slags was monitored as a function of pH (4, 5.5, 7, 8.5 and 10) under both atmospheres for different slag-water interaction times (1 day and 9 days). The leaching results were coupled with a geochemical model; Visual MINTEQ version 3.0, and a detailed morphological and mineralogical analysis was performed on the leached slags by scanning and transmission electron microscopy (SEM and TEM). Significant amounts of Ca, Fe and Zn were released under acidic conditions (pH 4) with a decrease towards the neutral to alkaline conditions (pH 7 and 10) for both LBF and ISF slags. On the other hand, Fe leachability was limited at neutral to alkaline pH for both slags. The concentrations of all elements increased gradually after 216 h compared to initial 24 h of leaching period. The presence of oxygen under open-air atmosphere not only enhanced oxidative weathering but also encouraged formation of secondary oxide and carbonate phases. Formation of carbonates and clay minerals was suggested by Visual MINTEQ which was further confirmed by SEM & TEM. The hydration and partial dissolution of hardystonite, as well as the destabilization of amorphous glassy matrix mainly contributed to the release of major elements, whereas the spinel related oxides were resistant against pH changes and atmospheres within the time frame concerned for both LBF and ISF slags. The total amount of Pb leached out at pH 7 under both atmospheres suggested that both LBF and ISF slags are prone to weathering even at neutral environmental conditions. PMID:27240207

  15. Effect of calcium silicate slag application on radium-226 concentrations in plant tissues

    SciTech Connect

    Mortvedt, J.J.

    1986-01-01

    A greenhouse pot experiment was conducted to determine if plants absorb Ra from slag applied to soil. Slag at rates equivalent to 0 and 22 mt/ha was mixed with Mountview silt loam (Typic Paleudults) limed to pH 5.8 and 7.2. Three clippings each of fescue (Festuca arundiancea Schreb.), and Swiss chard (Beta vulgaris L.), and one harvest of wheat (Triticum aestivum L.) for grain and straw were grown on separate series of treated soil, and plant samples were analyzed for radioactivity due to /sup 226/Ra uptake. Samples of sugarcane (Saccharum officinarum L.) forage and extracted juice from field experiments in Florida testing this slage as a Si source also were analyzed for radioactivity. Dry forage yields of fescue and wheat were not affected by slag applications, but those of Swiss chard were somewhat higher on slag-treated soil at pH 5.8. Wheat grain and straw yields were higher on soil at pH 7.2 than at pH 5.8 regardless of slag treatment. Uptake of /sup 226/Ra by fescue forage and wheat grain and straw was not affected by slag application. Concentrations of /sup 226/Ra were similar in forage and extracted juice from untreated sugarcane or that treated with slag at rates up to 5.6 mt/ha. These results suggest that plant uptake of radionuclides is negligible from calcium silicate slag applied at the recommended rates for liming acid soils or as a source of Si for sugarcane.

  16. Utilization of lightweight materials made from coal gasification slags. Quarterly report, September 1--November 30, 1997

    SciTech Connect

    1997-12-31

    In previous projects, Praxis investigated the utilization of as-generated slags for a wide variety of applications in road construction, cement and concrete production, agricultural applications, and as a landfill material. From these studies, the authors found that it would be extremely difficult for as-generated slag to find large-scale acceptance in the marketplace even at no cost because the materials it could replace were abundantly available at very low cost. It became apparent that a more promising approach would be to develop a variety of value-added products from slag that meet specific industry requirements. This approach was made feasible by the discovery that slag undergoes expansion and forms a lightweight material when subjected to controlled heating in a kiln at temperatures between 1,400 and 1,700 F. These results confirmed the potential for using expanded slag as a substitute for conventional lightweight aggregates (LWA). The technology to produce lightweight and ultra-lightweight aggregates (ULWA) from slag was subsequently developed by Praxis. The major objectives of the subject project are to demonstrate the technical and economic viability of commercial production of LWA and ULWA from slag and to test the suitability of these aggregates for various applications. The project goals are to be accomplished in two phases: Phase 1, comprising the production of LWA and ULWA from slag at the large pilot scale, and Phase 2, which involves commercial evaluation of these aggregates in a number of applications. This document summarizes the Phase 2 accomplishments to date along with the major accomplishments from Phase 1.

