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1

Silver-reductor method for determination of iron in iron ores and iron-ore sinters.  

PubMed

A new technique for the quick dissolution of iron ore, magnetite and sinter products has been developed. The sample is dissolved with thioglycollic acid and hydrochloric acid, the excess of thioglycollic acid is oxidized, and the iron is reduced in the silver reductor. PMID:18962704

Banerjee, S; Dutta, R K

1980-05-01

2

Melting Characteristics of Iron Ore Fine During Sintering Process  

Microsoft Academic Search

The whole melting curve of iron ore during sintering process was obtained, and the melting characteristics of iron ore were defined and explained. The whole melting process of mixture, mixed by iron ore and CaO reagent at basicity of 2.0 and 4.0, respectively, was observed using a SiC heating furnace with camcorder unit, and the melting curves of mixture that

Hong-ge LI; Jian-liang ZHANG; Yuan-dong PEI; Zhi-xing ZHAO; Ze-jun MA

2011-01-01

3

Ore-blending optimization model for sintering process based on characteristics of iron ores  

NASA Astrophysics Data System (ADS)

An ore-blending optimization model for the sintering process is an intelligent system that includes iron ore characteristics, expert knowledge and material balance. In the present work, 14 indices are proposed to represent chemical composition, granulating properties and high temperature properties of iron ores. After the relationships between iron ore characteristics and sintering performance are established, the "two-step" method and the simplex method are introduced to build the model by distinguishing the calculation of optimized blending proportion of iron ores from that of other sintering materials in order to improve calculation efficiency. The ore-blending optimization model, programmed by Access and Visual Basic, is applied to practical production in steel mills and the results prove that the present model can take advantage of the available iron ore resource with stable sinter yield and quality performance but at a lower cost.

Wu, Sheng-Li; Oliveira, Dauter; Dai, Yu-Ming; Xu, Jian

2012-03-01

4

ORGANIC EMISSIONS FROM IRON ORE SINTERING PLANTS: DETERMINATION OF CAUSES AND METHODS OF ABATEMENT  

EPA Science Inventory

The report gives results of a laboratory study to develop basic information on the emission of organics from iron ore sinter beds. Samples of sinter bed mix components (including several types of iron ore fines, blast furnace flue dust, rolling mill scale, anthracite coal, and li...

5

Characteristics of fly ash from the dry flue gas desulfurization system for iron ore sintering plants  

Microsoft Academic Search

The characteristics of fly ash from the flue gas desulfurization (FGD) system are important for its reuse and are mainly depend on the desulfurization process. The physical and chemical properties of DSF ash, which refers to fly ash from the dry FGD system for the iron ore sintering process, were investigated. Its mineralogical contents were determined by X-ray diffraction and

Guanghong Sheng; Peng Huang; Yaqin Mou; Chenhui Zhou

2011-01-01

6

Characteristics of fly ash from the dry flue gas desulfurization system for iron ore sintering plants  

Microsoft Academic Search

The characteristics of fly ash from the flue gas desulfurization (FGD) system are important for its reuse and are mainly depend on the desulfurization process. The physical and chemical properties of DSF ash, which refers to fly ash from the dry FGD system for the iron ore sintering process, were investigated. Its mineralogical contents were determined by X-ray diffraction and

Guanghong Sheng; Peng Huang; Yaqin Mou; Chenhui Zhou

2012-01-01

7

Extension of grate width, a means to boost iron ore sinter plant productivity and yield  

SciTech Connect

The component of shunted air infiltrating the waste gas system of a conventional travelling grate sinter machine due to the so called sidewall effect contributes negatively to the energetic efficiency of the sintering process itself, of the waste gas system, to the productivity and the yield and the quality consistency. Using the same air volume on an ignited iron ore sinter mix it will be more uniformly sintered if placed on a grate extended by an imperforate plate for a width of up to 60% of the bed height outside the edge of the suction area. Modifications on grate pallets, ignition hood, feeding and discharging devices allow for a low cost plant productivity increase of up to 20%, improving product quality consistency, yield, energy efficiency etc. in existing sinter plants. New sinter plants with the extended grate area can be built at comparatively lower investment considering the same production capacity mainly because of the shorter machine length and the smaller size suction and waste gas system. Better utilization of air in the sintering process results in higher concentration of polluting matter in the waste gas which is a precondition for the efficient elimination of the pollutants. The described grate extension can be applied in any grate sintering process. The D/L sintermachine of VOEST-ALPINE Iron and Steel Works at Linz, Austria since mid-1990 is furnished with an extended grate. It is a proof of the statements.

Stiasny, H.; Fuerschuss, H.

1993-01-01

8

Solid state sintering in the induration of iron ore pellets  

Microsoft Academic Search

Data is developed to show the relationship between pellet strength and shrinkage which accompanies induration. Systematic\\u000a measurements of shrinkage kinetics of a pure hematite reagent powder and of a commercial magnetite concentrate are presented,\\u000a and rate constants and activation energies evaluated. The discussion links the results of pellet induration research with\\u000a sintering theory, developed in support of powder metallurgy and

J. R. Wynnyckyj; T. Z. Fahidy

1974-01-01

9

Iron Ore.  

National Technical Information Service (NTIS)

Iron ore is an important mineral commodity because it is the primary source of iron, the metal most widely used by man. World production of iron ore in 1977 was estimated at 840 million tons, and an estimated 350 million tons was shipped in international ...

F. L. Klinger

1978-01-01

10

Reducing PAH emissions from the iron ore sintering process by optimizing its operation parameters.  

PubMed

This study set out to reduce polycyclic aromatic hydrocarbon (PAH) emissions from the iron ore sintering process by optimizing its operation parameters obtained from the Taguchi experimental design. Four operating parameters, including the water content (Wc; range = 6.0-7.0 wt %), suction pressure (Ps; range = 1000-1400 mmH2O), bed height (Hb; range = 500-600 mm), and type of hearth layer (HL; including sinter, hematite, and limonite) were selected and conducted on a pilot-scale sinter pot to simulate various sintering operating conditions of a real-scale sinter plant. We found that the resultant optimal combination (Wc = 6.5 wt %, Hb = 600 mm, Ps = 1400 mmH2O, and HL = limonite) could reduce the emission factor of total BaP equivalent concentration (EF(BaPeq)) up to 57.6% in comparison with the current operating condition of a real-scale sinter plant (Wc = 6.5 wt %, Hb = 550 mm, Ps = 1200 mmH2O, and HL = sinter). Through the ANOVA analysis, we found that Ps and Hb were the top two parameters affecting total EF(BaPeq) (accounting, respectively, for 70.9% and 21.2% of the total contribution of the four selected parameters). By examining both the sinter productivity and sinter strength, the values obtained from the optimal combination were quite comparable to those of the current operating condition. The above results further confirm the applicability of the obtained optimal combination for the real-scale sinter plant. PMID:19603662

Chen, Yu-Cheng; Tsai, Perng-Jy; Mou, Jin-Luh

2009-06-15

11

Studies into the formation of PBDEs and PBDD/Fs in the iron ore sintering process.  

PubMed

Polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and furans (PBDD/Fs) were detected in stack emissions from UK sinter plants. The sum of 36 PBDE congeners was measured at a mean concentration of 295 ng/N m(3) with a standard deviation of 96 ng/N m(3). The mean PBDD/F concentrations were 0.14 ng WHO-TEQ/m(3) (range=0.03-0.39). PBDD/F emission concentrations were approximately ten times lower than their PCDD/F homologues. To understand the possible formation mechanisms of brominated organic species in iron ore sintering, both full-scale and laboratory experiments using an experimental sintering process were carried out. A complete PBDE mass balance was undertaken for a full scale sinter plant showing that PBDEs were already present in the raw materials such as iron ores and coke breeze and that a significant proportion of the PBDE inputs were actually destroyed during the process. A number of controlled experiments were conducted using a laboratory-scale sintering apparatus (sinter pot). These were designed to investigate: (a) mass balance of PBDEs during sintering, (b) the relationship between the availability of bromide (as KBr) and PBDE emissions, and (c) the influence of the availability of both bromide and PBDEs on PBDD/F formation. As observed in the full scale plant, the PBDEs already present in the raw materials were mostly destroyed during the process (79-96%) for all sinter pot experiments. Increasing amounts of KBr in the raw sinter mix did not result in a significant increase in PBDE formation suggesting that there was no PBDE formation in sintering via de novo synthesis. No relationship was observed between PBDE inputs and PBDD/F emissions indicating that PBDEs did not act as precursors for PBDD/Fs formation. Finally, PBDD/F formation was enhanced substantially with increasing amounts of KBr suggesting that their formation mechanism was similar to that of PCDD/Fs via de novo synthesis. PMID:24742560

Drage, D S; Aries, E; Harrad, S

2014-07-01

12

Complexometric determination of aluminium in iron ore, sinter, concentrates and agglomerates.  

PubMed

A method for the complexometric determination of aluminium in iron ore, sinter, concentrates and agglomerates encountered in international trade is described. The sample is fused in a zirconium crucible with a mixed flux of sodium carbonate and sodium peroxide. The fused mass is completely soluble in hydrochloric acid. The R(2)O(3) oxides are then precipitated with ammonia and redissolved in hydrochloric acid. Elements such as iron, titanium and zirconium are separated from aluminium by solvent extraction with cupferron and chloroform. After removal of traces of organic matter from the aqueous phase, the solution is treated with an excess of EDTA, which is then back-titrated with zinc solution (Xylenol Orange as indicator). Addition of ammonium fluoride then releases EDTA equivalent to the aluminium and this is titrated with zinc solution. The method is rapid. The precision and accuracy are excellent, and the results comparable with those obtained by the referee method. PMID:18962398

Bhargava, O P

1979-02-01

13

Sintering Characteristics of Indian Chrome Ore Fines  

NASA Astrophysics Data System (ADS)

Chrome ore concentrate consists of high-temperature melting oxides such as Cr2O3, MgO, and Al2O3. The presence of these refractory constituents makes the ore a very high melting mineral. Hence, it is difficult to produce sinter from chrome ore by a pyrometallurgical route. Currently, chrome ore is ground to below 75 ?m, pelletized, heat hardened through carbothermic reaction at 1300 °C to 1400 °C, and then charged into a submerged electric arc furnace (EAF), along with lumpy ore for ferrochrome/charge-chrome production. Electricity is a major cost element in this extraction process. This work explores the sinterability of chrome ore. The objective of this study was to: (1) determine whether chrome ore is sinterable and, if so, (2) ascertain ways of achieving satisfactory properties at a low temperature of sintering. Sintering of the raw material feed could be a way to reduce electricity consumption, because during sintering a partial reduction of minerals is expected along with agglomeration. Studies carried out by the authors show that it is possible to agglomerate chrome ore fines through sintering. The chrome ore sinter thus produced was found to be inferior in strength, comparable to that of an iron ore sinter, but strength requirements may not be the same for both. Because the heat generation during chrome ore sintering is high owing to some exothermic reactions, compared with iron ore, and because chrome ore contains a high amount of fines, shallow-bed-depth sinter cake production was attempted in the laboratory-scale pot-sintering machine. The sintered product was found to be a good conductor of electricity because of the presence of phases such as magnetite and maghemite. This characteristic of the chrome ore sinter will subsequently have a favorable impact in terms of power consumption during the production of ferrochrome in a submerged EAF. The sinter made was melted in the arc furnace and it was found that the specific melting energy is comparable to that of heat-hardened chrome ore pellets but lower than briquettes and lump ore.

Nandy, Bikash; Chaudhury, Manoj Kumar; Paul, Jagannath; Bhattacharjee, D.

2009-10-01

14

Characteristics of fly ash from the dry flue gas desulfurization system for iron ore sintering plants.  

PubMed

The characteristics of fly ash from the flue gas desulfurization (FGD) system are important for its reuse and are mainly depend on the desulfurization process. The physical and chemical properties of DSF ash, which refers to fly ash from the dry FGD system for the iron ore sintering process, were investigated. Its mineralogical contents were determined by X-ray diffraction and thermogravimetry analysis, and its micro-morphology was studied by scanning electric micrograph analysis. The results show that DSF ash has a higher CaO and SO3 content, and the main sulfur form is sulfite, with only a part of it oxidized to sulfate. The major minerals present in DSF ash are hannebachite, anhydrite, calcite and portlandite; a minor constituent is calcium chloride. The particles of DSF ash are irregular, fragmentary and small, and hannebachite grows on their surfaces. Particle size is affected by the FGD process, and the ash size from the maximized emission reduction of the sintering-FGD process is lower than that from the circulating fluidized bed-FGD process. The particle size distribution of DSF ash follows the Rosin--Rammler-Bennet equation. PMID:22720407

Sheng, Guanghong; Huang, Peng; Mou, Yaqin; Zhou, Chenhui

2012-01-01

15

Influence of process changes on PCDD/Fs produced in an iron ore sintering plant  

SciTech Connect

This study investigated the influence of different charge typologies and additives on the PCDD/Fs amount produced and on the congener profiles in an iron ore sintering plant. Many tests were carried out combining different typologies of charge (iron materials) and solid fuel ('coke breeze' or 'anthracite') with or without the use of urea. The PCDD/Fs produced ranged from 1.2 to 22.7 {mu} g I-TEQ/ton of agglomerate, whereas the PCDD/Fs released to the ambient air ranged from 0.10 to 1.92 ng I-TEQ/Nm{sup 3} because of cleaning in an electrostatic precipitator (ESP) and a Wetfine scrubber (WS). A more homogeneous charge with a higher amount of fine particles charge appeared to produce a lower PCDD/Fs concentration due to a better combustion but this hypothesis needs further investigations on charges having different dimension particles. Only a synergitic action of urea and anthracite was able to reduce the high PCDD/Fs content due to the bad combustion of the more inhomogeneous charge with a lower amount of fine particles. The congener profile was a typical combustion process fingerprint because the PCDFs predominated, the highly chlorinated congeners (HeptaCDD and OctaCDD) prevailed in PCDDs, whereas in PCDFs the profile was more varied; 1,2,3,4,6,7,8-HeptaCDF was the main contributor to the total concentration while 2,3,4,7,8-PentaCDF was the main contributor to the I-TEQ concentration. Whereas all the parameters under scrutiny influenced strongly the amount of PCDD/Fs produced, they affected only slightly the fingerprint of PCDD/Fs. In all cases studied, the reduction obtained using urea, anthracite, or the more homogeneous charge with a higher amount of fine particles was slightly greater on the higher chlorinated congeners in respect to the lower ones.

Guerriero, E.; Bianchini, M.; Gigliucci, P.F.; Guarnieri, A.; Mosca, S.; Rossetti, G.; Varde, M.; Rotatori, M. [CNR, Monterotondo (Italy)

2009-01-15

16

Mechanisms in oxidation and sintering of magnetite iron ore green pellets  

Microsoft Academic Search

Thermal volume changes and oxidation mechanisms in magnetite iron ore green pellets balled with 0.5% bentonite binder, as a function of raw material fineness and pellet porosity, are shown. When a pellet starts to oxidize, a shell of hematite is formed around the pellet while the core still is magnetite. Dilatation curves were measured under non-oxidizing and oxidizing atmospheres to

S. P. E. Forsmo; P.-O. Samskog; B. M. T. Björkman

2008-01-01

17

Polycyclic aromatic hydrocarbon emission profiles and removal efficiency by electrostatic precipitator and wetfine scrubber in an iron ore sintering plant.  

PubMed

A monitoring campaign of polychlorinated dibenzo-p-dioxins and dibenzofurans, polyaromatic hydrocarbons (PAHs), and polychlorinated biphenyl was carried out in an Italian iron ore sintering plant by sampling the combustion gases at the electrostatic precipitator (ESP) outlet, at the Wetfine scrubber (WS) outlet, and by collecting the ESP dust. Few data are available on these micropollutants produced in iron ore sintering plants, particularly from Italian plants. This study investigates the PAH emission profiles and the removal efficiency of ESPs and WS. PAHs were determined at the stack, ESP outlet flue gases, and in ESP dust to characterize the emission profiles and the performance of the ESP and the WS for reducing PAH emission. The 11 PAHs monitored are listed in the Italian legislative decree 152/2006. The mean total PAH sum concentration in the stack flue gases is 3.96 microg/N x m3, in ESP outlet flue gases is 9.73 microg/N x m3, and in ESP dust is 0.53 microg/g. Regarding the emission profiles, the most abundant compound is benzo(b)fluoranthene, which has a relative low BaP toxic equivalency factors (TEF) value, followed by dibenzo(a,l)pyrene, which has a very high BaP(TEF) value. The emission profiles in ESP dust and in the flue gases after the ESP show some changes, whereas the fingerprint in ESP and stack flue gases is very similar. The removal efficiency of the ESP and of WS on the total PAH concentration is 5.2 and 59.5%, respectively. PMID:19044155

Guerriero, Ettore; Lutri, Antonina; Mabilia, Rosanna; Scianò, Maria Concetta Tomasi; Rotatori, Mauro

2008-11-01

18

Determining optimal operation parameters for reducing PCDD/F emissions (I-TEQ values) from the iron ore sintering process by using the Taguchi experimental design.  

PubMed

This study is the first one using the Taguchi experimental design to identify the optimal operating condition for reducing polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/ Fs) formations during the iron ore sintering process. Four operating parameters, including the water content (Wc; range = 6.0-7.0 wt %), suction pressure (Ps; range = 1000-1400 mmH2O), bed height (Hb; range = 500-600 mm), and type of hearth layer (including sinter, hematite, and limonite), were selected for conducting experiments in a pilot scale sinter pot to simulate various sintering operating conditions of a real-scale sinter plant We found that the resultant optimal combination (Wc = 6.5 wt%, Hb = 500 mm, Ps = 1000 mmH2O, and hearth layer = hematite) could decrease the emission factor of total PCDD/Fs (total EF(PCDD/Fs)) up to 62.8% by reference to the current operating condition of the real-scale sinter plant (Wc = 6.5 wt %, Hb = 550 mm, Ps = 1200 mmH2O, and hearth layer = sinter). Through the ANOVA analysis, we found that Wc was the most significant parameter in determining total EF(PCDD/Fs (accounting for 74.7% of the total contribution of the four selected parameters). The resultant optimal combination could also enhance slightly in both sinter productivity and sinter strength (30.3 t/m2/day and 72.4%, respectively) by reference to those obtained from the reference operating condition (29.9 t/m (2)/day and 72.2%, respectively). The above results further ensure the applicability of the obtained optimal combination for the real-scale sinter production without interfering its sinter productivity and sinter strength. PMID:18754384

Chen, Yu-Cheng; Tsai, Perng-Jy; Mou, Jin-Luh

2008-07-15

19

PCDD/Fs removal efficiency by electrostatic precipitator and wetfine scrubber in an iron ore sintering plant.  

PubMed

This study investigates the removal efficiency of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) by the APCDs of an iron ore sintering plant, an electrostatic precipitator (ESP) and a wetfine scrubbing system (WS). The removal efficiencies of the ESP on the total PCDD/Fs concentration and the total PCDD/Fs I-TEQ concentration are 44.3% and 41.4%, respectively, while those of the WS are 66.7% and 68.4%, respectively, but the vapor/solid phase distribution changes after APCDs abatement. At ESP inlet, the PCDD/Fs account for 31.2% in vapor phase and for 68.8% in particulate phase while, at ESP outlet, the PCDD/Fs account for 63.3% in vapor phase and for 36.7% in solid phase. The ESP removes effectively solid-phase PCDD/Fs for its effectiveness to capture the particulate while it is ineffective in removing vapor-phase PCDD/Fs. It, on the contrary, increase for the vaporization within the ESP, especially for these congeners with a lower chlorination degree, and for the PCDD/Fs "stripping" from particulate to gas-phase during the sampling. At WS inlet, the PCDD/Fs account for 63.3% in vapor phase and for 36.7% in solid phase while, at WS outlet, the PCDD/Fs account for 21.4% in vapor phase and for 78.6% in solid phase. Considering that WS outlet temperature is about 40 degrees C, the PCDD/Fs vapor-phase condense to particles: therefore, even if the particulate is removed by WS, the final result is that PCDD/Fs percentage decreases in vapor-phase and increases in solid-phase. PMID:19733437

Guerriero, Ettore; Guarnieri, Alessandra; Mosca, Silvia; Rossetti, Gianluca; Rotatori, Mauro

2009-12-30

20

Microbial reduction of iron ore  

DOEpatents

A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry.

Hoffmann, Michael R. (Pasadena, CA); Arnold, Robert G. (Pasadena, CA); Stephanopoulos, Gregory (Pasadena, CA)

1989-01-01

21

Prereduced Iron Ore Pellets: Preparation, Properties, Utilization.  

National Technical Information Service (NTIS)

A process for simultaneously reducing and indurating iron ore pellets was developed by Bureau of Mines laboratory research and confirmed on a continuous pilot plant basis. Moist iron ore concentrate was balled, mixed with solid reductant, and heated at ab...

M. M. Fine N. B. Melcher

1970-01-01

22

Minerals Yearbook, 1989: Iron Ore.  

National Technical Information Service (NTIS)

The United States produced 59.03 million metric tons (Mmt) of usable iron ore during 1989. Although the tonnage was only slightly more than that of 1988, significant improvements were made in pellet quality. For the first time, fluxed pellets accounted fo...

P. H. Kuck C. M. Cvetic

1989-01-01

23

Biologically induced iron ore at Gunma iron mine, Japan  

Microsoft Academic Search

The mineralogy of sedimentary iron ores from the Gunma iron mine are described to evaluate the role of microorganisms and plants in ore formation. The iron ore is composed of nanocrystalline goethite, well-crystallized jarosite and very small amounts of strengite. The ore characteristically occurs as thick-bands of alternating goethite and jarosite bands, thin-bands of different goethite grain sizes, and fossil-aggregate

JUNJI AKAI; KURUMI AKAI; MAKOTO ITO; SATOSHI NAKANO; YONOSUKE MAKI; ICHIRO SASAGAWA

1999-01-01

24

Reduction of double layered iron ore pellets  

Microsoft Academic Search

In the, present investigation an attempt has been made to study the reduction behaviour of double layer pellets consisting of a core of iron ore and a non-coking coal mixture within a shell of iron ore. The reduction tests were conducted under isothermal conditions in the temperature range 1000–1200°C. The variables (parameters) studied are reduction temperature, carbon\\/iron oxide ratio and

T. Sharma

1997-01-01

25

Iron ore: from depletion to abundance.  

PubMed

Following World War II, Americans feared their iron ore supplies were depleted. The steel industry attempted to increase supplies by exploring foreign countries for new, high-grade hematite ores and experimenting with technology that upgraded low-grade domestic taconite ores into acceptable, but apparently uneconomical, pellets. Government did little at first, but the Korean War renewed fears of domestic resource exhaustion. Congress quickly enacted loan guarantees, rapid tax write-offs, and other tax policies that helped commercialize taconite pellets for national defense. These policies lingered long after the Korean War ended. Other policies bolstering taconite were enacted on the state level well after taconite had replaced hematite as industry's ore of choice. Understanding how government policies helped to develop pelletized lean iron ore may help in thinking about current policy suggestions aimed at easing our energy crisis or other mineral shortages. For taconite, too much government help came too late. PMID:17783804

Kakela, P J

1981-04-10

26

Direct Biohydrometallurgical Extraction of Iron from Ore  

SciTech Connect

A completely novel approach to iron extraction was investigated, based on reductive leaching of iron by anaerobic bacteria. Microorganisms were collected from an anaerobic bog where natural seepage of dissolved iron was observed. This mixed culture was used to reduce insoluble iron in a magnetite ore to the soluble ferrous (Fe{sup +2}) state. While dissolution rates were slow, concentrations of dissolved iron as high as 3487 mg/l could be reached if sufficient time was allowed. A factorial study of the effects of trace nutrients and different forms of organic matter indicated that the best dissolution rates and highest dissolved iron concentrations were achieved using soluble carbohydrate (sucrose) as the bacterial food source, and that nutrients other than nitrogen, phosphorus, potassium, sodium, and acetate were not necessary. A key factor in reaching high levels of dissolved iron was maintaining a high level of carbon dioxide in solution, since the solubility of iron carbonates increases markedly as the quantity of dissolved carbon dioxide increases. Once the iron is dissolved, it has been demonstrated that the ferrous iron can then be electroplated from solution, provided that the concentration of iron is sufficiently high and the hydrogen ion concentration is sufficiently low. However, if the leaching solution is electrolyzed directly, organic matter precipitates at the cathode along with the metallic iron. To prevent this problem, the ferrous iron should be separated from the bulk solution in a more concentrated, purified form. One route to accomplishing this is to take advantage of the change in solubility of ferrous iron as a function of carbon dioxide concentration. By cycling the concentration of carbon dioxide in solution, it is possible to produce an iron-rich concentrate that should be suitable for electrolysis. This represents the first viable hydrometallurgical method for leaching iron directly from ore and producing metallic iron.

T.C. Eisele

2005-10-01

27

Potential low-grade iron ore deposits in metamorphosed banded iron formations, Northern Province, South Africa  

Microsoft Academic Search

Exploitation of low-grade iron ore would be quite unique in a South African context as South Africa is well endowed with\\u000a high-grade iron ore resources. Low-grade iron ore, defined as containing between 20 and 47% iron, is thought to be the primary\\u000a iron-bearing lithology from which most high-grade ore deposits formed, through different processes of enrichment. The low-grade\\u000a iron ores

G. du Plessis; G. J. Jonck; R. Kruger

1997-01-01

28

Method for Producing Prereduced Iron Ore Pellets.  

National Technical Information Service (NTIS)

The patent relates to green pellets composed to (1) finely ground iron ore or concentrate and (2) a binder such as bentonite clay heated to a temperature of about 1740F-2100F., preferably 1830F., under strongly reducing conditions, in the presence of a re...

M. M. Fine R. B. Schluter

1971-01-01

29

Kinetics of reduction of iron ore—coal pellets  

Microsoft Academic Search

Kinetic data on the reduction of iron ore-coal pellets are compared with similar data for lump ore. It is shown that, when ore and coal are mixed intimately, the reduction reactions are accelerated considerably. Ore-coal pellets offer some additional advantages, as discussed in the text.

S. B. Sarkar; H. S. Ray; I. Chatterjee

1989-01-01

30

Deep-seated iron ores from banded-iron formation  

Microsoft Academic Search

Very large iron ore deposits have formed in many parts of the world, evidently by the supergene alteration of Precambrian banded-iron formation (BIF). Some of these deposits extend to great depths, ranging to 2,400 m at Krivoyrog1, beyond the likely reach of oxygenated water. We propose here, on the basis of studies in the Hamersley Ranges, Western Australia, a mechanism

R. C. Morris; M. R. Thornber; W. E. Ewers

1980-01-01

31

Nanocrystalline iron sintering behavior and microstructural development  

Microsoft Academic Search

Nanocrystalline (20 nm) iron powder was closed-die sintered in a hydrogen atmosphere at a stress of 10.1 MPa and at temperatures between 670 and 1270 K. The maximum densification rate was approximately 6 × 10-4 s-1. Density greater than 90 pct was obtained at sintering temperatures greater than 990 K. Densification was marked microstructurally by local gradients which appeared after

D. L. Bourell; W. A. Kaysser

1994-01-01

32

Nanocrystalline iron sintering behavior and microstructural development  

Microsoft Academic Search

Nanocrystalline (20 nm) iron powder was closed-die sintered in a hydrogen atmosphere at a stress of 10.1 MPa and at temperatures\\u000a between 670 and 1270 K. The maximum densification rate was approximately 6 ? 10?4 s?1. Density greater than 90 pct was obtained at sintering temperatures greater than 990 K. Densification was marked microstructurally\\u000a by local gradients which appeared after

D. L. Bourell; W. A. Kaysser

1994-01-01

33

Exploring the Potentials of Tailings of Bukuru Cassiterite Deposit for the Production of Iron Ore Pellets  

Microsoft Academic Search

Cassiterite ore was sourced from Dogo-Na-Hawa, in Bukuru, Jos South Local Government of Plateau State, Nigeria. The ore was analyzed as mined and its various constituents noted. Previous study has shown considerable iron ore composition of the deposit. The present study entails the separation and analysis of magnetic mineral (mostly iron ore) from the ore. The beneficiated iron ore was

O. K. Abubakre; Y. O. Sule; R. A. Muriana

34

40 CFR 440.10 - Applicability; description of the iron ore subcategory.  

Code of Federal Regulations, 2013 CFR

...false Applicability; description of the iron ore subcategory. 440.10 Section...MINING AND DRESSING POINT SOURCE CATEGORY Iron Ore Subcategory § 440.10 Applicability; description of the iron ore subcategory. The provisions...

2013-07-01

35

Experimental characterization of constitutive data of iron ore pellets  

Microsoft Academic Search

For trustworthy numerical simulations of iron ore pellets flow, knowledge about the mechanical properties of pellets is needed. In this work, an elastic-plastic continuum material model for blast furnace iron ore pellets is worked out from an experimental data. The equipment used is a Norwegian simple shear apparatus, designed for compression and shear test of granular material with a grain

G. Gustafsson; H.-Å. Häggblad; S. Knutsson

2009-01-01

36

Simulation of convective drying of a cylindrical iron ore pellet  

Microsoft Academic Search

Purpose – The purpose of this paper is to numerically model convective drying of a two-dimensional iron ore pellet subjected to turbulent flow. Design\\/methodology\\/approach – Simulations of the iron ore pellet drying process are carried out with commercial computational fluid dynamics software. The moisture distribution inside the pellet is calculated from a diffusion equation and drying due to evaporation at

Anna-Lena Ljung; T. Staffan Lundström; Kent Tano

2011-01-01

37

Effects of bentonite fiber formation in iron ore pelletization  

Microsoft Academic Search

In the production of iron ore concentrate pellets, binders are required to improve pellet green strength. The most popular binder for this purpose is bentonite clay, which is added at a rate of approximately 0.5–1.0% by weight of moist concentrate. Bentonite is a significant cost item in iron ore pelletization, and also contributes undesirable amounts of silica to the finished

S. Komar Kawatra; S. Jayson Ripke

2002-01-01

38

Gold supported iron oxide–hydroxide derived from iron ore tailings for CO oxidation  

Microsoft Academic Search

Iron ore tailing, a waste material of iron ore industry, has been used to prepare iron oxide–hydroxide support for anchoring nano-gold particles. FeOOH was prepared from iron chloride solution obtained from acid digestion of iron ore tailing. Precipitation deposition method was used to prepare Au supported FeOOH. The samples were characterized by XRD, TEM, TG-DTA and FTIR. The XRD studies

R. Sakthivel; B. Das; B. Satpati; B. K. Mishra

2009-01-01

39

Investigation of Conventional- and Induction-Sintered Iron and Iron-Based Powder Metal Compacts  

NASA Astrophysics Data System (ADS)

Induction sintering was developed as an alternative method to conventional sintering to sinter iron-based powder metal (PM) compacts. Several compositions of compact such as pure iron, 3 wt.% copper mixed iron, or 3 wt.% bronze mixed iron were sintered by using induction sintering machines with 12 kW power and 30 kHz frequency. The mechanical properties, microstructural properties, densities, and microhardness values were investigated for both processes. Iron-based PM compacts sintered at 1120°C by induction in 8.33 min (500 s) were found to be similar to those sintered conventionally in 30 min. The results were compared with the experimental studies.

Çavdar, U?ur; Atik, Enver

2014-05-01

40

Investigation of Conventional- and Induction-Sintered Iron and Iron-Based Powder Metal Compacts  

NASA Astrophysics Data System (ADS)

Induction sintering was developed as an alternative method to conventional sintering to sinter iron-based powder metal (PM) compacts. Several compositions of compact such as pure iron, 3 wt.% copper mixed iron, or 3 wt.% bronze mixed iron were sintered by using induction sintering machines with 12 kW power and 30 kHz frequency. The mechanical properties, microstructural properties, densities, and microhardness values were investigated for both processes. Iron-based PM compacts sintered at 1120°C by induction in 8.33 min (500 s) were found to be similar to those sintered conventionally in 30 min. The results were compared with the experimental studies.

Çavdar, U?ur; Atik, Enver

2014-06-01

41

Hyperspectral Mapping of Bif and Iron Ores  

NASA Astrophysics Data System (ADS)

INTRODUCTION In the last 20 years, hyperspectral reflectance in the visible and near infrared (VNIR), shortwave infrared (SWIR) and thermal infrared (TIR) wavelength ranges have emerged as an objective and quick method to map minerals. The combination of these wavelength ranges is ideal to characterize most of the minerals occurring in banded iron-formation (BIF) and BIF-hosted high grade iron ores. VNIR is ideal for characterizing and mapping the abundance of hematite and goethite. The SWIR provides information on OH-bearing silicates and carbonates. TIR shows specific spectral absorption for anhydrous minerals. INSTRUMENTS AND SAMPLES Three hyperspectral sensors were used: (1) the NEO HYSPEX, (2) the SPECIM TIR and the CSIRO HyLogging™ systems. Samples include drill core and hand samples of Australian BIF and iron ore. RESULTS AND CONCLUSION In the VNIR and SWIR, magnetite has a very low reflectance and a featureless spectrum. The main diagnostic feature for hematite and goethite is the wavelength of the ferric oxide absorption near 900 nm. The shift of the minimum wavelength and the width of the feature are correlated to the hematite goethite ratio. In the TIR range magnetite shows a significant spectral peak at around 17.5 ?m and an increase in reflectance between 6 and 14.5 ?m ranging from 5 to 10%. Hematite shows an absorption at 6.5 ?m. Goethite has a reflectance peak doublet; the first at 11.3 ?m and the second at 12.6 ?m. In the VNIR and SWIR, quartz shows no diagnostic feature. In the TIR, quartz has been identified by an absorption feature at 8.625 ?m. The spectral shape of the main quartz feature shows high variability due to surface scattering. The second characteristic quartz feature is the doublet peaks at 12.5 ?m and 12.8 ?m. In the VNIR and SWIR, the carbonates are detected by their reflectance absorption at around 2.33 ?m, a wavelength region already occupied by OH bearing Fe-Mg minerals. On the other end, in the TIR, carbonates show a strong reflectance peak at around 6.5 ?m and a weaker peak located around 11.3 ?m. In the studied samples, riebeckite was the dominant hydroxyl-silicate. In the VNIR and SWIR the diagnostic feature is the doublet absorption at 2.33 and 2.4 ?m, In the TIR, riebeckite shows a combination of a small but significant reflection peak at 10.38 ?m and an absorption trough at 12.62 ?m. Quartz, carbonates and riebeckite distributions and their relative abundances were successfully mapped by using a combination of VNIR-SWIR and TIR. Quartz was detected in six samples. Additionally two variations of quartz could be discriminated namely chert and chalcedony. Two populations of carbonates, respectively dolomite and siderite, were identified in the BIF samples based on TIR well cross validated with the SWIR. The definite determination of riebeckite was done using a combination of SWIR and TIR, as in the TIR overlap with other minerals can hide the riebeckite features at 10.38 ?m and 12.62 ?m. This study showed that a combination of VNIR SWIR and TIR improved the accuracy of spectral characterization of BIF and high iron ores.

Ramanaidou, E. R.; Schodlok, M.

2012-12-01

42

Mineralogy and geochemistry of banded iron formation and iron ores from eastern India with implications on their genesis  

Microsoft Academic Search

The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling-Langalata iron ore deposits,\\u000a Singhbhum-North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the\\u000a geochemical evaluation of different iron ores. The geochemical and mineralogical characterization suggests that the massive,\\u000a hard laminated, soft laminated ore and blue dust had

Subrata Roy; A. S. Venkatesh

2009-01-01

43

A review of binders in iron ore pelletization  

Microsoft Academic Search

The majority of iron ores must be ground to a fine particle size to allow the iron oxides they contain to be concentrated, and the concentrate must then be agglomerated back into large enough particles that they can be processed in blast furnaces. The most common agglomeration technique is pelletization, which requires the use of binders to hold the iron

T. C. Eisele; S. K. Kawatra

2003-01-01

44

Microstructure of bentonite in iron ore green pellets.  

PubMed

Sodium-activated calcium bentonite is used as a binder in iron ore pellets and is known to increase strength of both wet and dry iron ore green pellets. In this article, the microstructure of bentonite in magnetite pellets is revealed for the first time using scanning electron microscopy. The microstructure of bentonite in wet and dry iron ore pellets, as well as in distilled water, was imaged by various imaging techniques (e.g., imaging at low voltage with monochromatic and decelerated beam or low loss backscattered electrons) and cryogenic methods (i.e., high pressure freezing and plunge freezing in liquid ethane). In wet iron ore green pellets, clay tactoids (stacks of parallel primary clay platelets) were very well dispersed and formed a voluminous network occupying the space available between mineral particles. When the pellet was dried, bentonite was drawn to the contact points between the particles and formed solid bridges, which impart strength to the solid compact. PMID:24397939

Bhuiyan, Iftekhar U; Mouzon, Johanne; Schröppel, Birgit; Kaech, Andres; Dobryden, Illia; Forsmo, Seija P E; Hedlund, Jonas

2014-02-01

45

Arsenic removal from contaminated water by natural iron ores  

Microsoft Academic Search

Natural iron ores were tested as adsorbents for the removal of arsenic from contaminated water. Investigated parameters included pH, adsorbent dose, contact time, arsenic concentration and presence of interfering species. Iron ore containing mostly hematite was found to be very effective for arsenic adsorption. As(V) was lowered from 1 mg\\/L to below 0.01 mg\\/L (US standard limit for drinking water)

W. Zhang; P. Singh; E. Paling; S. Delides

2004-01-01

46

20 CFR 404.1084 - Gain or loss from disposition of property; capital assets; timber, coal, and iron ore...  

Code of Federal Regulations, 2013 CFR

...property; capital assets; timber, coal, and iron ore; involuntary conversion. 404...property; capital assets; timber, coal, and iron ore; involuntary conversion. (a...or loss; (3) From the disposal of iron ore mined in the United States,...

2013-04-01

47

A new refining process for iron oxide using iron ore and its application to hard ferrites  

NASA Astrophysics Data System (ADS)

Kawasaki Steel Corporation and Kawatetsu Mining Co., Ltd. have developed a new refining process to extract iron oxide from iron ore to meet the increase in demand for iron oxide for high- grade hard ferrites. This article discusses the quality of iron oxides and the characteristics of the hard ferrite magnets produced from them.

Nakashima, S.; Ikeda, Y.; Hirose, S.; Nakamura, H.; Ito, T.

1992-03-01

48

A new refining process for iron oxide using iron ore and its application to hard ferrites  

Microsoft Academic Search

Kawasaki Steel Corporation and Kawatetsu Mining Co., Ltd. have developed a new refining process to extract iron oxide from\\u000a iron ore to meet the increase in demand for iron oxide for high- grade hard ferrites. This article discusses the quality of\\u000a iron oxides and the characteristics of the hard ferrite magnets produced from them.

S. Nakashima; Y. Ikeda; S. Hirose; H. Nakamura; T. Ito

1992-01-01

49

Nondispersive XFA or iron-ore mixtures for light elements  

SciTech Connect

Major problems in metallurgical processing include stabilizing the basicity of the agglomerate and improving its quality which requires prompt and reliable monitoring of the calcium oxide and silicon dioxide in the iron-ore charge materials. The authors have devised a nondispersive fluorescence analyzer for iron-ore powder materials that gives the contents of calcium oxide and silicon dioxide. The paper describes the apparatus and various elements in the samples that fluoresce. The authors conclude, based on their data, that this method provides reasonably high accuracy in single determinations as well as constant readings over prolonged periods.

Yuksa, L.K.; Kochmola, N.M.; Bondarenko, V.P.; Bogdanov, V.K.

1987-02-01

50

Assessment of Iron Ore Availability in Alabama and the Southeastern Appalachian Region.  

National Technical Information Service (NTIS)

Studies were conducted to assess the technical and economic feasibility of resuming mining of the Southeastern Appalachian Region iron ores. Also covered briefly in the study were environmental and socio-economic considerations. The iron ore resources and...

A. F. Hilleke H. N. McCarl H. S. Hanna T. A. Simpson

1978-01-01

51

Erosion resistance of arc-sprayed coatings to iron ore at 25 and 315 °C  

NASA Astrophysics Data System (ADS)

Iron ore pellets are sintered and reduced in large continuous industrial oil-fired furnaces. From the furnace, powerful fans extract large volumes of hot gas. Being exposed to gas-borne iron ore particles and temperatures ranging between 125 and 328 °C, fan components are rapidly eroded. Extensive part repair or replacement is required for maintaining a profitable operation. The arc spraying technique has been suggested for repair provided it could produce erosion-resistant coatings. Conventional and cored wires (1.6 mm diameter) were arc sprayed using various spray parameters to produce 250 to 300 µm thick coatings. Arc-sprayed coatings and reference specimens were erosion tested at 25 and 315 °C and impact angles of 25 and 90° in a laboratory gas-blast erosion rig. This device was designed to impact materials with coarse (32 to 300 µm) iron ore particles at a speed of 100 m/s. The coating volume loss due to erosion was measured with a laser profilometer built by National Research Council Canada several years ago. Few arc-sprayed coatings exhibited erosion resistance comparable with structural steel at low impact angles. Erosion of arc-sprayed coatings and reference specimens dramatically increases at 315 °C for both 25° and 90° impact angles. Erosion-enhanced oxidation was found to be responsible for the increase in volume loss above room temperature. Though arc spraying can be appropriate for on-site repair, the development of more erosion-resistant coatings is required for intermediate temperatures.

Dallaire, S.; Levert, H.; Legoux, J.-G.

2001-06-01

52

Application of LANDSAT satellite imagery for iron ore prospecting in the western desert of Egypt  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. The delineation of the geological units and geological structures through image interpretation, corroborated by field observations and structural analysis, led to the discovery of new iron ore deposits. A new locality for iron ore deposition, namely Gebel Qalamun, was discovered, as well as new occurrences within the already known iron ore region of Bahariya Oasis.

Elshazly, E. M.; Abdel-Hady, M. A.; Elghawaby, M. A.; Khawasik, S. M. (principal investigators)

1977-01-01

53

Direct laser sintering of iron–graphite powder mixture  

Microsoft Academic Search

In the present work, the role of graphite addition on the laser sintering of iron powder was studied. Powder mixtures containing iron and 0.4, 0.8, 1.2, and 1.6wt.% graphite were prepared by blending elemental powders. These powders were sintered layer-by-layer under nitrogen atmosphere using a continuous wave CO2 laser beam. A laser power of 70–225W, scan rate of 50–600mms?1, scan

A. Simchi; H. Pohl

2004-01-01

54

China's emergence as the world's leading iron-ore-consuming country  

USGS Publications Warehouse

China has become the leading iron ore consuming nation, and, based on recent steel production capacity increases and plans for more, its consumption will almost certainly to continue to grow. China's iron ore industry, however, faces a number of problems. China's iron ore is low-grade, expensive to process, and its mines are being depleted. For many Chinese steelmakers, particularly in the coastal regions, the delivered cost of domestic iron ore, is more than the delivered cost of foreign ore. Thus China's iron ore imports are expected to increase. As China's growth continues, it will almost certainly surpass Japan to become the leading iron ore importing country as well. Without China's increasing appetite for iron ore, the world iron ore market would be flat or declining. China's recent imports largely offset the slump in demand in North America and Europe. China is regarded by the iron ore industry as the growth sector for the next decade. Although Chinese imports are expected to continue their rapid increase and imports in other Asian countries are expected to continue growing, there appears to be enough greenfield and expansion projects to meet future demand for iron ore worldwide. Present suppliers of iron ore, Australia, Brazil, India, and South Africa, will probably be the chief beneficiaries of China's increasing consumption of iron ore. How long China can continue its extraordinary growth is the primary issue for the future of the iron ore industry. Based on the number and size of planned blast furnaces it appears that China's growth could continue for several more years. ?? 2004 Taylor and Francis.