  17. Effect of Slag Composition on Inclusions in Si-Deoxidized 18Cr-8Ni Stainless Steels

    NASA Astrophysics Data System (ADS)

    Ren, Ying; Zhang, Lifeng; Fang, Wen; Shao, Shijie; Yang, Jun; Mao, Weidong

    2016-04-01

    Laboratory experiments and thermodynamic calculation for the Si-deoxidized 18Cr-8Ni stainless steel with CaO-Al2O3-SiO2-CaF2-MgO-MnO slag were performed to investigate the effect of slag composition on inclusions in Si-deoxidized 18Cr-8Ni stainless steels. A high-basicity slag improved the cleanness of stainless steel, while a low basicity slag lowered the Al2O3 content in inclusions, lowering the melting temperature of inclusions and improving the deformability of inclusions. Approximately, 15 pct content of MgO in the initial slag was beneficial to reduce the corrosion of refractory and would not influence the composition of inclusions. The Al2O3 in slag should be lowered to a minimum to reduce the Al2O3 content in inclusions in Si-deoxidized 18Cr-8Ni stainless steel. The log X_{{{{Al}}_{ 2} {{O}}_{ 3} }}i + log X_{{MgO}}i - log X_{MnO}i - log X_{{{{SiO}}2 }}i of inclusions was expressed as a linear function of log a_{{{{Al}}_{ 2} {{O}}_{ 3} }}^{{s}} + log a_{{CaO}}^{{s}} - log a_{MnO}^{{s}} - log a_{{{{SiO}}2 }}^{{s}} of the slag, which was used to predict the composition of inclusions based on the activity of Al2O3, CaO, SiO2, and MnO in the slag. Moreover, the equilibrium curve of Al-O and the stability diagram of inclusions in Si-deoxidized 18Cr-8Ni stainless steel at 1873 K (1600 °C) were calculated.

  18. Phosphorus removal mechanisms in active slag filters treating waste stabilization pond effluent.

    PubMed

    Pratt, Chris; Shilton, Andy; Pratt, Steven; Haverkamp, Richard G; Bolan, Nanthi S

    2007-05-01

    Phosphorus (P) removal mechanisms from waste stabilization pond effluent by a melter slag filter were investigated. The studied filter had treated pond effluent for a decade, but lost its P removal efficiency after 5 years. The P distribution in the slag was examined by scanning electron microscopy (SEM), electron dispersive spectrometry (EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and chemical fractionation. The results showed the slag to be covered by a film comprising metal oxides/oxyhydroxides, organic resin, and Fe-phosphate precipitates. The slag porous matrix beneath this film hosted lower P concentrations and consisted of metal oxides/oxyhydroxides and calcmagnesium silicates. The study revealed the following mechanisms for P removal from effluent by the melter slag: (1) P adsorption onto metal oxides/oxyhydroxides which are ubiquitous throughout the porous slag matrix and its surface film; (2) P precipitation, mainly as Fe-phosphates (determined by SEM/EDS) on the surface film, derived from the release of metal ions into the solution phase; and (3) P sequestration by an amorphous organic resin that comprises a substantial proportion of the surface film, which was deduced by SEM/EDS and XRF. Results of chemical extractions performed on the slag demonstrated that 1 M HCl, which has been used to determine Ca-associated P in previous studies, is an unreliable Ca-P marker. By contrast, the citrate-dithionite reagent was shown to be a good indicator of Fe/Al-associated P and revealed that adsorption onto metal oxides/oxyhydroxides, in the porous matrix as well as its surface film, is the most significant P removal mechanism achieved by the slag filter.

  19. The Use Of Phosphates To Reduce Slag Penetration In Cr203-Based Refractories

    DOEpatents

    Kwong, Kyei-Sing; Dogan, Cynthia P.; Bennett, James P.; Chinn, Richard E.; Petty, Arthur V.

    2004-11-09

    A high-chromium refractory material that provides improved resistance to coal slag penetration is presented. The refractory mixture comprises a blend of chromium oxide, aluminum oxide and phosphates. The refractory mixture may be blended with an aggregate and cured. In addition a phosphorous oxide may be blended with chromium oxide and aluminum oxide and additionally an aggregate. The refractory mixture reduces the rate of coal slag penetration into the surface of the cured refractory.

  20. Phosphorus Equilibrium Between Liquid Iron and CaO-SiO2-MgO-Al2O3-FeO-P2O5 Slag Part 1: Literature Review, Methodology, and BOF Slags

    NASA Astrophysics Data System (ADS)

    Assis, Andre N.; Tayeb, Mohammed A.; Sridhar, Seetharaman; Fruehan, Richard J.

    2015-10-01

    Although the phosphorus reaction in steelmaking has been extensively studied, it continues to be a relevant topic as low phosphorus iron sources become less available and more expensive, necessitating the need for more accurate predictions of the partitioning of phosphorous as function of slag composition and temperature. The current study revisits some of the relevant literature on the topic and details the methodology and experimental setup used in recent studies on phosphorus equilibrium between liquid iron and slags. New data for BOF-type slags are presented, where equilibrium was approached from both metal and slag sides i.e., phosphorus was transferred from metal to slag and vice versa. It was found that slags with basicities higher than 2.5 and FeO contents around 20 to 25 wt pct can promote extensive dephosphorization, and high L P, ((pct P)/[pct P]), values were observed i.e., greater than 500.

  1. Competitive adsorption of copper(II), cadmium(II), lead(II) and zinc(II) onto basic oxygen furnace slag.

    PubMed

    Xue, Yongjie; Hou, Haobo; Zhu, Shujing

    2009-02-15

    Polluted and contaminated water can often contain more than one heavy metal species. It is possible that the behavior of a particular metal species in a solution system will be affected by the presence of other metals. In this study, we have investigated the adsorption of Cd(II), Cu(II), Pb(II), and Zn(II) onto basic oxygen furnace slag (BOF slag) in single- and multi-element solution systems as a function of pH and concentration, in a background solution of 0.01M NaNO(3). In adsorption edge experiments, the pH was varied from 2.0 to 13.0 with total metal concentration 0.84mM in the single element system and 0.21mM each of Cd(II), Cu(II), Pb(II), and Zn(II) in the multi-element system. The value of pH(50) (the pH at which 50% adsorption occurs) was found to follow the sequence Zn>Cu>Pb>Cd in single-element systems, but Pb>Cu>Zn>Cd in the multi-element system. Adsorption isotherms at pH 6.0 in the multi-element systems showed that there is competition among various metals for adsorption sites on BOF slag. The adsorption and potentiometric titrations data for various slag-metal systems were modeled using an extended constant-capacitance surface complexation model that assumed an ion-exchange process below pH 6.5 and the formation of inner-sphere surface complexes at higher pH. Inner-sphere complexation was more dominant for the Cu(II), Pb(II) and Zn(II) systems.

  2. In-situ observation of the behaviour of non-metallic inclusions at different interfaces in the system steel-slag-refractory

    NASA Astrophysics Data System (ADS)

    Michelic, S. K.; Dieguez Salgado, U.; Bernhard, C.

    2016-07-01

    The system steel-slag-refractory and reactions of non-metallic inclusions at its interfaces are decisive in numerous metallurgical processes. In order to obtain the desired steel cleanness level, a detailed understanding of the occurring interactions is needed. This study focuses on the in-situ observation of different reactions of non-metallic inclusions in steel and slag. For this purpose a Confocal Scanning Laser Microscope attached to a high temperature furnace is applied which enables the visualization of metallurgical phenomena at steelmaking temperatures up to 1700 °C. Two different examples are discussed: First, the agglomeration of different inclusion types in a Ca-treated steel is described and corresponding attraction forces are calculated. Secondly, the dissolution of Al2O3 and MgOAl2O3 in two slags of the system CaO-Al2O3-MgO-SiO2 is examined, including the evaluation of the governing dissolution mechanism. Finally, an outlook on further experimental possibilities is given.

  3. Simultaneous removal of Ni(II), As(III), and Sb(III) from spiked mine effluent with metakaolin and blast-furnace-slag geopolymers.

    PubMed

    Luukkonen, Tero; Runtti, Hanna; Niskanen, Mikko; Tolonen, Emma-Tuulia; Sarkkinen, Minna; Kemppainen, Kimmo; Rämö, Jaakko; Lassi, Ulla

    2016-01-15

    The mining industry is a major contributor of various toxic metals and metalloids to the aquatic environment. Efficient and economical water treatment methods are therefore of paramount importance. The application of natural or low-cost sorbents has attracted a great deal of interest due to the simplicity of its process and its potential effectiveness. Geopolymers represent an emerging group of sorbents. In this study, blast-furnace-slag and metakaolin geopolymers and their raw materials were tested for simultaneous removal of Ni(II), As(III) and Sb(III) from spiked mine effluent. Blast-furnace-slag geopolymer proved to be the most efficient of the studied materials: the experimental maximum sorption capacities for Ni, As and, Sb were 3.74 mg/g, 0.52 mg/g, and 0.34 mg/g, respectively. Although the capacities were relatively low due to the difficult water matrix, 90-100% removal of Ni, As, and Sb was achieved when the dose of sorbent was increased appropriately. Removal kinetics fitted well with the pseudo-second-order model. Our results indicate that geopolymer technology could offer a simple and effective way to turn blast-furnace slag to an effective sorbent with a specific utilization prospect in the mining industry.