Kirk, W. S.

2004-01-01

55

Rock magnetic properties and ore microscopy of the iron ore deposit of Las Truchas, Michoacan, Mexico  

NASA Astrophysics Data System (ADS)

Iron ore and host rocks have been sampled (90 oriented samples from 19 sites) from the Las Truchas mine, western Mexico. A broad range of magnetic parameters have been studied to characterize the samples: saturation magnetization, Curie temperature, density, susceptibility, remanence intensity, Koenigsberger ratio, and hysteresis parameters. Magnetic properties are controlled by variations in titanomagnetite content, deuteric oxidation, and hydrothermal alteration. Las Truchas deposit formed by contact metasomatism in a Mesozoic volcano-sedimentary sequence intruded by a batholith, and titanomagnetites underwent intermediate degrees of deuteric oxidation. Post-mineralization hydrothermal alteration, evidenced by pyrite, epidote, sericite, and kaolin, seems to be the major event that affected the minerals and magnetic properties. Magnetite grain sizes in iron ores range from 5 to >200 ?m, which suggest dominance of multidomain (MD) states. Curie temperatures are 580±5°C, characteristic of magnetite. Hysteresis parameters indicate that most samples have MD magnetite, some samples pseudo-single domain (PSD), and just a few single domain (SD) particles. AF demagnetization and IRM acquisition indicate that NRM and laboratory remanences are carried by MD magnetite in iron ores and PSD-SD magnetite in host rocks. The Koenigsberger ratio falls in a narrow range between 0.1 and 10, indicating the significance of MD and PSD magnetites.

Alva-Valdivia, L. M.; Urrutia-Fucugauchi, J.

1998-02-01

56

Direct reduction of iron ore by biomass char  

NASA Astrophysics Data System (ADS)

By using thermogravimetric analysis the process and mechanism of iron ore reduced by biomass char were investigated and compared with those reduced by coal and coke. It is found that biomass char has a higher reactivity. The increase of carbon-to-oxygen mole ratio (C/O) can lead to the enhancement of reaction rate and reduction fraction, but cannot change the temperature and trend of each reaction. The reaction temperature of hematite reduced by biomass char is at least 100 K lower than that reduced by coal and coke, the maximum reaction rate is 1.57 times as high as that of coal, and the final reaction fraction is much higher. Model calculation indicates that the use of burden composed of biomass char and iron ore for blast furnaces can probably decrease the temperature of the thermal reserve zone and reduce the CO equilibrium concentration.

Zuo, Hai-bin; Hu, Zheng-wen; Zhang, Jian-liang; Li, Jing; Liu, Zheng-jian

2013-06-01

57

Smoothed Particle Hydrodynamic Simulation of Iron Ore Pellets Flow  

SciTech Connect

In this work the Smoothed Particle Hydrodynamics (SPH) method is used to simulate iron ore pellets flow. A continuum material model describing the yield strength, elastic and plastic parameters for pellets as a granular material is used in the simulations. The most time consuming part in the SPH method is the contact search of neighboring nodes at each time step. In this study, a position code algorithm for the contact search is presented. The cost of contact searching for this algorithm is of the order of Nlog2N, where N is the number of nodes in the system. The SPH-model is used for simulation of iron ore pellets silo flow. A two dimensional axisymmetric model of the silo is used in the simulations. The simulation results are compared with data from an experimental cylindrical silo, where pellets are discharged from a concentric outlet. Primary the flow pattern is compared.

Gustafsson, G.; Haeggblad, H.-A.; Oldenburg, M. [Division of Solid Mechanics, Luleaa University of Technology, SE-971 87 Luleaa (Sweden)

2007-05-17

58

Smoothed Particle Hydrodynamic Simulation of Iron Ore Pellets Flow  

NASA Astrophysics Data System (ADS)

In this work the Smoothed Particle Hydrodynamics (SPH) method is used to simulate iron ore pellets flow. A continuum material model describing the yield strength, elastic and plastic parameters for pellets as a granular material is used in the simulations. The most time consuming part in the SPH method is the contact search of neighboring nodes at each time step. In this study, a position code algorithm for the contact search is presented. The cost of contact searching for this algorithm is of the order of Nlog2N, where N is the number of nodes in the system. The SPH-model is used for simulation of iron ore pellets silo flow. A two dimensional axisymmetric model of the silo is used in the simulations. The simulation results are compared with data from an experimental cylindrical silo, where pellets are discharged from a concentric outlet. Primary the flow pattern is compared.

Gustafsson, G.; Häggblad, H.-A.?.; Oldenburg, M.

2007-05-01

59

Production of Iron-Ore Pellets with an Organic Binder  

Microsoft Academic Search

Limestone is used as the flux in the production of iron-ore pellets, while bentonite clays are used as the binder. The consumption of these clays is within the range 0.4?3.0% [2]. Organic binders based on polyacrylamide can serve as a substitute for bentonite that makes it possible to reduce the consumption of binder and increase the Fe content of the

V. M. Chizhikova; R. M. Vainshtein; S. N. Zorin; T. I. Zainetdinov; G. A. Zinyagin; A. A. Shevchenko

2003-01-01

60

Cooling process of iron ore pellets in an annular cooler  

Microsoft Academic Search

A 3-D mathematical model was presented for the cooling process of iron ore pellets based on the laws of mass, momentum, and\\u000a heat transfer. The flow, pressure, and temperature fields were obtained by numerical simulation with the commercial software\\u000a FLUENT. In order to verify the model, a mass and energy balance field test was systematically carried out on an annular

Jun-Xiao Feng; Kai-Li Liang; Zhi-Bin Sun; Jing-Hai Xu; Yong-Ming Zhang; Jin-Bao Yang

2011-01-01

61

STATIC FATIGUE OF IRON ORE IN UNDERGROUND IRON MINES (LORRAINE, FRANCE)  

Microsoft Academic Search

Static fatigue of iron ore, a very porous rock that constitutes pillars in underground iron mines in Lorraine (France), was studied by performing multi-step uniaxial creep tests under partially saturated conditions, and the impact of water saturation was analyzed. Recorded strains and acoustic emissions show that saturation in water induces a strong increase in acoustic activity and inelastic volumetric dilation,

GRGIC Dragan; AMITRANO David; HOMAND Françoise

2008-01-01

62

Partial reduction of particulate iron ores and cyclone reactor  

SciTech Connect

An apparatus for iron or ferro-alloy smelting is described, comprising: bath smelter means for containing a smelting bath for reductive bath smelting of iron or ferro-alloy ore by coal/oxygen injection through use of endothermic nozzles directed into a smelting bath to form liquid iron or steel; a closed cyclone reactor having an upper end including an inlet end, said closed cyclone including an open lower exit positioned above the smelting bath within the bath smelter means; feed means for directing a continuous stream of fine ore particles into the cyclone reactor; and gas supply means for tangentially directing streams of oxygen, with or without air, and a fuel gas selected from the group consisting of producer gas, natural gas and methane for burning within the cyclone reactor to maintain the interior and contents of the cyclone reactor at an elevated temperature; the equilibrium partial pressure ratio of carbon monoxide to carbon dioxide exiting the cyclone reactor being maintained at a value sufficient to cause the melted ore at the elevated temperatures within the cyclone reactor to be partially reduced during the particulate residence time within the cyclone reactor.

Taylor, P.R.; Bartlett, R.W.; Abdel-Latif, M.

1993-07-20

63

Deep magnetic anomaly sources interpreted as Otanmäki type Iron ore reserves  

NASA Astrophysics Data System (ADS)

In Otanmäki ore province of Central Finland vertically integrated magnetization is estimated from two aeromagnetic coverages of different altitudes and by varying overall models of regional field. Petrophysically and geochemically determined magnetization of the mined deposits and correlation between it and ore concentration is used to evaluate iron ore reserves in the deeper part of known ore fields. Further, similar analysis is made to nearby magnetically anomalous areas covered by weakly magnetic metasediments, to estimate potential ore reserves at unexposed formations.

Korhonen, Juha; Kukkonen, Ilmo

2013-04-01

64

Raman Spectroscopic Characterisation of Australian Banded Iron Formation and Iron Ore  

NASA Astrophysics Data System (ADS)

In Australia and world-wide over the past 5-10 years, declining reserves of premium, high-grade (>64% Fe), low-P bearing iron ore, have seen iron ore producers increase their utilisation of lower Fe-grade, higher P/Al/Si ore. In Australia, the channel iron deposits (CID), bedded iron deposits (BID) and, more recently, BIF-derived magnetite iron deposits (MID) have seen increased usage driven mainly by the increased demand from Chinese steel mills (Ramanaidou and Wells, 2011). Efficient exploitation and processing of these lower-grade iron ores requires a detailed understanding of their iron oxide and gangue mineralogy and geochemistry. The common Fe-bearing minerals (e.g., hematite, magnetite, goethite and kenomagnetite) in these deposits, as well as gangue minerals such as quartz and carbonates, are all strongly Raman active (e.g., de Faria et al., 1997). Their distinct Raman spectra enable them to be easily detected and mapped in situ in either unprepared material or samples prepared as polished blocks. In this paper, using representative examples of Australian CID ore, martite-goethite bedded iron deposit (BID) ore and banded iron formation (BIF) examined as polished blocks, we present a range of Raman spectra of the key iron ore minerals, and discuss how Raman spectroscopy can be applied to characterising iron ore mineralogy. Raman imaging micrographs, obtained using a StreamLine Plus Raman imaging system, clearly identified the main Fe-oxide and gangue components in the CID, BID and BIF samples when compared to optical micrographs. Raman analysis enabled the unequivocal identification of diamond in the CID ore as a contaminant from the polishing paste used to prepare the sample, and confirmed the presence of hematite in the BID ore in the form of martite, which can be morphologically similar to magnetite and, thus, difficult to otherwise distinguish. Image analysis of Raman mineral maps could be used to quantify mineral abundance based on the number of 'pixels' identified for each phase normalised to the total number of 'pixels' for each area scanned. Shifts in the main phonon lines of goethite and hematite mapped in the CID samples examined were used to estimate the Al substitution in these phases (e.g., Ramanaidou et al. 1996) which were consistent with electron microprobe data. The Raman data demonstrated the Al-free nature of hematite (0.5 mol% Al) and showed that goethite in the CID cortex was more Al-rich (10 mol%) than goethite in the CID matrix (3 mol% Al). Shifts in the excitation bands of carbonate mapped in the BIF sample were well related to the Mg content of Fe-carbonate, based on the work of Rividi et al. (2010) and confirmed by in situ spot analysis using energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). This data confirmed the first world-wide occurrence of a high Mg-bearing siderite (pistomesite) in BIF. Detailed, in situ characterisation of the iron oxide and gangue mineralogy of iron ore deposits as provided by Raman spectroscopy provides a step change to current characterisation methods. Understanding and defining their mineralogy and geochemistry is critical in developing strategies to best manage and process existing BID and CID ores, as well as the newly emerging MID ores.

Wells, M. A.; Ramanaidou, E. R.

2012-04-01

65

Revegetation of coarse taconite iron ore tailing using municipal solid waste compost  

Microsoft Academic Search

On Minnesota's Mesabi Iron Range, coarse taconite iron ore tailing is often used as the principal material in the construction of dams for large tailing impoundments. Mineland reclamation rules in Minnesota require that tailing dams be vegetated to control erosion for dam stability and safety. Coarse taconite iron ore tailing is characterized chemically by an alkaline pH, low organic matter

Michael R. Norland; David L. Veith

1995-01-01

66

Synthesis of Fe-MCM-41 Using Iron Ore Tailings as the Silicon and Iron Source  

PubMed Central

Highly ordered Fe-MCM-41 molecular sieve was successfully synthesized by using n-hexadecyl-trimethyl ammonium bromide (CTAB) as the template and the iron ore tailings (IOTs) as the silicon and iron source. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance UV-visible spectroscopy, 29Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR), and nitrogen adsorption/desorption were used to characterize the samples. The results showed that the mesoporous materials had highly ordered 2-dimensional hexagonal structure. The synthesized sample had high surface area, and part of iron atoms is retained in the framework with formation of tetrahedron after removal of the template by calcinations. The results obtained in the present work demonstrate the feasibility of employing iron ore tailings as a potential source of silicon and iron to produce Fe-MCM-41 mesoporous materials.

Li, Xin; Yu, Honghao; He, Yan; Xue, Xiangxin

2012-01-01

67

High-carbon fly-ash as a binder for iron ore pellets  

SciTech Connect

The goal of this project was to convert currently unusable fly-ashes into a material that can be used as a binder for iron ore. Such a binder would also be useful for other high-volume markets, including foundry sand mold binders. Previously, the investigators used fly-ash in combination with calcium hydroxide as an additive while calcium chloride was added as a hardening accelerator. However, the addition of chloride salts have a detrimental effect because chlorine causes corrosion in processing equipment. Therefore, other potential hardening accelerators were investigated during this project. During production, dried iron-ore pellets are required to have crushing strength of at least 22.2 newtons (5 pounds force) per 12.7 mm (1/2 inch) diameter pellet. The pellets are then sintered at temperatures up to 1300 C and must not exhibit a significant degree of spalling or cracking. Pellets will therefore be tested to determine whether acceptable dry crushing strengths can be achieved.

Kawatra, S.K.; Eisele, T.C.; Ripke, S.J.; Ramirez, G.

1999-09-01

68

Innovative methodology for comprehensive utilization of iron ore tailings: part 1. The recovery of iron from iron ore tailings using magnetic separation after magnetizing roasting.  

PubMed

Iron ore tailings have become one kind of the most hazardous solid waste. In order to recycle iron in the tailings, we present a technique using magnetizing roasting process followed by magnetic separation. After analysis of chemical composition and crystalline phase, according to experimental mechanism, the effects of different parameters on recovery efficiency of iron were carried out. The optimum reaction parameters were proposed as the following: ratio of coal: iron ore tailings as 1:100, roasting at 800 degrees C for 30 min, and milling 15 min of roasted samples. With these optimum parameters, the grade of magnetic concentrate was 61.3% Fe and recovery rate of 88.2%. With this method, a great amount of iron can be reused. In addition, the microstructure and phase transformation of the process of magnetizing roasting were studied. PMID:19782467

Li, Chao; Sun, Henghu; Bai, Jing; Li, Longtu

2010-02-15

69

Stresses induced in iron-ore pellets by hydrogen reduction  

NASA Astrophysics Data System (ADS)

The objectives of this investigation were (a) to determine the effect of reduction temperature on the strength of iron ore agglomerates and (b) to develop enhanced understanding for the cracking associ-ated with reduction. Iron-ore agglomerates from two sources (Samarco Mineração and Bethlehem Steel) were reduced in a hydrogen atmosphere at temperatures varying from 873 K to 1373 K at intervals of 100 K and times varying from 30 to 300 minutes. The compressive strength at the ambient temperature of the pellets was determined after the various reduction treatments by using a piston-and-cylinder testing technique and computing the energy required in crushing them. The highest strength, at a specific level of reduction, was found after reduction at 1073 K, for both the Samarco and Bethlehem pellets. Profuse cracking of the pellets was observed after reduction. These cracks led to a weakening of the pellets. A mechanism for reduction-induced cracking, based on internal stresses due to volume changes produced by the chemical reactions, is presented.

Meyers, Marc André; Tantevee, Taveesiri

1986-01-01

70

Functions and molecular structure of organic binders for iron ore pelletization  

Microsoft Academic Search

Organic binders of iron ore pellets were widely investigated in past decades because they do not contaminate the product. This paper mainly involves the functions and molecular structure of ideal organic binders for iron ore pelletization based on fundamental principles of molecular design, interface chemistry, polymer science as well as failure model of a binding system. Investigation shows that good

Guanzhou Qiu; Tao Jiang; Hongxu Li; Dianzuo Wang

2003-01-01

71

Estimation and Evaluation of the Iron Ore Reserves of the United States - A Partial Survey, 1974-75. Iron Ore Reserves of the Mesabi Range, Minnesota. A Minerals Availability System Report.  

National Technical Information Service (NTIS)

This report is a comprehensive study of the iron ore reserves of the Mesabi Range, Minn. Iron ore has been classified into seven categories with descriptions of each category and the geologic factors affecting each reserve estimate. Iron ore reserves for ...

R. W. Marsden

1980-01-01

72

System for control of sinter formation in iron oxide reducing kilns  

SciTech Connect

A method and means for improving control of the process for directly reducing ores containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the temperature profile of the moving bed of solids is maintained such that the temperature is moderated to remain below the sintering temperature of the materials in the bed from the feed end zone for about the first two-thirds of the kiln length and the temperature is then maximized within sintering limitations in the working zone which is limited to about the last third of the kiln length. The temperature profile is controlled by regulating the volumes of air supplied to the kiln atmosphere from air injectors at spaced intervals along the length of the kiln, after establishing the appropriate proportion of coal steadily blown into the discharge end of the kiln for the particular process constituents being used.

Baker, A.C.; Keran, V.P.

1981-12-08

73

Innovative methodology for comprehensive utilization of iron ore tailings: part 2: The residues after iron recovery from iron ore tailings to prepare cementitious material.  

PubMed

In order to comprehensive utilization of iron ore tailings, this experimental research was to investigate the possibility of using the residues after iron recovery from iron ore tailings as raw materials for the preparation of cementitious material, abbreviated as TSC, including analyses of its mechanical properties, physical properties and hydration products. The TSC1 was prepared by blending 30% the residues, 34% blast-furnace slag, 30% clinker and 6% gypsum. Meanwhile, the raw iron ore tailings (before iron recovery) with the same proportion of TSC1 were selected to compare the cementitious activity of raw tailings and the residues after magnetizing roasting, denoted by TSC0. The hydration products of them were mostly ettringite, calcium hydroxide and C-S-H gel, characterized by XRD, IR and SEM. It was found that ettringite and C-S-H gel were principally responsible for the strength development of TSC mortars with curing time. The results showed that the kaolinite of the tailings was decomposed completely after magnetizing roasting, which promoted the cementitious property of TSC1. Moreover, the mechanical properties of TSC1 are well comparable with those of 42.5 ordinary Portland cement according to Chinese GB175-2007 standard. PMID:19782471

Li, Chao; Sun, Henghu; Yi, Zhonglai; Li, Longtu

2010-02-15

74

Liquid-phase sintering of iron aluminide-bonded ceramics  

SciTech Connect

Iron aluminide intermetallics exhibit excellent oxidation and sulfidation resistance and are therefore considered as the matrix in metal matrix composites, or the binder in hard metals or cermets. In this paper the authors discuss the processing and properties of liquid-phase sintered iron aluminide-bonded ceramics. It is found that ceramics such as TiB{sub 2}, ZrB{sub 2}, TiC, and WC may all be liquid phase-sintered. nearly complete densification is achieved for ceramic volume fractions ranging up to 60%. Depending on the composition, room temperature three point-bend strengths and fracture toughnesses reaching 1,500 MPa and 30 MPa m{sup 1/2}, respectively, have been found. Since the processing was carried out in a very simple manner, optimized processing is likely to result in further improvements.

Schneibel, J.H.; Carmichael, C.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1995-12-31

75

Some biological properties of respirable iron ore dust.  

PubMed

The respirable fraction of an ore dust from the North-West of Western Australia was tested for biological properties by inhalation and intrapleural implantation trials using rats and mice. Pulmonary histology indicated significant levels of interstitial pneumonia occasionally associated with bronchopneumonia, bronchiectasis, emphysema, and lung collapse over that found in age-matched control animals. While there was a significant increase of the incidence of tumors in general in WAG inbred rats up to 2 years following dust exposure, this did not persist into old age. No mesotheliomas were induced by any treatments associated with iron ore dust, although the rats were shown to be susceptible to crocidolite asbestos-induced mesothelioma. In the mouse models, tumors which are normally seen only in aged animals were induced with a significant number of bronchial adenomas being recorded following intrapleural implantation of dust into inbred BALB/c mice. Leukemia/lymphoma associated with murine leukemia virus was increased following dust inhalation by inbred C57BL mice. PMID:3032602

Keast, D; Sheppard, N P; Papadimitriou, J M

1987-04-01

76

Cooling process of iron ore pellets in an annular cooler  

NASA Astrophysics Data System (ADS)

A 3-D mathematical model was presented for the cooling process of iron ore pellets based on the laws of mass, momentum, and heat transfer. The flow, pressure, and temperature fields were obtained by numerical simulation with the commercial software FLUENT. In order to verify the model, a mass and energy balance field test was systematically carried out on an annular cooler in Shougang Mining Company. The maximum relative errors of temperature, pressure, and velocity between computational and testing results are 2.87%, -8.11%, and 7.14%, respectively, indicating the validity of the model. Further, the effects of process parameters, such as pellet diameter, bed thickness, air velocity, and temperature, on the pellet bed temperature profiles were studied.

Feng, Jun-Xiao; Liang, Kai-Li; Sun, Zhi-Bin; Xu, Jing-Hai; Zhang, Yong-Ming; Yang, Jin-Bao

2011-06-01

77

Characterization of an iron-based laser sintered material  

Microsoft Academic Search

Direct Metal Laser Sintering (DMLS) is a relatively new rapid tooling technique to fabricate near net-shaped parts. Properties of DMLS parts are governed by their microstructure. Hence, characterization of microstructure is of significant importance. In this study, a new iron-based DMLS material was characterized to unveil its metallic microstructure to support the prediction of end-user performance and the development of

Y. Wang; J. Bergström; C. Burman

2006-01-01

78

High-chromium cast iron sintered of sprayed powders  

Microsoft Academic Search

The paper examines basic technological characteristics of high-chromium cast iron powders resulting from gas or water melt\\u000a spraying. Sintering of billets made of these powders is investigated. It is shown that Fe-Cr-Mo-Cr powder alloys can combine\\u000a high hardness and thermal stability. Therefore, they are candidate materials for operation in intensive wear and at high temperatures.

G. A. Baglyuk; Yu. F. Ternovoi; V. N. Terekhov

2007-01-01

79

Effects of calcium hydroxide and calcium chloride addition to bentonite in iron ore pelletization.  

PubMed

Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder. PMID:17121116

Tugrul, Nurcan; Derun, Emek Moroydor; Pi?kin, Mehmet

2006-10-01

80

Application of Genetic Algorithm (GA) to estimate the rate parameters for solid state reduction of iron ore in presence of graphite  

Microsoft Academic Search

In the present article, Genetic Algorithm (GA) has been applied to estimate the rate parameters from experimental data during solid state reduction of iron ore in presence of graphite. Iron ore is charged and reduced as iron ore-graphite composite pellets in a laboratory scale packed bed reactor. The reduction of iron ore has been considered in three elementary steps, namely

Gour G. Roy

2009-01-01

81

Grinding Wear Behaviour of Stepped Austempered Ductile Iron as Media Material During Comminution of Iron Ore in Ball Mills  

Microsoft Academic Search

An attempt has been made to evaluate the suitability of austempered ductile iron (ADI) as media material for grinding iron ore in a ball mill. Spheroidal graphite (S.G) iron balls are austenitised at 900° C for 60 minutes and given stepped austempering treatment at 280° C for 30 minutes and 60 minutes followed by 380° C for 60 minutes in

H. Raghavendra; K. L. Bhat; K. Rajendra Udupa; M. M. Rajath Hegde

2011-01-01

82

Monitoring iron carbide production from iron ore by quantitative Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

The process of converting iron ore (principally Fe 2O 3 or Fe 3O 4) into iron carbide (Fe 3C) to be used as feedstock for steel-making yields complex mixtures of several iron containing compounds as a function of processing conditions. In addition to the above compounds (hematite, magnetite and cementite), the mixtures typically contain wustite (FeO) and metallic iron (Fe). Mössbauer spectroscopy has been developed into a quantitative analytical method for monitoring the degree of conversion to carbide from samples periodically extracted from a fluidized bed reactor type of pilot plant. Emphasis has been placed on standardizing and simplifying the analysis procedure for routine use in an industrial environment.

Stephens, Frank A.; Williamson, D. L.; Hager, John P.

1993-04-01

83

Reducing acid leaching of manganiferous ore: Effect of the iron removal operation on solid waste disposal  

Microsoft Academic Search

The process of reducing acid leaching of manganiferous ore is aimed at the extraction of manganese from low grade manganese ores. This work is focused on the iron removal operation. The following items have been considered in order to investigate the effect of the main operating conditions on solid waste disposal and on the process costs: (i) type and quantity

Ida De Michelis; Francesco Ferella; Francesca Beolchini; Francesco Vegliò

2009-01-01

84

Non-coke smelting reduction of iron ores: Process modelling  

NASA Astrophysics Data System (ADS)

The scarcity of coking coals and the high cost entailed in minimizing the emissions from the coke-making process as well as the relative inflexibility of large production capacity of the conventional blast-furnace ironmaking are the main reasons for the development of non-coke smelting reduction processes with the economical and ecological compatibility. The main objectives of the alternative processes development are to use ordinary coals directly, extend the range of usable raw materials, and allow the operation at a small scale. While most of smelting reduction processes are still in various stages of development, only the COREX ironmaking has successfully reached the industrial application with its first 300000 tpa plant operated in Pretoria, South Africa. The COREX process is composed of two main reactors: the vertical shaft furnace for the gaseous reduction of iron ore to sponge iron, and the melter-gasifier for the gasification of coal and smelting of iron. The gasification process generates the reducing gas mixture (CO and Hsb2) for use in the reduction furnace and also produces heat for smelting of the direct reduced iron. In the present work, the operating data of the COREX process are studied and process material and energy balances are prepared. The coal consumption rate of the COREX process is found higher than the coke consumption rate of the conventional process; however, the total energy consumption for the COREX process compares well with that of the blast furnace. The COREX process also generates surplus gas of high heating value which is suitable for many applications. A reduction model employing the diffusion-limited mass-transfer coupled with virtual equilibrium at core-interface is developed to determine the reduction of iron oxide pellets. The rate of oxygen-transfer between the solid and gas phases is computed by combining the Stefan-Maxwell multi-component diffusion formalism with the iterative equilibrium constant method. The computed results agree well with the observed data and the model is extended to simulate the reduction profiles in the reduction shaft of the COREX process. It is seen that the reduction process is mainly influenced by the pore-size and pore-structure of the reduced product layers.

Pichestapong, Pipat

85

Field Investigation and Testing of a Minnesota Clay Resource for Iron Ore Pellet Bonding.  

National Technical Information Service (NTIS)

Selected glacial lake clay deposits in Minnesota were sampled, tested, and evaluated to determine their suitability for use as a bonding agent in iron ore pellet manufacturing. Preliminary tests conducted on clay samples obtained from five ancient glacial...

J. H. Aase G. E. Leonhard

1968-01-01

86

Thermodynamic Consideration of the Removal of Iron from Titanium Ore by Selective Chlorination  

NASA Astrophysics Data System (ADS)

Thermodynamic study of the chlorination reactions of oxides such as titanium oxides and iron oxides at elevated temperatures was carried out in order to consider the removal of iron from titanium ore using selective chlorination method. In particular, various chlorination reactions were analyzed by utilizing chemical potential diagrams, and the applicability and usefulness of this thermodynamic study for analyzing the selective chlorination of titanium ore were demonstrated. Furthermore, chlorination reactions using various types of chlorinating agents were discussed from different viewpoints. It was shown that the selective chlorination of iron from titanium ore by HCl gas is thermodynamically feasible and efficient for upgrading titanium ore. Further, thermodynamic analysis showed that under certain conditions, TiCl4 can be used as a chlorinating agent for the iron in the ore, and iron can be removed by evaporation directly from the ore as chloride gas. The results presented in this study provide useful information for developing a process for upgrading low-grade titanium ore for use as a titanium smelting feed through a dry method.

Kang, Jungshin; Okabe, Toru H.

2014-04-01

87

Magnetite mineral nanoparticles synthesized naturally in an iron ore deposit  

NASA Astrophysics Data System (ADS)

We performed a mineralogical characterization and mineral magnetism study of the Peña Colorada iron ore, Mexico. The ore is formed partly by intergranular magnetite intergrowed with berthierine (Fe,Mg,Al)6(Si,Al)4O10(OH)8. The magnetite nanoparticles are forming aggregates of wide grain size spectra, from micro to nanometer scale. The smallest aggregates are formed by magnetite nanoparticles 2 to 30 grain size range, showing unusual physical and chemical behavior. The continuous agglomeration of nanoparticles formed more denser and compact magnetite microparticles. A magnetite concentrate to micrometric scale was reduced and divided into distinct range sizes: 85-56 ?m, 56-30 ?m, 30-22 ?m, 22-15 ?m, 15-10 ?m, 10-7 ?m and 7-1 ?m. Nanometric-scale magnetite 2-30 nm was identified by using high resolution Transmission Electron Microscopy (HRTEM). The magnetite and minerals associated were characterized by X-ray diffraction, transmitted and reflected light polarization, microscope and electron probe X-ray micro-analyzer, differential thermal analysis, gravimetric thermal analysis, and high-resolution transmission electron microscopy. Besides, results of Mössbauer spectroscopy, frequency-dependent magnetic susceptibility, isothermal remanent magnetization and magnetic susceptibility versus temperature were important in the research related to the origin of this deposit. To study magnetite nanoparticles, agglomeration processes and temperature effect implications, we developed an experimental process to re-create the environmental conditions that originated this nanoparticles. These processes start with direct precipitation to synthesize magnetite nanoparticles through a thermal and dehydration treatment of the berthierine base mineral, using diverse temperature ranges, from 360 °C to 750 °C and treatment time of two hours. This process allowed the nucleation and crystalline growth of a high number of magnetite nano-crystals with average size of 2 to 6 nm, homogeneous distribution in the colloidal matrix and a superparamagnetic behavior. Increase temperature provoke new magnetite nano-cores and constant growth of the ones already present. The union to magnetite nanoparticles favored the formation of aggregates nano-micrometric strongly compacted with the acquisition of ferromagnetic behavior. The mineralogical-textural characteristic of magnetite nanoparticles and its magnetic properties were an important guide to explain the environmental conditions for iron deposition, suggesting a marine sedimentary exhalative (SEDEX) origin assisted by bacterial.

Rivas-Sanchez, M. L.; Alva-Valdivia, L. M.

2013-05-01

88

Phosphorus retention capacity of iron-ore and blast furnace slag in subsurface flow constructed wetlands  

Microsoft Academic Search

Abstract The suitability of iron-ore and blast furnace slag for subsurface flow (SSF) constructed wetlands was studied over a period of four months. Dairy farm wastewater,(TP 45 mg l,) was promoted,by predominantly anaerobic,conditions due to continuous formation of amorphous,ferrous hydroxides. None of the substrates had adverse affects on reed growth. Keywords Phosphorus retention; constructed wetlands; iron-ore; blast furnace slag; dairy

B. grüneberg; J. Kern

89

Rock Magnetic and Oxide Microscopy Studies of two South American Iron-Ore Deposits  

Microsoft Academic Search

Microscopy and rock-magnetic studies of the iron oxide-ore and host rocks in the Cristales-Pleito Melon (Chile) and Jacupiranga (Brazil) deposits were carried out to characterize and compare the magnetic mineralogy and the processes that affected the natural remanent magnetization (NRM) during emplacement and evolution of the iron-ore deposits. The microscopy study under reflected light shows that magnetic carriers are mainly

L. M. Alva-Valdivia

2005-01-01

90

40 CFR 420.20 - Applicability; description of the sintering subcategory.  

Code of Federal Regulations, 2013 CFR

...resulting from sintering operations conducted by the heating of iron bearing wastes (mill scale and dust from blast furnaces and steelmaking furnaces) together with fine iron ore, limestone, and coke fines in an ignition furnace to produce an agglomerate for...

2013-07-01

91

Content and binding forms of heavy metals, aluminium and phosphorus in bog iron ores from Poland.  

PubMed

Bog iron ores are widespread in Polish wetland soils used as meadows or pastures. They are suspected to contain high concentrations of heavy metals, which are precipitated together with Fe along a redox gradient. Therefore, soils with bog iron ore might be important sources for a heavy metal transfer from meadow plants into the food chain. However, this transfer depends on the different binding forms of heavy metals. The binding forms were quantified by sequential extraction analysis of heavy metals (Fe, Mn, Cr, Co, Ni, Cd, Pb) as well as Al and P on 13 representative samples of bog iron ores from central and southwestern Poland. Our results showed total contents of Cr, Co, Ni, Zn, Cd, and Pb not to exceed the natural values for sandy soils from Poland. Only the total Mn was slightly higher. The highest contents of all heavy metals have been obtained in iron oxide fractions V (occluded in noncrystalline and poorly crystalline Fe oxides) and VI (occluded in crystalline Fe oxides). The results show a distinct relationship between the content of Fe and the quantity of Zn and Pb as well P. Water soluble as well as plant available fractions were below the detection limit in most cases. From this we concluded bog iron ores not to be an actual, important source of heavy metals in the food chain. However, a remobilization of heavy metals might occur due to any reduction of iron oxides in bog iron ores, for example, by rising groundwater levels. PMID:19398508

Kaczorek, Danuta; Brümmer, Gerhard W; Sommer, Michael

2009-01-01

92

Discrimination of iron ore deposits of granulite terrain of Southern Peninsular India using ASTER data  

NASA Astrophysics Data System (ADS)

This work describes a new image processing technique for discriminating iron ores (magnetite quartzite deposits) and associated lithology in high-grade granulite region of Salem, Southern Peninsular India using visible, near-infrared and short wave infrared reflectance data of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Image spectra show that the magnetite quartzite and associated lithology of garnetiferrous pyroxene granulite, hornblende biotite gneiss, amphibolite, dunite, and pegmatite have absorption features around spectral bands 1, 3, 5, and 7. ASTER band ratios ((1 + 3)/2, (3 + 5)/4, (5 + 7)/6) in RGB are constructed by summing the bands representing the shoulders of absorption features as a numerator, and the band located nearest the absorption feature as a denominator to map iron ores and band ratios ((2 + 4)/3, (5 + 7)/6, (7 + 9)/8) in RGB for associated lithology. The results show that ASTER band ratios ((1 + 3)/2, (3 + 5)/4, (5 + 7)/6) in a Red-Green-Blue (RGB) color combination identifies the iron ores much better than previously published ASTER band ratios analysis. A Principal Component Analysis (PCA) is applied to reduce redundant information in highly correlated bands. PCA (3, 2, and 1 for iron ores and 5, 4, 2 for granulite rock) in RGB enabled the discrimination between the iron ores and garnetiferrous pyroxene granulite rock. Thus, this image processing technique is very much suitable for discriminating the different types of rocks of granulite region. As outcome of the present work, the geology map of Salem region is provided based on the interpretation of ASTER image results and field verification work. It is recommended that the proposed methods have great potential for mapping of iron ores and associated lithology of granulite region with similar rock units of granulite regions of Southern Peninsular India. This work also demonstrates the ability of ASTER's to provide information on iron ores, which is valuable for mineral prospecting and exploration activities.

Rajendran, Sankaran; Thirunavukkarasu, A.; Balamurugan, G.; Shankar, K.

2011-04-01

93

The search for asbestos within the Peter Mitchell Taconite iron ore mine, near Babbitt, Minnesota  

Microsoft Academic Search

Asbestos crystallizes within rock formations undergoing intense deformation characterized by folding, faulting, shearing, and dilation. Some of these conditions have prevailed during formation of the taconite iron ore deposits in the eastern Mesabi Iron Range of Minnesota. This range includes the Peter Mitchell Taconite Mine at Babbitt, Minnesota. The mine pit is over 8 miles long, up to 1 mile

Malcolm Ross; Robert P. Nolan; Gordon L. Nord

2008-01-01

94

ORE DEPOSIT GENESIS IN THE CHILEAN IRON BELT (ATACAMA AREA,CHILE)  

Microsoft Academic Search

The Chilean Iron Belt appears in andesitic lavas of an island-arc, Neocomian in age. The iron ore comes from latter pyroxene-bearing dioritic rocks which suffered a high temperature leaching, accompagned by a sodic alteration. The concentration of Fe, then Ca-Mg cations, is located in volcanic fractured homfelses.

MENARD JEAN-JACQUES

95

Production of lightweight ceramisite from iron ore tailings and its performance investigation in a biological aerated filter (BAF) reactor.  

PubMed

The few reuse and large stockpile of iron ore tailings (IOT) led to a series of social and environmental problems. This study investigated the possibility of using the IOT as one of starting materials to prepare lightweight ceramisite (LWC) by a high temperature sintering process. Coal fly ash (CFA) and municipal sewage sludge (SS) were introduced as additives. The LWC was used to serve as a biomedium in a biological aerated filter (BAF) reactor for municipal wastewater treatment, and its purification performance was examined. The effects of sintering parameters on physical properties of the LWC, and leaching concentrations of heavy metals from the LWC were also determined. The microstructure and the phase composition of the LWC were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results revealed that: (1) IOT could be used to produce the LWC under the optimal sintering parameters; (2) the leaching concentrations of heavy metals from the LWC were well below their respective regulatory levels in the China Environmental Quality Standards for Surface Water (CEQS); and (3) the BAF reactor with the LWC serving as the biomedium achieved high removal efficiencies for COD(Cr) (>92%), NH(4)(+)-N (>62%) and total phosphate (T-P) (>63%). Therefore, the LWC produced from the IOT was suitable to serve as the biomedium in the municipal wastewater treatment. PMID:20227178

Liu, Yangsheng; Du, Fang; Yuan, Li; Zeng, Hui; Kong, Sifang

2010-06-15

96

Investigation on grinding wear behaviour of austempered ductile iron as media material during comminution of iron ore in ball mills  

Microsoft Academic Search

An attempt has been made to assess the grinding wear behaviour of austempered ductile iron (ADI) as media material in comminution\\u000a of Kudremukh haematite iron ore in a ball mill. Spheroidal graphite (S.G) iron balls were austenitised at 900°C for one hour\\u000a and austempered at 280°C and 380°C for different time durations. These materials were characterized by measuring hardness,\\u000a carrying

Raghavendra Hebbar

2011-01-01

97

Model for Evaluating the Concentration of Iron Upgraded during Pyrobeneficiation of Iron Oxide Ore Pelletized with Powdered Potassium Chlorate  

Microsoft Academic Search

Model for predicting the concentration of iron upgraded during pyrobeneficiation of iron oxide ore (pelletized with powdered potassium chlorate) has been derived. The model-predicted %Fe upgrades were found to agree a direct relationship between %Fe values and weight-input of KClO3 as exhibited by %Fe upgrades obtained from the experiment. The model; %Fe = 7.1367? indicates that iron upgrade is dependent

Chukwuka Ikechukwu Nwoye; Stephen Obiji; Livinus Anyika; Uchenna Chukwuma Nwoye

98

Unit for producing electrical steel from briquets in an iron-ore-bearing mono-charge  

Microsoft Academic Search

A new universal batch-operated closed arc furnace is proposed for making steel by direct reduction in a single-stage cycle.\\u000a The furnace represents a synthesis of ore-smelting furnaces and conventional steelmaking furnaces. It makes steel of the required\\u000a grade by direct reduction from briquets that contain iron ore. The cost of making the steel is 25–30% lower than the cost\\u000a incurred

G. V. Kashakashvili; V. I. Kldiashvili; S. A. Meboniya; G. A. Lomtatidze

2009-01-01

99

Multielement analysis of iron ore pellets by Laser-induced Breakdown Spectroscopy and Principal Components Regression  

Microsoft Academic Search

Laser-induced Breakdown Spectroscopy (LIBS) in combination with Principal Components Regression (PCR) has been applied to determine the elemental composition of a series of run-of-mine (ROM) iron ore samples. The samples were presented for measurement both as compressed pellets and as loose chipped material. The present paper details the results of the measurements of the compressed pellets. Results from ore chips

D. L. Death; A. P. Cunningham; L. J. Pollard

2008-01-01

100

Upgrading and dephosphorization of Western Australian iron ore using reduction roasting by adding sodium carbonate  

NASA Astrophysics Data System (ADS)

The technology of direct reduction by adding sodium carbonate (Na2CO3) and magnetic separation was developed to treat Western Australian high phosphorus iron ore. The iron ore and reduced product were investigated by optical microscopy and scanning electron microscopy. It is found that phosphorus exists within limonite in the form of solid solution, which cannot be removed through traditional ways. During reduction roasting, Na2CO3 reacts with gangue minerals (SiO2 and Al2O3), forming aluminum silicate-containing phosphorus and damaging the ore structure, which promotes the separation between iron and phosphorus during magnetic separation. Meanwhile, Na2CO3 also improves the growth of iron grains, increasing the iron grade and iron recovery. The iron concentrate, assaying 94.12wt% Fe and 0.07wt% P at the iron recovery of 96.83% and the dephosphorization rate of 74.08%, is obtained under the optimum conditions. The final product (metal iron powder) after briquetting can be used as the burden for steelmaking by an electric arc furnace to replace scrap steel.

Zhu, De-qing; Chun, Tie-jun; Pan, Jian; Lu, Li-ming; He, Zhen

2013-06-01

101

Iron and cancer: more ore to be mined  

PubMed Central

Iron is an essential nutrient that facilitates cell proliferation and growth. However, iron also has the capacity to engage in redox cycling and free radical formation. Therefore, iron can contribute to both tumour initiation and tumour growth; recent work has also shown that iron has a role in the tumour microenvironment and in metastasis. Pathways of iron acquisition, efflux, storage and regulation are all perturbed in cancer, suggesting that reprogramming of iron metabolism is a central aspect of tumour cell survival. Signalling through hypoxia-inducible factor (HIF) and WNT pathways may contribute to altered iron metabolism in cancer. Targeting iron metabolic pathways may provide new tools for cancer prognosis and therapy.

Torti, Suzy V.; Torti, Frank M.

2014-01-01

102

Morphological and mineralogical characterizations of oolitic iron ore in the Exi region, China  

NASA Astrophysics Data System (ADS)

The morphological and mineralogical characterizations of a Chinese oolitic iron ore (Exi deposit) were studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy in this work. It is shown that the Exi ore is mainly composed of hematite, quartz, apatite, and chlorite. The hematite is present as the oolitic layers and in the spaces between the aggregated ooids; quartz exists as granular particles in the spaces and as nucleuses in ooids; the harmful mineral, apatite, is associated with hematite as the oolitic layers, fine dissemination, granular particles in the spaces, and nucleuses in ooids. From the viewpoint of mineral beneficiation, it is hard to separate apatite and chlorite but easy to separate quartz from hematite in the Exi iron ore in recovering the iron values.

Song, Shao-xian; Campos-Toro, Ernesto Fabian; Zhang, Yi-min; Lopez-Valdivieso, Alejandro

2013-02-01

103

Synthesis of mesoporous silica materials (MCM-41) from iron ore tailings  

SciTech Connect

Highly ordered mesoporous materials were successfully synthesized by using the iron ore tailings as the silica source and n-hexadecyltrimethyl ammonium bromide as the template. The samples were detail characterized by powder X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy and N{sub 2} physisorption. The as-synthesized materials had high surface area of 527 m{sup 2} g{sup -1} and the mean pore diameter of 2.65 nm with a well-ordered two-dimensional hexagonal structure. It is feasible to prepare mesoporous MCM-41 materials using the iron ore tailings as precursor.