  4. Simultaneous removal of Ni(II), As(III), and Sb(III) from spiked mine effluent with metakaolin and blast-furnace-slag geopolymers.

    PubMed

    Luukkonen, Tero; Runtti, Hanna; Niskanen, Mikko; Tolonen, Emma-Tuulia; Sarkkinen, Minna; Kemppainen, Kimmo; Rämö, Jaakko; Lassi, Ulla

    2016-01-15

    The mining industry is a major contributor of various toxic metals and metalloids to the aquatic environment. Efficient and economical water treatment methods are therefore of paramount importance. The application of natural or low-cost sorbents has attracted a great deal of interest due to the simplicity of its process and its potential effectiveness. Geopolymers represent an emerging group of sorbents. In this study, blast-furnace-slag and metakaolin geopolymers and their raw materials were tested for simultaneous removal of Ni(II), As(III) and Sb(III) from spiked mine effluent. Blast-furnace-slag geopolymer proved to be the most efficient of the studied materials: the experimental maximum sorption capacities for Ni, As and, Sb were 3.74 mg/g, 0.52 mg/g, and 0.34 mg/g, respectively. Although the capacities were relatively low due to the difficult water matrix, 90-100% removal of Ni, As, and Sb was achieved when the dose of sorbent was increased appropriately. Removal kinetics fitted well with the pseudo-second-order model. Our results indicate that geopolymer technology could offer a simple and effective way to turn blast-furnace slag to an effective sorbent with a specific utilization prospect in the mining industry. PMID:26598283

  5. Recycling ground granulated blast furnace slag as cold bonded artificial aggregate partially used in self-compacting concrete.

    PubMed

    Gesoğlu, Mehmet; Güneyisi, Erhan; Mahmood, Swara Fuad; Öz, Hatice Öznur; Mermerdaş, Kasım

    2012-10-15

    Ground granulated blast furnace slag (GGBFS), a by-product from iron industry, was recycled as artificial coarse aggregate through cold bonding pelletization process. The artificial slag aggregates (ASA) replaced partially the natural coarse aggregates in production of self-compacting concrete (SCC). Moreover, as being one of the most widely used mineral admixtures in concrete industry, fly ash (FA) was incorporated as a part of total binder content to impart desired fluidity to SCCs. A total of six concrete mixtures having various ASA replacement levels (0%, 20%, 40%, 60%, and 100%) were designed with a water-to-binder (w/b) ratio of 0.32. Fresh properties of self-compacting concretes (SCC) were observed through slump flow time, flow diameter, V-funnel flow time, and L-box filling height ratio. Compressive strength of hardened SCCs was also determined at 28 days of curing. It was observed that increasing the replacement level of ASA resulted in decrease in the amount of superplasticizer to achieve a constant slump flow diameter. Moreover, passing ability and viscosity of SCC's enhanced with increasing the amount of ASA in the concrete. The maximum compressive strength was achieved for the SCC having 60% ASA replacement. PMID:22951223

  6. Recycling ground granulated blast furnace slag as cold bonded artificial aggregate partially used in self-compacting concrete.

    PubMed

    Gesoğlu, Mehmet; Güneyisi, Erhan; Mahmood, Swara Fuad; Öz, Hatice Öznur; Mermerdaş, Kasım

    2012-10-15

    Ground granulated blast furnace slag (GGBFS), a by-product from iron industry, was recycled as artificial coarse aggregate through cold bonding pelletization process. The artificial slag aggregates (ASA) replaced partially the natural coarse aggregates in production of self-compacting concrete (SCC). Moreover, as being one of the most widely used mineral admixtures in concrete industry, fly ash (FA) was incorporated as a part of total binder content to impart desired fluidity to SCCs. A total of six concrete mixtures having various ASA replacement levels (0%, 20%, 40%, 60%, and 100%) were designed with a water-to-binder (w/b) ratio of 0.32. Fresh properties of self-compacting concretes (SCC) were observed through slump flow time, flow diameter, V-funnel flow time, and L-box filling height ratio. Compressive strength of hardened SCCs was also determined at 28 days of curing. It was observed that increasing the replacement level of ASA resulted in decrease in the amount of superplasticizer to achieve a constant slump flow diameter. Moreover, passing ability and viscosity of SCC's enhanced with increasing the amount of ASA in the concrete. The maximum compressive strength was achieved for the SCC having 60% ASA replacement.