Yu Honghao, E-mail: honghaoyu@hotmail.com [School of Materials and Metalurgy, Northeastern University, Shenyang, 110004 (China); College of Material Science and Engineering, Shenyang Ligong University, Shenyang, 110168 (China); Xue Xiangxin; Huang Dawei [School of Materials and Metalurgy, Northeastern University, Shenyang, 110004 (China)

2009-11-15

104

Recovery of iron from high phosphorus oolitic iron ore using coal-based reduction followed by magnetic separation  

NASA Astrophysics Data System (ADS)

Oolitic iron ore is one of the most important iron resources. This paper reports the recovery of iron from high phosphorus oolitic iron ore using coal-based reduction and magnetic separation. The influences of reduction temperature, reduction time, C/O mole ratio, and CaO content on the metallization degree and iron recovery were investigated in detail. Experimental results show that reduced products with the metallization degree of 95.82% could be produced under the optimal conditions (i.e., reduction temperature, 1250°C; reduction time, 50 min; C/O mole ratio, 2.0; and CaO content, 10wt%). The magnetic concentrate containing 89.63wt% Fe with the iron recovery of 96.21% was obtained. According to the mineralogical and morphologic analysis, the iron minerals had been reduced and iron was mainly enriched into the metallic iron phase embedded in the slag matrix in the form of spherical particles. Apatite was also reduced to phosphorus, which partially migrated into the metallic iron phase.

Sun, Yong-sheng; Han, Yue-xin; Gao, Peng; Wang, Ze-hong; Ren, Duo-zhen

2013-05-01

105

Genesis of iron-apatite ores in Posht-e-Badam Block (Central Iran) using REE geochemistry  

NASA Astrophysics Data System (ADS)

Rare earth elements in apatites of different ore types show characteristic patterns which are related to different modes of formation of the ores. Most of the apatite-bearing iron ores are associated with alkaline magmas with LREE/HREE fractionation varying from moderate to steep. Iron-apatite deposits in Posht-e-Badam Block (Central Iran) have a high concentration of REE (more than 1000 ppm up to 2.5%), and show a strong LREE/HREE ratio with a pronounced negative Eu anomaly. This REE pattern is typical of magmatic apatite and quiet distinct from sedimentary apatites (phosphorites) which have a low REE contents and Ce negative anomalies. On the other hand, they are comparable to the REE patterns of apatites in Kiruna-type iron ores in different parts of the world. The REE patterns of apatites, iron-apatite ores and iron ores are similar and only have different REE contents. This similarity indicates a genetic relation for these rocks. Most of the iron-apatite deposits in Central Iran have similar REE patterns too, which in turn show a genetic relation for all of these deposits. This similarity indicates a similar origin and processes in their genesis. There are some small intrusions around some of the iron-apatite deposits that are petrographically identified as syenite and gabbro. These intrusions also have REE patterns similar to that of iron-apatite ores. This demonstrates a genetic relation between these intrusions and iron-apatite ores. The REE patterns of apatites in different deposits of Posht-e-Badam Block iron-apatite ores show an affinity to alkaline to sub-alkaline magmas and rifting environment. The alkaline host rocks of Central Iran iron-apatite ores are clearly related to an extensional setting where rifting was important (SSE-NNW fault lines). A probable source for this large scale ore forming processes is relatively low partial melting of mantle rocks. The ores have originated by magmatic differentiation as a late phase in the volcanic cycle forming sub-surface injections or surface flows. These ores have formed during magmatism as immiscible liquids (silicate and Fe-P-rich magmatic liquids) which separated from strongly differentiated magmas aided by a large volatile and alkali element content. Separation of an iron oxide melt and the ensuing hydrothermal processes dominated by alkali metasomatism were both involved to different degrees in the formation of Posht-e-Badam Block iron-apatite deposits. We proposed that the separation of an iron oxide melt and the ensuing hydrothermal processes dominated by alkali metasomatism were both involved to different degrees in the formation of Posht-e-Badam Block iron-apatite deposits.

Mokhtari, Mir Ali Asghar; Zadeh, Ghader Hossein; Emami, Mohamad Hashem

2013-06-01

106

Effects of laser sintering processing parameters on the microstructure and densification of iron powder  

Microsoft Academic Search

The densification behavior and the attendant microstructural features of iron powder processed by direct laser sintering were investigated. The effects of processing parameters such as laser power, scan rate, scan line spacing, thickness of layer, scanning geometry and sintering atmosphere were studied. A specific energy input (?) was defined using the “energy conservation” rule to explore the effects of the

A Simchi; H Pohl

2003-01-01

107

Thermal fatigue behavior of an iron-based laser sintered material  

Microsoft Academic Search

Direct metal laser sintering is a rapid manufacturing technique to make intricate and near net-shaped parts. An iron-based laser sintered metal was studied to evaluate its thermal fatigue properties. The test was performed using cylindrical specimens in a high power induction heating system equipped with a laser strain gauge for a contactless surface strain measurement. Initiation of thermal fatigue cracks

Y. Wang; J. Bergström; C. Burman

2009-01-01

108

Method for the production of mineral wool and iron from serpentine ore  

DOEpatents

Magnesium silicate mineral wools having a relatively high liquidus temperature of at least about 1400.degree. C. and to methods for the production thereof are provided. The methods of the present invention comprise melting a magnesium silicate feedstock (e.g., comprising a serpentine or olivine ore) having a liquidus temperature of at least about 1400.degree. C. to form a molten magnesium silicate, and subsequently fiberizing the molten magnesium silicate to produce a magnesium silicate mineral wool. In one embodiment, the magnesium silicate feedstock contains iron oxide (e.g., up to about 12% by weight). Preferably, the melting is performed in the presence of a reducing agent to produce an iron alloy, which can be separated from the molten ore. Useful magnesium silicate feedstocks include, without limitation, serpentine and olivine ores. Optionally, silicon dioxide can be added to the feedstock to lower the liquidus temperature thereof.

O'Connor, William K. (Albany, OR); Rush, Gilbert E. (Scio, OR); Soltau, Glen F. (Lebanon, OR)

2011-10-11

109

A dynamic mathematical model of the complete grate\\/kiln iron–ore pellet induration process  

Microsoft Academic Search

Induration (drying and hardening) of iron ore pellets is an energy-intensive feed preparation step for both the blast furnace\\u000a and direct reduction routes to iron. It is commonly carried out by a ‘grate\\/kiln’ process. A mathematical model of the process\\u000a is described, in which mechanistic models of the grate furnace, kiln, and cooler are linked to enable simulation of the

J. A. Thurlby

1988-01-01

110

Structure and properties of sinter-bonded iron powder layers produced by hot pressing  

Microsoft Academic Search

1.A study was made of the effect of hot-pressing parameters on some properties of PZhlM iron powder layers sinter-bonded to Type 45 steel substrate.2.The variation of the density and properties of sinter-bonded layers with hot-pressing temperature, pressure, and time is similar to that characterizing the hot pressing of iron powder compacts, although the actual values of density obtained are slightly

V. A. Martynov; M. S. Koval'chenko; R. G. Berezin; V. P. Petrenko; N. V. Avdeev

1978-01-01

111

Changing patterns of trade in the world iron ore and steel market: An econometric analysis  

Microsoft Academic Search

The world iron ore and steel trade is undergoing significant restructuring, with rapidly developing economies in regions such as China, India, and South Korea emerging as key centers of growth in the sector. Alternatively, the industrialized economies of the European Union, Japan, and North America are gradually losing their dominant role. This paper describes an econometric trade model that has

B. Stephen Labson

1997-01-01

112

Effect of suction on the mechanical behaviour of iron ore rock  

Microsoft Academic Search

The effect of suction on the behaviour of iron ore has been studied from both physical and mechanical points of view. The porosity and the suction phenomena have been analysed using different experimental techniques. Uniaxial compressive tests on partially saturated samples have shown that the suction is responsible for strength and cohesion improvement. Considering the theory of partially saturated porous

Dragan Grgic; Richard Giot; Françoise Homand; Albert Giraud

2005-01-01

113

Paleomagnetism of the late Ordovician Neda iron ore from Wisconsin, Iowa and Illinois  

Microsoft Academic Search

The Neda Iron Formation (Latest Ordovician) is a hematite and goethite rich oolitic ore which occurs in lens shaped deposits on top of the Maquoketa shale (Late Ordovician), at only few locations in Wisconsin, Iowa and Illinois. Thermal demagnetization of samples from these three states, indicates the remanence is carried by hematite. Chemical demagnetization suggests the remanence is produced by

William F. Kean

1981-01-01

114

DEWATERING OF IRON ORE MINES AND CAPABILITY TO PREDICT ENVIRONMENTAL IMPACTS - THE EXPERIENCE OF MBR  

Microsoft Academic Search

The Águas Claras and Mutuca iron ore mines, reached the watertable in the 80's, starting the dewatering by using series of deep wells. In the 90's, some communities located near the mines, complained about the possible interference in the stream's outflows and so, the areas covered by hydrogeological studies were enlarged in order to embrace the neighbourhood of the mines.

Leandro Quadros Amorim; Cesar Augusto; Paulino Grandchamp; Antônio Carlos Bertachini

2001-01-01

115

The extraction of lead from its ores by the iron-reduction process: A historical perspective  

Microsoft Academic Search

The iron-reduction process for extracting lead from its ores, as practiced in different parts of the world, is reviewed and discussed in this paper based on literary and documentary evidence. It has been shown that the early 14th century Indian reference of Thakkura Pheru appears to be the first evidence on this subject. This process was most vigorously adopted for

R. K. Dube

2006-01-01

116

Recovery of iron as a form of ferrous acetate precipitates from low-grade magnetite ore  

Microsoft Academic Search

This paper describes the recovery process of iron as a form of ferrous acetate from low-grade magnetite ore (Shinyemi Mine, Gangwon province, Korea). The magnetically separated magnetite powder was dissolved in aqueous oxalic acid solution. The dissolution fraction of magnetite concentrates was measured as a function of initial pH, reaction temperature and oxalic acid concentration. Optimum conditions for dissolution of

Jae-Kyeong Kim; Han-Sang Oh; Chang-Wha Jo; Yong-Jae Suh; Hee-Dong Jang; Kee-Kahb Koo

2010-01-01

117

Studies on the effect of flocculant adsorption on the dewatering of iron ore tailings  

Microsoft Academic Search

The adsorption characteristics of polyacrylamide polymer on iron ore tailings have been studied to understand the mechanism of adsorption. Adsorptions of both the anionic and non-ionic flocculants were analyzed using Langmuir isotherm and Freundlich isotherm. It was found that in comparison to the Langmuir model the Freundlich model was a better fit to the adsorption data according to the minimum

M. Dash; R. K. Dwari; S. K. Biswal; P. S. R. Reddy; P. Chattopadhyay; B. K. Mishra

2011-01-01

118

Sampling, Characterization, and Evaluation of Midwest Clays for Iron Ore Pellet Bonding.  

National Technical Information Service (NTIS)

The potential of using glacial lake clay from Minnesota, as well as other areas, as a binder for iron ore pellets was investigated. The best clay-characterizing procedures for predicting binder effectiveness were the cation exchange capacity using the met...

L. A. Haas J. A. Aldinger R. L. Blake S. A. Swan

1987-01-01

119

Binding mechanisms in wet iron ore green pellets with a bentonite binder  

Microsoft Academic Search

Fundamental research during the past decade has been focussed on understanding the role of viscous forces on agglomerate deformability and strength. Much of this work has been done on glass spheres using Newtonian liquids as a binder. In this work, we show the variations in plasticity and strength of magnetite iron ore green pellets with varying liquid saturations and binder

S. P. E. Forsmo; A. J. Apelqvist; B. M. T. Björkman; P.-O. Samskog

2006-01-01

120

Solution of one problem of control connected with the reduction of iron-ore pellets  

Microsoft Academic Search

The article examines the mathematical model of the process of heating iron-ore pellets, and a gas blown through them, by high-frequency currents, On the basis of the solution of the problem of control it becomes possible to evaluate the efficiency of the heater and to choose the optimum operating conditions for it.

V. B. Glasko; I. D. Kulagin; A. P. Matytsyn; M. K. Trubetskov

1984-01-01

121

Testing of Northern Michigan and Wisconsin Glacial Lake Clays for Utilization as Iron Ore Pellet Binder.  

National Technical Information Service (NTIS)

Glacial lake clay deposits in northern Michigan and Wisconsin were sampled, tested and found to be unsuited for use as a bonding agent in iron ore pellet manufacturing. Although the project effort gave negative results, this report has been prepared to de...

W. S. Miska

1968-01-01

122

The determination of porosity in iron ore green pellets by packing in silica sand  

Microsoft Academic Search

Porosity is a very important property of iron ore green pellets. At LKAB, the mercury porosimeter was replaced some years ago by the GeoPyc instrument, in which the sample volume is measured by packing in silica sand. Some critical features of the GeoPyc measurement are pointed out in this study. The green pellets need to be strengthened by spraying with

S. P. E. Forsmo; J. P. Vuori

2005-01-01

123

Quantitative image analysis of bubble cavities in iron ore green pellets  

Microsoft Academic Search

Scanning electron microscopy and image analysis was used for quantitative analysis of bubble cavities in iron ore green pellets. Two types of pellets prepared with and without addition of flotation reagent prior to balling were studied. The bubble cavity porosity amounted to 2.8% in the pellets prepared without addition of flotation reagent prior to balling. When flotation reagent was added

I. U. Bhuiyan; J. Mouzon; S. P. E. Forsmo; J. Hedlund

2011-01-01

124

Convective drying of an individual iron ore pellet – Analysis with CFD  

Microsoft Academic Search

The objective of this paper is to model convective drying of an individual iron ore pellet placed in a free stream of air with the aim to clarify the different stages of drying. A numerical model taking into account capillary flow of liquid moisture and internal vapor flow is developed and implemented in a commercial available software for Computational Fluid

Anna-Lena Ljung; T. Staffan Lundström; B. Daniel Marjavaara; Kent Tano

2011-01-01

125

Influence of Air Humidity on Drying of Individual Iron Ore Pellets  

Microsoft Academic Search

The influence of air humidity on drying is investigated at four inlet air dew points; Tdp = 273, 292, 313, and 333 K. A numerical model taking into account capillary transport of liquid and internal evaporation is applied to a spherical geometry representative for an individual iron ore pellet. Drying simulations are carried out with commercial computational fluid dynamic (CFD) software and the

Anna-Lena Ljung; T. Staffan Lundström; B. Daniel Marjavaara; Kent Tano

2011-01-01

126

Crumbling criteria for wet iron-ore pellets dried by the laminar convection process  

Microsoft Academic Search

The paper presents a study of the changes in the Posnov and Kirpichev numbers and of crack formation during the intensive laminar convective drying of iron-ore pellets. A relation is established between the criterion of crack formation and the hydrophysical properties of a nodulized sample.

V. M. Vityugin; T. G. Leont'eva; V. P. Gusev

1971-01-01

127

Solution of one problem of control connected with the reduction of iron-ore pellets  

NASA Astrophysics Data System (ADS)

The article examines the mathematical model of the process of heating iron-ore pellets, and a gas blown through them, by high-frequency currents, On the basis of the solution of the problem of control it becomes possible to evaluate the efficiency of the heater and to choose the optimum operating conditions for it.

Glasko, V. B.; Kulagin, I. D.; Matytsyn, A. P.; Trubetskov, M. K.

1984-12-01

128

On-line 3D surface measurement of iron ore green pellets  

Microsoft Academic Search

Ongoing research into an industrial prototype 3D imag- ing and analysis system is presented for non-contact mea- surement of the size of iron ore green pellets on the conveyor belt. The imaging hardware has been installed at a pellet production plant and captures 3D surface data of pellets on the conveyor belt. Segmentation methods based on mathe- matical morphology are

Matthew J. Thurley

2006-01-01

129

The effect of copper on iron reduction and its application to the determination of total iron content in iron and copper ores by potassium dichromate titration.  

PubMed

The International Standard Organization (ISO) specifies two titrimetric methods for the determination of total iron content in iron ores using potassium dichromate as titrant after reduction of the iron(III) by tin(II) chloride and/or titanium(III) chloride. These two ISO methods (ISO2597-1 and ISO2597-2) require nearly boiling-point temperature for iron(III) reduction and suffer from copper interference and/or mercury pollution. In this study, potassium borohydride was used for reduction of iron(III) catalyzed by copper ions at ambient temperatures. In the absence of copper, iron(III) reduction by potassium borohydride was sluggish while a trace amount of copper significantly accelerated the reduction and reduced potassium borohydride consumption. The catalytic mechanism of iron(III) reduction in sulfuric acid and hydrochloric acid was investigated. Potassium borohydride in sodium hydroxide solution was stable without a significant degradation within 24h at ambient conditions and the use of potassium borohydride prepared in sodium hydroxide solution was safe and convenient in routine applications. The applicability of potassium borohydride reduction for the determination of total iron content by potassium dichromate titration was demonstrated by comparing with the ISO standard method using iron and copper ore reference materials and iron ore samples. PMID:24840467

Hu, Hanjun; Tang, Yang; Ying, Haisong; Wang, Minghai; Wan, Pingyu; Jin Yang, X

2014-07-01

130

Blending of iron and silicon carbide powders for producing metal matrix composites by laser sintering process  

Microsoft Academic Search

Purpose – The purpose of this paper is to study the effect of blending time, SiC content and fill ratio on the homogeneity of iron-silicon carbide powder mixture, blended in double-cone blender; to evaluate density, microstructure and micro hardness of laser sintered iron and iron-SiC specimens; and study the feasibility of building a complex iron-SiC metal matrix composite (MMC) part

Cheekur Krishnamurthy Srinivasa; Chinnakurli Suryanarayana Ramesh; S. K. Prabhakar

2010-01-01

131

[Mineralogical effect correction for pressed iron ore samples in wavelength dispersive X-ray fluorescence analysis].  

PubMed

The possibility of correcting mineralogical effect for pressed powder pellets of iron ore samples was studied in wavelength dispersive X-ray fluorescence analysis of major and minor elements with 10 Chinese iron ore CRMs. Two methods were applied to reduce the influence of mineralogical effect. The first one is to check 20 angles for every sample before measurement to correct peak shift; another method is replacing peak intensity with peak area of the analytical line to correct the shape distortion of the spectrum. The K factors of the two methods for each element were compared to those from regular measurements. The results show that the calibration for most of the elements was improved, although to different degrees. The improvement in the calibration for sulfur is evident. The calibration for other elements can meet the general requirements except for total iron. PMID:18844184

Shan, Hua-Zhen; Zhuo, Shang-Jun; Sheng, Cheng; Shen, Ru-Xiang

2008-07-01

132

Paleomagnetism of the Late Ordovician Neda iron ore from Wisconsin, Iowa and Illinois  

NASA Astrophysics Data System (ADS)

The Neda Iron Formation (latest Ordovician) is a hematite and goethite rich oolitic ore which occurs in lens shaped deposits on top of the Maquoketa shale (Late Ordovician), at only a few locations in Wisconsin, Iowa and Illinois. Thermal demagnetization of samples from these three states, indicates the remanence is carried by hematite. Chemical demagnetization suggests the remanence is produced by the interstitial material rather than the oolites. The paleopole averaged for all sites from 25 samples of the Neda ore is at S45.4°, W48° (?95 = 16°). This pole position is similar to late Mississippian to early Permian of North America rather than latest Ordovician. The difference between the known age of the Neda and the time of magnetization suggests that the hematite in the ore was produced from dehydration of goethite probably as a result of tectonic uplift in Wisconsin during late Mississippian time. In addition, these results add evidence to the theory that the Neda ore was formed in two stages. The oolites were produced in a near shore environment during the shoaling of the Ordovician seas. The oolites were then incorporated in iron rich muds. Burial and later uplift dehydrated the iron hydroxide to hematite.

Kean, William F.

133

Mössbauer studies of iron ore from East Awinat mountains in Libya  

NASA Astrophysics Data System (ADS)

In this paper, we report studies of local and imported iron ores using the techniques of Mössbauer spectroscopy, X-ray diffraction, and chemical analysis. Results from Mössbauer spectroscopy and X-ray diffraction of the two ores indicate that the raw materials consist mainly of hematite with a magnetic field of 517 kOe. The d-spacings are consistent with ?-Fe2O3. A series of reduction processes in an H2 environment at 410 °C for the local ore was performed in order to understand the kinetics of reduction. The reduction was complete after 5 h and the spectra reveal only an ?-Fe phase with a hyperfine magnetic field of 330 kOe. On the other hand, the reduced pellets, from Misratah's Iron and Steel Factory (imported iron ore), reveal the presence of an additional phase. This phase was identified as ?9-carbide with a magnetic field of 208 kOe and an isomer shift of 0.22 mm/s.

Ellid, M. S.; Fallagh, F.

1994-12-01

134

Reducing acid leaching of manganiferous ore: Effect of the iron removal operation on solid waste disposal  

SciTech Connect

The process of reducing acid leaching of manganiferous ore is aimed at the extraction of manganese from low grade manganese ores. This work is focused on the iron removal operation. The following items have been considered in order to investigate the effect of the main operating conditions on solid waste disposal and on the process costs: (i) type and quantity of the base agent used for iron precipitation, (ii) effective need of leaching waste separation prior to the iron removal operation, (iii) presence of a second leaching stage with the roasted ore, which might also act as a preliminary iron removal step, and (iv) effect of tailings washing on the solid waste classification. Different base compounds have been tested, including CaO, CaCO{sub 3}, NaOH, and Na{sub 2}CO{sub 3}. The latter gave the best results concerning both the precipitation process kinetics and the reagent consumption. The filtration of the liquor leach prior to iron removal was not necessary, implying significant savings in capital costs. A reduction of chemical consumption and an increase of manganese concentration in the solution were obtained by introducing secondary leaching tests with the previously roasted ore; this additional step was introduced without a significant decrease of global manganese extraction yield. Finally, toxicity characteristic leaching procedure (TCLP) tests carried out on the leaching solid waste showed: (i) a reduction of arsenic mobility in the presence of iron precipitates, and (ii) the need for a washing step in order to produce a waste that is classifiable as not dangerous, taking into consideration the existing Environmental National Laws.

De Michelis, Ida; Ferella, Francesco [University of L'Aquila, Department of Chemistry, Chemical Engineering and Materials, Monteluco di Roio, 67040 L'Aquila (Italy); Beolchini, Francesca [Polytechnic University of Marche, Department of Marine Sciences, Via Brecce Bianche, 60131 Ancona (Italy)], E-mail: f.beolchini@univpm.it; Veglio, Francesco [University of L'Aquila, Department of Chemistry, Chemical Engineering and Materials, Monteluco di Roio, 67040 L'Aquila (Italy)

2009-01-15

135

Iron ore reduction in a continuously operated multistage lab-scale fluidized bed reactor—Mathematical modeling and experimental results  

NASA Astrophysics Data System (ADS)

Industrial-scale fluidized bed processes for iron ore reduction ( e.g., FIOR and FINMET) are operated by continuous feeding of ore, while laboratory tests are mostly performed under batchwise operation. The reduction behavior under continuous operation is influenced by both the residence time of the iron ore particles and the reduction kinetics, which is obtained by batch tests. In a mathematical model for such a process, the effect of both phenomena has to be considered. The residence time distribution of iron ore particles in a laboratory fluidized bed reactor was obtained by measuring the response of a step input and described by mathematical models similar to a continuously stirred tank reactor. In the same reactor, reduction tests with continuous feeding of iron ore were performed. Based on batch tests in a fluidized bed reactor, a mathematical model was developed to describe the kinetics of iron ore reduction under fluidized bed conditions. This kinetic model was combined with the fluidized bed reactor model to describe continuous iron ore reduction. In this detailed model, the change of gas composition while rising in the fluidized bed was considered. The degree of reduction and the gas conversion for reactors in series were calculated. The results obtained by the mathematical model were compared with experimental data from the laboratory-scale reactor.

Thurnhofer, A.; Schuster, S.; Löffler, G.; Habermann, A.; Winter, F.; Hofbauer, H.; Schenk, J. L.; Zirngast, J.

2006-08-01

136

Optimization model coupling both chemical compositions and high-temperature characteristics of sintering materials for sintering burden  

NASA Astrophysics Data System (ADS)

We developed a mathematical optimization model coupling chemical compositions and high-temperature characteristics of sintering materials, targeting the best quality and lowest cost. The simplex algorithm was adopted to solve this model. Four kinds of imported iron ores, two kinds of Chinese iron ore concentrates, and two kinds of fluxes were selected to verify both the model and the algorithm. The results confirmed the possibility of considering both chemical compositions and high-temperature characteristics of iron ores in the optimization model. This model provides a technical roadmap to obtain a precise mathematical correlation between the lowest cost and the grade of iron in sinters based on the condition of given raw materials, which can provide a reference to adjust the grade of iron in the sintering process for enterprise.

Li, Ke-jiang; Zhang, Jian-liang; Liu, Zheng-jian; Su, Bu-xin; Kong, Ling-tan; Yang, Tian-jun

2014-03-01

137

Iron and manganese removal by using manganese ore constructed wetlands in the reclamation of steel wastewater.  

PubMed

To reclaim treated steel wastewater as cooling water, manganese ore constructed wetland was proposed in this study for the removal of iron and manganese. In lab-scale wetlands, the performance of manganese ore wetland was found to be more stable and excellent than that of conventional gravel constructed wetland. The iron and manganese concentration in the former was below 0.05 mg/L at hydraulic retention time of 2-5 days when their influent concentrations were in the range of 0.16-2.24 mg/L and 0.11-2.23 mg/L, respectively. Moreover, its removals for COD, turbidity, ammonia nitrogen and total phosphorus were 55%, 90%, 67% and 93%, respectively, superior to the corresponding removals in the gravel wetland (31%, 86%, 58% and 78%, respectively). The good performance of manganese ore was ascribed to the enhanced biological manganese removal with the aid of manganese oxide surface and the smaller size of the medium. The presence of biological manganese oxidation was proven by the facts of good manganese removal in wetlands at chemical unfavorable conditions (such as ORP and pH) and the isolation of manganese oxidizing strains from the wetlands. Similar iron and manganese removal was later observed in a pilot-scale gravel-manganese-ore constructed wetland, even though the manganese ore portion in total volume was reduced from 100% (in the lab-scale) to only 4% (in the pilot-scale) for the sake of cost-saving. The quality of the polished wastewater not only satisfied the requirement for cooling water but also suitable as make-up water for other purposes. PMID:19443107

Xu, Jing-Cheng; Chen, Gu; Huang, Xiang-Feng; Li, Guang-Ming; Liu, Jia; Yang, Na; Gao, Sai-Nan

2009-09-30

138

Upgrading of Low-Grade Manganese Ore by Selective Reduction of Iron Oxide and Magnetic Separation  

NASA Astrophysics Data System (ADS)

The utilization of low-grade manganese ores has become necessary due to the intensive mining of high-grade ores for a long time. In this study, calcined ferruginous low-grade manganese ore was selectively reduced by CO, which converted hematite to magnetite, while manganese oxide was reduced to MnO. The iron-rich component was then separated by magnetic separation. The effects of the various reduction parameters such as particle size, reduction time, temperature, and CO content on the efficiency of magnetic separation were studied by single-factor experiments and by a comprehensive full factorial experiment. Under the best experimental conditions tested, the manganese content in the ore increased from around 36 wt pct to more than 44 wt pct, and almost 50 wt pct of iron was removed at a Mn loss of around 5 pct. The results of the full factorial experiments allowed the identification of the significant effects and yielded regression equations for pct Fe removed, Mn/Fe, and pct Mn loss that characterize the efficiency of the upgrading process.

Gao, Yubo; Olivas-Martinez, M.; Sohn, H. Y.; Kim, Hang Goo; Kim, Chan Wook

2012-12-01

139

Magneto-Mineralogical and Physico-Chemical Characterization of the Peña Colorada Iron-Ore, México: Genetic Implications  

NASA Astrophysics Data System (ADS)

Peña Colorada iron-ores represented by massive-disseminated ore and intergranular magnetite ore. Mössbauer spectroscopy shows differences in both magnetite-ores. Magnetite of massive-disseminated ore has a stable structure, with Fe in oxidation state III (Fe2O3) and Fe in oxidation state II (FeO). Magnetite of intergranular ore has a micro-margin of replacement with particular properties, because have radicals (OH-) in positions corresponding to oxygen, shifting alternatively Fe II by Fe III. Chlorite associated to intergranular magnetite is classified as chamosite (berthierine variety). Berthierine presents structural differences by X-ray diffraction at 550 oC temperature loosing its cristallinity becoming amorphous. Differential and gravimetric thermal analyses of berthierine show typical endo-thermal reactions at 430 oC and 510 oC by dehydratation, and endo-thermal reaction at 980 oC by structural change. We propose contact metamorphism and a hydrothermal phase, pursued by disseminated-massive magnetite deposition as the main processes acting in the formation of the Peña Colorada iron-ore deposit. Intergranular ore is sedimentary exhalative origin deposited together with berthierine. Massive-disseminated and intergranular ore have similar geochemical evolution and different conditions of deposit. Curie temperatures are mostly 580 ± 5oC typical of magnetite. Hysteresis parameters indicate that most samples present PSD to MD behavior. AF demagnetization and isothermal remanent magnetization (IRM) acquisition curves show that NRM and laboratory remanence are carried by MD magnetite in iron ores and PSD-SD magnetite in host rocks. Magnetic Force Microscope images for both ore minerals show good and diffuse magnetic domain definition, respectively. Lack of clarity of the intergranular ore image is due to environment, temperature and formation conditions related to magnetostatic changes and magnetocrystalline anisotropy of grains.

Rivas, M. L.; Alva-Valdivia, L. M.; Urrutia, J.; Gogitchaichvili, A.

2004-05-01

140

Environmentally safe design of tailing dams for the management of iron ore tailings in Indian context.  

PubMed

The need for the disposal of iron ore tailings in an enviornmentally firiendly manner is of great concern. This paper investigates the soil engineering properties for the construction of iron ore tailing dam, its foundation, construction materials and design data used for the construction analysis of the tailing dam. Geophysical investigations were carried out to establish the bedrock below the spillway. A computer programme taking into account the Swedish Slip Circle Method of analysis was used in the stability analysis of dam. It also focuses on the charactierstics of the tailings reponsible for the determination of optimum size of tailing pond for the containment of the tailings. The studies on the settling characteristics of tailings indicate much less area in comparison to the area provided in the existing tailing ponds in India. In the proposed scheme, it is suggested to provide an additional unit of sedimentation tank before the disposal of tailings to the tailing pond. PMID:17051916

Ghose, Mrinal K; Sen, P K

2005-10-01

141

Closed system Fischer-Tropsch synthesis over meteoritic iron, iron ore and nickel-iron alloy. [deuterium-carbon monoxide reaction catalysis  

NASA Technical Reports Server (NTRS)

Experiments were performed in which meteoritic iron, iron ore and nickel-iron alloy were used to catalyze (in Fischer-Tropsch synthesis) the reaction of deuterium and carbon monoxide in a closed vessel. Normal alkanes and alkenes and their monomethyl substituted isomers and aromatic hydrocarbons were synthesized. Iron oxide and oxidized-reduced Canyon Diablo used as Fischer-Tropsch catalysts were found to produce aromatic hydrocarbons in distributions having many of the features of those observed in carbonaceous chondrites, but only at temperatures and reaction times well above 300 C and 6-8 h.

Nooner, D. W.; Gibert, J. M.; Gelpi, E.; Oro, J.

1976-01-01

142

Mössbauer and XRD Comparative Study of Host Rock and Iron Rich Mineral Samples from Paz del Rio Iron Ore Mineral Mine in Colombia  

Microsoft Academic Search

A comparative study between the host rock and the iron rich mineral samples from the Paz del Rio iron ore mineral mine in Colombia was performed using X-ray diffraction and Mössbauer spectroscopy. Diffraction results of the iron rich mineral sample show that goethite, hematite, quartz, kaolinite and siderite are the main phases, and that a small amount of illite is

M. Fajardo; G. A. Pérez Alcázar; A. M. Moreira; N. L. Speziali

2004-01-01

143

Continuous X-ray fluorescence analysis of iron ore mixtures in the production of agglomerate  

Microsoft Academic Search

A system is developed for the continuous control of the chemical composition of iron ore mixtures (IOMs) by X-ray fluorescence analysis (XRF) directly on the conveyor belt. The system was found to be efficient under the conditions of mining and smelting production\\u000a at the Magnitogorsk Metallurgical Combine. The proposed XRF method does not require sampling; provides the required accuracy;\\u000a and

N. V. Alov; A. I. Volkov; A. I. Usherov; E. N. Ishmets’ev; E. V. Usherova

2010-01-01

144

The extraction of lead from its ores by the iron-reduction process: A historical perspective  

Microsoft Academic Search

The iron-reduction process for extracting lead from its ores, as practiced in different parts of the world, is reviewed and\\u000a discussed in this paper based on literary and documentary evidence. It has been shown that the early 14th century Indian reference\\u000a of Thakkura Pher? appears to be the first evidence on this subject. This process was most vigorously adopted for

R. K. Dube

2006-01-01

145

CO 2 emission reduction costs for iron ore-based steelmaking in Sweden  

Microsoft Academic Search

Possibilities to reduce CO2 emissions and related costs at Swedish iron-ore based steelmaking in Sweden have been estimated. An evaluation of the direct impact on costs for emission-reducing measures due to the inclusion in the EU ETS is also made.Two different abatement options, based on previously implemented measures at SSAB Oxelösund as well as some future measures that could be

Malin Ribbenhed; Mathias Thorén; Catarina Sternhufvud

2008-01-01

146

Mathematical model for a straight grate iron ore pellet induration process of industrial scale  

Microsoft Academic Search

A mathematical model is developed for induration of the iron-ore pellets in an industrial-scale plant based on the laws of mass, heat and momentum transfer. Physicochemical processes occurring during the induration of pellets such as drying of moisture, calcination of limestone and coke-magnetite reaction are considered to evaluate the gradient of temperature within the pellets. Differential equations describing transport phenomena

S. K. Sadrnezhaad; A. Ferdowsi; H. Payab

2008-01-01

147

Studies on the influence of a flotation collector reagent on iron ore green pellet properties  

Microsoft Academic Search

The properties of iron ore green pellets with varying additions of a surface-active flotation collector reagent (Atrac) were studied by small-scale balling. The compression strength and plasticity were measured with a semi-automatic measuring device and the pressure curves were saved and subjected to further mathematical treatment. The green pellet breakage was also filmed with a high-speed camera. Adding Atrac to

S. P. E. Forsmo; B. M. T. Björkman; P.-O. Samskog

2008-01-01

148

Redaction of iron ore pellets with domestic lignite coal in a rotary tube furnace  

Microsoft Academic Search

In the present work, reduction of iron ore pellets with domestic lignite coal in a semi-pilot scale rotary tube furnace was investigated. The variables of the experimental study were the coal consumption ratio (CFFixFeTot), the temperature of the environment and the residence time. At the temperature of 1000°C and a coal consumption ratio of 0.40, reduction process was completed at

N. Narçin; S. Aydln; K. ?e?en; F. Dikeç

1995-01-01

149

A dynamic mathematical model of the complete grate/kiln iron-ore pellet induration process  

NASA Astrophysics Data System (ADS)

Induration (drying and hardening) of iron ore pellets is an energy-intensive feed preparation step for both the blast furnace and direct reduction routes to iron. It is commonly carried out by a ‘grate/kiln’ process. A mathematical model of the process is described, in which mechanistic models of the grate furnace, kiln, and cooler are linked to enable simulation of the entire process. The model includes equations for the gas stream pressure balances and process controller responses, and provides dynamic solutions. The validation of the model for an operating plant is discussed and steady-state solutions are compared with data from the plant.

Thurlby, J. A.

1988-02-01

150

Sulphur isotopes in Lower Proterozoic iron and sulphide ores in northern Sweden  

NASA Astrophysics Data System (ADS)

The present investigation deals with sulphur isotope distribution in Lower Proterozoic iron and sulphide mineralizations in northern Sweden. The contrasting sulphur isotope patterns are indicative of different genesis. Some 267 sulphur isotope analyses of pyrite, pyrrhotite, chalcopyrite, sphalerite, galena and bornite from 23 occurrences have been performed. Some deposits exhibit uniform compositions, although the mean ? 34S values are clearly different, while other mineralizations have widely fluctuating values. The ? 34S values in syngenetic, exhalative sedimentary skarn iron ores, quartz-banded iron ores and sulphide mineralizations of the 2.0 2.5 Ga old (Lapponian) Greenstone group show a large spread, supporting the existence of bacteriogenic sulphate reduction processes. The spread of the sulphur isotope values ( ? 34S = -8 to +25‰), and the non-equilibrium conditions, point to a biogenic rather than to an inorganic reduction of seawater sulphate. The isotopic composition of the sulphides in the epigenetic Lannavaara iron ores which were formed by a hydrothermal scapolite-tourmalme-related process, indicates a sulphur source similar to that of the Greenstone group. The ? 34S values of Cu-(Au) sulphide mineralizations in the Malmberget region (e.g. Aitik), which were formed by a similar process and hosted by the volcanics-volcanoclastics of the 1.9 Ga old Porphyry group, are slightly below zero ‰, indicating a magmatic origin. The existence of different sulphur compositions for these mineralization types formed by a similar hydrothermal process, probably reflects the influence of the host rock, the solutions leaching pre-existing sulphides. In southern Norrbotten, epigenetic, Cu-Zn-Pb veintype mineralizations in metavolcanics and metasediments have ? 34S values close to zero ‰ indicating a magmatic origin. The sulphur isotope data of the volcanogenic, massive sulphide ores of the Skellefte district, in particular the ores of the Adak dome, are close to zero ‰. The lead and sulphur isotopic features of the sulphides in northern Sweden show that the ore-forming processes were of a different nature on both sides of the Archean-Proterozoic border, implying differences in the crustal development. Lead isotopes show that lead was mobilized from specific sources on each side of the border. The sulphur of the sulphides in the Greenstone group in NE Sweden and Finland was introduced by sedimentary processes, whereas the sulphur of the sulphide occurrences towards the SW, mainly in the Porphyry group, is dominated by a magmatic sulphur component.

Frietsch, R.; Billström, K.; Perdahl, J. A.

1995-06-01

151

Mineralogy and trace-element geochemistry of the high-grade iron ores of the Águas Claras Mine and comparison with the Capão Xavier and Tamanduá iron ore deposits, Quadrilátero Ferrífero, Brazil  

Microsoft Academic Search

Several major iron deposits occur in the Quadrilátero Ferrífero (QF), southeastern region of Brazil, where metamorphosed and heterogeneously deformed banded iron formation (BIF) of the Cauê Formation, regionally called itabirite, was transformed into high- (Fe >64%) and low-grade (30% < Fe < 64%) hematite ores. Based on their mineralogical composition, three major types of itabirites occur in the QF: siliceous,

Carlos Alberto Spier; Sonia Maria Barros de Oliveira; Carlos Alberto Rosière; José Domingos Ardisson

2008-01-01

152

Iron ore industry emissions as a potential ecological risk factor for tropical coastal vegetation.  

PubMed

In the coastal zone of the Espírito Santo state, Brazil, fragments of restinga, which form a natural ecosystem, share their space with an increasing number of iron ore industries. The iron ore dust and SO(2) originating from the industry processing activities can interfere with the vegetation of the adjacent ecosystems at various levels. This study was undertaken in order to evaluate the effects of industry emissions on representative members of the restinga flora, by measuring physiological and phenological parameters. Foliar samples of Ipomoea pes caprae, Canavalia rosea, Sophora tomentosa, and Schinus terebinthifolius were collected at three increasing distances from an ore industry (1.0, 5.0, and 15.0 km), and were assessed for their dust deposition, chlorophyll, and Fe content. Phenological monitoring was focused on the formation of shoots, flowers, and fruits and was also performed throughout the course of a year. The results showed that the edaphic characteristics and the mineral constitutions of the plants were affected by industry emissions. In addition, the chlorophyll content of the four species increased with proximity to the industry. Phenological data revealed that the reproductive effort, as measured by fruit production, was affected by emissions and S. tomentosa was the most affected species. The use of an integrative approach that combines biochemical and ecological data indicates that the restinga flora is under stress due to industry emissions, which on a long-term basis may put the ecosystem at risk. PMID:18320266

Kuki, Kacilda N; Oliva, Marco A; Pereira, Eduardo G

2008-07-01

153

Iron Ore Industry Emissions as a Potential Ecological Risk Factor for Tropical Coastal Vegetation  

NASA Astrophysics Data System (ADS)

In the coastal zone of the Espírito Santo state, Brazil, fragments of restinga, which form a natural ecosystem, share their space with an increasing number of iron ore industries. The iron ore dust and SO2 originating from the industry processing activities can interfere with the vegetation of the adjacent ecosystems at various levels. This study was undertaken in order to evaluate the effects of industry emissions on representative members of the restinga flora, by measuring physiological and phenological parameters. Foliar samples of Ipomoea pes caprae, Canavalia rosea, Sophora tomentosa, and Schinus terebinthifolius were collected at three increasing distances from an ore industry (1.0, 5.0, and 15.0 km), and were assessed for their dust deposition, chlorophyll, and Fe content. Phenological monitoring was focused on the formation of shoots, flowers, and fruits and was also performed throughout the course of a year. The results showed that the edaphic characteristics and the mineral constitutions of the plants were affected by industry emissions. In addition, the chlorophyll content of the four species increased with proximity to the industry. Phenological data revealed that the reproductive effort, as measured by fruit production, was affected by emissions and S. tomentosa was the most affected species. The use of an integrative approach that combines biochemical and ecological data indicates that the restinga flora is under stress due to industry emissions, which on a long-term basis may put the ecosystem at risk.

Kuki, Kacilda N.; Oliva, Marco A.; Pereira, Eduardo G.

2008-07-01

154

Calibration Equations for Energy-Dispersive XRF Determination of Copper, Iron and Lead in Copper Ore Slurries.  

National Technical Information Service (NTIS)

Calibration equations for the X-ray fluorescence analysis determination of copper, iron and lead in copper ore slurries have been derived and tested. The measurement of Ksub( alpha ) lines of copper and iron and Lsub( alpha ) line of lead excited by rays ...

M. Lakosz

1976-01-01

155

Elemental analysis of some Egyptian ores and industrial iron samples by neutron activation analysis.  

PubMed

Elemental analysis of iron ore samples and first industrial iron production prepared by the Egyptian Iron and Steel Company of Helwan near Cairo were determined by instrumental neutron activation analysis technique. Five samples from each kind were irradiated for a 48 hours at a thermal neutron flux of 4 x 10(12) n/(cm2.s) in the first Egyptian research reactor ET-RR-1. Also the Pneumatic irradiation Rabbit system (PIRS) attached to the reactor in Inshass, was used to measure the elements of short-life time. The gamma-ray spectra were recorded by means of the hyper pure germanium detection system. The concentration percentage values of major, minor and trace elements are presented. The long and short lived isotopes were considered. A comparative study and a discussion on the elemental concentration values are given. PMID:11590711

Srror, A; Abdel-Basset, N; Abdel-Haleem, A S; Hassan, A M

2001-01-01

156

Fatigue and Microstructure of Iron Based Sintered Alloys  

Microsoft Academic Search

Direct metal laser sintering is a relatively new fabrication technique for near net shaped parts. It is for instance extensively used for die parts when making industrial forming tools. Another, yet more unexplored process is the starch consolidation method using environmentally friendly starch and water to shape components. A powder suspension is transformed into a green body by starch swelling

Yu WANG; Jens Bergström

2007-01-01

157

Carbothermic Reduction of Nickeliferous Laterite Ores for Nickel Pig Iron Production in China: A Review  

NASA Astrophysics Data System (ADS)

Both the consumption and production of crude stainless steel in China rank first in the world. In 2011, the nickel production in China amounted to 446 kilotons, with the proportion of electrolytic nickel and nickel pig iron (NPI) registering 41.5% and 56.5%, respectively. NPI is a low-cost feedstock for stainless steel production when used as a substitute for electrolytic nickel. The existing commercial NPI production processes such as blast furnace smelting, rotary kiln-electric furnace smelting, and Krupp-Renn (Nipon Yakin Oheyama) processes are discussed. As low-temperature (below 1300°C) reduction of nickeliferous laterite ores followed by magnetic separation could provide an alternative avenue without smelting at high temperature (~1500°C) for producing ferronickel with low cost, the fundamentals and recent developments of the low-temperature reduction of nickeliferous laterite ores are reviewed.

Rao, Mingjun; Li, Guanghui; Jiang, Tao; Luo, Jun; Zhang, Yuanbo; Fan, Xiaohui

2013-11-01

158

Laser sintering of separated and uniformly distributed multiwall carbon nanotubes integrated iron nanocomposites  

NASA Astrophysics Data System (ADS)

Uniform distribution of carbon nanotubes (CNTs) in metal matrix during additive manufacturing of nanocomposites is always a challenge since the CNTs tend to aggregate in the molten pool. In this study, Multiwall carbon nanotubes (MWNTs) were separated and distributed uniformly into iron matrix by laser sintering process. MWNTs and iron powders were mixed together by magnetic stir, coated on steel 4140 surface, followed by laser sintering. Due to the fast heating and cooling rate, the CNTs are evenly distributed in the metal matrix. The temperature field was calculated by multiphysics simulation considering size effects, including size dependent melting temperature, thermal conductivity, and heat capacity. The SEM, TEM, and XRD were used to understand the laser sintering of CNT integrated nanocomposites. The results proved the feasibility of this technique to synthesize MWNTS integrated metal matrix nanocomposites.

Lin, Dong; Richard Liu, C.; Cheng, Gary J.

2014-03-01

159

Low cost improvements in air pollution control for ARMCO's Ashland, Kentucky Works Sinter Plant  

SciTech Connect

Particulate emissions from sinter plants can contribute a significant percentage of the total emissions from integrated steelmaking facilities. A well-known sinter plant air pollution phenomenon is called blue haze emissions. These emissions are caused when hydrocarbons introduced by filter cake, coke breeze, and mill scale are not burned in the sintering process and pass through the system as a very finely divided stable dispersed fog. The Sinter Plant at Ashland Works consists of Dravo-Lurgi traveling grate sintering machine which processes a mixture of materials including iron ore, iron pellet fines, blast furnace flue dust, limestone, melt shop slag, coke breeze and sinter return fines. This system is illustrated by the authors. Upon completion of the sintering process, the hot agglomerated sinter product is discharged to the sinter crusher. The sinter is then cooled and screened for use in Ashland Works' Amanda Blast Furnace. This system is illustrated. The Ashland Works Sinter Plant complex consists of a Sintering Machine Building, Sinter Screens Building and Ore Screens Building. For the purposes of this study, the Ore Transfer Tower Building was also included. The general layout of the complex is illustrated.

Felton, S.S. (ARMCO Inc., Ashland, KY (US))

1987-01-01

160

Recovery Behavior of Rare Earth from Bayan Obo Complex Iron Ore  

NASA Astrophysics Data System (ADS)

A novel process is presented for recovering rare earth from Bayan Obo complex iron ore. The iron ore was reduced and melting separated to produce iron nugget and rare-earth-rich slag. In order to investigate the influence of cooling rate on mineral components, especially the enrichment behavior of RE-containing mineral, the slag was remelted at 1673 K (1400 °C) and the liquid slags were cooled using three types of cooling conditions, water quenching, air cooling, and furnace cooling. Subsequently, the slags were leached by hydrochloric acid to evaluate the relations between leaching efficiency of rare earth and cooling conditions. The results indicated that the slags under different cooling conditions mainly contained fluorite, cefluosil, and cuspidine. The rare-earth mineral is more fully crystallized when the cooling rate of the liquid slag was decreased. The proportion of Ce (III) to Ce (IV) increases with the increase of heating time and decrease of cooling rate. It has been found that the influence of cooling rate on the leaching rate of the rare earth is slight. From water quenching to furnace cooling, the leaching rate of rare earth increases from 97.00 pct to 99.48 pct. After being filtered, filtrate can be used to produce rare-earth chloride. Leached residue, with CaF2 of 64.45 pct and ThO2 of 0.05 pct, can be used to recover CaF2 and extract nuclear source material.

Ding, Yingui; Xue, Qingguo; Wang, Guang; Wang, Jingsong

2013-02-01

161

Characterization by high performance liquid chromatography (HPLC) of the solubilization of phosphorus in iron ore by a fungus  

Microsoft Academic Search

Summary The value of iron ore is adversely affected by phosphorus in concentrations over 0.03% by weight. The present research concerns the use of metabolic products of aPenicillium-like fungus to leach insoluble phosphates (hydroxyapatite) from ores. Ion chromatography was used to measure metabolism of glucose into acidic fragments. The rate and products of glucose degradation depended on both the chemical

Edwin J. Parks; Gregory J. Olson; Frederick E. Brinckman; Franco Baldi

1990-01-01

162

Study of nonisothermal reduction of iron ore-coal/char composite pellet  

SciTech Connect

Cold-bonded composite pellets, consisting of iron ore fines and fines of noncoking coal or char, were prepared by steam curing at high pressure in an autoclave employing inorganic binders. Dry compressive strength ranged from 200 to 1,000 N for different pellets. The pellets were heated from room temperature to 1,273 K under flowing argon at two heating rates. Rates of evolution of product gases were determined from gas chromatographic analysis, and the temperature of the sample was monitored by thermocouple as a function of time during heating. Degree of reduction, volume change, and compressive strength of the pellets upon reduction were measured subsequently. Degree of reduction ranged from 46 to 99 pct. Nonisothermal devolatilization of coal by this procedure also was carried out for comparison. It has been shown that a significant quantity (10 to 20 pct of the pellet weight) of extraneous H[sub 2]O and CO[sub 2] was retained by dried pellets. This accounted for the generation of additional quantities of H[sub 2] and CO during heating. Carbon was the major reductant, but reduction by H[sub 2] also was significant. Ore-coal and ore-char composites exhibited a comparable degree of reduction. However, the former showed superior postreduction strength due to a smaller amount of swelling upon reduction.

Dutta, S.K. (Maharaja Shyaji Rao Univ. of Baroda (India). Dept. of Metallurgical Engineering); Ghosh, A. (Indian Institute of Technology, Kanpur (India). Dept. of Metallurgical Engineering)

1994-02-01

163

Study of nonisothermal reduction of iron ore-coal/char composite pellet  

NASA Astrophysics Data System (ADS)

Cold-bonded composite pellets, consisting of iron ore fines and fines of noncoking coal or char, were prepared by steam curing at high pressure in an autoclave employing inorganic binders. Dry compressive strength ranged from 200 to 1000 N for different pellets. The pellets were heated from room temperature to 1273 K under flowing argon at two heating rates. Rates of evolution of product gases were determined from gas Chromatographie analysis, and the temperature of the sample was monitored by thermocouple as a function of time during heating. Degree of reduction, volume change, and compressive strength of the pellets upon reduction were measured subsequently. Degree of reduction ranged from 46 to 99 pct. Nonisothermal devolatilization of coal by this procedure also was carried out for comparison. It has been shown that a significant quantity (10 to 20 pct of the pellet weight) of extraneous H2O and CO2 was retained by dried pellets. This accounted for the generation of additional quantities of H2 and CO during heating. Carbon was the major reductant, but reduction by H2 also was significant. Ore-coal and ore-char composites exhibited a comparable degree of reduction. However, the former showed superior postreduction strength due to a smaller amount of swelling upon reduction.

Dutta, S. K.; Ghosh, A.

1994-01-01

164

Mössbauer and XRD Comparative Study of Host Rock and Iron Rich Mineral Samples from Paz del Rio Iron Ore Mineral Mine in Colombia  

Microsoft Academic Search

A comparative study between the host rock and the iron rich mineral samples from the Paz del Rio iron ore mineral mine in\\u000a Colombia was performed using X-ray diffraction and Mssbauer spectroscopy. Diffraction results of the iron rich mineral sample\\u000a show that goethite, hematite, quartz, kaolinite and siderite are the main phases, and that a small amount of illite is

M. Fajardo; G. A. Pérez Alcázar; A. M. Moreira; N. L. Speziali

2004-01-01

165

Multi-element analysis of iron ore pellets by Laser-induced Breakdown Spectroscopy and Principal Components Regression  

NASA Astrophysics Data System (ADS)

Laser-induced Breakdown Spectroscopy (LIBS) in combination with Principal Components Regression (PCR) has been applied to determine the elemental composition of a series of run-of-mine (ROM) iron ore samples. The samples were presented for measurement both as compressed pellets and as loose chipped material. The present paper details the results of the measurements of the compressed pellets. Results from ore chips will be reported separately. LIBS spectral data was recorded in three separate spectral regions to measure major, minor and trace components of the iron ore sample pellets. Background stripping, normalization and spectral cleaning were applied to minimize the relative standard deviations of the LIBS data. PCR analysis was then applied to produce calibration models for iron, aluminum, silicon, manganese, potassium and phosphorous. These calibration models were then validated using independent LIBS measurements. Robust calibration models were determined for iron, aluminum, silicon and potassium, whilst the results for manganese were encouraging. Phosphorous, present at low levels in the ores measured, remained the most difficult element to determine accurately. The combination of LIBS and PCR shows potential for in-situ on-line determination of ore composition.

Death, D. L.; Cunningham, A. P.; Pollard, L. J.

2008-07-01

166

Standard test method for aluminum in iron ores by complexometric titration  

SciTech Connect

This method covers the determination of aluminum in iron ores, concentrates, and agglomerates in the concentration range from 0.25 to 5% aluminium. The sample is fused in a zirconium crucible with a mixed flux of sodium carbonate and sodium peroxide. The fused mass is dissolved in dilute hydrochloric acid. The R/sub 2/O/sub 3/ hydroxides are precipitated with ammonia and redissolved in hydrochloric acid. Iron, titanium, etc., are removed with cupferron and chloroform. The aqueous phase is treated with nitric and perchloric acids and evaporated to dryness. After dissolving in dilute hydrochloric acid, the solution is filtered, and the filtrate is treated with an excess of ethylenediaminetetraacetic acid (EDTA). The excess EDTA is titrated with a standard zinc solution using xylenol orange indicator. Ammonium fluoride is added to release the EDTA bound to aluminum. This EDTA is then titrated with standard zinc solution, and the percent aluminum is calculated.

Not Available

1980-01-01

167

Physicochemical formation conditions of banded iron formations and high-grade iron ores in the region of the Kursk Magnetic Anomaly: Evidence from isotopic data  

Microsoft Academic Search

The oxygen and carbon isotopic compositions of minerals from banded iron formations (BIFs) and high-grade ore in the region\\u000a of the Kursk Magnetic Anomaly (KMA) were determined in order to estimate the temperature of regional metamorphism and the\\u000a nature of rock-and ore-forming solutions. Magnetite and hematite of primary sedimentary or diagenetic origin have ?18O within the range from +2 to

V. I. Belykh; E. I. Dunai; I. P. Lugovaya

2007-01-01

168

Comprehensive analysis of slope stability and determination of stable slopes in the Chador-Malu iron ore mine using numerical and limit equilibrium methods  

Microsoft Academic Search

One of the critical aspects in mine design is slope stability analysis and the determination of stable slopes. In the Chador-Malu iron ore mine, one of the most important iron ore mines in central Iran, it was considered vital to perform a comprehensive slope stability analysis. At first, we divided the existing rock hosting pit into six zones and a

M ATAEI; S BODAGHABADI

2008-01-01

169

Grinding Wear Behaviour of Stepped Austempered Ductile Iron as Media Material During Comminution of Iron Ore in Ball Mills  

SciTech Connect

An attempt has been made to evaluate the suitability of austempered ductile iron (ADI) as media material for grinding iron ore in a ball mill. Spheroidal graphite (S.G) iron balls are austenitised at 900 deg. C for 60 minutes and given stepped austempering treatment at 280 deg. C for 30 minutes and 60 minutes followed by 380 deg. C for 60 minutes in each case. These materials are characterised by measuring hardness, analysing X-ray diffraction (X-RD), studying microstructure using optical and scanning electron microscope (SEM). Grinding wear behaviour of these materials was assessed for wear loss in wet condition at different pH value of the mineral slurry and found that the wear rate of grinding media material decreases with increase in pH of the slurry. The wear resistance of ADI balls were compared with forged En31 steel balls and found that the stepped austempered ductile iron is superior to forged En31 steel balls.

Raghavendra, H. [Research scholar, Department of Metallurgical and Materials Engineering, N.I.T.K., Surathkal (India); Bhat, K. L.; Udupa, K. Rajendra [Professor, Department of Metallurgical and Materials Engineering, N.I.T.K., Surathkal (India); Hegde, M. M. Rajath [Research Scholar, Institute for Technology Research and Innovation (ITRI), Geelong Technology Precinct (GTP), Waurn Ponds, Victoria 3216 (Australia)

2011-01-17

170

Application of indigenous sulfur-oxidizing bacteria from municipal wastewater to selectively bioleach phosphorus from high-phosphorus iron ore: effect of particle size.  

PubMed

The effects of ore particle size on selectively bioleaching phosphorus (P) from high-phosphorus iron ore were studied. The average contents of P and Fe in the iron ore were 1.06 and 47.90% (w/w), respectively. The particle sizes of the ores used ranged from 58 to 3350 microm. It was found that the indigenous sulfur-oxidizing bacteria from municipal wastewater could grow well in the slurries of solid high-phosphorus iron ore and municipal wastewater. The minimum bioleaching pH reached for the current work was 0.33. The P content in bioleached iron ore reduced slightly with decreasing particle size, while the removal percentage of Fe decreased appreciably with decreasing particle size. The optimal particle size fraction was 58-75 microm, because the P content in bioleached iron ore reached a minimum of 0.16% (w/w), the removal percentage of P attained a maximum of 86.7%, while the removal percentage of Fe dropped to a minimum of 1.3% and the Fe content in bioleached iron ore was a maximum of 56.4% (w/w) in this case. The iron ores thus obtained were suitable to be used in the iron-making process. The removal percentage of ore solid decreased with decreasing particle size at particle size range of 106-3350 microm. The possible reasons resulting in above phenomena were explored in the current work. It was inferred that the particle sizes of the iron ore used in this work have no significant effect on the viability of the sulfur-oxidizing bacteria. PMID:23530328

Shen, Shaobo; Rao, Ruirui; Wang, Jincao

2013-01-01

171

Palaeoproterozoic metavolcanic and metasedimentary succession hosting the Dannemora iron ore deposits, Bergslagen region, Sweden  

NASA Astrophysics Data System (ADS)

The Dannemora inlier constitutes some of the best preserved primary structures and textures in the metavolcanic and metasedimentary rocks in the Bergslagen region. The aim for this study was to define and interpret the primary textures and deposition environment to obtain a better understanding of the palaeoenvironment in which the Dannemora iron ore deposit formed. In addition, the region has been subjected to at least two fold episodes therefore the establishment of stratigraphy and younging directions were crucial for structural interpretations. The Bergslagen region, located in the south-central Sweden, represents a back-arc setting active c. 1.9 Ga and consisted of numerous large calderas, that accommodated pyroclastic deposits of great thicknesses. The Dannemora inlier is composed of the supracrustal the Dannemora Formation, which is dominated by of metavolcanic rocks and subordinated by marble. The succession is 700-800 m and is divided into a lower and an upper member. The latter hosts the second largest iron ore deposit in the Bergslagen region. The ore is hosted by manganiferous skarn and dolomitic carbonate (marble) and is situated within uppermost part of the upper member positioned in an isoclinal syncline. From reflection seismic imaging and 3-D processing, the ore has been interpreted to reach depths of c. 2000 m. The presence of an anticline west of the ore bearing syncline is suggested by the geochemical similarities of rock units. Undisturbed layers of ash-siltstone with normal grading and fluid-escape structures, units of pyroclastic density currents and ash-fall in the eastern part of the Dannemora inlier indicate subaqueous deposition below wave base of the upper member. Reworking of the volcaniclastic deposits is evident in e.g. channels and cross-bedding, on the other hand, implies deposition above wave base of the upper member in the central part of Dannemora inlier. The thickness of the marble in the eastern part is c. 80 m and in the central part the < 20 m, and the magnetic anomaly is greater in the former compare to the latter. The Dannemora Formation consists mainly of ignimbrites and ash-fall deposits, and their pyroclastic origin is evident in characteristic textures e.g. fragmented crystals of mainly quartz, pumice clasts, cuspate and Y-shaped former glass shards. The presence of feldspar replaced pumice clasts, in the lower member, indicates deposition at high temperature. But, the scattered and scarcity of spherulites and lack of welding-compacted fiamme is interpreted as only slightly welding of the ignimbrites. The sericite-replaced glass shards with preserved primary shapes indicate that the upper member was not welded. Scattered epidote spots in the metavolcanic rocks were previously interpreted as altered limestone clasts and consequent subaquatic deposition. But as the matrix of their host rock and the "clasts" has similar textures, they were probably selectively altered, epidote-rich spots related to the intrusions of basaltic dykes. We conclude that the pronounced positive magnetic anomaly and the thicker marble in the eastern part of the Dannemora inlier supports an interpretation of increased amount of iron ore in the eastern compared to the central part.

Dahlin, P.

2012-04-01

172

Mineralogy and trace-element geochemistry of the high-grade iron ores of the Águas Claras Mine and comparison with the Capão Xavier and Tamanduá iron ore deposits, Quadrilátero Ferrífero, Brazil  

Microsoft Academic Search

Several major iron deposits occur in the Quadrilátero Ferrífero (QF), southeastern region of Brazil, where metamorphosed and\\u000a heterogeneously deformed banded iron formation (BIF) of the Cauê Formation, regionally called itabirite, was transformed into\\u000a high- (Fe >64%) and low-grade (30%?ores. Based on their mineralogical composition, three major types\\u000a of itabirites occur in the QF: siliceous, dolomitic, and amphibolitic itabirite.

Carlos Alberto Spier; Sonia Maria Barros de Oliveira; Carlos Alberto Rosière; José Domingos Ardisson

2008-01-01

173

Estyuninky's Deformation Characteristics of the Iron-Ore Deposit by Gravimetric Means  

NASA Astrophysics Data System (ADS)

Gravitation is the main energy source of many processes which happen in crust. Gravity possesses the leading role in structurization; it defines a tectonic broken state and permeability of the geological medium, having significant importance at an ore deposition. Because of the gravitation density naturally changes, permeability and other properties of the geological medium changes too. Presence in crust of density heterogeneity of a various form and the sizes and properties change, show its compound stress of deformation condition. Studying of the deformations caused by gravitation, represents great expected and research interest. Theoretical basis of studying of these deformations consists on ratios between components of a pure tensor deformation and its first invariant -dilatation and results of measurement of gravity force. The method of deformation studying of the geological medium, developed on this basis, was called a method of the tektonophysic analysis of a gravitational field (MTPAGF). The detailed analysis of results of MTPAGF was made for the region of the Estyuninsky iron-ore deposit. The deposit region is characterized by a reversed dilatation. The zero isoline of dilatation divides it into two parts. To the east of this isoline where there is a deposit, a dilatation positive and rather small size. To the west - a dilatation negative and it increases as approaching a protrusion. Thus, to the east of the zero isoline the geological medium is in stretching mode, which promote relative expansion of the medium, improvement of its permeability. Thanks to it favorable conditions for an ore deposition here were created. To the west f the zero isoline medium is in a compression mode. Therefore it is characterized by smaller permeability. The border of change of a sign of a dilatation probably was important a role of the peculiar deformation barrier blocking migration through it of ore substance. It is possible to make the following conclusion of the analysis of deformation characteristics of the geological medium: small values of principal values of deformation and positive dilatation and, as a result, low level of specific energy of volume deformation, can evidence and to rather low tendency of the medium to destruction. As the deposit is located in the medium with such deformation properties, so there is some optimum broken state (permeability) of the medium optimum for an ore deposition. Extreme cases: very small and very big permeability complicate development of this process. In a little permeable medium it doesn't go at all, in very permeable - (at lack of screens) the disseminated or interspersed mineralization is formed. That work was supported by grant RFBR 10-05-00013.

Vandysheva, Ksenya; Filatov, Vladimir

2013-04-01

174

Phytoremediation: a novel approach for utilization of iron-ore wastes.  

PubMed

Large quantities of iron-ore tailings are being generated annually in the world from mining and processing of iron ores. It has been estimated that around 10-15% of the iron ore mined in India has remained unutilized and discarded as slimes during mining and subsequent processing. Soil contamination resulting from mining activities affects surrounding flora and fauna and presents a large clean-up challenge to the mining industry. Innovative new methodologies have been proposed and among the most promising are those that rely on new phytoremediation technology. In this paper we address and review the status of phytoremediation as a technology to reduce and control contaminated mine wastes. Several different approaches and different plant species are used to remove environmentally toxic metals from mine waste sites. Such approaches have the objective of restoring mining waste sites to human and animal use, or at least, to curtail or eliminate the off-site movement of toxic entities that potentially could reach humans. How well phytoremediation performs as an alternative soil restoration technology depends on several factors, including the composition of soil, toxicity level of the contaminant, degree to which plant species fit natural local growth patterns and type of concentration of metal/contaminant in such plants. Phytoremediation has opened prospects for less costly, yet practicable approaches to clean-up contaminated waste sites, particularly those associated with mineral extraction mining. We discuss several plant species that are capable of phytoextracting and/or phytostabilizing harmful elements from contaminated soil and water; such processes are prospectively effective for addressing waste problems that derive from mining and processing activities, as well as those that derive from mitigating the threat posed by waste that surrounds mining sites. Unfortunately, phytoremediation is still in the embryonic stage, and more research is needed to find the plant species that will be most effective for addressing different mining waste scenarios. Such plants must be able to survive and even thrive in heavily contaminated soil and be able to mitigate the pollutants that exist in the soil in which these plants will grow. PMID:20652667

Mohanty, Monalisa; Dhal, Nabin Kumar; Patra, Parikshita; Das, Bisweswar; Reddy, Palli Sita Rama

2010-01-01

175

Mineralogy and trace-element geochemistry of the high-grade iron ores of the Águas Claras Mine and comparison with the Capão Xavier and Tamanduá iron ore deposits, Quadrilátero Ferrífero, Brazil  

NASA Astrophysics Data System (ADS)

Several major iron deposits occur in the Quadrilátero Ferrífero (QF), southeastern region of Brazil, where metamorphosed and heterogeneously deformed banded iron formation (BIF) of the Cauê Formation, regionally called itabirite, was transformed into high- (Fe >64%) and low-grade (30% < Fe < 64%) hematite ores. Based on their mineralogical composition, three major types of itabirites occur in the QF: siliceous, dolomitic, and amphibolitic itabirite. Unlike other mines in the QF, the Águas Claras Mine contained mainly high-grade ores hosted within dolomitic itabirite. Two distinct types of high-grade ore occurred at the mine: soft and hard. The soft ore was the most abundant and represented more than 85% of the total ore mined until it was mined out in 2002. Soft and hard ores consist essentially of hematite, occurring as martite, anhedral to granular/tabular hematite and, locally, specularite. Gangue minerals are rare, consisting of dolomite, sericite, chlorite, and apatite in the hard and soft ores, and Mn-oxides and ferrihydrite in the soft ore where they are concentrated within porous bands. Chemical analyses show that hard and soft ores consist almost entirely of Fe2O3, with a higher amount of detrimental impurities, especially MnO, in the soft ore. Both hard and soft ores are depleted in trace elements. The high-grade ores at the Águas Claras Mine have at least a dual origin, involving hypogene and supergene processes. The occurrence of the hard, massive high-grade ore within “fresh” dolomitic itabirite is evidence of its hypogene origin. Despite the contention about the origin of the dolomitic itabirite (if this rock is a carbonate-rich facies of the Cauê Formation or a hematite-carbonate precursor of the soft high-grade ore), mineralogical and geochemical features of the soft high-grade ore indicate that it was formed by leaching of dolomite from the dolomitic itabirite by meteoric water. The comparison of the Águas Claras, Capão Xavier and Tamanduá orebodies shows that the original composition of the itabiritic protore plays a major role in the genesis of high- and low-grade soft ores in the QF. Under the same weathering and structural conditions, the dolomitic itabirite is the more favorable to form high-grade deposits than siliceous itabirite. Field relations at the Águas Claras and Capão Xavier deposits suggest that it is not possible to form huge soft high-grade supergene deposits from siliceous itabirite, unless another control, such as impermeable barriers, had played an important role. The occurrence in the Tamanduá Mine of a large, soft, high-grade orebody formed from siliceous itabirite and closely associated with hypogene hard ore suggests that large, soft, high-grade orebodies of the Quadrilátero Ferrífero, which occur within siliceous itabirite, have a hypogene contribution in their formation.

Spier, Carlos Alberto; de Oliveira, Sonia Maria Barros; Rosière, Carlos Alberto; Ardisson, José Domingos

2008-02-01

176

Plant trial of a neutron inelastic scattering gauge for the online analysis of hot reduced iron ores  

NASA Astrophysics Data System (ADS)

The HIsmelt Process is a direct smelting process involving a coal-injected smelting reactor with the off-gas passing through a circulating fluidised bed in which fine iron ore is pre-reduced and pre-heated. Control of the pre-reduction system would benefit from an on-line measurement of the degree of pre-reduction (PRD). However, the on-line measurements need to be made on hot ore in circumstances where access to representative sample streams is very difficult. An on-line gauge based on the measurement of neutron inelastic scatter gamma-rays has been installed and calibrated at the HIsmelt plant in Kwinana, Western Australia. The gauge uses an 241Am-Be neutron source and a BGO detector inside a water-cooled tube surrounded by hot iron ore. THe gauge monitors the iron, oxygen, carbon and silica contents of the ore based neutron inelastic scatter gamma-rays at 0.85, 6.13, 4.43 and 1.78 MeV respectively. In plant trials at HIsmelt the gauge determined iron, oxygen, carbon, silica and PRD to within 2.2 wt. percent, 0.6 wt. percent, 0.5 wt. percent, 1.0 wt. percent and 0.4 percent respectively. Potential application so this technology in other direct reduction and smelting processes will also be discussed.

Lim, Cheryl S.; Sowerby, Brian; Rainey, S.; Hardie, G. J.

1997-02-01

177

SIMULATION OF HEAT TRANSFER AND FLUID FLOW IN A POROUS BED OF IRON ORE PELLETS DURING UP DRAUGHT DRYING  

Microsoft Academic Search

Iron ore pellets is one of the most refined products for companies such as LKAB and it is therefore a global need for research in the area in order to optimize the production and improve quality. This work aim at modelling and optimizing the drying zone of a travelling grate pelletizing plant and to start with, a model of velocity

Anna-Lena LJUNG; T. Staffan LUNDSTRÖM; Kent TANO

178

Virtual indurator: A tool for simulation of induration of wet iron ore pellets on a moving grate  

Microsoft Academic Search

Pelletization of iron ore fines is an important step in an integrated steel plant. It essentially involves balling of fine powders on a rotating disk or drum to produce wet pellets and induration on a moving grate to produce fired pellets. The development of a user-friendly simulation tool, virtual indurator, for induration is presented here. The simulator is based on

Sushanta Majumder; Pradeepkumar Vasant Natekar; Venkataramana Runkana

2009-01-01

179

Characterization of haul road dust in an Indian opencast iron ore mine  

NASA Astrophysics Data System (ADS)

Vehicular traffic on unpaved haul roads of the opencast mines has been identified as the most prolific source of fugitive dust. An intensive study was carried out in Noamundi Iron ore mines of Tata Iron and Steel Co. in January-February 1994 to characterize the airborne aerosol mainly contributed from unpaved haul road, traffic exhaust and re-entrained dust from the other activities of the mine. Percentage of suspended particulate matter at the various size ranges and free silica content of each of the size ranges of haul road dust were determined. Concentrations of eight trace elements, namely, zinc, copper, lead, manganese, cobalt, nickel, cadmium and iron were determined and found to be varying in the range 13.92-16.34, 0.06-0.09, 0.71-0.79, 0.14-0.15, 0.08-0.11, 0.15-0.17, 0.003-0.004 and 390-401.20 ?g m -3, respectively. A study on enrichment factor and varimax rotated factor analysis indicates the four major sources namely soil/road dust, vehicle exhaust, metallic corrosion and, galvanized material, tire wear and zinc compound in rubber material which appear to contribute trace elements to airborne aerosol.

Sinha, Subrato; Banerjee, S. P.

180

A risk assessment for exposure to grunerite asbestos (amosite) in an iron ore mine.  

PubMed

The potential for health risks to humans exposed to the asbestos minerals continues to be a public health concern. Although the production and use of the commercial amphibole asbestos minerals-grunerite (amosite) and riebeckite (crocidolite)-have been almost completely eliminated from world commerce, special opportunities for potentially significant exposures remain. Commercially viable deposits of grunerite asbestos are very rare, but it can occur as a gangue mineral in a limited part of a mine otherwise thought asbestos-free. This report describes such a situation, in which a very localized seam of grunerite asbestos was identified in an iron ore mine. The geological occurrence of the seam in the ore body is described, as well as the mineralogical character of the grunerite asbestos. The most relevant epidemiological studies of workers exposed to grunerite asbestos are used to gauge the hazards associated with the inhalation of this fibrous mineral. Both analytical transmission electron microscopy and phase-contrast optical microscopy were used to quantify the fibers present in the air during mining in the area with outcroppings of grunerite asbestos. Analytical transmission electron microscopy and continuous-scan x-ray diffraction were used to determine the type of asbestos fiber present. Knowing the level of the miner's exposures, we carried out a risk assessment by using a model developed for the Environmental Protection Agency. PMID:10097051

Nolan, R P; Langer, A M; Wilson, R

1999-03-30

181

A risk assessment for exposure to grunerite asbestos (amosite) in an iron ore mine  

PubMed Central

The potential for health risks to humans exposed to the asbestos minerals continues to be a public health concern. Although the production and use of the commercial amphibole asbestos minerals—grunerite (amosite) and riebeckite (crocidolite)—have been almost completely eliminated from world commerce, special opportunities for potentially significant exposures remain. Commercially viable deposits of grunerite asbestos are very rare, but it can occur as a gangue mineral in a limited part of a mine otherwise thought asbestos-free. This report describes such a situation, in which a very localized seam of grunerite asbestos was identified in an iron ore mine. The geological occurrence of the seam in the ore body is described, as well as the mineralogical character of the grunerite asbestos. The most relevant epidemiological studies of workers exposed to grunerite asbestos are used to gauge the hazards associated with the inhalation of this fibrous mineral. Both analytical transmission electron microscopy and phase-contrast optical microscopy were used to quantify the fibers present in the air during mining in the area with outcroppings of grunerite asbestos. Analytical transmission electron microscopy and continuous-scan x-ray diffraction were used to determine the type of asbestos fiber present. Knowing the level of the miner’s exposures, we carried out a risk assessment by using a model developed for the Environmental Protection Agency.

Nolan, R. P.; Langer, A. M.; Wilson, Richard

1999-01-01

182

Active and passive behavior of sintered iron in ammoniacal ammonium carbonate solution  

NASA Astrophysics Data System (ADS)

The anodic dissolution behavior of sintered iron in ammoniacal ammonium carbonate solution (pH = 9.7) has been investigated with the aid of electrochemical techniques. Surface films formed on bulk iron during air exposure or immersion in the ammoniacal solution were characterized by using X-ray photoelectron spectroscopy (XPS). Immersion in the ammoniacal solution gave an apparent open circuit potential (OCP) in the range of E = 0.04 to 0.09 V, standard hydrogen electrode (SHE); at these potentials, no dissolution of Fe was detected. Potential transients obtained during cathodic reactivation and the XPS results suggest that an air-formed oxide of Fe3O4 is responsible for this behavior. The anodic polarization behavior of sintered Fe was similar to that of bulk Fe, showing active, passive, and oxygen evolution regions. A very high current density observed in the passive region for some sintered specimens was attributable to active dissolution within the pore structure, analogous to conditions during crevice corrosion. The presence of oxygen in the solution stabilized both the passive film and the more noble apparent OCP.

Kim, H. S.; Kho, Y. T.; Osseo-Asare, K.; Pickering, H. W.

1991-06-01

183

The application of median indicator kriging and neural network in modeling mixed population in an iron ore deposit  

NASA Astrophysics Data System (ADS)

This paper presents the results of a study comparing median indicator kriging and an artificial neural network in the estimation of iron grades in the Jalal-Abad Zarrand iron ore deposit located in the southern Iran. The data used in this study is from 2017 composite samples with 2 m length from 32 exploration boreholes. The iron grade data is sparse, irregularly spaced and has mixed distribution, which can be problematic for the stationarity assumptions of the widely used ordinary kriging estimation method. The two estimation techniques applied in this study make no assumptions about the distribution of the sample data, and accommodate moderately mixed sample populations.

Badel, Mehdi; Angorani, Saeed; Shariat Panahi, Masoud

2011-04-01

184

Distribution behavior of phosphorus in the coal-based reduction of high-phosphorus-content oolitic iron ore  

NASA Astrophysics Data System (ADS)

This study focuses on the reduction of phosphorus from high-phosphorus-content oolitic iron ore via coal-based reduction. The distribution behavior of phosphorus (i.e., the phosphorus content and the phosphorus distribution ratio in the metal, slag, and gas phases) during reduction was investigated in detail. Experimental results showed that the distribution behavior of phosphorus was strongly influenced by the reduction temperature, the reduction time, and the C/O molar ratio. A higher temperature and a longer reaction time were more favorable for phosphorus reduction and enrichment in the metal phase. An increase in the C/O ratio improved phosphorus reduction but also hindered the mass transfer of the reduced phosphorus when the C/O ratio exceeded 2.0. According to scanning electron microscopy analysis, the iron ore was transformed from an integral structure to metal and slag fractions during the reduction process. Apatite in the ore was reduced to P, and the reduced P was mainly enriched in the metal phase. These results suggest that the proposed method may enable utilization of high-phosphorus-content oolitic iron ore resources.

Sun, Yong-sheng; Han, Yue-xin; Gao, Peng; Ren, Duo-zhen

2014-04-01

185

Adsorption and removal of arsenic from water by iron ore mining waste.  

PubMed

There is a global need to develop low-cost technologies to remove arsenic from water for individual household water supply. In this study, a purified and enriched waste material (treated magnetite waste, TMW) from the Trai Cau's iron ore mine in the Thai Nguyen Province in Vietnam was examined for its capacity to remove arsenic. The treatment system was packed with TMW that consisted of 75% of ferrous-ferric oxide (Fe(3)O(4)) and had a large surface area of 89.7 m(2)/g. The experiments were conducted at a filtration rate of 0.05 m/h to treat groundwater with an arsenic concentration of 380 microg/L and iron, manganese and phosphate concentrations of 2.07 mg/L, 0.093 mg/L and 1.6 mg/L respectively. The batch experimental results show that this new material was able to absorb up to 0.74 mg arsenic/g. The results also indicated that the treatment system removed more than 90% arsenic giving an effluent with an arsenic concentration of less than 30 microg/L while achieving a removal efficiency of about 80% for Mn(2 + ) and PO(4) (3-). This could be a promising and cost-effective new material for capturing arsenic as well as other metals from groundwater. PMID:19901461

Nguyen, Tien Vinh; Nguyen, Thi Van Trang; Pham, Tuan Linh; Vigneswaran, Saravanamuth; Ngo, Huu Hao; Kandasamy, J; Nguyen, Hong Khanh; Nguyen, Duc Tho

2009-01-01

186

Effectiveness of sodium silicate as gangue depressants in iron ore slimes flotation  

NASA Astrophysics Data System (ADS)

The recovery of iron from the screw classifier overflow slimes by direct flotation was studied. The relative effectiveness of sodium silicates with different silica-to-soda mole ratios as depressants for silica and silicate bearing minerals was investigated. Silica-to-soda mole ratio and silicate dosage were found to have significant effect on the separation efficiency. The results show that an increase of Fe content in the concentrate is observed with concomitant reduction in SiO2 and Al2O3 levels when a particular type of sodium silicate at a proper dosage is used. The concentrate of 58.89wt% Fe, 4.68wt% SiO2, and 5.28wt% Al2O3 with the weight recovery of 38.74% and the metal recovery of 41.13% can be obtained from the iron ore slimes with 54.44wt% Fe, 6.72wt% SiO2, and 6.80wt% Al2O3, when Na2SiO3 with a silica-to-soda mole ratio of 2.19 is used as a depressant at a feed rate of 0.2 kg/t.

Rao, Danda Srinivas; Vijayakumar, Tadiparthi Venkata; Rao, Sripada Subba; Prabhakar, Swarna; Raju, Guntamadugu Bhaskar

2011-10-01

187

Physicochemical formation conditions of banded iron formations and high-grade iron ores in the region of the Kursk Magnetic Anomaly: Evidence from isotopic data  

NASA Astrophysics Data System (ADS)

The oxygen and carbon isotopic compositions of minerals from banded iron formations (BIFs) and high-grade ore in the region of the Kursk Magnetic Anomaly (KMA) were determined in order to estimate the temperature of regional metamorphism and the nature of rock-and ore-forming solutions. Magnetite and hematite of primary sedimentary or diagenetic origin have ?18O within the range from +2 to 6‰. During metamorphism, primary iron oxides, silicates, and carbonates were involved in thermal dissociation and other reactions to form magnetite with ?18O = +6 to +11‰. As follows from a low ?18Oav = -3.5‰ of mushketovite (magnetite pseudomorphs after hematite) in high-grade ore, this mineral was formed as a product of hematite reduction by organic matter. The comparison of ?18O of iron oxides, siderite, and quartz from BIFs formed at different stages of the evolution of the Kursk protogeosyncline revealed specific sedimentation (diagenesis) conditions and metamorphism of the BIFs belonging to the Kursk and Oskol groups. BIF of the Oskol Group is distinguished by a high ?18O of magnetite compared to other Proterozoic BIFs. Martite ore differs from host BIF by a low ?18O = -0.2 to -5.9‰. This implies that oxygen from infiltration water was incorporated into the magnetite lattice during the martite formation. Surface water penetrated to a significant depth through tectonic faults and fractures.

Belykh, V. I.; Dunai, E. I.; Lugovaya, I. P.

2007-04-01

188

Did the Kiruna iron ores form as a result of a metasomatic or igneous process? New U-Pb and Nd data for the iron oxide apatite ores and their host rocks in the Norrbotten region of northern Sweden  

NASA Astrophysics Data System (ADS)

A number of iron deposits near Kiruna in the Norrbotten region of northern Sweden are of the iron oxide apatite (IOA) type of deposits; also referred to as Kiruna-type deposits. They are commonly considered a subgroup or end-member of iron oxide copper gold (IOCG) deposits, containing no economic grades of copper or gold. Both IOCG and IOA deposits are characterized by abundant low-Ti Fe oxides, an enrichment in REE, and intense sodium and potassium wall-rock alteration adjacent to the ores. Deposits of these types are of a great economic importance, not only for iron, but also for other elements such as rare earth elements (REE) or uranium. Kiruna, the type locality of the IOA type of mineral deposits, is the focus of this study. Despite a century-long mining history and 2500 Mt of iron ore produced in the region to date (with grades of 30 to 70 wt.% Fe), the genesis of these deposits is poorly understood: theories of a magmatic vs. a hydrothermal or metasomatic origin have been debated, and the timing of mineralization of the ores in the Norbotten region has never been directly dated. The results anticipated from this study will provide a better understanding of the nature of the IOA type of mineral deposits and their relation to IOCG deposits such as Olympic Dam in Australia. An array of geochemical methods is used in order to gain insights on the emplacement history of the host rocks, their subsequent alteration, and the ore genesis of these deposits. This includes in situ U/Pb geochronology of zircon, monazite, and titanite to constrain the timing between host rock emplacement, alteration and mineralization. Isotopic data from whole rocks and in situ at mineral scale will provide constraints on the involvement of hydrothermal fluids and their possible sources, as well as on the sources of Fe, U, and the REE. Newly obtained Sm-Nd isotopic data points to distinct source differences between host rocks, ore and alteration related samples. Preliminary in situ U-Pb dating of zircon from both host rock and ore samples confirms a previously documented event around 1880 - 1900 Ma in the Norrbotten region. However, U-Pb in monazite from an ore sample suggests a further event at ca. 1650 Ma, a period of known activity in Fennoscandia. Further investigation and more U-Pb data are needed to confirm those dates and how the iron mineralization is related to those two events. The combination of U-Th-Pb ages, tracer isotopes and trace element abundances at mineral scale (e.g., Lu-Hf in zircon, and Sm-Nd in monazite, apatite, titanite), along with the O isotopic composition of zircon, will be used to decipher whether the Kiruna iron ore deposits are of metasomatic or igneous origin. Overall, the study also intends to develop a predictive model for exploration of similar iron oxide apatite deposits worldwide.

Westhues, A.; Hanchar, J. M.; Whitehouse, M. J.; Fisher, C. M.

2012-12-01

189

[Iron ore, economic geology and networks of experts between Wisconsin and the state of Minas Gerais, 1881-1914].  

PubMed

This article deals with the "discovery" of Brazilian iron ore from two perspectives. The first examines the increasing emphasis of the geosciences and their practical application and global reach since the second half of the nineteenth century. While in Brazil economic geology was integrated step by step into state institutions, at the global level it experienced its moment of triumph with the 11th International Geological Congress in 1910. The second deals with a specific social network with a decisive role in the race for Brazilian iron ore: with transnational experts juggling between the logic of the market and that of the academy. The article reveals the importance of local negotiations in the incorporation of the subsoil of Minas Gerais into the global space of mining. PMID:24554136

Fischer, Georg

2014-01-01

190

Rock-magnetic and oxide microscopy studies of the El Laco iron-ore deposits, Chilean High Andes: implications for magnetometric modeling  

Microsoft Academic Search

Microscopy and rock-magnetic studies of the iron oxide-ore and host rocks in the El Laco deposits were carried out to characterize the magnetic mineralogy and the processes that affected the natural remanent magnetization (NRM) during emplacement and evolution of the iron-ore deposits. Particular attention was paid to identify the magnetic mineralogical composition (magnetite and\\/or titanomagnetite, and hematite and\\/or titanohematite, and

L. Alva-Valdivia; A. Gogichaishvili; M. L. Rivas; J. Morales; J. Gonzalez; J. Urrutia-Fucugauchi

2003-01-01

191

Effect of reduction roasting by using bio-char derived from empty fruit bunch on the magnetic properties of Malaysian iron ore  

NASA Astrophysics Data System (ADS)

Beneficiation of Malaysian iron ore is becoming necessary as iron resources are depleting. However, the upgrading process is challenging because of the weak magnetic properties of Malaysian iron ore. In this study, bio-char derived from oil palm empty fruit bunch (EFB) was utilized as an energy source for reduction roasting. Mixtures of Malaysian iron ore and the bio-char were pressed into briquettes and subjected to reduction roasting processes at 873-1173 K. The extent of reduction was estimated on the basis of mass loss, and the magnetization of samples was measured using a vibrating sample magnetometer (VSM). When reduced at 873 K, the original goethite-rich ore was converted into hematite. An increase in temperature to 1073 K caused a significant conversion of hematite into magnetite and enhanced the magnetic susceptibility and saturation magnetization of samples. The magnetic properties diminished at 1173 K as the iron ore was partially reduced to wustite. This reduction roasting by using the bio-char can assist in upgrading the iron ore by improving its magnetic properties.

Yunus, Nurul A.; Ani, Mohd H.; Salleh, Hamzah M.; Rashid, Rusila Z. A.; Akiyama, Tomohiro; Purwanto, Hadi; Othman, Nur E. F.

2014-04-01

192

The search for asbestos within the Peter Mitchell Taconite iron ore mine, near Babbitt, Minnesota.  