  7. Experimental determination of nonequilibrium transport parameters reflecting the competitive sorption between Cu and Pb in slag-sand column.

    PubMed

    Chung, Jaeshik; Kim, Young-Jin; Lee, Gwanghun; Nam, Kyoungphile

    2016-07-01

    Competitive sorption and resulting nonequilibrium transport of Cu and Pb were investigated using slag as a primary sorbent. A series of estimation models were applied based on the equilibrium, and nonequilibrium sorption respectively, and finally calibrated by incorporating the experimentally determined batch kinetic data. When applied individually, the behavior of metals in slag-sand column were well predicted by both equilibrium and nonequilibrium models in CXTFIT code. However, coexisting Cu and Pb exhibited competition for sorption sites, generating an irregular breakthrough curves such as overshoot (higher concentration in effluent than the feed concentration) of Cu and corresponding earlier peak of Pb followed by gradual re-rising. Although two-site nonequilibrium model further considers coupled hydrochemical process, desorption of the Cu from competition made the model prediction inaccurate. However, the parameter estimation could be improved by incorporating the experimentally determined mass transfer rate, ωexp from batch kinetics. Based on the calibrated model, the fraction of instantaneous retardation, βexp of Pb decreased from 0.41 in the single system to 0.30 in the binary system, indicating the shift from equilibrium to nonequilibrium state, where which of Cu increased from 0.39 to 0.94, representing the shift towards equilibrium. The modified results were also compared with five-step sequential extraction data, confirming that the shift of particular metal fractions from the competition triggered the nonequilibrium transport. PMID:27060642

  8. Direct Extraction of Ti and Ti Alloy from Ti-Bearing Dust Slag in Molten CaCl2

    NASA Astrophysics Data System (ADS)

    Chen, Chaoyi; Zhao, Chong; Li, Junqi; Yang, Shufeng

    2016-06-01

    Using process of solid oxygen-ion conducting membrane (SOM), titanium metal and its alloy can be prepared directly from Ti-bearing dust slag by immersing it in the molten CaCl2 at 1,100℃, which has been proposed by constant voltage of 3.5 V for 2-6 h. The dust slag was ball-milled and pressed into pellets, then employed as the cathode, while the liquid copper, which was saturated with graphite powder and encased in yttria-stabilized zirconia (YSZ) tube, acted as the anode. The effect of forming pressure and electrolytic time on products was analyzed. The results show that the content of titanium increased with electrolytic time and the characteristic morphology presents as granule. Ti-Fe alloy can be obtained from Ti-Fe residue by 6 h electrolysis. For titanium-rich residue, when the forming pressure of pellets decreased from 6 to 3 MPa, only electrolysis for more than 4 h can completely remove the oxygen, and pure titanium is obtained by 6 h electrolysis. Besides, there is an unprecedented finding that the porous cathode is conducive to the removal of impurity elements.

  9. Effect of Boric Acid Concentration on Viscosity of Slag and Property of Weld Metal Obtained from Underwater Wet Welding

    NASA Astrophysics Data System (ADS)

    Guo, Ning; Guo, Wei; Xu, Changsheng; Du, Yongpeng; Feng, Jicai

    2015-06-01

    Underwater wet welding is a crucial repair and maintenance technology for nuclear plant. A boric acid environment raises a new challenge for the underwater welding maintenance of nuclear plant. This paper places emphasis on studying the influence of a boric acid environment in nuclear plant on the underwater welding process. Several groups of underwater wet welding experiments have been conducted in boric acid aqueous solution with different concentration (0-35000 ppm). The viscosity of the welding slag and the mechanical properties of welds, such as the hardness, strength, and elongation, have been studied. The results show that with increasing boric acid concentration, the viscosity of the slag decreases first and then increases at a lower temperature (less than 1441 °C). However, when the temperature is above 1480 °C, the differences between the viscosity measurements become less pronounced, and the viscosity tends to a constant value. The hardness and ductility of the joints can be enhanced significantly, and the maximum strength of the weld metal can be reached at 2300 ppm.