PubMed

Asbestos crystallizes within rock formations undergoing intense deformation characterized by folding, faulting, shearing, and dilation. Some of these conditions have prevailed during formation of the taconite iron ore deposits in the eastern Mesabi Iron Range of Minnesota. This range includes the Peter Mitchell Taconite Mine at Babbitt, Minnesota. The mine pit is over 8 miles long, up to 1 mile wide. Fifty three samples were collected from 30 sites within areas of the pit where faulting, shearing and folding occur and where fibrous minerals might occur. Eight samples from seven collecting sites contain significant amounts of ferroactinolite amphibole that is partially to completely altered to fibrous ferroactinolite. Two samples from two other sites contain ferroactinolite degraded to ropy masses of fibers consisting mostly of ferrian sepiolite as defined by X-ray diffraction and TEM and SEM X-ray spectral analysis. Samples from five other sites contain unaltered amphiboles, however some of these samples also contain a very small number of fiber bundles composed of mixtures of grunerite, ferroactinolite, and ferrian sepiolite. It is proposed that the alteration of the amphiboles was caused by reaction with water-rich acidic fluids that moved through the mine faults and shear zones. The fibrous amphiboles and ferrian sepiolite collected at the Peter Mitchell Mine composes a tiny fraction of one percent of the total rock mass of this taconite deposit; an even a smaller amount of these mineral fragments enter the ambient air during mining and milling. These fibrous minerals thus do not present a significant health hazard to the miners nor to those non-occupationally exposed. No asbestos of any type was found in the mine pit. PMID:18060674

Ross, Malcolm; Nolan, Robert P; Nord, Gordon L

2008-10-01

193

Georgenia soli sp. nov., isolated from iron-ore-contaminated soil in India.  

PubMed

A Gram-positive actinobacterium (CC-NMPT-T3(T)) was isolated from iron-ore-contaminated soil near New Mangalore Port, Karnataka, India. Based on 16S rRNA gene sequence similarity studies, strain CC-NMPT-T3(T) belongs to the genus Georgenia and is most closely related to Georgenia muralis (98.6 %), Georgenia ruanii (97.4 %) and Georgenia thermotolerans (97.4 %). The peptidoglycan is of the type A4alpha l-Lys<--l-Glu. The predominant isoprenoid quinone is menaquinone MK-8(H(4)) and the polar lipid profile is composed of the predominant compound diphosphatidylglycerol, moderate amounts of a phosphatidylinositol-mannoside, phosphatidylinositol and minor amounts of another phosphatidylmannoside and phosphatidylglycerol. The major fatty acids of strain CC-NMPT-T3(T) are anteiso-C(15 : 0) and iso-C(15 : 0). The results of DNA-DNA hybridizations, and physiological and biochemical tests allowed a clear phenotypic differentiation of strain CC-NMPT-T3(T) from all other Georgenia species. Strain CC-NMPT-T3(T) represents a novel species, for which the name Georgenia soli sp. nov. is proposed. The type strain is CC-NMPT-T3(T) (=DSM 21838(T)=CCM 7658(T)). PMID:19666812

Kämpfer, P; Arun, A B; Busse, H-J; Langer, S; Young, C-C; Chen, W-M; Schumann, P; Syed, A A; Rekha, P D

2010-05-01

194

THE REMEDIATION OF ABANDONED IRON ORE MINE SUBSIDENCE IN ROCKAWAY TOWNSHIP, NEW JERSEY  

SciTech Connect

This report represents the thirteenth Technical Progress Report issued in connection with the subsidence remediation projects undertaken by Rockaway Township in Morris County, New Jersey. This report provides a summary of the major project work accomplished during this semi annual reporting period and contemplated for the subsequent reporting period. This report is issued as part of the project reporting provisions set forth in the Cooperators Agreement between the United States Government--Department of Energy, and Rockaway Township. The purpose of the Cooperators Agreement is for the Department of Energy to provide technical and financial assistance in a coordinated effort with Rockaway Township to develop and implement a multi-phased plan to remediate ground stability problems associated with abandoned mining activity. Primarily during the 1800's, extensive iron ore mining and prospecting was undertaken in Rockaway Township, part of the Dover District Mining region in Morris County. The abandoned mining activity has resulted in public safety hazards associated with ground collapse and surface subsidence features evolving in both developed and undeveloped areas within Rockaway Township. At the Green Pond Mine site at the Township's Jacobs Road Compost Storage Facility, construction was completed during this reporting period and surface monitoring began. Surface monitoring was conducted periodically at the Mt. Hope Road subsidence work area and adjacent areas after the January 2000 construction effort.

Gary Gartenberg

2003-12-01

195

Interactions between Magnetite Oxidation and Flux Calcination during Iron Ore Pellet Induration  

NASA Astrophysics Data System (ADS)

Many chemical reactions take place simultaneously during the induration of iron ore pellets produced from magnetite concentrates. Two of the most important are magnetite oxidation and calcination of carbonate fluxes. The first reaction consumes oxygen diffusing into the pellet, while the second reaction produces carbon dioxide that must diffuse out of the pellet. A mathematical model combining the two reactions and gaseous diffusion within the pellet has been developed to quantify the interaction between the two reactions. This combined mathematical model showed that current induration plant mathematical models for the mass and energy balance around a pellet furnace are inaccurate in treating magnetite oxidation and flux calcination as separate reactions. Assuming separate reactions can lead to an error of up to 20 pct conversion of magnetite at the end of the preheat stage. This combined mathematical model, confirmed by experiments with single pellets, also demonstrated that calcination of fluxes also tends to follow a “shrinking core” model rather than reacting simultaneously across the pellet, as existing whole plant models assume. Modifying induration plant mathematical models in accordance with the findings of this article could lead to further savings in energy costs for pellet plants.

Firth, Andrew R.; Garden, John F.

2008-08-01

196

Photosynthesis and oxidative stress in the restinga plant species Eugenia uniflora L. exposed to simulated acid rain and iron ore dust deposition: Potential use in environmental risk assessment  

Microsoft Academic Search

The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The

Natália Rust Neves; Marco Antonio Oliva; Danilo da Cruz Centeno; Alan Carlos Costa; Rogério Ferreira Ribas; Eduardo Gusmão Pereira

2009-01-01

197

The Remediation of Abandoned Iron Ore Mine Subsidence in Rockaway Township, New Jersey  

SciTech Connect

This report represents the twenty-seventh and Final Technical Progress Report issued in connection with the subsidence remediation projects undertaken by Rockaway Township in Morris County, New Jersey. This report provides a summary of the major project work accomplished during this last reporting period ending June 30, 2010 and a summary of the work accomplished since the agreement inception in 1997. This report is issued as part of the project reporting provisions set forth in the Cooperatorâ??s Agreement between the United States Government - Department of Energy, and Rockaway Township. The purpose of the Cooperatorâ??s Agreement is for the Department of Energy to provide technical and financial assistance in a coordinated effort with Rockaway Township to develop and implement a multi-phased plan to remediate ground stability problems associated with abandoned mining activity. Primarily during the 1800â??s, extensive iron ore mining and prospecting was undertaken in Rockaway Township, part of the Dover District Mining region in Morris County. The abandoned mining activity has resulted in public safety hazards associated with ground collapse and surface subsidence features evolving in both developed and undeveloped areas within Rockaway Township. At the Green Pond Mine site at the Townshipâ??s Jacobs Road Compost Storage Facility, surface monitoring continued after completion of construction in September 2003. Surface monitoring was conducted periodically at the Mt. Hope Road subsidence work area and adjacent areas after the January 2000 construction effort. In March 2007, a seventh collapse occurred over a portion of the White Meadow Mine in a public roadway at the intersection of Iowa and Erie Avenues in Rockaway Township. After test drilling, this portion of the mine was remediated by drilling and grouting the stopes.

Gartenberg, Gary; Poff, Gregory

2010-06-30

198

Photosynthesis and oxidative stress in the restinga plant species Eugenia uniflora L. exposed to simulated acid rain and iron ore dust deposition: potential use in environmental risk assessment.  

PubMed

The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPM(Fe)) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPM(Fe) application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers. PMID:19321190

Neves, Natália Rust; Oliva, Marco Antonio; da Cruz Centeno, Danilo; Costa, Alan Carlos; Ribas, Rogério Ferreira; Pereira, Eduardo Gusmão

2009-06-01

199

Effect of particle fineness on the finely disseminated iron ore for beneficiation  

NASA Astrophysics Data System (ADS)

This paper focused on Oolitic hematite ore which consists of extremely unequal disseminated particles that are fine-grained and easy to become muddy, It presents the effect of particle fineness, roasting temperature and roasting time and other variables on the beneficiation of this ore. The effect of particle fineness on the concentrate quality was also studied after magnetic roasting, the so-called process of ``magnetic roasting-stage grinding-low intensity magnetic separation-cationic reverse flotation'' was adopted to treat the raw ore under various experimental conditions including particle fineness, roasting temperature and roasting time, etc. it is found the concentrate grade of TFe of raw ore can be increased from 48.32%(original) to 61.30% at a recovery rate of 80.73%. Results show that the effect of particle fineness on mineral processing indexes is significant.

Qiu, T. S.; Zhang, W. X.; Fang, X. H.; Gao, G. K.

2013-06-01

200

Ore and coal beneficiation method  

Microsoft Academic Search

This patent describes a method for the separation of iron pyrite from a pulverized mineral ore comprising iron pyrites as a first constituent and a second constituent selected from the group consisting of coal and non-ferrous metal ores by air froth flotation of an aqueous pulp of the pulverized mineral ore. The improvement comprises incorporating in the pulp from about

Abadi

1987-01-01

201

Magnetite and Native Gold Nanoparticles: Relation with Hydrothermal-Sedimentary Exhalative Environments in Iron-Ore Deposit  

NASA Astrophysics Data System (ADS)

We report for the first time on the finding of magnetite and native gold nanoparticles in an iron-ore deposit. Initial results contribute to understanding the peculiar behaviour and distinctive physical, chemical and magnetic characteristics of the nanoparticles in the iron ore. Study of the natural magnetite nanoparticles provides information on the grain-size effects in their properties and in their nanomineral phases of transformation from temperature effects. This is used to develop a model of the genetic and environmental conditions of nanoparticles formation. Crystallographic studies in magnetite nanoparticles and berthierine were performed by high resolution TEM, and by X-ray diffraction, differential and gravimetric thermal analysis and Mössbauer spectroscopy. We observe magnetite nanoparticles semi-spherical shapes from 2 to 14 nm included in berthierine; continuous formation magnetite nanoparticles for nucleation in the hydrothermal-diagenetic processes provoks aggregates of nanoparticles associated to berthierine, both minerals are genetic indicators of hydrothermal-sedimentary exhalative environments. In our study, we found one locality of berthierine and chamosite in the Peña Colorada deposit. Results permit to observe in the magnetite nanoparticles a high heating resistance, high Curie temperature, Tc = 690 oC d high frequency dependent factor. Mössbauer spectroscophy shows a doublet of distinctive nanophases of Fe2 and Fe3 resulting from magnetite with superpragmatic behaviour.

Rivas-Sanchez, M.; Alva-Valdivia, L.; Urrutia-Fucugauchi, J.; Arenas-Alatorre, J.; Ruiz-Sandoval, M.; Ramos-Molina, M.

2007-05-01

202

Integrated Iron and Steel Industry Final Report. Manual Testing. Youngstown Sinter Company Younstown, Ohio. Volume 2.  

National Technical Information Service (NTIS)

The purpose of the testing at the Youngstown Sinter Company (YSC) plant in Youngstown, Ohio was to perform all activities necessary to characterize the baghouse sintering plant windbox (Strand Baghouse) for the following emission components: (1) Particula...

1999-01-01

203

Losses and dilution of iron ore in mass-caving systems in Krivoi Rog mines  

Microsoft Academic Search

Conclusions  \\u000a \\u000a \\u000a \\u000a 1) \\u000a \\u000a The enrichment of caved capping rock and the impoverishment of the ore during discharge constitute a single process.\\u000a \\u000a \\u000a \\u000a \\u000a 2) \\u000a \\u000a The small specific proportion of the lump fractions and the thinly lamellar structure of the ore exclude marked effects of\\u000a filtration and attrition on the quantitative aspect of ore impoverishment in Krivbass mines.\\u000a \\u000a \\u000a \\u000a \\u000a 3) \\u000a \\u000a The difference in the grain-size

V. K. Martynov; G. E. Simforov; L. G. Drochilov; A. A. Koval'skaya

1969-01-01

204

Abrasive wear behaviour of laser sintered iron–SiC composites  

Microsoft Academic Search

Direct metal laser sintering (DMLS) is one of the popular rapid prototyping technologies for producing metal prototypes and tooling of complex geometry in a short time. However, processing of metal matrix composites (MMCs) by laser sintering is still in infant stage. Thermal cracks and de-bonding of reinforcements are reported while processing MMCs by laser sintering process. There are reports on

C. S. Ramesh; C. K. Srinivas; B. H. Channabasappa

2009-01-01

205

Reduction Kinetics of Iron Ore-Graphite Composite Pellets in a Packed-Bed Reactor under Inert and Reactive Atmospheres  

NASA Astrophysics Data System (ADS)

The rate of reduction of iron ore-graphite composite pellets in a packed-bed reactor under controlled atmosphere (inert and reducing) has been studied through experiments and modeling exercises. A customized high-mass, high-temperature thermogravimetric setup was constructed to carry out reduction experiments in a packed-bed reactor. A very low overall apparent activation energy estimated from experimental data indicates that the packed-bed reduction is unlikely to be chemical kinetics controlled. A kinetic model has been developed to calculate the temporal evolution of various phases of iron oxides and metallic iron. The rate-dependent parameters of the kinetic model are estimated from experimental data by applying an optimization tool. The predicted phases at various degrees of reduction were verified by X-ray diffraction and metallographic investigation, and a reasonable agreement between the results has been observed. It is observed that both the rate and the extent of metallic-iron production increase under reactive atmosphere. In addition, a simplified thermal model has been developed to ascertain the role of heat transfer on the kinetics of the reduction process under inert atmosphere. The reduction kinetics of the packed bed under reactive atmosphere, on the other hand, is not controlled by heat transfer and might possibly be controlled by CO-gas mass transfer through the pellets.

Chowdhury, G. M.; Roy, G. G.; Roy, S. K.

2008-04-01

206

Effects of simulated deposition of acid mist and iron ore particulate matter on photosynthesis and the generation of oxidative stress in Schinus terebinthifolius Radii and Sophora tomentosa L.  

PubMed

Particulate matter is a natural occurrence in the environment, but some industries, such as the iron ore sector, can raise the total amount of particles in the atmosphere. This industry is primarily a source of iron and sulfur dioxide particulates. The effects of the pollutants from the iron ore industries on representatives of restinga vegetation in a Brazilian coastal ecosystem were investigated using physiological and biochemical measures. Two species, Schinus terebinthifolius and Sophora tomentosa, were exposed to simulated deposition of acid mist and iron ore particulate matter in acrylic chambers in a greenhouse. Parameters such as gas exchange, fluorescence emission, chlorophyll content, total iron content, antioxidant enzyme activity and malondialdehyde content were assessed in order to evaluate the responses of the two species. Neither treatment was capable of inducing oxidative stress in S. terebinthifolius. Nevertheless, the deposition of iron ore particulates on this species increased chlorophyll content, the maximum quantum efficiency of photosystem II and the electron transport rate, while iron content was unaltered. On the other hand, S. tomentosa showed a greater sensitivity to the treatments. Plants of S. tomentosa that were exposed to acid mist had a decrease in photosynthesis, while the deposition of iron particulate matter led to an increase in iron content and membrane permeability of the leaves. The activities of antioxidant enzymes, such as catalases and superoxide dismutase, were enhanced by both treatments. The results suggested that the two restinga species use different strategies to overcome the stressful conditions created by the deposition of particulate matter, either solid or wet. It seems that while S. terebinthifolius avoided stress, S. tomentosa used antioxidant enzyme systems to partially neutralize oxidative stress. The findings also point to the potential use of S. tomentosa as a biomarker species under field conditions. PMID:18571219

Kuki, Kacilda Naomi; Oliva, Marco Antônio; Pereira, Eduardo Gusmão; Costa, Alan Carlos; Cambraia, José

2008-09-15

207

Effect of Tapioca Flour on the Anionic Flotation of Gangue from Iron Ores.  

National Technical Information Service (NTIS)

The differences in starch demands that occur between ore types subjected to the anionic flotation of calcium-activated gangue and the range of residual starch contents expected to give the best metallurgical response were evaluated on a batch and pilot pl...

A. F. Colombo

1972-01-01

208

Hydraulic Hoisting of Crushed Ores. A Feasibility Study and Pilot-Plant Investigation on Coarse Iron Ore Transportation by Centrifugal Pumps.  

National Technical Information Service (NTIS)

The trend in mining is toward giant open pit mines because of their suitability for mechanization and highly productive mining. To compete with ore from such mines, new ways of working and transporting ore from underground mines must be found. A hydraulic...

A. Sellgren

1977-01-01

209

A study on plasticity and compression strength in wet iron ore green pellets related to real process variations in raw material fineness  

Microsoft Academic Search

The main binding force in wet iron ore green pellets has been found to be the cohesive force of the viscous binder. The wet compression strength (wet-CS) in green pellets is, however, also influenced by the green pellet plasticity. A certain degree of plasticity is needed to sustain the green pellet growth rate. Too much plasticity results in decreased bed

S. P. E. Forsmo; P.-O. Samskog; B. M. T. Björkman

2008-01-01

210

The effect of iron-ore particles on the metal content of the brown alga Padina gymnospora (Espírito Santo Bay, Brazil).  

PubMed

The iron-ore particles discharged by a pellet processing plant (Espírito Santo Bay, Brazil) cover the seabed of Camburi Beach and consequently, the epibenthic community. In order to determine the importance of the contribution of the iron-ore deposits to the metal concentration in macroalgae of Espirito Santo Bay, four methods of cleaning particulate material adhered to the surface of thalli were tested prior to metal tissue analysis (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) of Padina gymnospora. In addition, heavy metal concentrations were determined in individuals of P. gymnospora from a site (Frade Island) not affected by the iron-ore particles. The most efficient cleaning treatment, a combination of scraping and washing with an ethanol-seawater solution (NA+SC+ET) removed a number of particles on the surface of thalli 10 times higher than that observed in the control (C). Using this treatment, the total-metal concentrations were reduced by 78% for Fe and 50% for Al respect to the control. However, Fe, Al and Cu concentrations after treatment NA+SC+ET were significantly higher than those found at Frade Island. It is suggested that the iron-ore deposit might be a source for metal availability to macroalgae exposed to the dumped material at Espirito Santo Bay. PMID:12628209

Nassar, Cristina A G; Salgado, Leonardo T; Yoneshigue-Valentin, Yocie; Amado Filho, Gilberto M

2003-01-01

211

Os isotopic composition of steels: Constraints on sources of Os in steel & crustal isotopic evolution of iron ores  

NASA Astrophysics Data System (ADS)

Metal contamination during sample processing is a potential concern in Os-isotope studies. We examined Os concentrations and Os isotopes in industrial steels. Samples include high Cr stainless steels (>10.5% Cr), low alloy steels (>=92% Fe) and high alloy steels (<92% Fe). The chief components used to make steel are iron ore, chromites and coke. Coke is derived from coals that have low Os concentration (~36 ppt) [1]. Chromites in steels are mined from chromitites, which have high average Os concentrations and mantle-like 187Os/188Os ratios (~88 ppb Os, 187Os/188Os ? 0.127×24) [2]. Iron ores used in US steel manufacturing derive chiefly from magnetites mined from iron-bearing formations such as Banded Iron Formations (BIF), which have median Os concentration of ~4.8 ppb and radiogenic 187Os/188Os ? 0.358×388 [3]. Os concentrations in the measured steels span a wide range, from 0.03 to 22 ppb. The 187Os/188Os ratios vary from 0.144-4.12. Such high Os concentrations and radiogenic isotopic compositions confirm that metal contamination can affect Os-isotope compositions during sample processing, particularly for low-[Os] samples. There is no correlation between C and Os concentration in steel, indicating that coke is not a major Os source in steels. Os concentrations in steels are positively correlated with Cr content, suggesting that chromite-derived Os dominates the Os budget in stainless steels. 187Os/188Os is negatively correlated with Cr content, ranging from 0.144-0.195 in high-Cr (>10.5 % Cr) steels but from 0.279-4.12 in low-Cr steels. In addition, there is a positive correlation between 1/Os and 187Os/188Os, consistent with two-component mixing of Os derived from magnetite ore and chromites. Lower Os concentrations in steels than expected from simple mixing of magnetite and chromitite suggest some volatile Os loss during smelting. Although the current data is limited, the 186Os-187Os trend defined by the steel analyses can be utilized to extrapolate compositions of the end-member chromite and BIF components. 186Os/188Os values in steels range from 0.119830×5 to 0.119842×42, indistinguishable from the upper mantle. Extrapolation of the 186Os-187Os trend to 187Os/188Os values typical for chromites results in an estimated 186Os/188Os value of 0.119832×4, within error of values previously reported for chromites [4,5]. Extrapolation of the chromite-steel trend to the highly radiogenic (continental crust-like) 187Os values found in BIFs results in much greater uncertainty, but the extrapolated value (0.119834×11) is also indistinguishable from the upper mantle. We estimate an upper bound for the initial ?186Os of the 1.8 Ga BIF source of magnetite ore of ~0.3, similar to initial ?186Os in black shales (0.3-0.5) and freshwater Mn-nodule (1.6), but lower than in loess (1-2.4) [6]. Aqueous deposits and precipitates may sample Os derived from crustal sources with systematically lower time-integrated Pt/Os than the sources for loess. [1] Baioumy H.M et al., Chem Geo 2011 [2] Walker R.J et al., GCA 2002 [3] Ripley E.M et al., Chem Geo 2008 [4] Walker R.J et al., EPSL 2005 [5] Brandon A.D et al., Science 1998 [6] McDaniel D.K et al., GCA 2004

Chatterjee, R. N.; Lassiter, J. C.

2013-12-01

212

Decline in the lung cancer hazard: a prospective study of the mortality of iron ore miners in Cumbria.  

PubMed Central

The mortality of 1947 Cumbrian iron ore miners has been studied over the period 1939-82 in relation to that among other groups of men in England and Wales: (a) all men, (b) men of similar social class, and (c) men living in similar types of (mainly rural) area. Significant excesses were found for deaths from tuberculosis and respiratory diseases compared with each of the reference populations. Lung cancer showed an excess over that in comparable (mainly rural) areas of England and Wales, as reported in a previous study using a proportionate method of analysis and which covered the period 1948-67 but no appreciable excess after 1967. Reasons for this decline are discussed.

Kinlen, L J; Willows, A N

1988-01-01

213

A Mathematical Model of Gas Flow Distribution in the Grate-Kiln Iron Ore Pellets Induration Process  

NASA Astrophysics Data System (ADS)

Although models for general gas (e.g. natural gas) pipeline networks have been well established, research on another kind of gas networks we named gas passage networks (i.e. GPN; set that gas pass through spaces) in industry is rare. The features of the GPN are hard-determination leakage (i.e. 24.4%), quite-different thermophysical-properties, more cycles and not engaging cycle energy equations directly. And the gas network of grate-kiln-cooler (GKC) plant used for iron ore pellets induration is belong to this type. This paper develops a mathematical model to evaluate the flow distribution in this kind. Further, a field test was systematically carried out on a GKC plant in China. At last, the result shows that good agreement was observed, indicating the validity of the model.

Feng, Junxiao; Zhang, Yu; Zhang, Yiyang; Xie, Zhiyin; Zhang, Cai

2010-03-01

214

Friction and wear behavior of laser-sintered iron–silicon carbide composites  

Microsoft Academic Search

Laser sintering is currently one of the most popular techniques to develop innovative materials for many of the high tech industrial applications owing to its ability to build complex parts in a short time. As such, material researchers are focusing on developing advanced metal matrix composites through selective laser sintering method to develop an intricate component eliminating delay in production

C. S. Ramesh; C. K. Srinivas

2009-01-01

215

Geochemistry of Late Mesozoic dioritic porphyries associated with Kiruna-style and stratabound carbonate-hosted Zhonggu iron ores, Middle–Lower Yangtze Valley, Eastern China: Constraints on petrogenesis and iron sources  

Microsoft Academic Search

Several small Mesozoic sodium-rich dioritic porphyries associated with huge iron oxide deposits occur in the Zhonggu iron ore field, in the eastern part of the Middle–Lower Yangtze River Belt (MLYRB) in the Yangtze craton. We present bulk-rock major and trace element and Sr and Nd isotopic compositions of the three representative dioritic porphyries: the Gushan, Hemushan and Baixiangshan dioritic intrusions.

Tong Hou; Zhaochong Zhang; John Encarnacion; Yangsong Du; Zhidan Zhao; Junlai Liu

2010-01-01

216

Preparation and characterization of iron aluminide based intermetallic alloy from titaniferous magnetite ore  

Microsoft Academic Search

Intermetallic alloys such as iron aluminide (Fe3Al) display an attractive combination of physical and mechanical properties. It is a potential candidate for application demanding high strength, superior oxidation, sulphidation and corrosion resistance. However, the utilization of this alloy is limited owing to problems of its preparation by conventional techniques and poor room temperature ductility. The present paper is, therefore, an

S. P. Chakraborty; I. G. Sharma; P. R. Menon; A. K. Suri

2003-01-01

217

Paleomagnetism, rock magnetism and opaque mineralogy of iron ore deposits from southern Mexico and their implications for quantitative modelling of magnetometric data  

SciTech Connect

Paleomagnetism, Rock Magnetism and Opaque Mineralogy of Iron Ore Deposits from Southern Mexico and Their Implications for Quantitative Modelling of Magnetometric Data. The tectonic history of the Pacific continental margin is critical for understanding their mineral deposits. The margin presents intrusive and volcanic activity characteristic of magmatic arcs of subduction zones, which are genetically related with deposits of Cu, Fe, Mo, Au, and Ag. Although the tectonic history has been complex, involving oblique plate subduction, lateral movements, accretion of magmatic arcs and oceanic plateaux, and lateral displacements of major blocks, the mineral deposits are spatially distributed along elongated belts that roughly follow the margin. The authors have conducted paleomagnetic, rock magnetic, and petrological studies of the iron ore deposits to investigate genesis, magnetic mineralogy, stratigraphic relationships, metamorphism, and applications on quantitative modelling of magnetometric data. The remanent magnetization and susceptibility data are necessary for interpretation of magnetic anomalies. The results permit a comparison of the mineral deposits along the continental margin.

Alva-Valdivia, L.M.; Fucugauchi, Urrutia, J.; Bohnel, H.; Moran Zenteno, D.J. (Universidad Nacional Autonoma de Mexico, Mexico City (Mexico))

1990-06-01

218

[Clinical and morphologic characteristics of lung cancer in miners of Krivoy Rog iron-ore region and of uranium mines of Zhovti Vody].  

PubMed

Clinical and morphological features of cancer were observed in two groups of miners (of Krivoy Rog iron-ore and Zholty Vody uranium mines), working in hazardous labour conditions. In both of groups the disease course had typical features for lung cancer. Roentgenologic changes were observed, central cancer of left and right lung was revealed by bronchoscopy method. In all the cases lung cancer was morphologically proved and classified as squamous. Rapid progression of the disease and late medical aid appealability cause the patients consulted with their doctors only at the stage of II-III, sometimes III of the disease and it makes a distinction of lung cancer in miners of iron-ore and uranium mines. In order to prevent such a late diagnostics all the miners should be referred to the group of risk on lung cancer. PMID:17051723

Bednaryk, O M; Filipchenko, L L; Pan'kova, A O; Kryvoshe?, L O; Slinchenko, M Z

2004-01-01

219

Evidence of dilatant and non-dilatant damage processes in oolitic iron ore: P-wave velocity and acoustic emission analyses  

NASA Astrophysics Data System (ADS)

Uniaxial and triaxial compression experiments were performed on oolitic iron ores to investigate damage processes. Most of these experiments included four indirect measurements of damage evolution, that is, P-wave velocity and maximum amplitude received during pulse transmission experiments, elastic properties (apparent Youn?s modulus and apparent Poisso?s ratio) and acoustic emission (AE) monitoring. The mechanical behaviour deduced from strain measurements is dilatant for some samples and non-dilatant for the other samples. However, variations in elastic properties indicate damage processes for all samples. AE source mechanism analysis shows two different microscopic damage processes: (1) for dilatant rock, the development of axial extensive microcracks as well as their interaction and coalescence lead to the formation of shear macroscopic discontinuities; (2) for non-dilatant oolitic iron ore, both compressive and shear micromechanisms take place and interact with macroscopic fractures. A particular consistency between the four types of measurements employed was observed.

Wassermann, J.; Senfaute, G.; Amitrano, D.; Homand, F.

2009-06-01

220

Monitoring sintering burn-through point using infrared thermography.  

PubMed

Sintering is a complex industrial process that applies heat to fine particles of iron ore and other materials to produce sinter, a solidified porous material used in blast furnaces. The sintering process needs to be carefully adjusted, so that the combustion zone reaches the bottom of the material just before the discharge end. This is known as the burn-through point. Many different parameters need to be finely tuned, including the speed and the quantities of the materials mixed. However, in order to achieve good results, sintering control requires precise feedback to adjust these parameters. This work presents a sensor to monitor the sintering burn-through point based on infrared thermography. The proposed procedure is based on the acquisition of infrared images at the end of the sintering process. At this position, infrared images contain the cross-section temperatures of the mixture. The objective of this work is to process this information to extract relevant features about the sintering process. The proposed procedure is based on four steps: key frame detection, region of interest detection, segmentation and feature extraction. The results indicate that the proposed procedure is very robust and reliable, providing features that can be used effectively to control the sintering process. PMID:23939585

Usamentiaga, Rubén; Molleda, Julio; Garcia, Daniel F; Bulnes, Francisco G

2013-01-01

221

Rock-Magnetic and Oxide Microscopic Studies of the El Laco Iron Ore Deposits, Chilean Andes, and Implications for Magnetic Anomaly Modeling  

Microsoft Academic Search

Microscopic and rock-magnetic studies of the ores and host rocks of the El Laco iron oxide deposits permit us to characterize the magnetic mineralogy and the processes affecting natural remanent magnetization (NRM) during emplacement and evolution of the deposits. Particular attention was devoted to identifying the magnetic mineral composition (magnetite and\\/or titanomagnetite, and hematite and\\/or titanohematite, and titanomaghemite) and grain

L. M. Alva-Valdivia; M. L. Rivas; A. Goguitchaichvili; J. Urrutia-Fucugauchi; J. A. Gonzalez; J. Morales; S. Gómez; F. Henríquez; J. O. Nyström; R. H. Naslund

2003-01-01

222

Study of moisture transfer during the strand sintering process  

NASA Astrophysics Data System (ADS)

Moisture transfer during the strand sintering operation was studied both experimentally and using a mathematical model. The drying of iron ore pellets was found to occur in two distinct periods: one at a constant drying rate and the other at a decreasing drying rate, whereas the drying of zinc ore pellets always occurs at a decreasing drying rate. Characteristic drying curves were determined for both materials. The moisture transfer mechanisms during the sintering process were demonstrated in detail, including the recondensation of water in the cold layers of the bed and the formation of an inert, overmoistened zone. The mathematical model presented simulates all of these phenomena and is used to calculate the variables related to moisture transfer. The model is adaptable to other processes where a hot gas passes through a moist packed bed.

Patisson, F.; Bellot, J. P.; Ablitzer, D.

1990-02-01

223

Quantitative measurements of loss on ignition in iron ore using laser-induced breakdown spectroscopy and partial least squares regression analysis.  

PubMed

Laser-induced breakdown spectroscopy (LIBS) and partial least squares regression (PLSR) have been applied to perform quantitative measurements of a multiple-species parameter known as loss on ignition (LOI), in a combined set of run-of-mine (ROM) iron ore samples originating from five different iron ore deposits. Global calibration models based on 65 samples and their duplicates from all the deposits with LOI ranging from 0.5 to 10 wt% are shown to be successful for prediction of LOI content in pressed pellets as well as bulk ore samples. A global independent dataset comprising a further 60 samples was used to validate the model resulting in the best validation R(2) of 0.87 and root mean square error of prediction (RMSEP) of 1.1 wt% for bulk samples. A validation R(2) of 0.90 and an RMSEP of 1.0 wt% were demonstrated for pressed pellets. Data preprocessing is shown to improve the quality of the analysis. Spectra normalization options, automatic outlier removal and automatic continuum background correction, which were used to improve the performance of the PLSR method, are discussed in detail. PMID:21144150

Yaroshchyk, Pavel; Death, David L; Spencer, Steven J

2010-12-01

224

U?Pb systematics of stilbite-bearing low-temperature mineral assemblages from the Malmberget iron ore, northern Sweden  

NASA Astrophysics Data System (ADS)

Minerals with a low thermal stability strongly constrain the history of cooling and later tectonic reworking of an area, provided these minerals can be dated. The possible use of stilbite, a Ca?Al-silicate of the zeolite group, for geochronologic studies was investigated. Open fractures in the Palaeoproterozoic Malmberget iron ore, northern Sweden, contain low-temperature mineral assemblages with various combinations of apatite, stilbite, calcite, biotite, and less commonly titanite and monazite. Two generations of fractures, that are characterized by calcite and stilbite with distinctly radiogenic initial 87Sr/ 86Sr at ca. 0.720 and ca. 0.708, are dated at ca. 1740 Ma (monazite) and 1620-1613 Ma (titanite), respectively. Apatite samples, even those intimately intergrown with ca. 1740 Ma old monazite, yield U-Pb ages at 1620-1600 Ma, which indicates that apatite apparently recrystallized and reset its U?Pb system. Older stilbite yields a secondary lead isochron at 1730 ± 6.4 Ma (2?), which unequivocally demonstrates that the ambient temperature in the Malmberget area from then on remained below the thermal stability of stilbite (ca. 150°C). Stilbite is a natural ion-exchanger and its U-Pb systematics indicates recent mobility of uranium and lead. However, the 1730 ± 6.4 Ma (2?) age demonstrates that some of the older stilbite was not disturbed during younger fracturing. Hydrothermally altered and secondary stilbite samples yield scattered lead arrays that correspond to secondary isochrons at ca. 1650-1600 D4a, which agrees with the U-Pb titanite and apatite ages. Thus, in combination with other geochronometers, the generally imprecise stilbite ages provide information on the cooling history of an area.

Romer, Rolf L.

1996-06-01

225

Basic properties of sintering dust from iron and steel plant and potassium recovery.  

PubMed

With the production of crude steel, China produces several million tons of sintering dusts which contain a great deal of valuable metals such as, K, Na, Zn, Pb. If discharged directly without adequate treatment, these elements can lead to adverse effects on the environment. Therefore, it is very necessary to determine how to separate these elements from the dust before discharge. Several physical and chemical detection methods were used to study the basic properties of sintering dust. At the same time, preliminary experiments on the recovery of the potassium resources from the sintering dust were carried out. The mean particle size of the electrostatic precipitator (ESP) dust determined by a laser granulometer was 41.468 microm. Multi-point BET and single-point BET analysis showed that the surface area of the ESP dust was 2.697 m2/g. XRD measurements detected the following phases in the ESP dust: Fe2O3, Fe3O4, KCl and NaCl, and Fe2O3, Fe3O4 and SiO2 in the water-washed dust. SEM-EDS results proved that in the ESP dust, K mostly existed in the form of KCl particles without being coated. Leaching experiments showed that the KCl in the ESP dust could be separated and recovered by water leaching and fractional crystallization. Through the recovery experiments, the yield of K-Na vaporized crystalline salt was 18.56%, in which the mass fractions of KCl, NaCl, CaSO4 and K2SO4 were about 61.03%, 13.58%, 14.03% and 9.97%, respectively. This process is technically viable and considerable in economic benefit. There was almost no secondary pollution produced in the whole recovery process. PMID:24191613

Zhan, Guang; Guo, Zhancheng

2013-06-01

226

Integrated Iron and Steel Industry Final Report. Manual Testing. Youngstown Sinter Company Youngstown, Ohio. Volume 3. Appendices.  

National Technical Information Service (NTIS)

The purpose of the testing at the Youngstown Sinter Company (YSC) plant in Youngstown, Ohio was to perform all activities necessary to characterize the baghouse sintering plant windbox (Strand Baghouse) for the following emission components: (1) Pariculat...

1999-01-01

227

Integrated Iron and Steel Industry Final Report. Manual Testing. Youngstown Sinter Company Youngstown, Ohio. Youngstown, Ohio. Volume 1.  

National Technical Information Service (NTIS)

The objective of the testing at the Youngstown Sinter Company (YSC) plant in Youngstown, Ohio, was to perform all activities necessary to characterize the baghouse sintering plant windbox (Strand Baghouse) for the following emission components: Particulat...

1999-01-01

228

Effect of Import of Iron Ore and Semi-Finished Steel on the National Security: An Investigation Conducted Under Section 232 of the Trade Expansion Act of 1962, as amended.  

National Technical Information Service (NTIS)

This report summarizes the findings of an investigation conducted by the Secretary of Commerce (Secretary) pursuant to Section 232 ofthe Trade Expansion Act of 1962, as amended, 19 U.S.C. 1862 (Section 232), into the effects of imports of iron ore and sem...

2001-01-01

229

Determination of tellurium in ores, concentrates and related materials by graphite-furnace atomic-absorption spectrometry after separations by iron collection and xanthate extraction.  

PubMed

A method for determining approximately 0.01 mug/g or more of tellurium in ores, concentrates, rocks, soils and sediments is described. After sample decomposition and evaporation of the solution to incipient dryness, tellurium is separated from > 300 mug of copper by co-precipitation with hydrous ferric oxide from an ammoniacal medium and the precipitate is dissolved in 10M hydrochloric acid. Alternatively, for samples containing 300 mug of copper, the salts are dissolved in 10M hydrochloric acid. Tellurium in the resultant solutions is reduced to the quadrivalent state by heating and separated from iron, lead and various other elements by a single cyclohexane extraction of its xanthate complex from approximately 9.5M hydrochloric acid in the presence of thiosemicarbazide as a complexing agent for copper. After washing with 10M hydrochloric acid followed by water to remove residual iron, chloride and soluble salts, tellurium is stripped from the extract with 16M nitric acid and finally determined, in a 2% v/v nitric acid medium, by graphite-furnace atomic-absorption spectrometry at 214.3 nm in the presence of nickel as matrix modifier. Small amounts of gold and palladium, which are partly co-extracted as xanthates if the iron-collection step is omitted, do not interfere. Co-extraction of arsenic is avoided by volatilizing it as the bromide during the decomposition step. The method is directly applicable, without the co-precipitation step, to most rocks, soils and sediments. PMID:18964927

Donaldson, E M; Leaver, M E

1990-02-01

230

Process for the production of sintered bauxite spheres  

SciTech Connect

A process is disclosed for producing high strength sintered bauxite spheres usable as fracture propping agents in oil or gas wells. Proppants are produced by continuous spray-granulation of an aqueous binder-containing aluminous ore suspension to form granules which are subsequently sintered. Suitable starting materials include ores of high aluminum silicate content.

Lunghofer, E.P.; Mortensen, S.; Ward, A.P.

1984-04-03

231

The influence of premolding load on the electrical behavior in the initial stage of electric current activated sintering of carbonyl iron powders  

NASA Astrophysics Data System (ADS)

This paper reports the premolding load effect on the electrical behavior in the initial stage of electric current activated sintering of carbonyl iron powders. An electrical network model is put forward to estimate the uniformity of electric current in a powder compact subjected to different premolding loads in the initial stage. The improvement in current uniformity can be reflected from a simultaneous increase in the number N and the mass fraction ? of conductive particle chains in the compact. Both N and ? are found to follow a power law with the premolding load F for different exponent values. When ? is equal to 1, a critical load is reached, at which point the current flows through all particles during sintering. Using the results of the model and the electrical contact theory, it is also found that only an increased temperature of less than 20 K across the particle contacts. The distribution of temperature is uniform in particles. This is clearly different from the general acceptance that local high temperature is created at contact during electric current activated sintering. The neck formation and growth are thought to be mainly due to heat bonding and electromigration, of which effects on mass transport are pronouncedly enhanced by increasing the bulk temperature. Because of the poor current uniformity and relatively large power dissipation, a soft thermal breakdown is observed in the sample with high initial resistance. A reduction in premolding load may cause an increase in the initial electrical resistance of the compact. Owing to the unique voltage-current characteristic of electric current activated sintering, a higher initial resistance of compact means more thermal energy is involved, consequently producing a higher bulk temperature and getting a better quality of sintering. This also provides theoretical explanation for the experimental results from Inoue and Istomina.

Ye, Yongquan; Li, Xiaoqiang; Hu, Ke; Lai, Yangen; Li, Yuanyuan

2013-06-01

232

Sorption behavior of Pb(II) and Cd(II) on iron ore slime and characterization of metal ion loaded sorbent.  

PubMed

The present investigation evaluates the sorption effectiveness of Pb(II) and Cd(II) ions on iron ore slime (IOS) obtained from Jindal Steel Ltd., Vijayanagaram, India. The sorption followed pseudo-second-order kinetics for both the cations. Pb(II) and Cd(II) sorption increased with the increase in pH from 2 to 4.5. The sorption data fitted well to Freundlich model as compared to Langmuir model. Synergistic effect of Pb(II) and Cd(II) on their sorption on IOS sample showed that Pb(II) sorption increases in presence of Cd(II) whereas Cd(II) sorption decreases. Presence of chloride or sulphate resulted in increased Pb(II) sorption but adversely affected Cd(II) sorption. The XRD patterns of Pb(II) adsorbed on IOS sample showed disappearance of some silica peaks and shifting of hematite peaks corresponding to 104 and 110 plane. For Cd(II) sorbed IOS sample, only peak shift for hematite of 104 and 110 plane was observed. Shifting of IR bands indicated that the Pb(II) sorption occurred through an inner sphere mechanism where as Cd(II) sorption occurred through outer sphere mechanism. EPMA studies showed that Pb(II) form a uniform thin layer and Cd(II) concentrate only on iron oxide phase. Regeneration and stability data on metal ion loaded IOS sample has been included. PMID:19185424

Mohapatra, M; Rout, K; Mohapatra, B K; Anand, S

2009-07-30

233

Mathematical modeling of the reduction process of iron ore particles in two stages of twin-fluidized beds connected in series  

NASA Astrophysics Data System (ADS)

A mathematical model is presented to describe the reduction process of iron ore particles in two stages of twin-fluidized beds (TFBs) connected in series: prereduction and final reduction stages. Main features of the model are the inclusion of particle degradation phenomenon to account for its effect on reduction of iron oxides and reduction kinetics for multiparticles having a wide size distribution. It was found that about 90 pct of overall particle degradation occurs in the prereduction stage mainly due to thermal stress and volume expansion. The reduction degree of particles larger than 1 mm decreased fast with increasing particle size in both the prereduction and final reduction stages. However, the particles sized between 0.2 and 1 mm showed mild increase in reduction degree, and steep increase for the fines smaller than 0.2 mm. The reduction degree was also gradually decreased with increasing the gas oxidation degree of feed gas in both the prereduction and final reduction stages. It was found that to obtain a desired reduction degree, it is of great importance to control the bed temperature in stage I rather than in stage II. The optimum range of residence time was 15 to 20 minutes in the prereduction stage and 30 to 35 minutes in the final reduction stage.

Hahn, Y. B.; Chang, K. S.

1998-10-01

234

Assessment of Vegetation Establishment on Tailings Dam at an Iron Ore Mining Site of Suburban Beijing, China, 7 Years After Reclamation with Contrasting Site Treatment Methods  

NASA Astrophysics Data System (ADS)

Strip-mining operations greatly disturb soil, vegetation and landscape elements, causing many ecological and environmental problems. Establishment of vegetation is a critical step in achieving the goal of ecosystem restoration in mining areas. At the Shouyun Iron Ore Mine in suburban Beijing, China, we investigated selective vegetation and soil traits on a tailings dam 7 years after site treatments with three contrasting approaches: (1) soil covering (designated as SC), (2) application of a straw mat, known as "vegetation carpet", which contains prescribed plant seed mix and water retaining agent (designated as VC), on top of sand piles, and (3) combination of soil covering and application of vegetation carpet (designated as SC+VC). We found that after 7 years of reclamation, the SC+VC site had twice the number of plant species and greater biomass than the SC and VC sites, and that the VC site had a comparable plant abundance with the SC+VC site but much less biodiversity and plant coverage. The VC site did not differ with the SC site in the vegetation traits, albeit low soil fertility. It is suggested that application of vegetation carpet can be an alternative to introduction of topsoil for treatment of tailings dam with fine-structured substrate of ore sands. However, combination of topsoil treatment and application of vegetation carpet greatly increases vegetation coverage and plant biodiversity, and is therefore a much better approach for assisting vegetation establishment on the tailings dam of strip-mining operations. While application of vegetation carpet helps to stabilize the loose surface of fine-structured mine wastes and to introduce seed bank, introduction of fertile soil is necessary for supplying nutrients to plant growth in the efforts of ecosystem restoration of mining areas.

Yan, Demin; Zhao, Fangying; Sun, Osbert Jianxin

2013-09-01

235

Ore metals through geologic history.  

PubMed

The ores of chromite, nickel, copper, and zinc show a wide distribution over geologic time, but those of iron, titanium, lead, uranium, gold, silver, molybdenum, tungsten, and tin are more restricted. Many of the limitations to specific time intervals are probably imposed by the evolving tectonic history of Earth interacting with the effects of the biomass on the evolution of the earth's s surface chemistry. Photosynthetic generation of free oxygen and "carbon" contributes significantlly to the diversity of redox potentials in both sedimentary and igneous-related processes of ore formation, influencing the selection of metals at the source, during transport, and at the site of ore deposition. PMID:17777763

Meyer, C

1985-03-22

236

Mathematical Modeling of the Kinetics of Carbothermic Reduction of Iron Oxides in Ore-Coal Composite Pellets  

Microsoft Academic Search

The kinetics of the carbothermic reduction of iron oxides in a composite pellet made of taconite concentrate and high-volatility\\u000a coal has been studied by means of mathematical modeling that simultaneously takes into account the transfer rates of both\\u000a the mass and the heat, and the rates of chemical reactions. The computational results, which have been validated with experimental\\u000a data in

Kang Sun; W.-K. Lu

2009-01-01

237

Geochemical investigations and Fluid inclusion studies on iron ores from Qatruyeh area, Sanandaj-Sirjan zone, SW Iran: implications for a hydrothermal-metasomatic genetic model  

NASA Astrophysics Data System (ADS)

The Qatruyeh iron deposits are located in the eastern edge of the NW-SE trending Sanandaj-Sirjan metamorphic zone of southwestern Iran and are hosted by a Late Proterozoic to Early Paleozoic sequence dominated by metamorphosed carbonate rocks. The ores occur as layered bodies, with lesser amounts within disseminated magnetite- and hematite-bearing veins. Geochemical analyses of the high-field strength, large ion lithophile, and rare earth elements (REE) indicate that mineralization within the low-grade layered magnetite ores was related to magmatic process accompanied by Na-Ca alteration. The stage is shown by metasomatic replacement textures, gradational contact between layered magnetite and host rock and mineral assemblages of actinolite + titanite + siderite + tourmaline (dravite) + quartz + paragonite. Chemical analyses on layered magnetite show Zn, Cr, LREE and Co/Ni ratio were enriched, whereas V and HREE were depleted. Subsequent to formation, low-temperature hydrothermal activity produced hematite ores with associated propyllitic-sericitic alteration with hematite (specularite) + chlorite + epidote + muscovite + quartz assemblages. The metacarbonate host rocks are LILE-depleted and HFSE-enriched due to metasomatic alteration. REE were relatively immobile during host rock alterations. Microthermometric analyses generally, have been described and measured only on primary inclusions of two-phase liquid +vapor (type A), and two-phase vapor +liquid with (type B). Type A inclusions are dominated by more than 80 vol % of H2O at room temperature. The first ice temperature of melting (Tm) often occurs around -24.5° to -19.5° C. Salinities determined by last ice Tm were 3.5 to 15 weight percent NaCl equivalent (size of inclusions between 2.5 and 15?m) for inclusions trapped in whole quartz samples. The average of homogenization temperature (Th) values change between 300 and 345°C and Tm measurements range from -11.3° to -3.5°C. Homogenization temperature exists for primary types (A) of fluid inclusion may indicate episodes of hydrothermal activities in mesothermal systems for Fe deposits in this region. Type B inclusions, characterized by much more gas bubble within an aqueous liquid are commonly found in all selected samples. Type B inclusions are dominated by more than 60 vol % H2O-CO2 at room temperature. In the Type B inclusions liquid-CO2 homogenize to vapor in the temperature range 396° to 410°C. A general increase in Th values is observed for Type B inclusions in comparison to Type A. Values of Tm of type B inclusions fall within a narrow range from -54.9 to -55.4oC. Salinities determined by last ice Tm were 2.8 to 3.9 weight percent NaCl equivalent. These fluids consist of mixtures of H2O and CO2, the most common fluids released during metamorphic reactions. Fluid inclusion data indicate that the ore forming fluids at Qatruyeh were CO2-bearing, low to moderately saline, NaCl-MgCl2-CaCl2-H2O rich fluids. Fluid mixing, cooling and effervescence played an important role in the formation of the Qatruyeh deposits. Therefore, The range of homogenization temperatures, presence of CO2 in quartz fluid inclusions and an increase in pH indicate that the mixing of fluids and reaction with dolomitic-marble host rock were the most important mechanisms for deposition of magnetite.

Asadi, Sina; Rajabzadeh, Mohammad Ali

2010-05-01

238

Acid-base properties and surface complexation modeling of phosphate anion adsorption by wasted low grade iron ore with high phosphorus.  

PubMed

The adsorption phenomena and specific reaction processes of phosphate onto wasted low grade iron ore with high phosphorus (WLGIOWHP) were studied in this work. Zeta potential and Fourier transform infrared spectroscopy (FTIR) analyses were used to elucidate the interaction mechanism between WLGIOWHP and aqueous solution. The results implied that the main adsorption mechanism was the replacement of surface hydroxyl groups by phosphate via the formation of inner-sphere complex. The adsorption process was characterized by chemical adsorption onto WLGIOWHP. The non-electrostatic model (NEM) was used to simulate the surface adsorption of phosphate onto WLGIOWHP. The total surface site density and protonation constants for NEM (NT=1.6×10(-)(4)mol/g, Ka1=2.2×10(-)(4), Ka2=6.82×10(-)(9)) were obtained by non-linear data fitting of acid-base titrations. In addition, the NEM was used to establish the surface adsorption complexation modeling of phosphate onto WLGIOWHP. The model successfully predicted the adsorption of phosphate onto WLGIOWHP from municipal wastewater. PMID:24910055

Yuan, Xiaoli; Bai, Chenguang; Xia, Wentang; An, Juan

2014-08-15

239

The influences of mining subsidence on the ecological environment and public infrastructure: a case study at the Haolaigou Iron Ore Mine in Baotou, China  

Microsoft Academic Search

The scope and extent of mine subsidence caused by exploitation of metal ores are usually low. However, in some cases, owing\\u000a to such factors as special geological conditions in ore body, backward mining technology and unsound management systems, exploitation\\u000a of metal ores would also lead to a large area of mine subsidence, causing great damages to the mining environment and

Xiong Wu; Xiao-Wei Jiang; Yu-Fu Chen; Hong Tian; Neng-Xiong Xu

2009-01-01

240

REE signatures in 3.51 Ga BIF and Bedded Chert from Iron Ore Group, Singhbhum Craton, India: Implications for Paleoarchean Ocean Oxygenation  

NASA Astrophysics Data System (ADS)

The metasedimentary rock records in Archaean greenmstone belts provide primary information on evolution of the early Earth. The bedded cherts and BIFs in particular have been studied from Paleo-Mesoarchean greenstone belts for understanding the nature of the oceanic circulation and for the record of early life. However, scarcity of low-strained Paleo-Mesoarchean successions is a major impediment in this regard. The southern Iron Ore Group (SIOG) (3506.8 × 2.3 Ma, U-Pb SHRIMP on zircon by Mukhopadhyay et al., 2008) of the Singhbhum Craton, eastern India includes low-grade bimodal volcanics-ultramafics and BIF -bearing greenstone succession. The bedded chert and BIFs in this succession show significant stratigraphic variation that suggests a stratified ocean and availability of dissolved oxygen in deep-water regime. Bedded chert occurs interleaved with either metabasics or with the silicic volcanics in the lower part of the succession. BIF occurs only towards the top of the succession conformably overlying the silicic volcanics. The bedded cherts with REE and other trace element compositions such as Cu, Co, Ni, Zr, Hf pointing towards contributions from terrigenous or silicic as well as mafic volcanic sources. In contrast BIFs with very low alumina content and superchondritic Y/Ho ratios (36.2 to 40.1) indicate negligible inputs from terrigenous source and is comparable to cherts from Cenozoic ridges. REE-compositions of the bedded chert with respect to PAAS show a flat pattern with feeble positive Eu-anomaly and negligible negative Ce-anomaly. The REE patterns in BIF though similar but show much stronger positive Eu-anomaly and negative Ce-anomaly in comparison. Stratigraphic trend in the geochemical proxies from bedded cherts to BIF, thus record a relative increase in positive Eu-anomaly and decrease in Ce-anomaly. The increase in Eu-anomaly coincident with the BIF deposition up section is likely to suggest increase in in hydrothermal input and ridge spreading. The increased rate of spreading consequently ushers in relative sea rise and much diminished terrigenous inputs during BIF deposition. The Ce-depletion on the other hand may be related to partial removal from seawater during iron formation deposition. The partial fractionation of Ce warrants oxidation in the ocean water column. In Paleoarchean oceans that are believed to be stratified, such condition of oxidation would mean BIF-deposition above the chemocline. Terrigenous starved deep-water BIF deposition in proximity to hydrothermal spreading centres and at shallow water depth would then likely to suggest a condition of pelagic platform on top of spreading ridge with thickening oceanic crust that might have accreted close to the chemocline through accumulation or tectonic underplating. Mukhopadhyay, J., Beukes, N.J., Armstrong, R.A., Zimmermann, U., Ghosh, G., and Medda, R.A. 2008. Dating the Oldest Greenstone in India: A 3.51-Ga Precise U-Pb SHRIMP Zircon Age for Dacitic Lava of the Southern Iron Ore Group, Singhbhum craton. Journal of Geolog, v. 116, p. 449-461.

Mukhopadhyay, J.; Ghosh, G.

2013-12-01

241

Firing an iron ore pelletizing kiln with low-Btu gas from lignite. Report of investigations/1982  

SciTech Connect

This Bureau of Mines report summarizes the performance characteristics of a 30-day around-the-clock gasification-pelletizing test conducted in October and November of 1980 with North Dakota Indianhead lignite. Gasification was conducted in a commercial-size, 6.5-ft-diam, single-stage, fixed-bed, atmospheric pressure producer with a rated capacity of about 30 million Btu/hr. Iron oxide pellets made from a commercial hematite concentrate were fired with the low-Btu gas in a 2.8-ft-diam by 35-ft-long pilot plant rotary kiln at a rate of 900 lb of pellets per hour. Gasifier operations at fuel feed rates up to 3 tons of lignite per hour and hematite pellet induration with raw 160-Btu/std ft3 lignite gas are described.

Nigro, J.C.

1982-05-01

242

Dioxins from thermal and metallurgical processes: recent studies for the iron and steel industry  

Microsoft Academic Search

In thermal metallurgical processes such as iron ore sintering and metal smelting operations, large flows of off-gases are generated. Mainly due to residue recycling in such processes, chlorine and volatile organics are always present in the feed. As a consequence of “de novo” formation, the off-gases from such processes typically contain dioxins in the range 0.3–30 ng I-TEQ\\/Nm3. So far

A. Buekens; L. Stieglitz; K. Hell; H. Huang; P. Segers

2001-01-01

243

[The characteristics of individual environmental factors and the health of the population of the Krivoi Rog iron ore basin].  

PubMed

Giant mining industry enterprises and huge iron-and-steel works are located in Krivbas. 169 mll. cu. m. of solid waste, over II.8 mll. cu. m. of waste water, nearly 1.3 mll. tons of dust and gaseous substances are created annually through the production process. Data available from numerous investigations both in this country and abroad refer health characteristics in the community to the environmental contamination. Demographic situation in Krivbas is marked by 22.4% reduction in birth-rate over the last 20 years, 49.2% increase in mortality rates. General mortality showed 2.4-fold increase over the last 5 years. The diseases of respiratory, circulatory and digestive organs are found to prevail as are complications of pregnancy and delivery; on the increase are malignant tumours. 1,600-1,700 diseases per 1,000 children are generally recorded. Planning of measures on protection and promotion of the environment (E) is to be carried out in consecutive order according to the E priority factors in their impact on health in the community. It is necessary that a concept of prenosological diagnosis be used in organization of diagnostic centres for detection of groups at risk for development of a pathology, which undertaking will contribute to early diagnosis as well as timely and well-targeted organization of preventive measures. There is a need for the environmental legislation and mechanisms of its implementation to be improved. PMID:7604586

Lysy?, A Iu; Samko, I S; Lysa, L O

1994-01-01

244

Mathematical modeling of the kinetics of carbothermic reduction of iron oxides in ore-coal composite pellets  

SciTech Connect

The kinetics of the carbothermic reduction of iron oxides in a composite pellet made of taconite concentrate and high-volatility coal has been studied by means of mathematical modeling that simultaneously takes into account the transfer rates of both the mass and the heat, and the rates of chemical reactions. The computational results, which have been validated with experimental data in the literature, confirm that the overall rate of the carbothermic reduction, which is strongly endothermic, is limited by heat-transfer steps. From a kinetics viewpoint, the optimum composition of the composite pellet is approximately in accordance with the stoichiometry, when CO is assumed to be the sole oxide of carbon in the gas. To raise the temperature of the pellet from its ambient value to furnace temperature, the heat required is greater than that needed for sustaining all chemical reactions, including the Boudouard reaction. The gaseous product consists mainly of CO and H{sub 2}, except in the very initial stage. The overall observable reaction rate, in terms of the volumetric rate of the generation of gases, peaks at approximately 30 seconds of reaction time.

Sun, K.; Lu, W.K. [McMaster University, Hamilton, ON (Canada). Dept. for Material Science and Engineering

2009-02-15

245

Mathematical Modeling of the Kinetics of Carbothermic Reduction of Iron Oxides in Ore-Coal Composite Pellets  

NASA Astrophysics Data System (ADS)

The kinetics of the carbothermic reduction of iron oxides in a composite pellet made of taconite concentrate and high-volatility coal has been studied by means of mathematical modeling that simultaneously takes into account the transfer rates of both the mass and the heat, and the rates of chemical reactions. The computational results, which have been validated with experimental data in the literature, confirm that the overall rate of the carbothermic reduction, which is strongly endothermic, is limited by heat-transfer steps. From a kinetics viewpoint, the optimum composition of the composite pellet is approximately in accordance with the stoichiometry, when CO is assumed to be the sole oxide of carbon in the gas. To raise the temperature of the pellet from its ambient value to furnace temperature, the heat required is greater than that needed for sustaining all chemical reactions, including the Boudouard reaction. The gaseous product consists mainly of CO and H2, except in the very initial stage. The overall observable reaction rate, in terms of the volumetric rate of the generation of gases, peaks at approximately 30 seconds of reaction time.

Sun, Kang; Lu, W.-K.

2009-02-01

246

Sponge iron: economic, ecological, technical and process-specific aspects  

NASA Astrophysics Data System (ADS)

The process cycle sponge iron/hydrogen/iron oxide offers a simple possibility to store the energy of synthesis gases in the form of sponge iron, and at the same time to reform and to condition these synthesis gases. As 'product' of this energy storage one receives pure hydrogen which is intended for the running of fuel cells. The process cycle is investigated on two levels: (i) on a general level, economic, ecological and technical conditions are investigated and established, and (ii) on the process-specific level industrially produced iron ore pellets are tested for their suitability for employment in cyclic operation with synthesis gases. Mechanical strength, porosity, speed of reaction, additives and attendant materials (gangue) determine the properties of the pellets. The reaction degree of the iron contained in the pellets should be large and will remain constant. Negative influences such as sintering and carbonization should be avoided as far as possible in order to achieve a high number of cycles.

Selan, M.; Lehrhofer, J.; Friedrich, K.; Kordesch, K.; Simader, G.

247

Process for treating sulfide-bearing ores  

SciTech Connect

A process for removing sulfur from sulfide-bearing ores by reacting water vapor with the sulfide-bearing ore forming hydrogen sulfide while simultaneously regenerating water vapor by reacting the hydrogen sulfide with lime. Advantageously, the process occurs in the absence of a net consumption or production of gaseous species so that the process can be carried out in a closed system with respect to the gaseous species. Sulfidebearing ores which can be treated using the process of this invention include sulfide-bearing ores of molybdenum, zinc, iron, mercury, and copper. Advantageously, the molybdenum oxide so produced from the sulfide-bearing ore of molybdenum can be reacted further with lime and water producing calcium molybdate and hydrogen. The chalcopyrite form of the sulfide-bearing ore of copper produces bornite and magnetite.

Sohn, H.Y.

1983-03-15

248

VIEW LOOKING WEST OF SINTERING PLANT, HEYL & PATTERSON CAR ...  

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

VIEW LOOKING WEST OF SINTERING PLANT, HEYL & PATTERSON CAR DUMPER AT BLAST FURNACE NO. 3, BLAST FURNACE NO. 1 ORE BRIDGE IN BACKGROUND. - Pittsburgh Steel Company, Monessen Works, Blast Furnace No. 3, Donner Avenue, Monessen, Westmoreland County, PA

249

Preparation of pure iron/Ni-Zn ferrite high strength soft magnetic composite by spark plasma sintering  

NASA Astrophysics Data System (ADS)

A dense microcellular structure is fabricated using micron-sized pure iron powder cladded with 10 wt% Zn0.5Ni0.5Fe2O4 nanopowder by filling the pure iron with Ni-Zn-ferrites composite and subjecting the mixture to a temperature of 600 °C. The SEM image shows that the thickness of cell wall is in the range of 1.0-2.0 ?m, and the inner dimension of the alloy is in the range of 15-40 ?m. By coating Ni-Zn-ferrites, the electrical resistivity is increased. The composite exhibits not only good soft magnetic properties but also good mechanical strength.

Wang, Minggang; Zan, Zhao; Deng, Na; Zhao, Zhankui

2014-06-01

250

Linear shrinkage of metal powder compacts during sintering  

Microsoft Academic Search

The influence exerted by various factors (particle size, particle size distribution, ultrafine powder addition, sintering temperature, etc.) on the linear shrinkage ratio during sintering was examined. Electrolytic, atomized, and ultrafine copper powders, as well as electrolytic iron powder, were used.

H. H. Hausner; O. V. Roman

1965-01-01

251

Reduction of Iron-Oxide-Carbon Composites: Part I. Estimation of the Rate Constants  

NASA Astrophysics Data System (ADS)

A new ironmaking concept using iron-oxide-carbon composite pellets has been proposed, which involves the combination of a rotary hearth furnace (RHF) and an iron bath smelter. This part of the research focuses on studying the two primary chemical kinetic steps. Efforts have been made to experimentally measure the kinetics of the carbon gasification by CO2 and wüstite reduction by CO by isolating them from the influence of heat- and mass-transport steps. A combined reaction model was used to interpret the experimental data and determine the rate constants. Results showed that the reduction is likely to be influenced by the chemical kinetics of both carbon oxidation and wüstite reduction at the temperatures of interest. Devolatilized wood-charcoal was observed to be a far more reactive form of carbon in comparison to coal-char. Sintering of the iron-oxide at the high temperatures of interest was found to exert a considerable influence on the reactivity of wüstite by virtue of altering the internal pore surface area available for the reaction. Sintering was found to be predominant for highly porous oxides and less of an influence on the denser ores. It was found using an indirect measurement technique that the rate constants for wüstite reduction were higher for the porous iron-oxide than dense hematite ore at higher temperatures (>1423 K). Such an indirect mode of measurement was used to minimize the influence of sintering of the porous oxide at these temperatures.

Halder, S.; Fruehan, R. J.

2008-12-01

252

On-line iron-ore slurry monitoring for real-time process control of pellet making processes using laser-induced breakdown spectroscopy: graphitic vs. total carbon detection  

NASA Astrophysics Data System (ADS)

Chemical composition of iron-ore pellets has a significant impact on their quality and commercial value. Laser-induced breakdown spectroscopy (LIBS) technique has been extensively tested on line, at industrial pelletizing plants. It proved successful at measuring Si, Ca, Mg, Al and graphitic C contents of different iron-ore slurries prior to filtration and pelletizing. For this specific application, the sensitivity of the technique compares with the one obtained from dedicated chemical laboratories. But the real advantage of LIBS technique is that the results are delivered continuously and in real time compared to periodic sampling and standard analytical delays of more than 1 h. Consequently, LIBS gives a more representative reading of the state of the process — particularly when rapid perturbations occur — and allows process optimization and quality improvement. In this work, special attention was given to the fact that the detection system, with specific settings, gives direct measurement for either graphitic carbon (coke breeze) or total carbon (coke breeze, flux and natural carbonate). Graphitic carbon content is a key parameter for both the pellet production cost and its final commercial value. LIBS is a sensitive technique that can detect small variations. But matrix effects affect the spectral lines and it is sometimes difficult to establish universal calibration curve. This problem is partially overcome by the use of a multivariable calibration that corrects for matrix effects and evaluates a confidence level based on expertise for each measurement. Current research is aimed at the development of commercial equipment for continuous industrial use.

Barrette, Louis; Turmel, Simon

2001-06-01

253

The investigation of the microstructure and mechanical properties of ordered alominide-iron (boron) nanostructures produced by mechanical alloying and sintering  

NASA Astrophysics Data System (ADS)

In this study, mechanical alloying (MA) of Fe-50Al, Fe-49.5Al-1B, and Fe-47.5Al-5B (at.%) alloy powders and mechanical properties of sintered products of the as-milled powders were investigated. X-ray diffraction (XRD) results showed the addition of B caused more crystallite refinement compared to the B-free powders. To consider the sintering and ordering behaviors of the parts produced from cold compaction of the powders milled for 80 h, sintering was conducted at various temperatures. It was found that the sintering temperature has no meaningful effect on the long-range order parameter. The transformation of the disordered solid solution developed by MA to ordered Fe-Al- (B) intermetallics was a consequence of sintering. Also, the nano-scale structure of the samples was retained even after sintering. The microhardness of pore-free zones of the nanostructured specimens decreased by increasing the sintering temperature. Moreover, the sintering temperature has no effect on the compressive yield stress. However, the fracture strain increased by increasing the sintering temperature. The samples containing 1 at.% B showed more strain to fracture compared with the B-free and 5 at.% B samples.

Izadi, S.; Akbari, Gh.; Janghorban, K.; Ghaffari, M.

254

Iron  

Microsoft Academic Search

Iron poisoning causes its metabolic effects in proportion to the concentrations of free iron. Toxicity is therefore related to dose ingested. The amount of iron in different salts varies, and iron concentrations may rise and fall, making plasma concentrations difficult to interpret in acute poisoning. Clinical features include severe gastrointestinal irritation, cardiovascular collapse and direct organ damage to liver and

D. Nicholas Bateman

2007-01-01

255

PHASE II CALDERON PROCESS TO PRODUCE DIRECT REDUCED IRON RESEARCH AND DEVELOPMENT PROJECT  

SciTech Connect

This project was initially targeted to the making of coke for blast furnaces by using proprietary technology of Calderon in a phased approach, and Phase I was successfully completed. The project was then re-directed to the making of iron units. In 2000, U.S. Steel teamed up with Calderon for a joint effort to produce directly reduced iron with the potential of converting it into molten iron or steel consistent with the Roadmap recommendations of 1998 prepared by the Steel Industry in cooperation with the Department of Energy by using iron ore concentrate and coal as raw materials, both materials being appreciably lower in cost than using iron pellets, briquettes, sinter and coke.

Albert Calderon

2006-01-30

256

PHASE II CALDERON PROCESS TO PRODUCE DIRECT REDUCED IRON RESEARCH AND DEVELOPMENT PROJECT  

SciTech Connect

This project was initially targeted to the making of coke for blast furnaces by using proprietary technology of Calderon in a phased approach, and Phase I was successfully completed. The project was then re-directed to the making of iron units. In 2000, U.S. Steel teamed up with Calderon for a joint effort to produce directly reduced iron with the potential of converting it into molten iron or steel consistent with the Roadmap recommendations of 1998 prepared by the Steel Industry in cooperation with the Department of Energy by using iron ore concentrate and coal as raw materials, both materials being appreciably lower in cost than using iron pellets, briquettes, sinter and coke.

Albert Calderon

2006-04-19

257

Phase II Calderon Process to Produce Direct Reduced Iron Research and Development Project  

SciTech Connect

This project was initially targeted to the making of coke for blast furnaces by using proprietary technology of Calderon in a phased approach, and Phase 1 was successfully completed. The project was then re-directed to the making of iron units. In 2000, U.S. Steel teamed up with Calderon for a joint effort to produce directly reduced iron with the potential of converting it into molten iron or steel consistent with the Roadmap recommendations of 1998 prepared by the Steel Industry in cooperation with the Department of Energy by using iron ore concentrate and coal as raw materials, both materials being appreciably lower in cost than using iron pellets, briquettes, sinter and coke.

Albert Calderon

2007-03-31

258

40 CFR 420.20 - Applicability; description of the sintering subcategory.  

Code of Federal Regulations, 2010 CFR

...EFFLUENT GUIDELINES AND STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY...operations conducted by the heating of iron bearing wastes (mill scale and...steelmaking furnaces) together with fine iron ore, limestone, and coke fines in...

2010-07-01

259

Precipitation of uranium peroxide from the leach liquor of uranium ores.  

National Technical Information Service (NTIS)

A chemical precipitation process of recovering uranium from the leach liquor of uranium ores was investigated. The process primarily includes the precipitation of iron with lime, the preprocessing of the slurry of iron hydroxides and the precipitation of ...

Gao Xizhen Lin Sirong Guo Erhua Lu Shijie

1995-01-01

260

Geochronology\\/geochemistry of the Washan dioritic porphyry associated with Kiruna-type iron ores, Middle-Lower Yangtze River Valley, eastern China: implications for petrogenesis\\/mineralization  

Microsoft Academic Search

The Early Cretaceous Washan dioritic porphyry is spatially and temporally associated with Kiruna-type iron oxide deposits in the Ningwu basin, Middle-Lower Yangtze River Valley (MLYRV). We present new LA-ICP-MS U–Pb dating + zircon Lu–Hf isotopic studies, as well as bulk-rock major + trace element and Sr + Nd isotopic compositions of the porphyry. LA-ICP-MS U–Pb zircon analyses suggest that the

Tong Hou; Zhaochong Zhang; John Encarnacion; He Huang; Meng Wang

2012-01-01

261

Processing of Cobalt-Copper-Arsenic Complex Ore Concentrate  

Microsoft Academic Search

Extraction of cobalt from complex ore flotation concentrates obtained from the Blackbird Mine. Idaho. USA is reviewed. After flotation of a primary copper concentrate, a bulk concentrate is recovered containing major amounts of cobalt, arsenic, and iron, with minor amounts of copper and nickel. This concentrate can be upgraded during flotation by removing iron, but with considerable cobalt loss. Chemical

ROBERT W. BARTLETT

1995-01-01

262

Isotachophoretic separation behavior of rare-earth EDTA chelates and analysis of minor rare-earth elements in an iron ore by bidirectional isotachophoresis-particle-induced X-ray emission.  

PubMed

Mobilities of 16 anions of rare-earth-EDTA 1:1 chelate (RE-EDTAs) were isotachophoretically measured by using two leading electrolytes (pH 3.6 and 6.0) in order to assess their separation behavior. The leading electrolyte was 20 mM hydrochloric acid. The pH of the solution was adjusted to 3.6 by adding beta-alanine and to 6.0 by adding histidine. The obtained mobilities were very close to each other in the range 20.1x10(-5)-21.9x10(-5) cm2 V(-1) s(-1) with the minimum mobilities for Pr-EDTA and Nd-EDTA for pH 3.6 and 6.0, respectively, and pH dependence was hardly observed. On the basis of the above knowledge. minor rare-earth elements in a standard iron ore sample were determined as RE-EDTAs by bidirectional isotachophoresis-particle-induced X-ray emission (PIXE), where the Fe(II) matrix digested by alkali fusion was separated as Fe(II)Phen3(2+) (phen = 1,10-phenanthroline). Since 5% of the total iron was still detected as Fe(III)EDTA- and might disturb PIXE analysis of RE-EDTA-, itaconic acid was used as the spacer for Fe(III)EDTA- and RE-EDTA-. The fractions of RE-EDTA- were successfully analyzed off-line by a multielemental analytical method, PIXE [analytical result (3.62% (w/w) as RE2O3]; the nominal value was 3.37% (w/w) as RExOy. PMID:11442049

Hirokawa, T; Nishimoto, K; Jie, Y; Ito, K; Nishiyama, F; Ikuta, N; Hayakawa, S

2001-06-15

263

Solubilization of Cu 2+ from copper ore by iron-oxidizing bacteria isolated from the natural environment and identification of the enzyme that determines Cu 2+ solubilization activity  

Microsoft Academic Search

Solubilization of Cu2+ from copper concentrate by 67 strains of iron-oxidizing bacteria isolated from the natural environment was studied. In the case of static growth on copper concentrate (5%)-salt medium (pH 2.5) at 30°C, Cu2+ solubilization activities of 65 strains including Thiobacillus ferrooxidans strains AP19-3, OK-2, OK-3, OK1–50, Funis and NASF-1 ranged from 2.5–3.5 mg Cu2+\\/ml\\/33 d. In contrast, the

Tsuyoshi Sugio; Fauzia Akhter

1996-01-01

264

Studies into the formation of dioxins in the sintering process used in the iron and steel industry. 1. Characterisation of isomer profiles in particulate and gaseous emissions  

Microsoft Academic Search

Dioxin analyses using a DB5MS chromatography column are presented for samples of dust from an electrostatic precipitator and emissions from the main stack of a UK sinter plant. The analyses have been repeated using the SP2331 column, for which the elution order has been determined for the whole range of tetra to octachlorodibenzo-p-dioxins and dibenzofurans, and which provides a larger

Tianshu Wang; David R Anderson; Dennis Thompson; Malcolm Clench; Ray Fisher

2003-01-01

265

Purification of Trona Ores.  

National Technical Information Service (NTIS)

The present invention is a trona concentrate and a process for floating gangue material from trona ore that comprises forming an emulsion, conditioning the trona ore at a high solids content in a saturated trona suspension, and then floating and removing ...

J. D. Miller X. Wang M. Li

2005-01-01

266

A comparison of the CATHIA-T sampler, the GK2.69 cyclone and the standard cowled sampler for thoracic fiber concentrations at a Taconite (iron ore)-processing mill.  

PubMed

Several recommendations have been made to the effect that the most appropriate health-based size-selective criterion for fibers is the thoracic convention of the International Organization for Standardization (ISO). The performance of two thoracic samplers, the CATHIA-T (37-mm filter) and the GK2.69 cyclone (37-mm filter), was investigated against the standard 25-mm cowled sampler (current NIOSH 7400 standard method) to determine the effect of thoracic sampling on field results. A total of 270 samples: 80 field and 10 field blank samples for each sampler type, were taken from seven stations in the processing mill of an iron ore mine whose ore contains amphibole minerals. Slides were prepared using the dimethyl formamide/Euparal technique and relocatable cover slips. Two counters examined the slides according to NIOSH 7400 counting A rules with phase contrast microscopes. Prior to counting the sample slides, four reference slides were randomly selected and counted three times on different days to compare the coefficient of variation (CV) between and within counters. Also, seven reference slides were chosen to explore variability between the two microscopes. The average CV between counters (0.148) showed slightly higher than the average CVs within counters (0.072 for Counter 1 and 0.119 for Counter 2). The average CV between the two microscopes was 0.147. Compared to the standard cowled sampler, the overall fiber concentration was lower for the CATHIA-T sampler (CATHIA-T/Cowled = 0.63) and higher for the GK2.69 cyclone (GK2.69/Cowled = 1.66). The result for the CATHIA-T sampler is as expected from laboratory trials, but the result for the GK2.69 cyclone is not as expected. In conclusion, the CATHIA-T sampler has a potential advantage as a high-flow static sampler for screening coarse particles. However, these findings resulted from one field sampling site that contains amphibole minerals, not all of which are asbestiform. Thus, additional field samples from other environments might be helpful to confirm the performance of these samplers. PMID:18195326

Lee, Eun Gyung; Harper, Martin; Nelson, John; Hintz, Patrick J; Andrew, Michael E

2008-01-01

267

Dried leaves — Novel reductant for acid leaching of manganese ore  

Microsoft Academic Search

In the present investigation results on the use of dried leaves as a reductant for manganese ore leaching is reported. A complete\\u000a flow-sheet consisting of steps such as reductive acid leaching, enrichment of leach solution by recycling, iron removal and\\u000a crystallization has been developed for the preparation of manganese sulphate monohydrate from manganese ore of Gujarat Mineral\\u000a Development Corporation (GMDC),

D. Hariprasad; M. K. Ghosh; S. Anand

2009-01-01

268

Summary of the mineralogy of the Colorado Plateau uranium ores  

USGS Publications Warehouse

In the Colorado Plateau uranium has been produced chiefly from very shallow mines in carnotite ores (oxidized vanadiferous uranium ores) until recent deeper mining penetrated black unoxidized ores in water-saturated rocks and extensive exploration has discovered many deposits of low to nonvanadiferous ores. The uranium ores include a wide range from highly vanadiferous and from as much as one percent to a trace of copper, and contain a small amount of iron and traces of lead, zinc, molybdenum, cobalt, nickel, silver, manganese, and other metals. Recent investigation indicates that the carnotite ores have been derived by progressive oxidation of primary (unoxidized) black ores that contain low-valent uranium and vanadium oxides and silicates. The uranium minerals, uraninite and coffinite, are associated with coalified wood or other carbonaceous material. The vanadium minerals, chiefly montroseite, roscoelite, and other vanadium silicates, occur in the interstices of the sandstone and in siltstone and clay pellets as well as associated with fossil wood. Calcite, dolomite, barite and minor amounts of sulfides, arsenides, and selenides occur in the unoxidized ore. Partially oxidized vanadiferous ore is blue black, purplish brown, or greenish black in contrast to the black or dark gray unoxidized ore. Vanadium combines with uranium to form rauvite. The excess vanadium is present in corvusite, fernandinite, melanovanadite and many other quadrivalent and quinquevalent vanadium minerals as well as in vanadium silicates. Pyrite and part or all of the calcite are replaced by iron oxides and gypsum. In oxidized vanadiferous uranium ores the uranium is fixed in the relatively insoluble minerals carnotite and tyuyamunite, and the excess vanadium commonly combines with one or more of the following: calcium, sodium, potassium, magnesium, aluminum, iron, copper, manganese, or barium, or rarely it forms the hydrated pentoxide. The relatively stable vanadium silicates are little affected by oxidation. The unoxidized nonvanadiferous ores contain uraninite and coffinite in close association with coalified wood and iron and copper sulfides, and traces of many other sulfides, arsenides and selenides. The oxidized nonvanadiferous ores differ from the vanadiferous ores because, in the absence of vanadium to complex the uranium, a great variety of secondary yellow and greenish-yellow uranyl minerals are formed. The uranyl sulfates and carbonates are more common than the oxides, phosphates, arsenates, and silicates. Because the sulfates and carbonates are much less stable that carnotite, the oxidized nonvanadiferous ores occure only as halos around cores of unoxidized ore and do not form large oxidized deposits close to the surface of the ground as carnotite ores. Oxidation has taken place since the lowering of the water table in the present erosion cycle. Because of local structures and the highly lenticular character of the fluviatile host rocks perched water tables and water-saturated lenses of sandstone are common high above the regional water table. Unoxidized ore has been preserved in these water-saturated rocks and the boundary between oxidized and unoxidized ore is very irregular.

Weeks, Alice D.; Coleman, Robert Griffin; Thompson, Mary E.

1956-01-01

269

P-V-T equation of state for ?-iron up to 80 GPa and 1900 K using the Kawai-type high pressure apparatus equipped with sintered diamond anvils  

NASA Astrophysics Data System (ADS)

In order to determine the P-V-T equation of state of ?-iron, in situ X-ray observations were carried out at pressures up to 80 GPa and temperatures up to 1900 K using the Kawai-type high pressure apparatus equipped with sintered diamond anvils which was interfaced with synchrotron radiation. The present results indicate the unit cell volume at ambient conditions V0 = 22.15(5) Å3, the isothermal bulk modulus KT0 = 202(7) GPa and its pressure derivative K?T0 = 4.5(2), the Debye temperature ?0 = 1173(62) K, Grüneisen parameter at ambient pressure ?0 = 3.2(2), and its logarithmic volume dependence q = 0.8(3). Furthermore, thermal expansion coefficient at ambient pressure was determined to be ?0(K-1) = 3.7(2) × 10-5 + 7.2(6) × 10-8(T-300) and Anderson-Grüneisen parameter ?T = 6.2(3). Using these parameters, we have estimated the density of ?-iron at the inner core conditions to be ˜3% denser than the value inferred from seismological observation. This result indicates that certain amount of light elements should be contained in the inner core as well as in the outer core but in definitely smaller amount.

Yamazaki, Daisuke; Ito, Eiji; Yoshino, Takashi; Yoneda, Akira; Guo, Xinzhuan; Zhang, Baohua; Sun, Wei; Shimojuku, Akira; Tsujino, Noriyoshi; Kunimoto, Takehiro; Higo, Yuji; Funakoshi, Ken-ichi

2012-10-01

270

Two modelling approaches to water-quality simulation in a flooded iron-ore mine (Saizerais, Lorraine, France): a semi-distributed chemical reactor model and a physically based distributed reactive transport pipe network model.  

PubMed

The flooding of abandoned mines in the Lorraine Iron Basin (LIB) over the past 25 years has degraded the quality of the groundwater tapped for drinking water. High concentrations of dissolved sulphate have made the water unsuitable for human consumption. This problematic issue has led to the development of numerical tools to support water-resource management in mining contexts. Here we examine two modelling approaches using different numerical tools that we tested on the Saizerais flooded iron-ore mine (Lorraine, France). A first approach considers the Saizerais Mine as a network of two chemical reactors (NCR). The second approach is based on a physically distributed pipe network model (PNM) built with EPANET 2 software. This approach considers the mine as a network of pipes defined by their geometric and chemical parameters. Each reactor in the NCR model includes a detailed chemical model built to simulate quality evolution in the flooded mine water. However, in order to obtain a robust PNM, we simplified the detailed chemical model into a specific sulphate dissolution-precipitation model that is included as sulphate source/sink in both a NCR model and a pipe network model. Both the NCR model and the PNM, based on different numerical techniques, give good post-calibration agreement between the simulated and measured sulphate concentrations in the drinking-water well and overflow drift. The NCR model incorporating the detailed chemical model is useful when a detailed chemical behaviour at the overflow is needed. The PNM incorporating the simplified sulphate dissolution-precipitation model provides better information of the physics controlling the effect of flow and low flow zones, and the time of solid sulphate removal whereas the NCR model will underestimate clean-up time due to the complete mixing assumption. In conclusion, the detailed NCR model will give a first assessment of chemical processes at overflow, and in a second time, the PNM model will provide more detailed information on flow and chemical behaviour (dissolved sulphate concentrations, remaining mass of solid sulphate) in the network. Nevertheless, both modelling methods require hydrological and chemical parameters (recharge flow rate, outflows, volume of mine voids, mass of solids, kinetic constants of the dissolution-precipitation reactions), which are commonly not available for a mine and therefore call for calibration data. PMID:18037533

Hamm, V; Collon-Drouaillet, P; Fabriol, R

2008-02-19

271

Two modelling approaches to water-quality simulation in a flooded iron-ore mine (Saizerais, Lorraine, France): A semi-distributed chemical reactor model and a physically based distributed reactive transport pipe network model  

NASA Astrophysics Data System (ADS)

The flooding of abandoned mines in the Lorraine Iron Basin (LIB) over the past 25 years has degraded the quality of the groundwater tapped for drinking water. High concentrations of dissolved sulphate have made the water unsuitable for human consumption. This problematic issue has led to the development of numerical tools to support water-resource management in mining contexts. Here we examine two modelling approaches using different numerical tools that we tested on the Saizerais flooded iron-ore mine (Lorraine, France). A first approach considers the Saizerais Mine as a network of two chemical reactors (NCR). The second approach is based on a physically distributed pipe network model (PNM) built with EPANET 2 software. This approach considers the mine as a network of pipes defined by their geometric and chemical parameters. Each reactor in the NCR model includes a detailed chemical model built to simulate quality evolution in the flooded mine water. However, in order to obtain a robust PNM, we simplified the detailed chemical model into a specific sulphate dissolution-precipitation model that is included as sulphate source/sink in both a NCR model and a pipe network model. Both the NCR model and the PNM, based on different numerical techniques, give good post-calibration agreement between the simulated and measured sulphate concentrations in the drinking-water well and overflow drift. The NCR model incorporating the detailed chemical model is useful when a detailed chemical behaviour at the overflow is needed. The PNM incorporating the simplified sulphate dissolution-precipitation model provides better information of the physics controlling the effect of flow and low flow zones, and the time of solid sulphate removal whereas the NCR model will underestimate clean-up time due to the complete mixing assumption. In conclusion, the detailed NCR model will give a first assessment of chemical processes at overflow, and in a second time, the PNM model will provide more detailed information on flow and chemical behaviour (dissolved sulphate concentrations, remaining mass of solid sulphate) in the network. Nevertheless, both modelling methods require hydrological and chemical parameters (recharge flow rate, outflows, volume of mine voids, mass of solids, kinetic constants of the dissolution-precipitation reactions), which are commonly not available for a mine and therefore call for calibration data.

Hamm, V.; Collon-Drouaillet, P.; Fabriol, R.