  10. Iron blast furnace slag/hydrated lime sorbents for flue gas desulfurization.

    PubMed

    Liu, Chiung-Fang; Shih, Shin-Min

    2004-08-15

    Sorbents prepared from iron blast furnace slag (BFS) and hydrated lime (HL) through the hydration process have been studied with the aim to evaluate their reactivities toward SO2 under the conditions prevailing in dry or semidry flue gas desulfurization processes. The BFS/HL sorbents, having large surface areas and pore volumes due to the formation of products of hydration, were highly reactive toward SO2, as compared with hydrated lime alone (0.24 in Ca utilization). The sorbent reactivity increased as the slurrying temperature and time increased and as the particle size of BFS decreased; the effects of the liquid/solid ratio and the sorbent drying conditions were negligible. The structural properties and the reactivity of sorbent were markedly affected by the BFS/HL ratio; the sorbent with 30/70 ratio had the highest 1 h utilization of Ca, 0.70, and SO2 capture, 0.45 g SO2/g sorbent. The reactivity of a sorbent was related to its initial specific surface area (Sg0) and molar content of Ca (M(-1)); the 1 h utilization of Ca increased almost linearly with increasing Sg0/M. The results of this study are useful to the preparation of BFS/HL sorbents with high reactivity for use in the dry and semidry processes to remove SO2 from the flue gas.

  11. Iron blast furnace slag/hydrated lime sorbents for flue gas desulfurization.

    PubMed

    Liu, Chiung-Fang; Shih, Shin-Min

    2004-08-15

    Sorbents prepared from iron blast furnace slag (BFS) and hydrated lime (HL) through the hydration process have been studied with the aim to evaluate their reactivities toward SO2 under the conditions prevailing in dry or semidry flue gas desulfurization processes. The BFS/HL sorbents, having large surface areas and pore volumes due to the formation of products of hydration, were highly reactive toward SO2, as compared with hydrated lime alone (0.24 in Ca utilization). The sorbent reactivity increased as the slurrying temperature and time increased and as the particle size of BFS decreased; the effects of the liquid/solid ratio and the sorbent drying conditions were negligible. The structural properties and the reactivity of sorbent were markedly affected by the BFS/HL ratio; the sorbent with 30/70 ratio had the highest 1 h utilization of Ca, 0.70, and SO2 capture, 0.45 g SO2/g sorbent. The reactivity of a sorbent was related to its initial specific surface area (Sg0) and molar content of Ca (M(-1)); the 1 h utilization of Ca increased almost linearly with increasing Sg0/M. The results of this study are useful to the preparation of BFS/HL sorbents with high reactivity for use in the dry and semidry processes to remove SO2 from the flue gas. PMID:15382877

  12. Steel Slag and Shredded Tires as Media for Blind Inlets to Improve Water Quality

    NASA Astrophysics Data System (ADS)

    Gonzalez, J. M.; Smith, D. R.; Livingston, S.

    2015-12-01

    Off-site transport of contaminants through surface runoff affects water quality. Blind inlets are proven conservation practices for reducing surface runoff, and consequently reducing nutrient loadings from small agricultural closed depressions to water bodies. Gravel is the most widely used blind inlet media to reduce flow, but not to sorb contaminants from the water. Readily available byproducts, such as steel slag and shredded tires, could be used as alternative media in blind inlets to sorb nutrients and pesticides from surface runoff. Sorption isotherms were performed to investigate the sorption capabilities of steel slag and shredded tires for phosphate and atrazine in electrolyte background solutions containing either 10 mM CaCl2 or KCl. Results of this research demonstrated that phosphate and atrazine were irreversibly sorbed by the steel slag and shredded tires. The steel slag increased the pH solution increased about 4 pH units after the sorption step; while the pH of the solution with shredded tires remained the same. Desorption of the phosphate and atrazine was low from the steel slag and shredded tires, respectively. Thus, the above results suggest that the steel slag and shredded tires can potentially be used as media to sorb phosphate and atrazine, respectively.