2008-02-01

272

26. NORTHERN VIEW OF ORE YARD WITH ORE BRIDGES IN ...  

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

26. NORTHERN VIEW OF ORE YARD WITH ORE BRIDGES IN THE BACKGROUND. BLAST FURNACES ALONG THE RIGHT SIDE. (Martin Stupich) - U.S. Steel Duquesne Works, Blast Furnace Plant, Along Monongahela River, Duquesne, Allegheny County, PA

273

Next Generation Metallic Iron Nodule Technology in Electric Arc Steelmaking - Phase II  

Microsoft Academic Search

The current trend in the steel industry is a gradual decline in conventional steelmaking from taconite pellets in blast furnaces, and an increasing number of alternative processes using metallic scrap iron, pig iron and metallized iron ore products. Currently, iron ores from Minnesota and Michigan are pelletized and shipped to the lower Great Lakes ports as blast furnace feed. The

Donald R. Fosnacht; Iwao Iwasaki; Richard F. Kiesel; David J. Englund; David W. Hendrickson; Rodney L. Bleifuss

2010-01-01

274

P-V-T equation of state for ?-iron up to 80 GPa and 1900 K using the Kawai-type high pressure apparatus equipped with sintered diamond anvils  

NASA Astrophysics Data System (ADS)

The earth's core is considered to be predominantly composed of iron alloy [e.g., Birch, 1952]. Although, it was clarified that the inner core is solid from the seismological observation in early 20th century, the crystal structure of iron in the inner core condition has long been open question. However, recent progress in high pressure experiment using the diamond anvil cell (DAC) have revealed that the iron and its Ni-alloy assumes the hexagonal closed packed structure (hcp, ?-iron) under the inner core conditions [Tateno et al., 2010, 2012]. Therefore, the P-V-T equation of state of ?-iron is crucial information to understand the nature of the inner core. Despite many studies on the direct volume measurement by X-ray diffraction study of ?-iron at high pressure [Mao and Bell, 1979; Jephcoat et al., 1986; Huang et al., 1987; Mao et al., 1990; Funamori et al., 1996; Dubrovinsky et al., 1998, 2000; Uchida et al., 2001; Dewaele et al., 2006; Boehler et al., 2008; Ono et al., 2010], P-V-T relationship of ?-iron has not been well determined yet. This is mainly due to the limitations in experimental P-T ranges and lack of precision of X-ray diffraction data. In this study, we used a KMA equipped with sintered diamond (SD) anvils which enable us to generate pressure to ~100 GPa at present [Yamazaki, 2011]. The KMA allows stable and uniform sample temperature and high quality data because of the large sample volume and wide d-value range (~0.85~3 Å) with a polychromatic X-ray beam for diffraction. We precisely measured volumes of ?-iron up to 80 GPa and 1900 K, which enables us to derive more reliable thermoelastic parameters by fitting to suitable equation of state. The P-V-T data set of ?-iron was fitted to a single EOS model based on the Mie-Grüneisen equation and we obtained unit cell volume V0=22.15(5) Å^3, KT0=202(7) GPa, K0'=4.5(2), ?0=3.2(2), ?0=1173(62) K and q=0.8(3) when third-order Birch-Murnaghan equation was used, whereas we obtained V0=22.17(6) Å^3, KT0=196(8) GPa, K0'=4.8(2), ?0=3.2(2), ?0=1168(61) K and q=0.8(3) when Vinet equation was used. The thermal expansion coefficient at ambient pressure was determined to be ?0(K^-1)=3.7(2)*10^-5+7.2(6)*10^-8*(T-300) and Anderson-Grüneisen parameter ?T=6.2(3). Density of the inner core at around the inner and outer core boundary region (~330 GPa) is estimated to be 12.76 g/cm^3 from seismic observation (e.g., PREM [Dziewonski and Anderson, 1981]). In the comparison with the density of iron, thermal expansion derived from the volume data of iron at high temperature is a key factor. In this study, we successfully obtained volume data at high temperature, and we calculated the density of iron at 330 GPa and 6000K to be 13.12 and 13.18 g/cm^3 using a third-order Birch-Murnaghan equation and Vinet equation, respectively, corresponding to the density deficits of 2.7 and 3.1 %, respectively. These estimations are similar to those by Dubrovinsky et al [2000], Uchida et al. [2001] and Dewaele et al. [2006]. Because Ni-alloying into ?-iron is expected to increase its density, by approximately 0.4% [Mao et al., 1990], it is highly likely that the inner core contains certain amounts of light elements such as Si, C, O, S, and H, as same situation as the outer core but definitely smaller amount.

Yamazaki, D.; Ito, E.; Yoshino, T.; Yoneda, A.; Guo, X.; Shimojuku, A.; Tsujino, N.; Kunimoto, T.; Higo, Y.; Funakoshi, K.

2012-12-01

275

38. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE ...  

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

38. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE FROM THE GEORGE M. CARL.' VIEW LOOKING EAST. (Also see OH-18-14, OH-18-39, and OH-18-40) - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

276

14. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE ...  

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

14. HULETT ORE UNLOADERS IN MOTION; UNLOADING CANADIAN RED ORE FROM THE 'GEORGE M. CAR.' VIEW LOOKING EAST. (Also see OH-18-38, OH-18-39, and OH-18-40.) - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

277

Extraction of copper from an oxidized (lateritic) ore using bacterially catalysed reductive dissolution.  

PubMed

An oxidized lateritic ore which contained 0.8 % (by weight) copper was bioleached in pH- and temperature-controlled stirred reactors under acidic reducing conditions using pure and mixed cultures of the acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans. Sulfur was provided as the electron donor for the bacteria, and ferric iron present in goethite (the major ferric iron mineral present in the ore) acted as electron acceptor. Significantly more copper was leached by bacterially catalysed reductive dissolution of the laterite than in aerobic cultures or in sterile anoxic reactors, with up to 78 % of the copper present in the ore being extracted. This included copper that was leached from acid-labile minerals (chiefly copper silicates) and that which was associated with ferric iron minerals in the lateritic ore. In the anaerobic bioreactors, soluble iron in the leach liquors was present as iron (II) and copper as copper (I), but both metals were rapidly oxidized (to iron (III) and copper (II)) when the reactors were aerated. The number of bacteria added to the reactors had a critical role in dictating the rate and yield of copper solubilised from the ore. This work has provided further evidence that reductive bioprocessing, a recently described approach for extracting base metals from oxidized deposits, has the potential to greatly extend the range of metal ores that can be biomined. PMID:24687752

Nancucheo, Ivan; Grail, Barry M; Hilario, Felipe; du Plessis, Chris; Johnson, D Barrie

2014-07-01

278

57 Fe Mössbauer spectroscopy of banded iron formations from eastern India  

Microsoft Academic Search

Selected numbers of representative banded iron formations collected from various mines of iron ore supergroups were investigated\\u000a using ore microscopy and Mössbauer spectroscopy. The ore microscopy results have been corroborated and compared with Mössbauer\\u000a spectroscopy outcome. Different iron-bearing minerals present in these banded iron-formations have been quantified by 57Fe Mössbauer spectroscopy. The obtained results have been discussed on the basis

P. K. Nayak; D. Das; P. Singh; V. Chakravortty

2004-01-01

279

[Determination of gold in copper matte and sintered copper material].  

PubMed

Ore sample, pretreated at 650 degrees C, was decomposed with aqua regia. Gold in the sample solution was then pre-concentrated by adsorbing with polyurethane foam plastic, released with thiourea solution, and determined by inductively coupled plasma-atomic emission spectrometry and flame atomic absorption spectrometry. Based on the characteristic of the copper matte and sinter containing copper, the effects of sample dissolving condition, matrix effect and interference of coexisting elements were investigated. The accuracy, precision and detection limit were discussed. The results of test show that both of the two methods were suitable for determining the contents of gold in copper matte and sintered copper material. PMID:21800614

Ge, Yu-wei; Xiao, Li-mei; Suo, Jin-ling; Wang, Cheng; Hu, Xiao-min; Zhao, Shu-yun

2011-05-01

280

Heat pipes with porous sintered wicks  

SciTech Connect

In this study a vertical sintering oven is constructed and instrumented to enable a realization of sintering experiments of bronze inside capper tubes. The sintering oven consists of ceramic core around which is rolled helical electrical resistance of KW in power. The outside shell is made up of an iron tube and is thermically isolated. A thermocouple passes through the top cover and is perfectly isolated and sealed. This thermocouple is used to measure the average temperature of the oven. The tube to be sintered is hung inside the ceramic tube. In order to ensure an inert atmosphere, a small diameter tube is soldered to the top cover and is connected to a helium gas cylinder fitted with a pressure regulator. In these experiments various particle sizes were used. Various sintering temperature and times. After the tubes are sintered, they are removed and tested hydrodynamically to verify the pressure drop and measure the permeability. Results are plotted showing the effect of temperature and residence time on these parameters. Selected tubes are then prepared as heat pipes and put for testing to determine the thermal performance of the tubes. Parameters such as working temperature, mass of working fluid, angle of inclination are investigated, analysed and discussed. It is found that heat pipes with sintered material have a reasonably good thermal performance as compared to mesh wicked tubes. Another advantage is that sintered tubes are easy to fabricate and prepare and thus the fabrication cost is much below mesh wicked tubes. It is hoped that this cost reduction will allow large scale use of these tubes in heat exchangers and energy recuperators.

Ismail, K.A.R.; Liu, C.Y.

1983-12-01

281

Bioprocessing of ores: Application to space resources  

NASA Technical Reports Server (NTRS)

The role of microorganisms in the oxidation and leaching of various ores (especially those of copper, iron, and uranium) is well known. This role is increasingly being applied by the mining, metallurgy, and sewage industries in the bioconcentration of metal ions from natural receiving waters and from waste waters. It is concluded that bioprocessing using bacteria in closed reactors may be a variable option for the recovery of metals from the lunar regolith. Obviously, considerable research must be done to define the process, specify the appropriate bacteria, determine the necessary conditions and limitations, and evaluate the overall feasibility.

Johansson, Karl R.

1992-01-01

282

Geochemistry of banded iron formation of Orissa, India  

Microsoft Academic Search

Major and trace element analyses of representative samples of various types of banded iron-formation and its various minerals, associated sediments, iron ores and volcanic tuff from different localities of Orissa, India, are presented in this paper. The Orissa banded iron-formation is classified as Precambrian banded iron formation and is similar to the oxide facies iron formation of Lake Superior type.

Tapan Majumder; K. L. Chakraborty; Auditeya Bhattacharyya

1982-01-01

283

Magnetic and flotation studies of banded hematite quartzite (BHQ) ore for the production of pellet grade concentrate  

NASA Astrophysics Data System (ADS)

To identify and establish beneficiation techniques for banded hematite quartzite (BHQ) iron ore, a comprehensive research on BHQ ore treatment was carried out. The BHQ ore was assayed as 38.9wt% Fe, 42.5wt% SiO2, and 1.0wt% Al2O3. In this ore, hematite and quartz are present as the major mineral phases where goethite, martite, and magnetite are present in small amounts. The liberation of hematite particles can be enhanced to about 82% by reducing the particle size to below 63 ?m. The rejection of silica particles can be obtained by magnetic and flotation separation techniques. Overall, the BHQ ore can be enriched to 65.3wt% Fe at 61.9% iron recovery. A flowsheet has been suggested for the commercial exploitation of the BHQ ore.

Das, B.; Mishra, B. K.; Prakash, S.; Das, S. K.; Reddy, P. S. R.; Angadi, S. I.

2010-12-01

284

The genesis of ores  

SciTech Connect

Human history and technology have been shaped by metals. How did they become concentrated in minable deposits located so conveniently near the earth's surface The author explains the mechanisms of fluid transport-by magma, water and even air and wind-responsible for the chemical and physical interactions that created bodies of metallic ores throughout geologic history. From their formation to their modification at the surface of the earth, ore deposits are geologically transitory and reflect dynamic processes within the earth as well as atmospheric and climatic influences on hydrologic systems. As highly reactive supracrustal systems, they then serve as geochemical sensors providing a powerful record and set of tracer elements for deducing the history, transport paths and forces operative in the crust.

Brimhall, G. (Univ. of California, Berkeley (USA))

1991-05-01

285

The biological leaching of an auriferous pyrite ore  

NASA Astrophysics Data System (ADS)

The oxidation of an auriferous pyrite ore sample was evaluated in biological leaching experiments for subsequent gold recovery via cyanidation. In batch cultures, organisms derived from the mine site oxidized pyrite and ferrous iron at pH values as low as pH 0.6. The recovery of gold was variable in shake flask experiments. In stirred tank bioreactor leaching, gold recovery was proportional to the extent of iron dissolution by bioleaching. The leaching of arsenic from the sample was also directly proportional to iron dissolution.

Riekkola-Vanhanen, Marja; Heimala, Seppo; Sivelä, Carita A.; Viguera, Felipe; Varjola, Irma; Niemelä, Seppo I.; Tuovinen, Olli H.

1993-12-01

286

ORE CONVEYANCE SYSTEM AND ADIT. LOOKING WEST. ORE FROM THE ...  

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

ORE CONVEYANCE SYSTEM AND ADIT. LOOKING WEST. ORE FROM THE MINES ABOVE AT THE RIDGELINE AND TO THE RIGHT WAS CONVEYED TO THIS AREA AND DUMPED INTO THE SHAFT AT CENTER. THIS SHAFT OPENS INTO THE ADIT AT BOTTOM CENTER. THERE IS ANOTHER SHAFT OPENING INTO THE ADIT JUST ABOVE THE ADIT BEHIND THE STONE WALL. THE ORE WAS LOADED INTO TRAM CARS INSIDE THE ADIT AND CONVEYED ON TRACKS TO THE TRESTLE LEADING TO THE PRIMARY ORE BIN AT THE TRAM TERMINAL. TRACKS CAN BE SEEN LEADING FROM THE ADIT AND TO THE LEFT. THE ORE WAS THEN DUMPED INTO A CHUTE AT THE END OF THE TRESTLE CARRYING IT INTO THE ORE BIN AT THE TRAM TERMINAL(SEE CHUTE ON CA-291-30). - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

287

Sintered plaque characteristics  

NASA Technical Reports Server (NTRS)

The structural transformations occurring during sintering, the fabrication of a slurry produced sintered plaque, are detailed. Degradation of the positive electrode in performance in cycling in a nickel hydrogen battery were traced to the quality of the sintered plaque. Electrode degradation was found to be a limiting factor in the battery cycle life. Details of microstructural characterization and distribution of pores, examination of plastic flow during shrinkage, and observations of the rounding of nickel powder particles during the slurry process are presented.

Vaidyanathan, H.

1982-01-01

288

Single-Step Ironmaking from Ore to Improve Energy Efficiency  

SciTech Connect

The pig iron nugget process was developed as an alternative to the traditional blast furnace process by Kobe Steel. The process aimed to produce pig iron nuggets, which have similar chemical and physical properties to blast furnace pig iron, in a single step. The pig iron nugget process utilizes coal instead of coke and self reducing and fluxing dried green balls instead of pellets and sinters. In this process the environmental emissions caused by coke and sinter production, and energy lost between pellet induration (heat hardening) and transportation to the blast furnace can be eliminated. The objectives of this research were to (1) produce pig iron nuggets in the laboratory, (2) characterize the pig iron nugget produced and compare them with blast furnace pig iron, (3) investigate the furnace temperature and residence time effects on the pig iron nugget production, and (4) optimize the operational furnace temperatures and residence times. The experiments involved heat treatment of self reducing and fluxing dried green balls at various furnace temperatures and residence times. Three chemically and physically different products were produced after the compete reduction of iron oxides to iron depending on the operational furnace temperatures and/or residence times. These products were direct reduced iron (DRI), transition direct reduced iron (TDRI), and pig iron nuggets. The increase in the carbon content of the system as a function of furnace temperature and/or residence time dictated the formation of these products. The direct reduced iron, transition direct reduced iron, and pig iron nuggets produced were analyzed for their chemical composition, degree of metallization, apparent density, microstructure and microhardness. In addition, the change in the carbon content of the system with the changing furnace temperature and/or residence time was detected by optical microscopy and Microhardness measurements. The sufficient carbon dissolution required for the production of pig iron nuggets was determined. It was determined that pig iron nuggets produced had a high apparent density (6.7-7.2 gr/cm3), highly metallized, slag free structure, high iron content (95-97%), high microhardness values (> 325 HVN) and microstructure similar to white cast iron. These properties made them a competitive alternative to blast furnace pig iron.

S.K. Kawatra; B. Anamerie; T.C. Eisele

2005-10-01

289

Gaseous reduction of iron oxides: Part III. Reduction-oxidation of porous and dense iron oxides and iron  

Microsoft Academic Search

The internal reduction of high-grade granular hematite ore in hydrogen and carbon monoxide, and also the internal oxidation\\u000a of porous iron granules in CO2-CO mixtures have been investigated. To assist the interpretation of the rate data for porous iron and iron oxides, rate measurements\\u000a have been made also with dense wustite, previously grown on iron by oxidation. The iron formed

E. T. Turkdogan; J. V. Vinters

1972-01-01

290

Sintering Reaction of Pseudoleucite Syenite: Thermodynamic Analysis and Process Evaluation  

NASA Astrophysics Data System (ADS)

On the basis of comprehensive analysis of the modal composition of a pseudoleucite syenite ore sample, collected from the Zijin Hill of Lin County, Shanxi Province, thermodynamic analysis of the pseudoleucite syenite sintering process with sodium carbonate as the additive was carried out. It indicated that when the pseudoleucite syenite was sintered at 760-880°C for 1.0-1.5 h, with sodium carbonate as the additive. The decomposition rate of minerals in the pseudoleucite syenite could reach 97.1%. The thermodynamic calculation shows that it needs to consume Na 2CO 3, i.e., 0.65 t treating per ton pseudoleucite syenite ore and approximately 95% of Na 2CO 3 could be recycled. This process consumes heat energy (2.29-2.48)×10 -6 kJ, corresponding to standard coal 190.97-206.82 kg as the thermal efficiency was 40% and CO 2 emission was 0.77-0.81 t. Compared with the Russian limestone-sintering technique, the natural mineral resources and energy consumptions and greenhouse gas emissions of the soda-sintering technique were reduced by 65%, 63%, and 65%, respectively. It is, therefore, feasible that the procedure suggested in this article could be industrialized providing both economic benefit and environmental conservation.

TAN, Danjun; MA, Hongwen; LI, Ge; LIU, Hao; ZOU, Dan

291

Silicon nitride sintered body  

NASA Technical Reports Server (NTRS)

The sintering of silicon carbide and it production are described. The method of production is by calcination in which molding is followed by sintering without compression. The invention improves the composition of the silicon carbide ceramic. Six examples of the invention are illustrated and discussed.

Suzuki, K.; Shinohara, N.

1984-01-01

292

Electronic Ore-Sorting Tests on Native Copper Ore.  

National Technical Information Service (NTIS)

The test program evaluated the use of belt and rotary sorters on various size and grade fractions of ore. Both plant-scale sorting and lab sorting tests were run. The plant sorting objectives were to determine the sortability of different ores and the eff...

J. K. Ahlness J. C. Kirchner

1980-01-01

293

Molecular Structure of Iron  

NSDL National Science Digital Library

Since antiquity, Iron has been known for its malleability and abundance. Iron is a soft grey metal that is very ductile and easy to work; it can be rolled, hammered, bent, and tempered. Iron makes up 5% of the earth's crust in the form of ores such as hematite, limonite, magnetite, and taconite. This makes it the second most abundant metal, following aluminum. Most iron is used to manufacture carbon steel: iron with about 1.5% carbon and traces of other elements, but it is also used for many other alloys and steels of various types. Iron melts at 1808 degrees Kelvin and boils at 3023 degrees Kelvin. Insufficient iron in the bloodstream causes anemia, a medical condition causing unusual tiredness and other symptoms resulting from underdeveloped or few red blood cells.

2003-04-16

294

Borehole Mining of Phosphate Ores.  

National Technical Information Service (NTIS)

This report presents the results of a technical, economic, and environmental feasibility study of phosphate ore recovery by the hydraulic borehole mining method. The experiments resulted in the recovery of 1,696 tons of ore from 3 boreholes during a 65-ho...

L. E. Scott

1981-01-01

295

Sintering titanium powders  

SciTech Connect

Recently, there has been renewed interest in low-cost titanium. Near-net-shape powder metallurgy offers the potential of manufacturing titanium articles without costly and difficult forming and machining operations; hence, processing methods such as conventional press-and-sinter, powder forging and powder injection molding are of interest. The sintering behavior of a variety of commercial and experimental titanium powders was studied. Commercial powders were acquired that were produced different routes: (i) sponge fines from the primary titanium processing; (ii) via the hydride-dehydride process; and (iii) gas atomization. The influence of vacuum sintering time (0.5 to 32 hrs) and temperature (1200, 1275 or 1350°C) on the microstructure (porosity present) of cold pressed powders was studied. The results are discussed in terms of the difference in powder characteristics, with the aim of identify the characteristics required for full density via press-and-sinter processing. Near-net-shape tensile bars were consolidated via cold pressed and sintered. After sintering, a sub-set of the tensile bars was hot-isostatic pressed (HIPed). The microstructure and properties of the bars were compared in the sintered and HIPed conditions.

Gerdemann, Stephen J.; Alman, David E.

2005-09-01

296

Numerical investigation of sinter cooling process in sinter cooler  

NASA Astrophysics Data System (ADS)

In this paper, the sinter cooling process is numerically studied to get the pressure field, velocity field and temperature field when the fluid flows through the porous media by developing a two-dimensional unsteady state computational model. The inlet velocity, layer height, porosity and sinter layer distribution are the main parameters affecting the sinter cooling process. The computational fluid dynamics (CFD) technique is employed to investigate the influences of thermal process of the four parameters. When high temperature sinters are loaded into the sinter cooler from the sintering machine, phenomena of the non-uniform distribution of sinter size takes place which always causes the non-uniform distribution of sinter temperature field and leads to the deformation of the conveyors. In order to get a uniform sinter temperature field, several recommendations are proposed. The results discussed in this paper would be important for the further understanding of the thermal process and transformation of the sinter cooler.

Liu, Y.; Wang, J.; Yuan, X.; Yang, J.; Wang, Q. W.

2013-07-01

297

Manganese and ferromanganese ores from different tectonic settings in the NW Himalayas, Pakistan  

NASA Astrophysics Data System (ADS)

In Pakistan manganese and ferromanganese ores have been reported from the Hazara area of North West Frontier Province, Waziristan agencies in the Federally Administered Tribal Areas and the Lasbela-Khuzdar regions of Baluchistan. This study is focused on comparison of mineralogy and geochemistry of the continental ferromanganese ores of Hazara and the ophiolitic manganese ores of the Waziristan area of Pakistan. In the Hazara area, ferromanganese ores occur at Kakul, Galdanian and Chura Gali, near Abbottabad, within the Hazira Formation of the Kalachitta-Margala thrust belt of the NW Himalayas of the Indo-Pakistan Plate. The Cambrian Hazira Formation is composed of reddish-brown ferruginous siltstone, with variable amounts of clay, shale, ferromanganese ores, phosphorite and barite. In Waziristan, manganese ores occur at Shuidar, Mohammad Khel and Saidgi, within the Waziristan ophiolite complex, on the western margin of the Indo-Pakistan Plate in NW Pakistan. These banded and massive ores are hosted by metachert and overlie metavolcanics. The ferromanganese ores of the Hazara area contain variable amount of bixbyite, partridgeite, hollandite, pyrolusite and braunite. Bixbyite and partridgeite are the dominant Mn-bearing phases. Hematite dominates in Fe-rich ores. Gangue minerals are iron-rich clay, alumino-phosphate minerals, apatite, barite and glauconite are present in variable amounts, in both Fe-rich and Mn-rich varieties. The texture of the ore phases indicates greenschist facies metamorphism. The Waziristan ores are composed of braunite, with minor pyrolusite and hollandite. Hematite occurs as an additional minor phase in the Fe-rich ores of the Shuidar area. The only silicate phase in these ores is cryptocrystalline quartz. The chemical composition of the ferromanganese ores in Hazara suggests that the Mn-Fe was contributed by both hydrogenous and hydrothermal sources, while the manganese ores of Waziristan originated only from a hydrothermal source. It is suggested that the Fe-Mn ores of the Hazara area originated from a mixed hydrothermal-hydrogenetic source in shallow water in a ontinental shelf environment due to the transgression and regression of the sea, while the Mn ores of Waziristan were formed at sea-floor spreading centers within the Neo-Tethys Ocean, and were later obducted as part of the Waziristan ophiolite complex.

Tahir Shah, Mohammad; Moon, Charles J.

2007-02-01

298

Method for leaching cobalt from oxidised cobalt ores  

US Patent & Trademark Office Database

A method for leaching cobalt from a non-lateritic oxidized cobalt ore, the method comprising the method steps of: curing the non-lateritic oxidized cobalt ore to be leached through the application of an aqueous solution of a cobalt reducing agent selected from the group: iron (II) salts, sulfite salts, sulfur dioxide, and combinations thereof; at a pressure of between about atmospheric pressure and about 5 atmospheres, at a temperature between about 5.degree. C. and about 65.degree. C.; wherein the pH of the aqueous solution of the cobalt reducing agent is between about 1.0 and 10.0; and wherein the relative volumes of the aqueous solution of the cobalt reducing agent and the non-lateritic oxidized cobalt ore to be leached are such that the combination of the aqueous solution of the cobalt reducing agent and the non-lateritic oxidized cobalt ore to be leached forms a mixture with a solids content not less than about 100 g/L of aqueous solution; substantially retaining the aqueous solution of the cobalt reducing agent in contact with the non-lateritic oxidized cobalt; and leaching the cured ore at a pressure of between about atmospheric pressure and about 5 atmospheres, at a temperature between about 5.degree. C. and about 65.degree. C., through the application of an ammonium carbonate solution containing free ammonia thereby producing a pregnant leach solution; then passing the pregnant leach solution resulting to a means for cobalt recovery.

2013-07-16

299

Microwave sintering of ceramics  

SciTech Connect

Successful adaptation of microwave heating to the densification of ceramic materials require a marriage of microwave and materials technologies. Using an interdisciplinary team of microwave and materials engineers, we have successfully demonstrated the ability to density ceramic materials over a wide range of temperatures. Microstructural evolution during microwave sintering has been found to be significantly different from that observed in conventional sintering. Our results and those of others indicate that microwave sintering has the potential to fabricate components to near net shape with mechanical properties equivalent to hot pressed or hot isostatically pressed material. 6 refs., 11 figs.

Snyder, W.B.

1989-01-01

300

Liquid phase sintering of tungsten composites under microgravity: Influence of liquid\\/particle surface energy  

Microsoft Academic Search

Tungsten-nickel-iron heavy metals are fabricated from powders by liquid phase sintering. A study of the sintering mechanism of heavy metals with a low amount of tungsten particles can, depending on sedimentation, only be done under microgravity. At two earlier Texus flights, No 10 & 19, the growth rate and agglomeration of tungsten particles under microgravity were compared to that under

L. B. Ekbom; B. Lei; A. Eliasson; A. Jarfors

1991-01-01

301

Effect of the powder characteristics of Sisub3Nsub4 on the microstructure of sintered bodies  

NASA Technical Reports Server (NTRS)

Silicon nitride powders sintered with the addition of 2 wt% Mg0 to 95% theoretical density after attrition milling and subsequent purification were evaluated. Preparation of the powders is described. The powder characteristics (specific surfaces, iron concentration, and oxygen content), and density, weight loss, and phase state of the sinter bodies as a function of powder preparation are presented.

Woetting, G.; Hausner, H.

1981-01-01

302

Determination of beryllium in ores and rocks by a dilution-fluorometric method with morin  

USGS Publications Warehouse

Beryllium in concentrations as little as a few parts per million is determined fluorometrically with morin in low grade ores by a dilution method without separations. A high sensitivity is obtained by the adoption of instrumental and reaction conditions that give a satisfactory ratio of beryllium to blank fluorescence and at the same time minimize iron interference. Data on the behavior of 47 ions are given. The method is applied to ores containing bertrandite and beryl as the beryllium minerals.

May, R.; Grimaldi, F. S.

1961-01-01

303

Sintered wire annode  

DOEpatents

A plurality of high atomic number wires are sintered together to form a porous rod that is parted into porous disks which will be used as x-ray targets. A thermally conductive material is introduced into the pores of the rod, and when a stream of electrons impinges on the sintered wire target and generates x-rays, the heat generated by the impinging x-rays is removed by the thermally conductive material interspersed in the pores of the wires.

Falce, Louis R. (Surprise, AZ); Ives, R. Lawrence (Saratoga, CA)

2007-12-25

304

Microwave sintering process model.  

PubMed

In order to simulate and optimize the microwave sintering of a silicon nitride and tungsten carbide/cobalt toolbits process, a microwave sintering process model has been built. A cylindrical sintering furnace was used containing a heat insulating layer, a susceptor layer, and an alumina tube containing the green toolbit parts between parallel, electrically conductive, graphite plates. Dielectric and absorption properties of the silicon nitride green parts, the tungsten carbide/cobalt green parts, and an oxidizable susceptor material were measured using perturbation and waveguide transmission methods. Microwave absorption data were measured over a temperature range from 20 degrees C to 800 degrees C. These data were then used in the microwave process model which assumed plane wave propagation along the radial direction and included the microwave reflection at each interface between the materials and the microwave absorption in the bulk materials. Heat transfer between the components inside the cylindrical sintering furnace was also included in the model. The simulated heating process data for both silicon nitride and tungsten carbide/cobalt samples closely follow the experimental data. By varying the physical parameters of the sintering furnace model, such as the thickness of the susceptor layer, the thickness of the allumina tube wall, the sample load volume and the graphite plate mass, the model data predicts their effects which are helpful in optimizing those parameters in the industrial sintering process. PMID:15323110

Peng, Hu; Tinga, W R; Sundararaj, U; Eadie, R L

2003-01-01

305

Tribological Properties of Sintered Polycrystalline and Single Crystal Silicon Carbide.  

National Technical Information Service (NTIS)

Tribological studies and X-ray photoelectron spectroscopy analyses were conducted with sintered polycrystalline and single crystal silicon carbide surfaces in sliding contact with iron at various temperatures to 1500 C in a vacuum of 30 nPa. The results i...

D. H. Buckley K. Miyoshi M. inivasan

1982-01-01

306

The role of volatiles in the reduction of iron oxides  

NASA Astrophysics Data System (ADS)

With iron ore reduction processes using coal-ore pellets or mixtures, it is possible that volatiles from the coals can contribute to the overall reduction. By identifying the possible reducing species in the volatiles as H2/CO and simulating these constituents, the rates for H2 and CO were investigated in the temperature and reduction range of interest where hydrogen was the major reductant and studied in detail. In the initial stages of the present study, the fundamentals of hydrogen reduction of fine powder were found to be a complex mechanism of chemical kinetics and mass transfer. Complete uniform reduction for porous and dense iron ores were not observed contrary to existing work regarding this subject. Morphological observations of iron ores reduced at low and high temperatures showed a topochemical receding interface to be dominating with an intermediate region developing for higher temperature samples indicating the importance of pore mass transfer at the later stages of reduction. Although the activation energy of 50˜56 kJ/mole for these powder samples were comparable to the literature values for solely chemical kinetics controlled reactions, the reaction rates were not proportional to sample weight and also did not exhibit complete uniform internal reduction. The calculated mass transfer rates were comparable to the observed rate which suggested that bulk mass transfer is important to the mixed-control. The reaction rate at the mixed control regime was found to be first order with respect to hydrogen partial pressure. Results of reducing iron oxide powders in a mixture of He-40%H2 -5%CO and H2-1%H2S showed that H2S and CO which is involved with the volatiles does not affect the rate at the reduction range of interest indicating the role of volatiles is dominated by the hydrogen reduction. The single composite pellet experiments at 900 and 1000°C showed significant fixed carbon reduction to occur above 1000°C. Depending upon the type of carbon reductant in the composite pellet, secondary reactions with carbon and H2O was possible. Sintering of the pellets did not occur until a significant amount of reduction was obtained and thus for volatile reduction it is likely that the effects of sintering was negligible. To determine the possibility of volatile reduction, a layer of Fe 2O3 powders were spread over HV coals resulting in the reduction of the top layer by about 20% at 1000°C after 1000 seconds. The morphology of the reduced Fe2O3 layer indicated that the reduction is higher near the interface of Coal/Fe2O3. The volatile reduction of a single layer of composite pellet was found to be negligible. However, the reduction of Fe2O3 pellets at the top layer by the volatiles from the bottom layers of a three-layer pellet geometry was observed to be about 15%. From the morphological observations and the computed rates of bulk mass transfer, volatile reduction seems to be controlled by a mixed-controlled mechanism of bulk mass transfer and the limited-mixed control. Using the reduction information obtained from the single pellet experiments reduced in hydrogen, an empirical relationship was obtained to approximately predict the amount of volatile reduction up to 20%.

Sohn, Il

307

Novel Binders and Methods for Agglomeration of Ore  

SciTech Connect

Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process, and advanced ironmaking processes, where binders must function satisfactorily over an extraordinarily large range of temperatures (from room temperature up to over 1200 C). As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching and advanced primary ironmaking. This project has identified several acid-resistant binders and agglomeration procedures that can be used for improving the energy efficiency of heap leaching, by preventing the ''ponding'' and ''channeling'' effects that currently cause reduced recovery and extended leaching cycle times. Methods have also been developed for iron ore processing which are intended to improve the performance of pellet binders, and have directly saved energy by increasing filtration rates of the pelletization feed by as much as 23%.

S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

2006-12-31

308

REMOVAL OF ARSENIC FROM GROUNDWATER USING NATURALLY OCCURRING IRON OXIDES IN RURAL REGIONS OF MONGOLIA  

EPA Science Inventory

We have found that the iron oxide particles produced by grinding naturally occurring iron ores are very effective in removing arsenic from water. The arsenic adsorption isothermal of the particles h...

309

Sintering of calcium phosphate bioceramics.  

PubMed

Calcium phosphate ceramics have become of prime importance for biological applications in the field of bone tissue engineering. This paper reviews the sintering behaviour of these bioceramics. Conventional pressureless sintering of hydroxyapatite, Ca10(PO4)6(OH)2, a reference compound, has been extensively studied. Its physico-chemistry is detailed. It can be seen as a competition between two thermally activated phenomena that proceed by solid-state diffusion of matter: densification and grain growth. Usually, the objective is to promote the first and prevent the second. Literature data are analysed from sintering maps (i.e. grain growth vs. densification). Sintering trajectories of hydroxyapatite produced by conventional pressureless sintering and non-conventional techniques, including two-step sintering, liquid phase sintering, hot pressing, hot isostatic pressing, ultrahigh pressure, microwave and spark plasma sintering, are presented. Whatever the sintering technique may be, grain growth occurs mainly during the last step of sintering, when the relative bulk density reaches 95% of the maximum value. Though often considered very advantageous, most assisted sintering techniques do not appear very superior to conventional pressureless sintering. Sintering of tricalcium phosphate or biphasic calcium phosphates is also discussed. The chemical composition of calcium phosphate influences the behaviour. Similarly, ionic substitutions in hydroxyapatite or in tricalcium phosphate create lattice defects that modify the sintering rate. Depending on their nature, they can either accelerate or slow down the sintering rate. The thermal stability of compounds at the sintering temperature must also be taken into account. Controlled atmospheres may be required to prevent thermal decomposition, and flash sintering techniques, which allow consolidation at low temperature, can be helpful. PMID:23212081

Champion, E

2013-04-01

310

Sintering and Hiping with Additives.  

National Technical Information Service (NTIS)

The effects of additives on pressureless and pressure assisted sintering are described using examples which cover basic principles of interactions of additives with the host material. Solid state sintering and hot isostatic pressing with a small amount of...

W. A. Kaysser G. Petzow M. Mitkov

1988-01-01

311

SinterHab  

NASA Astrophysics Data System (ADS)

This project describes a design study for a core module on a Lunar South Pole outpost, constructed by 3D printing technology with the use of in-situ resources and equipped with a bio-regenerative life support system. The module would be a hybrid of deployable (CLASS II) and in-situ built (CLASS III) structures. It would combine deployable membrane structures and pre-integrated rigid elements with a sintered regolith shell for enhanced radiation and micrometeorite shielding. The closed loop ecological system would support a sustainable presence on the Moon with particular focus on research activities. The core module accommodates from four to eight people, and provides laboratories as a test bed for development of new lunar technologies directly in the environment where they will be used. SinterHab also includes an experimental garden for development of new bio-regenerative life support system elements. The project explores these various concepts from an architectural point-of-view particularly, as they constitute the building, construction and interior elements. The construction method for SinterHab is based on 3D printing by sintering of the lunar regolith. Sinterator robotics 3D printing technology proposed by NASA JPL enables construction of future generations of large lunar settlements with little imported material and the use of solar energy. The regolith is processed, placed and sintered by the Sinterator robotics system which combines the NASA ATHLETE and the Chariot remotely controlled rovers. Microwave sintering creates a rigid structure in the form of walls, vaults and other architectural elements. The interior is coated with a layer of inflatable membranes inspired by the TransHab project. The life-support system is mainly bio-regenerative and several parts of the system are intrinsically multifunctional and serve more than one purpose. The plants for food production are also an efficient part of atmosphere revitalization and water treatment. Moreover, the plants will be used as a "winter garden" for psychological and recreational purposes. The water in the revitalization system has a multifunctional use, as radiation shielding in the safe-haven habitat core. The garden module creates an artificial outdoor environment mitigating the notion of confinement on the lunar surface. Fiber optics systems and plasma lamps are used for transmission of natural and artificial light into the interior.

Rousek, Tomáš; Eriksson, Katarina; Doule, Ond?ej

2012-05-01

312

Natural Ores as Oxygen Carriers in Chemical Looping Combustion  

SciTech Connect

Chemical looping combustion (CLC) is a combustion technology that utilizes oxygen from oxygen carriers (OC), such as metal oxides, instead of air to combust fuels. The use of natural minerals as oxygen carriers has advantages, such as lower cost and availability. Eight materials, based on copper or iron oxides, were selected for screening tests of CLC processes using coal and methane as fuels. Thermogravimetric experiments and bench-scale fixed-bed reactor tests were conducted to investigate the oxygen transfer capacity, reaction kinetics, and stability during cyclic reduction/oxidation reaction. Most natural minerals showed lower combustion capacity than pure CuO/Fe{sub 2}O{sub 3} due to low-concentrations of active oxide species in minerals. In coal CLC, chryscolla (Cu-based), magnetite, and limonite (Fe-based) demonstrated better reaction performances than other materials. The addition of steam improved the coal CLC performance when using natural ores because of the steam gasification of coal and the subsequent reaction of gaseous fuels with active oxide species in the natural ores. In methane CLC, chryscolla, hematite, and limonite demonstrated excellent reactivity and stability in 50-cycle thermogravimetric analysis tests. Fe{sub 2}O{sub 3}-based ores possess greater oxygen utilization but require an activation period before achieving full performance in methane CLC. Particle agglomeration issues associated with the application of natural ores in CLC processes were also studied by scanning electron microscopy (SEM).

Tian, Hanjing; Siriwardane, Ranjani; Simonyi, Thomas; Poston, James

2013-08-01

313

Sintering silicon nitride  

NASA Technical Reports Server (NTRS)

Oxides having a composition of (Ba(1-x)Sr(x))O-Al2O3-2SiO2 are used as sintering aids for producing an improved silicon nitride ceramic material. The x must be greater than 0 to insure the formation of the stable monoclinic celsian glass phase.

Bansal, Narottam P. (inventor); Levine, Stanley R. (inventor); Sanders, William A. (inventor)

1993-01-01

314

Composition of Lead Sinter.  

National Technical Information Service (NTIS)

Microscopic and electroprobe studies of lead sinters and roasted mixtures of lead sulfide with varying amounts of SiO2, CaO, Fe2O3, and ZnS are presented. The studies show that lead silicates, lead-zinc silicate, calcium-zinc silicate, and spinels or ferr...

W. M. Dressel E. R. Cole P. G. Barnard W. C. Clinton

1975-01-01

315

Electrochemical processes in recovering metals from ores  

SciTech Connect

Chalcopyrite (CuFeS{sub 2}) is one of the most abundant copper-bearing minerals in the U.S. Oxidative leaching and smelting and refining are the most common methods used for recovering copper from chalcopyrite. One of the problems associated with oxidative leaching is the formation of an elemental sulfur product layer around the unreacted chalcopyrite core. The sulfur coating slows the reaction by inhibiting both the diffusion of the oxidant to the unreacted core, and the diffusion of the copper and iron species to the bulk solution. Another problem with leaching is that the iron and copper are oxidized simultaneously. Both appear in the bulk solution in their most oxidized states. The direct electrodissolution of copper sulfide ore slurries could reduce the number of steps involved in the copper recovery process, possibly leading to significant reductions in energy consumption and operating costs. The potential application of electrodissolution processes in hydrometallurgy has been reviewed. This paper reviews investigations of the electrochemical dissolution of chalcopyrite, digenite (Cu{sub 1.8}S), chalcocite (Cu{sub 2}S) and covellite (CuS).

Felker, D.L. (Hypalon Technical Polymer Product Dept., DuPont, Beaumont, TX (US)); Bautista, R.G. (Nevada Univ., Reno, NV (USA). Dept. of Chemical and Metallurgical Engineering)

1990-04-01

316

Leaching of molybdenum and arsenic from uranium ore and mill tailings  

USGS Publications Warehouse

A sequential, selective extraction procedure was used to assess the effects of sulfuric acid milling on the geochemical associations of molybdenum and arsenic in a uranium ore blend, and the tailings derived therefrom. The milling process removed about 21% of the molybdenum and 53% of the arsenic initially present in the ore. While about one-half of the molybdenum in the ore was water soluble, only about 14% existed in this form in the tailings. The major portion of the extractable molybdenum in the tailings appears to be associated with hydrous oxides of iron, and with alkaline earth sulfate precipitates. In contrast with the pattern seen for molybdenum, the partitioning of arsenic into the various extractable fractions differs little between the ore and the tailings. ?? 1984.

Landa, E. R.

1984-01-01

317

Siliceous sedimentary rock-hosted ores and petroleum  

SciTech Connect

Geological, biological, oceanographic, and geochemical principles involved in forming mineral deposits associated with siliceous rocks are integrated in this collection. The book emerged from a decade of research by 142 scientists from 33 countries who worked with the International Geological Correlations Project under editor James R. Hein. It reveals how several economic ores and petroleum were formed in siliceous sediments in coastal ocean basins. This collection places each ore-deposit type into a genetic model emphasizing coastal upwelling; displays all chert occurrences on paleographic maps for each period of the Phanerozoic; covers phosphate, uranium, diatomite, manganese, iron, barite, and petroleum deposits; and gives the first evidence of a bacterially mediated, diagenetic origin for manganese deposits.

Hein, J.R.

1987-01-01

318

The Iron Blast Furnace: A Study in Chemical Thermodynamics  

Microsoft Academic Search

The smelting of iron ore into metallic iron was first accomplished by primitive blast furnaces approximately three thousand years ago. Improvements in the process over many centuries eventually led to the mass production of iron and to the industrial revolution. The reactions of the blast furnace involve 1) combustion of the fuel and its conversion into carbon monoxide, 2) reduction

Richard S. Treptow; Luckner Jean

1998-01-01

319

2. Photocopied June 1978 'THE IRON DAM.' VIEW OF THE ...  

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

2. Photocopied June 1978 'THE IRON DAM.' VIEW OF THE IRON DAM, THE OUTCROPPING OF THE ORE FOUND IN 1826 BY HENDERSON. FURNISHED WATER TO SAWMILL. SOURCE: BENSON LOSSING, THE HUDSON, FROM THE WILDERNESS TO THE SEA, TROY, NEW YORK, 1866, p. 25 - Adirondack Iron & Steel Company, New Furnace, Hudson River, Tahawus, Essex County, NY

320

Electrode regulator system for ore smelting electric arc furnace based on active disturbance rejection control technology  

Microsoft Academic Search

The heat which electric furnace smelt iron alloy is needed is provided by electrode extreme. When the position of electrode extreme is perfect, the power consumption and productivity of production unit are in good state, so take control of electrode position is very important. Electrode regulator system of ore smelting electric arc furnace is a nonlinear, multivariate, parameter-time-varying system, its

Wang Yuhua; Miao Jianlin

2010-01-01

321

Nutrient Effect on the Biological Leaching of a Black-Schist Ore  

PubMed Central

The purpose of the study was to examine the influence of inorganic N (NH4+, NO3-) and phosphate on the biological oxidation of a sulfidic black-schist ore which contained pyrrhotite as the main iron sulfide. Iron was initially solubilized as Fe2+ from the ore and subsequently oxidized to Fe3+ in shake flask experiments. Under these experimental conditions, iron dissolution from pyrrhotite was mainly a chemical reaction, with some enhancement by bacteria, whereas the subsequent Fe2+ oxidation was bacterially mediated, with negligible contribution from chemical oxidation. Phosphate amendment did not enhance Fe2+ oxidation. Chemical analysis of leach solutions with no exogenous phosphate revealed that phosphate was solubilized from the black-schist ore. Ammonium amendment (6 mM) enhanced Fe2+ oxidation, whereas the addition of nitrate (6 and 12 mM) had a negative effect. An increase in the temperature from 30 to 35°C slightly enhanced Fe2+ oxidation, but the effect was statistically not significant. The precipitation of potassium jarosite was indicative of Fe2+ oxidation and was absent in nitrate-inhibited cultures because of the lack of Fe2+ oxidation. The black-schist ore also contained phlogopite, which was altered to vermiculite in iron-oxidizing cultures.