  13. Effect of annealing treatment on the crystallisation and leaching of dumped base metal smelter slags.

    PubMed

    Maweja, Kasonde; Mukongo, Tshikele; Mbaya, Richard K; Mochubele, Emela A

    2010-11-15

    Leaching tests of base metals contained in two smelter slags were undertaken in ammonia and nitric acid solutions aiming to recover Co, Cu and Zn. Leaching tests were conducted at 25 and 60°C at pH=0 and 3 in HNO(3) and pH=12 in NH(4)OH media. XRD analysis revealed that the dumped slags were amorphous. Annealing these slags at 1180°C produced crystalline phases comprising diopside, magnetite and fayalite. SEM and EDS analysis revealed that Cu and Pb compounds have concentrated in the magnetite phase, whereas another phase rich in Zn and Cu was located in the diopside matrix. ICP-OES analysis of the pregnant leaching solutions (PLS) showed that 30-60% of Co, Cu and Zn were released from the amorphous slags treated in HNO(3) at pH=0, and lesser in ammonia. However, the contamination by Fe and Pb was higher at pH=0. The contamination of the PLS obtained by leaching of the crystallised slags remained low. The low Fe and Pb contamination was attributed in this case to the chemical stability of the crystalline phases formed upon annealing treatment. The higher solubilisation of metals contained in amorphous slags was attributed to the collapse of silicate structures during nitric acid leaching at pH∼0. PMID:20674164

  14. The thermodynamic behavior of sulfur in BaO-BaF2 slags

    NASA Astrophysics Data System (ADS)

    Rachev, Ivan P.; Tsukihashi, Fumitaka; Sano, Nobuo

    1991-06-01

    A gas-slag-metal equilibration technique was used to determine the sulfide capacity of the BaO-BaF2 system at 1473 and 1573 K. The dependence of carbonate capacity on the slag composition was also measured at these temperatures. It was found that the BaO-BaF2 system has the highest sulfide capacities among the fluxes which are of metallurgical interest. The dependence of sulfide and carbonate capacities on the partial pressure of O2 and CO2 was also investigated. The partial pressure of CO2 proved to have a strong effect on these values at the investigated temperatures. The influence of temperature on the sulfide and carbonate capacities was studied in the temperature range between 1423 and 1623 K. The data for sulfide and carbonate capacities were correlated in order to check if the carbonate capacity can be used as a measure of basicity of slags. It was found that the carbonate capacity can be used as a representative measure of the slag basicity at low contents of BaO and at temperatures higher than 1623 K when the carbonate dissolution into the slag is low and the ratio of the activity coefficient of a sulfide ion to that of a carbonate ion is independent of slag composition.

  15. Synthesis of steel slag ceramics: chemical composition and crystalline phases of raw materials

    NASA Astrophysics Data System (ADS)

    Zhao, Li-hua; Wei, Wei; Bai, Hao; Zhang, Xu; Cang, Da-qiang

    2015-03-01

    Two types of porcelain tiles with steel slag as the main raw material (steel slag ceramics) were synthesized based on the CaO-Al2O3-SiO2 and CaO-MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, α-quartz, magnetite, and pyroxene crystals (augite and diopside) in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction (XRD) and electron probe X-ray microanalysis (EPMA) results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

  16. Disposal of High-Temperature Slags: A Review of Integration of Heat Recovery and Material Recycling

    NASA Astrophysics Data System (ADS)

    Sun, Yongqi; Zhang, Zuotai

    2016-09-01

    Nowadays with the continuous urbanization in China, the carbon emission and resource shortage have been serious issues, for which the disposal of blast furnace slags (BFS) and steel slags (SS) discharged from the metallurgical industry make up a significant strategy. The output of crude steel reached 823 Mt in China in 2014 and the thermal heat in these slags was equivalent to ~18 Mt of standard coal. Herein, the recent advances were systemically reviewed and analyzed, mainly from two respects, i.e., integration of heat recovery and material recycling and crystallization control of the slags. It was first found that for the heat recovery from BFS, the most intensively investigated physical method and chemical method were centrifugal granulation and gasification reaction, respectively. Furthermore, a two-step approach could contribute to a promising strategy for the treatment of slags, i.e., the liquid slags were first granulated into small particles, and then other further treatment was performed such as gasification reaction. With regard to SS, the effective disposal could be achieved using a selective crystallization and phase separation (SCPS) method, and moreover, the solid solution of 2CaO·SiO2 and the target phases could act as a promising enriched phase to extract the valuable elements.

  17. The composition and temperature dependence of the sulfide capacity of metallurgical slags

    NASA Astrophysics Data System (ADS)

    Sosinsky, Nd. J.; Sommerville, I. D.

    1986-06-01

    The concept of optical basicity and its applicability as a means of correlating the available data on the sulfide capacity of metallurgical slags has been reviewed. An excellent correlation based on very extensive data at 1500 °C, which was discussed in a previous paper, is combined with good correlations based on considerably less data at 1550 °C and 1650 °C to quantify the effect of temperature on the sulfide capacity of slags. The combined effects of slag composition and temperature have been expressed in the equation, log C s = [(22690 - 54640A)/7] + 43.6A - 25.2. Use of this equation permits the calculation of the sulfide capacity of a slag at any temperature between 1400 °C and 1700 °C simply from a knowledge of its chemical composition, and can be employed for virtually any oxide slag of interest in the field of iron and steelmaking. This, in turn, permits calculation of the equilibrium distribution of sulfur between this slag and iron or steel, provided that the oxygen potential is known or can be calculated from the degree of deoxidation applied.

  18. Utilization of Illinois slags for the production of ultra-lightweight aggregates

    SciTech Connect

    Choudhry, V. ); Zimmerle, T. ); Banerjee, D.D. )

    1993-01-01

    The objective of this program is to demonstrate that solid residues (slag) from the gasification of Illinois coals can be utilized to manufacture ultra-lightweight aggregates (ULWA). Conventional ULWAs are made by pyroprocessing perlite ores and have unit weights in the range of 3--15 lb/ft[sup 3]. In a previous project, Praxis Engineers demonstrated at the pilot scale that lightweight aggregates with unit weights of 40--55 lb/ ft[sup 3] can be produced from Illinois coal slags, which is suitable for making lightweight cement concrete and precast blocks. These tests also indicated that a product with a unit weight of less than 25 lb/ft[sup 3] could be produced from slag. This project is aimed at testing the potential for producing ULWA from Illinois coal slags. Target applications include loose fill insulation, insulating concrete, lightweight precast products such as concrete blocks and rooftiles, and filtration media. Laboratory- and pilot-scale testing is being conducted in Phase I to identify operating conditions for the expansion of Illinois slags to produce ULWA. Following this, a large batch of expanded slag will be produced, for evaluation in various applications in Phase II.

  19. A novel comprehensive utilization of vanadium slag: As gamma ray shielding material.

    PubMed

    Dong, Mengge; Xue, Xiangxin; Yang, He; Liu, Dong; Wang, Chao; Li, Zhefu

    2016-11-15

    New exploration of vanadium slag as gamma ray shielding material was proposed, the shielding properties of vanadium slag was higher than concrete when the energy of photons was in 0.0001MeV-100000MeV. Vanadium slag/epoxy resin composites were prepared, shielding and material properties of materials were tested by (60)Co gamma ray, simultaneous DSC-TGA, electronic universal testing machine and scanning electron microscopy, respectively. The results showed that the shielding properties of composite would be better with the increase of vanadium slag addition amount. The HVL (half value layer thickness) of vanadium slag was between Lead and concrete while composite was higher than concrete when the addition amount of vanadium slag was 900 used as material to shield (60)Co gamma ray, also the resistance temperature of composite was about 215°C and the bending strength was over 10MPa. The composites could be used as injecting mortar for cracks developed in biological concrete shields, coating for the floor of the nuclear facilities, and shielding materials by itself. PMID:27343141

  20. Reuse of EAF Slag as Reinforcing Filler for Polypropylene Matrix Composites

    NASA Astrophysics Data System (ADS)

    Cornacchia, G.; Agnelli, S.; Gelfi, M.; Ramorino, G.; Roberti, R.

    2015-06-01

    Electric-arc furnace (EAF) slag, the by-product of steel fabricated at the EAF, is in most cases still sent to dumps, with serious environmental consequences. This work shows an innovative, economically convenient application for EAF slag: its use as reinforcing filler for polypropylene. Composites based on polypropylene containing 10-40 wt.% of EAF slag particles were prepared by melt compounding followed by injection molding. A physical-chemical analysis of the EAF slag was performed to determine microstructural features and main component phases. Leaching tests demonstrated that, although EAF slag can release small amounts of toxic elements, such as heavy metals, incorporating such material into the polymeric matrix immobilizes the heavy metals inside that matrix. The mechanical characterization of the polymer-based composites was performed. Incorporating EAF slag particles raises the Young's modulus and the tensile strength at yield, whereas elongation at break and the impact strength of the polymer-based composite are significantly reduced only when large amounts of filler are added, i.e., 30% or more.