Niemela, Seppo I.; Riekkola-Vanhanen, Marja; Sivela, Carita; Viguera, Felipe; Tuovinen, Olli H.

1994-01-01

322

A MIXED CHEMICAL REDUCTANT FOR TREATING HEXAVALENT CHROMIUM IN A CHROMITE ORE PROCESSING SOLID WASTE  

EPA Science Inventory

We evaluated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in a chromite ore processing solid waste (COPSW). The COPSW is characterized by high pH (8.5 -11.5), high Cr(VI) concentrations in the solid phase (up to 550 mg kg-1) and...

323

Recovery of Arsenic from Ores and Concentrates.  

National Technical Information Service (NTIS)

This invention relates to recovery of arsenic, in the form of As2O3, from arsenical ores and concentrates. Typical of such ores are arseno-pyrite, cobaltite, niccolite, enargite, and speiss. Concentrates of the ores are prepared by conventional means such...

C. M. Flynn T. G. Carnahan

1982-01-01

324

Method for beneficiating coal ore  

Microsoft Academic Search

A new heavy liquid parting medium comprising an emulsion of water and a substantially water immiscible heavy parting liquid for use in beneficiating ores by gravity separations such as sink -float processes. The specific gravity of the emulsion parting medium can be adjusted by proportioning the relative amounts of water and the substantially water immiscible heavy liquid. Asmined coal is

Irons

1983-01-01

325

Conical O-ring seal  

DOEpatents

A shipping container for radioactive or other hazardous materials which has a conical-shaped closure containing grooves in the conical surface thereof and an O-ring seal incorporated in each of such grooves. The closure and seal provide a much stronger, tighter and compact containment than with a conventional flanged joint.

Chalfant, Jr., Gordon G. (North Augusta, SC)

1984-01-01

326

Liquid Phase Sintering  

NASA Technical Reports Server (NTRS)

Industry spends billions of dollars each year on machine tools to manufacture products out of metal. This includes tools for cutting every kind of metal part from engine blocks to Shuttle main engine components. Cutting tool tips often break because of weak spots or defects in their composition. Based on a new concept called defect trapping, space offers a novel environment to study defect formation in molten metal materials as they solidify. After the return of these materials from space, researchers can evaluate the source of the defect and seek ways to eliminate them in products prepared on Earth. A widely used process for cutting tip manufacturing is liquid phase sintering. Compared to Earth-sintered samples which slump due to buoyancy induced by gravity, space samples are uniformly shaped and defects remain where they are formed. By studying metals sintered in space the US tool industry can potentially enhance its worldwide competitiveness. The Consortium for Materials Development in Space along with Wyle Labs, Teledyne Advanced Materials, and McDornell Douglas have conducted experiments in space.

2004-01-01

327

Utilisation of sinter-hardening treatment for various sintered steels  

Microsoft Academic Search

Purpose: Purpose of this paper was to present the benefits of powder metallurgy technology and development of sinter-hardening process applied to different steels including pre-alloyed Ni-Mo steels with W addition, Astaloy CrM and experimental sintered duplex stainless steels. The mechanical properties, focusing in particular on hardness and wear resistance, of two different sinter-hardened steels were described. Microstructure characteristic of produced

L. A. Dobrza?ski a; J. Otr?ba; Z. Brytan; M. Rosso

328

Bog iron formation in the Nassawango Creek watershed, Maryland, USA  

USGS Publications Warehouse

The Nassawango bog ores in the modern environment for surficial geochemical processes were studied. The formation of Nassawango bog ores was suggested to be due to inorganic oxidation when groundwater rich in ferrous iron emerges into the oxic, surficial environment. It was suggested that the process, providing a phosphorus sink, may be an unrecognized benefit for mitigating nutrient loading from agricultural lands. It is found that without the effect of iron fixing bacteria, bog deposites could not form at significant rates.

Bricker, O. P.; Newell, W. L.; Simon, N. S.

2004-01-01

329

Ferric iron reduction by sulfur- and iron-oxidizing bacteria. [Clostridium and Methanobacterium  

Microsoft Academic Search

Acidophilic bacteria of the genera Thiobacillus and Sulfolobus are able to reduce ferric iron when growing on elemental sulfur as an energy source. It has been previously thought that ferric iron serves as a nonbiological oxidant in the formation of acid mine drainage and in the leaching of ores, but these results suggest that bacterial catalysis may play a significant

T. D. Brock; J. Gustafson

1976-01-01

330

Forging the anthropogenic iron cycle.  

PubMed

Metallurgical iron cycles are characterized for four anthropogenic life stages: production, fabrication and manufacturing, use, and waste management and recycling. This analysis is conducted for year 2000 and at three spatial levels: 68 countries and territories, nine world regions, and the planet. Findings include the following: (1) contemporary iron cycles are basically open and substantially dependent on environmental sources and sinks; (2) Asia leads the world regions in iron production and use; Oceania, Latin America and the Caribbean, Africa, and the Commonwealth of Independent States present a highly production-biased iron cycle; (3) purchased scrap contributes a quarter of the global iron and steel production; (4) iron exiting use is three times less than that entering use; (5) about 45% of global iron entering use is devoted to construction, 24% is devoted to transport equipment, and 20% goes to industrial machinery; (6) with respect to international trade of iron ore, iron and steel products, and scrap, 54 out of the 68 countries are net iron importers, while only 14 are net exporters; (7) global iron discharges in tailings, slag, and landfill approximate one-third of the iron mined. Overall, these results provide a foundation for studies of iron-related resource policy, industrial development, and waste and environmental management. PMID:17711233

Wang, Tao; Müller, Daniel B; Graedel, T E

2007-07-15

331

Spark plasma sintering of hydroxyapatite powders  

Microsoft Academic Search

Dense hydroxyapatite (HA) compacts have been successfully fabricated by a spark plasma sintering (SPS). The sintering behavior of HA powders at different temperatures ranging from 850°C to 1100°C was studied. Results showed that spark plasma sintering resulted in rapid densification to near theoretical density. The HA compact was homogeneously sintered at 950°C in a short sintering duration of 5min, while

Y. W. Gu; N. H. Loh; K. A. Khor; S. B. Tor; P. Cheang

2002-01-01

332

Mineral Phases and Release Behaviors of As in the Process of Sintering Residues Containing As at High Temperature  

PubMed Central

To investigate the effect of sintering temperature and sintering time on arsenic volatility and arsenic leaching in the sinter, we carried out experimental works and studied the structural changes of mineral phases and microstructure observation of the sinter at different sintering temperatures. Raw materials were shaped under the pressure of 10?MPa and sintered at 1000~1350°C for 45?min with air flow rate of 2000?mL/min. The results showed that different sintering temperatures and different sintering times had little impact on the volatilization of arsenic, and the arsenic fixed rate remained above 90%; however, both factors greatly influenced the leaching concentration of arsenic. Considering the product's environmental safety, the best sintering temperature was 1200°C and the best sintering time was 45?min. When sintering temperature was lower than 1000°C, FeAsS was oxidized into calcium, aluminum, and iron arsenide, mainly Ca3(AsO4)2 and AlAsO4, and the arsenic leaching was high. When it increased to 1200°C, arsenic was surrounded by a glass matrix and became chemically bonded inside the matrix, which lead to significantly lower arsenic leaching.

Wang, Xingrun; Zhang, Fengsong; Nong, Zexi

2014-01-01

333

On the development of direct metal laser sintering for rapid tooling  

Microsoft Academic Search

An iron based powder blend has been developed for rapid tooling using a direct laser sintering process. The powder consists of a mixture of different elements including Fe, C, Cu, Mo and Ni. High sintering activities were obtained by tailoring the powder characteristics and optimizing the chemical constituents. The manufacturing of complex-shaped parts is possible at rates of 6.75cm3\\/h according

A Simchi; F Petzoldt; H Pohl

2003-01-01

334

PHASE II CALDERON PROCESS TO PRODUCE DIRECT REDUCED IRON RESEARCH AND DEVELOPMENT PROJECT  

SciTech Connect

The commercialization path of the Calderon technology for making a feedstock for steelmaking with assistance from DOE initially focused on making coke and work was done which proved that the Calderon technology is capable of making good coke for hard driving blast furnaces. U.S. Steel which participated in such demonstration felt that the Calderon technology would be more meaningful in lowering the costs of making steel by adapting it to the making of iron--thus obviating the need for coke. U.S. Steel and Calderon teamed up to jointly work together to demonstrate that the Calderon technology will produce in a closed system iron units from iron concentrate (ore) and coal competitively by eliminating pelletizing, sintering, coking and blast furnace operation. If such process steps could be eliminated, a huge reduction in polluting emissions and greenhouse gases (including CO{sub 2}) relating to steelmaking would ensue. Such reduction will restructure the steel industry away from the very energy-intensive steelmaking steps currently practiced and drastically reduce costs of making steel. The development of a technology to lower U.S. steelmaking costs and become globally competitive is a priority of major importance. Therefore, the development work which Calderon is conducting presently under this Agreement with the U.S. Department of Energy becomes more crucial than ever. During the 3rd quarter of 2005 which the present report covers, virtually all the effort to advance the Calderon technology to make iron units was concentrated towards forming a team with a steelmaker who needs both iron units in the form of hot metal and a substitute for natural gas (SNG), both being major contributors to higher costs in steelmaking. Calderon felt that a very good candidate would be Steel Dynamics (SDI) by virtue that it operates a rotary hearth facility in Butler, Indiana that uses large amounts of natural gas to reduce briquettes made from ore and coal that they subsequently melt in a submerged arc furnace that is a large consumer of electric power. This facility is operated as a division of SDI under the name of Iron Dynamics (IDI). It is no secret that IDI has had and still has a great number of operational problems, including high cost for natural gas.

Albert Calderon

2005-10-14

335

Massive deep-sea sulphide ore deposits discovered on the East Pacific Rise  

USGS Publications Warehouse

Massive ore-grade zinc, copper and iron sulphide deposits have been found at the axis of the East Pacific Rise. Although their presence on the deep ocean-floor had been predicted there was no supporting observational evidence. The East Pacific Rise deposits represent a modern analogue of Cyprus-type sulphide ores associated with ophiolitic rocks on land. They contain at least 29% zinc metal and 6% metallic copper. Their discovery will provide a new focus for deep-sea exploration, leading to new assessments of the concentration of metals in the upper layers of the oceanic crust. ?? 1979 Nature Publishing Group.

Francheteau, J.; Needham, H. D.; Choukroune, P.; Juteau, T.; Seguret, M.; Ballard, R. D.; Fox, P. J.; Normark, W.; Carranza, A.; Cordoba, D.; Guerrero, J.; Rangin, C.; Bougault, H.; Cambon, P.; Hekinian, R.

1979-01-01

336

Leaching of radionuclides from uranium ore and mill tailings ( Ra- 226, Tn-230).  

USGS Publications Warehouse

The major part of the extractable uranium is associated with a readily acid-soluble fraction in both ore and tailings. The major part of the extractable 226Ra was associated with an iron, manganese hydrous-oxide fraction in the ore and tailings. Thorium-230 was the least leachable of the radionuclides studied. The major portion of the extractable 230Th was associated with alkaline-earth sulphate precipitates, organic matter, or both. The specific effects of milling on each of the nuclides are discussed.-Author

Landa, E. R.

1982-01-01

337

Improving properties of P/M steels through liquid phase sintering  

SciTech Connect

Steady state liquid phase sintering was utilized to achieve virtually full density in hypereutectoid steels at a temperature of 1175 C. The non-uniform porosity observed in the microstructure of certain liquid phase sintered compacts was accounted for by a proposed liquid phase capillary flow and consequent localized densification. Recommendations are made for avoiding this segregated porosity and were successfully used to prepare high density hypoeutectoid steels by short time transient liquid phase sintering (approx. 10 minutes) at a moderate temperature (1175 C). The mechanical properties of these sintered steels are close to commercial wrought steels and much better than commercial P/M steels. A new intermetallic compound based on the copper-manganese-silicon systems had very desirable properties for use in transient liquid phase sintering of ferrous materials. Its melting point is 780 C and tendency to wet iron is remarkable. During heating to the sintering temperature, the compound melts and spreads rapidly over all the surfaces which effectively reduces the diffusion distance to the order of one particle radius. The addition of this new material to iron base powders has a beneficial effect on the sintered density, hardness, tensile and transverse rupture strength. 8 references, 10 figures.

Pickus, M.R.

1984-01-01

338

Characterization of spark plasma sintered Ag nanopowders.  

PubMed

The low temperature sintering behaviour of nanocrystalline Ag powder (with an average size of 70 nm) was characterized. Using spark plasma sintering (SPS), the Ag nanopowders can be successfully sintered at low pressure for only 5 min without external heating, and the sintering density increases and porosity decreases significantly with increase in the sintering temperature. Nanoindentation has been used to characterize the SPS sintered Ag samples. The mechanisms of the low sintering temperature behaviour of the nano-Ag powder and the nanoscale mechanical performance have been discussed. Compression tests were also used to characterize the mechanical properties of the sintered Ag sample with a maximum strain up to 15%. PMID:20173250

Fu, Y Q; Shearwood, C; Xu, B; Yu, L G; Khor, K A

2010-03-19

339

A Phenomenological Theory of Sintering  

Microsoft Academic Search

Sintering occurs when powders are heated to temperatures near their melting points. This paper deals with the rapid increase of density during the sintering of single substances The increase of density cannot be explained by volume diffusion of vacant lattice sites or surface migration of atoms, but must involve macroscopic flow. The driving force for this flow is surface tension,

J. K. Mackenzie; R. Shuttleworth

1949-01-01

340

Microwave sintering of multiple articles  

DOEpatents

Apparatus and method for producing articles of alumina and of alumina and silicon carbide in which the articles are sintered at high temperatures using microwave radiation. The articles are placed in a sintering container which is placed in a microwave cavity for heating. The rates at which heating and cooling take place is controlled.

Blake, Rodger D. (Santa Fe, NM); Katz, Joel D. (Los Alamos, NM)

1993-01-01

341

SELECTIVE LASER SINTERING OF ZIRCONIA  

Microsoft Academic Search

A combination of Selective Laser Sintering and colloidal infiltration has been used to create partially stabilized zirconia molds for titanium casting. The mold material system was chosen for its low reactivity with molten titanium and thermal shock resistance. The base material, stabilized zirconia mixed with a copolymer binder, was pre-processed before laser sintering into the desired green shape. The average

NICOLE R. HARLAN; DAVID BOURELL; JOSEPH J. BEAMAN

342

Photooxidation of hydrated Fe2+-significance for banded iron formations  

Microsoft Academic Search

The Precambrian banded iron formations (BIFs) are the major iron ore sources on the Earth. They consist of extensive iron-rich and iron-poor layers within siliceous sedimentary rocks1,2. The banding has been attributed to variations in the conditions for precipitation of Fe2+ in ancient seas. The most favoured precipitating agent is oxygen3-8 this would lead in the first place to insoluble

Paul S. Braterman; A. Graham Cairns-Smith; Robert W. Sloper

1983-01-01

343

Metal extraction from ores by heap leaching  

NASA Astrophysics Data System (ADS)

Heap leaching low-grade ores has become a major contributor to the extraction of economically important metals, notably copper and gold. The state-of-the-art in heap leaching is reviewed with emphasis on process engineering. Rock leaching, including rock pore diffusion and mineral kinetics, solution flow, and retention in ore heaps during percolation leaching, and bio-oxidation of sulfidic ores are covered. Oxygen transport into heaps by gaseous diffusion, natural convection, and forced air ventilation is discussed. Strategies for optimizing heap leaching include ore crushing, ore agglomeration, low-cost air ventilation of sulfide ore heaps undergoing bio-oxidation using fans, and the use of aggregate metal extraction rate constants in making metallurgical business decisions about heap leaching.

Bartlett, Robert W.

1997-08-01

344

Enhanced sintering of an Fe-Ni-P coated composite powder prepared by electroless nickel plating  

NASA Astrophysics Data System (ADS)

An Fe-8.2 % Ni-6.0 % P powder was prepared by electroless nickel plating on a carbonyl iron powder, where phosphorous appeared as a contaminant of the plating process. Because of the high phosphorous concentration, persistent liquid phase sintering was effective at temperatures higher than 1000 °C. The sintered microstructure was dramatically different from the conventional approaches, where a low concentration of phosphorous was added in the form of Fe3P. Sintering the alloy at a temperature as low as 1050 °C for 30 min yielded a sintered density of 98.6% theoretical and rounded grains having an average grain size of 53 µm. The rounded grains were surrounded by a large volume fraction of intergranular (Fe,Ni)3P phase, arising from the high phosphorous concentration, which slightly deteriorated the magnetic saturation but significantly increased the electrical resistivity of the alloy. Generally speaking, the magnetic saturation of the sintered alloy was improved with respect to the iron-phosphorus, iron-nickel, or iron-silicon alloys fabricated by powder processing.

Chan, T. Y.; Lin, S. T.

1997-10-01

345

The seal reliability analysis of oring seals  

Microsoft Academic Search

First, the seal reliability function of the O-ring, that is the maximum contact stress between O-ring and plunger must be greater than the fluid pressure, is established, then on the basis of the nonlinear constitutive equation Mooney-Rivlin of rubber material, the finite element model of the O-ring is built using commercial software ABAQUS, according to the finite element model, the

Faguo Sun; Tianxiang Yu; Weimin Cui; Xiao Zong

2009-01-01

346

Tourmaline in the central Swedish ore district  

Microsoft Academic Search

More than 40 recently discovered tourmaline occurrences have been investigated in the Mid-Proterozoic Bergslagen ore district of central Sweden. Some are spatially associated with ores, others with zones of leaching, remobilization and migmatization. Among the tourmaline-bearing ore deposits are the Dammberg ZnPb-Fe sulphide deposit, the Sala Pb-Zn-Ag deposit, the Dalkarlsberg, Pershyttan and Håksberg Fe oxide deposits, the Leja Cu deposit,

R. H. Hellingwerf; K. Gatedal; V. Gallagher; J. H. Baker

1994-01-01

347

Softened-Stainless-Steel O-Rings  

NASA Technical Reports Server (NTRS)

In fabrication of O-ring of new type, tube of 304 stainless steel bent around mandril into circle and welded closed into ring. Ring annealed in furnace to make it soft and highly ductile. In this condition, used as crushable, deformable O-ring seal. O-ring replacements used in variety of atmospheres and temperatures, relatively inexpensive, fabricated with minimum amount of work, amenable to one-of-a-kind production, reusable, and environmentally benign.

Marquis, G. A.; Waters, William I.

1993-01-01

348

The Origin of Cu/Au Ratios in Porphyry-Type Ore Deposits  

NASA Astrophysics Data System (ADS)

Microanalysis of major and trace elements in sulfide and silicate melt inclusions by laser-ablation inductively coupled plasma mass spectrometry indicates a direct link between a magmatic sulfide liquid and the composition of porphyry-type ore deposits. Copper (Cu), gold (Au), and iron (Fe) are first concentrated in a sulfide melt during magmatic evolution and then released to an ore-forming hydrothermal fluid exsolved late in the history of a magma chamber. The composition of sulfide liquids depends on the initial composition and source of the magma, but it also changes during the evolution of the magma in the crust. Magmatic sulfide melts may exert the dominant direct control on the economic metal ratios of porphyry-type ore deposits.

Halter, Werner E.; Pettke, Thomas; Heinrich, Christoph A.

2002-06-01

349

Recovery of Mercury from Cinnabar Ores by Electrooxidation.  

National Technical Information Service (NTIS)

An electrolytic technique for oxidizing ore slurried with brine was investigated to determine its effectiveness in extracting mercury from ores. Optimization experiments conducted on a 2.5 pound mercury per ton ore resulted in 95 percent mercury extractio...

B. J. Scheiner D. E. Shanks R. E. Linstrom

1973-01-01

350

The modes of occurrence of rare-earths ores and the issues on their beneficiation processes  

NASA Astrophysics Data System (ADS)

Rare-earths (RE) ores can largely be divided into the following four types in terms of the modes of occurrence. In each type of RE ores, there are some issues on beneficiation processes, which should be resolved for their successful exploitation. 1. Fine-grained phosphates with iron oxides: This type ores are commonly found from weathered carbonatite and IOCG deposits. The former is Araxa (Brazil), Zandkopsdrift (South Africa), Mt. Weld (Australia) and Yen Phu (Vietnam), and the latter Bayan Obo (China), Vergenoeg (South Africa) and Olympic Dam (Australia). Main RE minerals are monazite, xenotime and florencite contained in the aggregates of iron oxides such as goethite, hematite and magnetite. Fluorite often occurs in the latter type ores. The phosphates and iron oxides occur commonly as very fine grains (< 10 micron meters), and thus they are not readily separated by conventional physical processing. 2. Fluorapatite veins: This type ores are found from the deposits related to alkaline igneous rocks. Nolans Bore (Australia), Palabora (South Africa) and Mushugai Khudag (Mongolia) are the examples. RE is contained mostly in fluorapatite and associated monazite. It is expected that RE can be produced as byproducts of phosphorus fertilizer. However, dissolution of fluorapatite by sulfuric acid causes the coprecipitation of RE with gypsum, which is a refractory material. 3. Silicates and niobium oxides: This type ores are found from hydrothermally altered alkaline plutonic rocks or pegmatitic veins related to alkaline magmatism. Nechalacho and Strange Lake (Canada), Kvanefjeld (Greenland), Bokan Mountain (US), Norra Karr (Sweden) and Dubbo (Australia) are the representative deposits. Main RE minerals are zircon, eudialyte, mosandrite, fergusonite and allanite. They are relatively enriched in heavy RE, and it is expected that part of RE can be produced as byproducts of zirconium. However, their acid dissolution often causes the coprecipitation of RE with silica gel, which is also a refractory material. 4. Medium- to coarse-grained carbonates: This type ores occur in less weathered carbonatite bodies. Mountain Pass (US), Maoniuping (China) and Dong Pao (Vietnam) are the representative deposits. Bastnasite is a main RE mineral. Though, the ores can readily be beneficiated by conventional flotation and dissolved by acid solution, they are always depleted in heavy RE.

Takagi, T.

2012-04-01

351

Sintering of optical wave-guide glasses  

Microsoft Academic Search

Sintering kinetics of glasses prepared by external vapour-deposition technique were quantitatively measured at temperatures ranging from 1000 to 1390° C. Sintering kinetics of borosilicates are consistent with the model proposed for the viscous flow sintering mechanism. The magnitude and the activation energy of the viscosity data derived from the sintering data agree reasonably well with the published data in the

M. F. Yan; J. B. Macchesney; S. R. Nagel; W. W. Rhodes

1980-01-01

352

Low temperature sintering semiconducting barium strontium titanate  

Microsoft Academic Search

Low temperature sintering has become a very important research area in ceramics processing and sintering as a promising process to obtain grain size below 100nm. For electronic ceramics, low temperature sintering is particularly difficult, because not only the required microstructure but also the desired electronic properties should be obtained. In this dissertation, the effect of liquid sintering aids and particle

Wenzhong Wu

2007-01-01

353

Compositional Variability of Rutile in Hydrothermal Ore Deposits  

NASA Astrophysics Data System (ADS)

Rutile is a relatively common accessory phase in many geological environments, and although it is almost always composed dominantly of TiO2, it is also associated with a wide range of minor and trace element substitutions. The most prominent minor elements that occur in rutile are Fe, Cr, V, Nb and Ta. Like Ti, the latter two elements are essentially immobile in most non-magmatic metallic ore deposits, and their concentrations in rutile are largely influenced by precursor mineral compositions. Iron, Cr and V concentrations vary considerably in rutile hosted by ore deposits, and reflect combinations of precursor mineral composition and the bulk chemistry of the local mineralized or altered rock environment. However, in hydrothermal alteration zones, rutile compositions are clearly anomalous compared to those in unaltered host rocks, and have distinctive elemental associations and substitutions in different types of ore deposits. We have evaluated the mineral chemistry of rutile in >40 ore deposits worldwide. In general, rutile in volcanogenic massive sulfide deposits contains Sn (and locally W, Sb and/or Cu). Rutile from mesothermal and related gold deposits invariably contains W, and in some of the larger and more important deposits, also contains Sb and/or V. Tungsten-bearing detrital rutile grains from the Witwatersrand suggest that paleoplacer mineralization may have had a mesothermal/orogenic gold source. In some magmatic-hydrothermal Pd-Ni-Cu deposits, rutile contains Ni and Cu. Rutile associated with granite-related Sn deposits has strongly elevated concentrations of Sn and W, and granite-pegmatite W-Sn deposits contain rutile with these elements plus Nb and Ta. The Olympic Dam deposit hosts rutile that is enriched in W, Sn and Cu. Rutile associated with porphyry and skarn Cu and Cu-Au deposits tends to contain elevated W, Cu (and sometimes V). Although many ore deposits have well-defined and diagnostic rutile compositions, there are some compositional overlaps between mineralization types. Nevertheless, element combinations and ratios can be used to distinguish qualitatively between rutile compositions for most ore deposit types, and statistical methods can be used to provide more quantitative evaluation. Rutile occurs in significant abundance (typically 0.05 to 0.5 vol%) in most metallic ore deposits and is most plentiful in sulfidic systems where high fS2 and/or fO2 conditions stabilize rutile in the presence of minerals such as pyrite and hematite. Rutile is also persistent in weathering environments, and is likely to survive transport by glacial and fluvial processes. As a common component of heavy mineral sands, rutile is readily separable by routine magnetic, heavy liquid, and other density methods. These features, combined with the sensitive compositional variations in altered and mineralized rocks noted above, and the relative ease of analyses by routine electron microprobe methods, suggest that rutile has considerable potential as a geochemical indicator mineral for hydrothermal ore deposits, analogous to the kimberlite indicator minerals such as Cr-pyrope, magnesiochromite and picroilmenite that are used regularly in diamond exploration.

Clark, J. R.; Williams-Jones, A. E.

2009-05-01

354

Low grade ores – Smelt, leach or concentrate?  

Microsoft Academic Search

Metallic ore grades are falling globally as the higher grade reserves are exploited first and are progressively depleted. At the same time, the demand for primary metals extracted from these ores is expected to increase, despite increased levels of dematerialisation and recycling. Sustainability concerns have highlighted the need to meet these demands while at the same time minimising resource consumption

T. Norgate; S. Jahanshahi

2010-01-01

355

O-ring fiber optic pressure sensor  

NASA Astrophysics Data System (ADS)

Two optical fiber pressure sensor techniques are applied to the measurement of the distributed pressure of an O-ring. These sensors are polarimetrically and interferometrically based. Experimental results are presented for measuring the pressure exerted on an O-ring placed in a vacuum chamber and are compared with analytical results. Resolution and dynamic range of the fiber sensors are discussed.

Bouzid, Ahmed; Abushagur, Mustafa A.; He, Zhijian; Kosten, Susan E.

1994-04-01

356

Processing of Gold Bearing Antimony Ore  

Microsoft Academic Search

A wet chemical process was developed for the separation of gold from gold-bearing antimony sulphide ores. The ore sample was taken from the mine Urquidi from Oruro in Bolivia. It contained roughly 33% Sb in the form of antimonite. 24% Si in the form of quartz, small quantities of Pb, Fe, Cu, and Ni as well as 63 g\\/t gold,

E. GOCK; J. F. CORDOVA EQUIVAR

1995-01-01

357

A Linear Programming Model of Integrated Iron and Steel Production  

Microsoft Academic Search

Integrated steel mills usually have a choice over the use of various materials and production processes. Different ores may be used in the production of iron; steel scrap and iron can be used in different proportions in the production of steel. The economical usage rate of all materials is a function of numerous variables, among which the market price of

Tibor Fabian

1958-01-01

358

Ceramic powder for sintering materials  

NASA Technical Reports Server (NTRS)

Surface activity of ceramic powders such as MgO and Al2O3, for use in sintering with sp. emphasis on their particle size, shape, particle size distribution, packing, and coexisting additives and impurities are reviewed.

Akiya, H.; Saito, A.

1984-01-01

359

Sintering behaviour of hydroxyapatite bioceramics.  

PubMed

The sintering behaviour of a commercial HA and synthesized HA was investigated over the temperature range of 700 degrees C to 1400 degrees C in terms of phase stability, bulk density, Young's modulus and Vickers hardness. In the present research, a wet chemical precipitation reaction was successfully employed to synthesize a submicron, highly crystalline, high purity and single phase stoichiometric HA powder that is highly sinteractive particularly at low temperature regimes below 1100 degrees C. It has been revealed that the sinterability of the synthesized HA was significantly greater than that of the commercial HA. The temperature for the onset of sintering and the temperature required to achieve densities above 98% of theoretical value were approximately 150 degrees C lower for the synthesized HA than the equivalent commercial HA. Nevertheless, decomposition of HA phase upon sintering was not observed in the present work for both powders. PMID:19024998

Ramesh, S; Tan, C Y; Aw, K L; Yeo, W H; Hamdi, M; Sopyan, I; Teng, W D

2008-07-01

360

Study of Munella Ores. (puka Region, Albania)  

NASA Astrophysics Data System (ADS)

The study of Munella ores is based on four analysis (A, B, Cand cores). They represent different types of minerals in the Munella area. Cores were taken by the geologist of Puka Geological Enterprise. A Core: It represents an ore with pyrite and chalcopyrite where copper and sulfur contents are 0.77 and 8.2% respectively. B Core: This core represents an ore with spharelites and pyrite where zinc content is 1.5% and 2.9% sulfur one. C Core: It is a chalcopyrite ore, massive in nature, where copper content is 2.01% and 36% sulfur one. D Core: It also represents copper- zinc-sulfur ore where their content is 0.66, 1.00 and 4.28% respectively. Each core is studied individually by selective schema to have copper, zinc and pyrite concentrates. Copper and pyrite concentrates will be the first material for pyro- metallurgical industry.

Liçaj, Engjell; Mandili, Jorgo; Tabaku, Boran; Thomo, Niko

2010-01-01

361

Method of sintering ceramic materials  

DOEpatents

A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density. 2 figs.

Holcombe, C.E.; Dykes, N.L.

1992-11-17

362

Method of sintering ceramic materials  

DOEpatents

A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

Holcombe, Cressie E. (Knoxville, TN); Dykes, Norman L. (Oak Ridge, TN)

1992-01-01

363

Ceramic surfaces and sintering  

SciTech Connect

We produced ultrafine faceted alumina particles (UFPs), 20--50 nm in diameter, by an arc-discharge method and sintered small clusters of them as they were carried through a tube furnace by flowing gas. The experiment was conducted under near UHV clean environment and specimens were examined in a UHV H9000 TEM. The UFPs produced in this study were transition alumina phases ({gamma}{delta} and {theta}). We found new {delta} and {theta} phases which were different from those in earlier studies. We developed two computer programs to simulate the shape, 3-D arrangement, and random contact of UFPs. Gaps were discovered to exist between particles due to random contact and possibly rotation and slip after contact. As no shrinkage was found, surface diffusion was identified as the dominant mechanism that was responsible for the formation of necks'' by filling in the gaps. These necks had well-defined, atomically-sharp contact angles, which suggest that the neck growth process was controlled by faceting.

Marks, L.D.

1991-08-01

364

The application of Taguchi’s method in the experimental investigation of the laser sintering process  

Microsoft Academic Search

The selective laser sintering (SLS) of iron powder has been investigated through a number of experiments statistically planned\\u000a as per Taguchi L8 design. Seven input parameters, namely, laser peak power density, laser pulse on-time, laser scan speed,\\u000a stepping distance (distance traveled between pulses), interval–spot ratio (ratio of laser scan line interval and laser spot\\u000a diameter), size range of iron powder

S. Dingal; T. R. Pradhan; J. K. Sarin Sundar; A. Roy Choudhury; S. K. Roy

2008-01-01

365

Iron control in zinc pressure leach processes  

NASA Astrophysics Data System (ADS)

The occurrence of zinc in sulfide ore deposits is generally accompanied by various iron minerals. Hence, even the most efficient concentrators generally produce a zinc concentrate with significant iron content. The efficient recovery of zinc metal from zinc concentrates requires the rejection of iron residue in a form that minimizes the zinc entrainment. Careful control of the iron precipitation step is important, so that the iron residue produced is amenable to efficient liquid-solid separation in order to obtain high zinc recoveries. In hydrometallurgical zinc processes, the coprecipitation of minor impurities along with iron precipitation is also important in producing zinc-sulfate solution from which high-purity zinc cathode can be electrowon. The integration of Dynatec’s zinc pressure leach process with existing roast-leach-electrowin plants employing various methods of iron rejection is briefly described in this article, along with the application of two-stage pressure leaching in stand-alone processes.

Buban, K. R.; Collins, M. J.; Masters, I. M.

1999-12-01

366

Comparative leaching of minerals by sulphuric acid in a Chinese ferruginous nickel laterite ore  

Microsoft Academic Search

The Yuanjiang nickel laterite ore containing mainly maghemite, goethite and lizardite was leached by sulphuric acid at atmospheric pressure and the residues were characterized using X-ray diffraction and scanning electron microscopy\\/X-ray energy dispersive spectroscopy. The relationship was discussed between the extraction of nickel, cobalt, iron, magnesium, aluminum, and the dissolution behaviour of the laterite minerals; as well as the extent

Kui Liu; Qiyuan Chen; Huiping Hu

2009-01-01

367

Reductive leaching of manganiferous ores by glucose and H 2SO 4: effect of alcohols  

Microsoft Academic Search

The effect of alcohols on the dissolution of manganese, calcium, and iron from manganiferous ore is reported. The extractive process was studied in sulphuric acid solution by using glucose as reducing agent. The alcohols were employed in order to evaluate their effect on the leaching performance with and without glucose as reducing agent. Three different alcohols MeOH, EtOH, and n-BuOH,

M Trifoni; L Toro; F Vegliò

2001-01-01

368

Application of solution-mineral equilibrium chemistry to solution mining of uranium ores  

Microsoft Academic Search

Modern methods of uranium solution mining are typically accompanied by gains and losses of mass through reagent consumption by rock-forming minerals, with subsequent formation of clay minerals, gypsum, carbonates, and iron oxyhydroxides. A systematic approach to alleviate such problems involves the application of leach solutions that are in equilibrium with the host-rock minerals but in disequilibrium with the ore-forming minerals.

A. C. Riese; C. J. Propp

1980-01-01

369

Scoping studies on recovery of uranium from man-made ores  

Microsoft Academic Search

The potential for recovery of enriched uranium from spent nuclear fuel which has been consolidated into a nuclear waste form was explored in the studies reported here. The waste form of interest is iron-enriched basalt (IEB), a silicate-based, fused-cast ceramic. The IEB samples, or man-made uranium ores (MMUO), are in two different mineralogical forms. From the results of the scoping

R. L. Miller; J. M. Welch; J. E. Flinn

1983-01-01

370

An assessment of the carbothermic reduction of ilmenite ore by statistical design  

Microsoft Academic Search

The demand for titanium ores and concentrates is largely driven by the demand for titanium pigments and titanium metal products, which in turn follows the growth of the global economy. The carbothermic reduction of ilmenite up to 1200°C was found to proceed through the formation of a series of oxides (TinO2n?1) and iron metal. Statistical analysis provides a method to

A. A. Francis; A. A. El-Midany

2008-01-01

371

Determination of small amounts of molybdenum in tungsten and molybdenum ores  

USGS Publications Warehouse

A rapid method has been developed for the determination of small amounts of molybdenum in tungsten and molybdenum ores. After removing iron and other major constituents the molybdenum thiocyanate color is developed in water-acetone solutions, using ammonium citrate to eliminate the interference of tungsten. Comparison is made by titrating a blank with a standard molybdenum solution. Aliquots are adjusted to deal with amounts of molybdenum ranging from 0.01 to 1.30 mg.

Grimaldi, F. S.; Wells, R. C.

1943-01-01

372

A Survey of Modern Iron Ore Pelletizing Processes.  

National Technical Information Service (NTIS)

The development of pelletizing, from a world production of 20 million tons in 1960 to 145 million tons in 1972 and a projected 200 million tons by 1977 is discussed. The change in pelletizing philosophy, from the initial concept of being a convenient and ...

R. L. Lappin F. B. Traice

1973-01-01

373

Recent iron ore formation in Lake Malawi, Africa  

Microsoft Academic Search

Nontronit, Limonit (und Opal) sowie Vivianit werden an zahlreichen Stellen des südlichen Malawi-Sees in Wassertiefen bis 250 m (aerober Bereich) abgeschieden und bilden dort die jüngste sedimentäre Einheit über Diatomit oder grobklastischem Sediment. Es muß angenommen werden, daß die Bildung der Eisenmineralien aus geothermalen Lösungen erfolgt, die reich an gelöster Kieselsäure und Fe2+ (untergeordnet Mn2+) sind, wobei Eisen und Mangan

German Müller; U. Förstner

1973-01-01

374

Influence of flux additives on iron ore oxidized pellets  

Microsoft Academic Search

Six additives, i.e., limestone, lime, magnesite, magnesia, dolomite and light-burned-dolomite, were added for investigating\\u000a their influences on the pellet quality. For green balls, adding lime and light-burned-dolomite makes the wet drop strength\\u000a decrease firstly, and then increase with further increase of additive dosage. Ca(OH)2 affects the bentonite properties at the beginning, but the binding property of Ca(OH)2 will be main

Xiao-hui Fan; Min Gan; Tao Jiang; Li-shun Yuan; Xu-ling Chen

2010-01-01

375

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

376

Metallization of Pelletized, Domestic, Iron Oxide Superconcentrates with Lignite and Coal in a Rotary Kiln.  

National Technical Information Service (NTIS)

An investigation was undertaken with the objective of producing metallized pellets from domestic iron ore superconcentrates using lignite and subbituminous coal as reductants. Feed materials to the metallizing process consisted of commercially indurated i...

R. E. Peterson C. Prasky

1976-01-01

377

Investigation of the Role of Sintering in Gas-Solid Interactions. Progress Report.  

National Technical Information Service (NTIS)

The following research has been done: an investigation of the influence of the decomposition of a precursor (Cd(OH) sub 2 ) on the particle size of a ceramic product (CdO), and the influence of sintering on the reduction of iron oxides. (ERA citation 09:0...

Z. A. Munir

1983-01-01

378

Method of making bonded or sintered permanent magnets  

DOEpatents

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density.

McCallum, R. William (Ames, IA); Dennis, Kevin W. (Ames, IA); Lograsso, Barbara K. (Ames, IA); Anderson, Iver E. (Ames, IA)

1995-11-28

379

Method of making bonded or sintered permanent magnets  

DOEpatents

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density. 14 figs.

McCallum, R.W.; Dennis, K.W.; Lograsso, B.K.; Anderson, I.E.

1995-11-28

380

Method of making bonded or sintered permanent magnets  

DOEpatents

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density.

McCallum, R.W.; Dennis, K.W.; Lograsso, B.K.; Anderson, I.E.

1993-08-31

381

25. FRONT END LOADERS MOMENTARILY IN REPOSE IN THE ORE ...  

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

25. FRONT END LOADERS MOMENTARILY IN REPOSE IN THE ORE STORAGE YARD. AN ORE BRIDGE THAT FORMERLY TRANSFERRED ORE WITHIN THE STORAGE YARD WAS DESTROYED BY A BLIZZARD IN 1978. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

382

Nanostructured hydroxyapatite by microwave sintering.  

PubMed

In this work, nanostructured HA ceramics with dense microstructure were prepared by microwave sintering process and their microstructures were compared with the case of conventional sintering. Commercially obtained HA powder with Ca/P molar ratio of 1.67 was used as a starting material. The powder of granular type consists of nanocrystalline particles of 20-30 nm in size. The as-received HA powder or the powder calcined at 800 degrees C, followed by ball-milling was used for the preparation of HA disks. Microwave sintering was conducted at 1200 degrees C for 5 min with a heating rate of 50 degrees C/min. HA ceramics with the sintered densities of approximately 96-97% of the theoretical were obtained. XRD analysis showed that all detectable peaks are identical to pure hydroxyapatite. The HA sintered body made of calcined and ball-milled powder showed uniform microstructure with grain size of 300-400 nm and with finer sub-grains of 30-40 nm. PMID:18464431

Seo, Dong Seok; Hwang, Kyu Hong; Lee, Jong Kook

2008-02-01

383

Prospecting For Magnetite Ore Deposits With A Innovative Sensor's of Unique Fundamentally New Magnetometer.  

NASA Astrophysics Data System (ADS)

After careful study of principles and abilities of all existing magnetmeters of all three revolutions in magnetic prospecting we have come to the conclusion that they cannot solve local guestions of the magnetic prospecting or determine centre coordinates of magnetite ore body before drilling Electromagnetism lows and achievents magnetprospectings and radioelectronics of all 20th century serve as a theoretical base of the "locator". While creating this cardinally new magnetmeter , we borrowed different things from radio-prospectors, magnetprospectors, wireless operators and combined all of them while creating the "locators''. The "locators' construction is bas ed on the "magnetic intensification" principle ,owing to which this "locators" are characterised by hight sensitiveness and ability to determine centers of even little commercial magnetite ore deposits with relatively weak magnetic anomalies. The main advantage of the "locators" over existing ones is that it can solve local questions determine centre coordinates. A remarkably simple locator construction determine direction of the on-surface measurings towards the ore body centre and gives approximate prognosis resourses before/withour/ drilling. The "locators" were worked out for the first time in history , they have 2 licences. The fundamental design and drawbacks of the existing magnetometers have been inherited from the original magnetometre dating back two or three hundred years. The developers of the existing magnetometres have all gone along the same well- beaten track of replacing the primitive sensor in the form of a piece of ore hung on a string at first by an arrow sensor and later by magnetically oriented protons and quanta, with amplification of the sensors' OUTPUT signal. Furthermore, all the existing magnetometres are imperfect in that they, lacking the directivity of the ground-level magnetic measurements, only record the overall magnetic vector field generated by all the ore bodies around the measurement point. The result is often misleading as an intense magnetic anomaly may be registered in a place where is no ore, and vice versa. Such false anomalies and maps may serve as the only guide in iron ore prospecting. The reserves' forecast based on such magnetic maps are also false as they may yield figures exceeding the actual reserves by tens or even hundreds of times. The existing magnetometres are often insufficiently sensitive and incapable of detecting small commercial processable ore bodies with a weak magnetic anomaly (less than 0.1% of the Earth's field). As regards new large iron ore deposits with strong anomalies, the probabilities of encountering them nowadays are becoming increasingly smaller. Confidence in the good performance and the advantages of the new magnetometres patented by the Magnitogorsk Iron and Steel Works is based on the following considerations: The anomalies' magnetic field is several times stronger than the magnetic field of the Earth; To cite two historical instances, the Sokolovskoye ore deposit in Kazakhstan was discovered in 1949 not by prospectors but by a civil aviation pilot, M.Surgutanov, using an ordinary airplane compass. The Kursk Magnetic Anomaly was discovered in 1778 by Professor I.Inozemtsev using a piece of ore hung on a string. The magnetometres patented by the MMK team, are based on the electromagnetism laws of Ampere, Ohm, Weber, Maxwell and Tesla. The history of magnetic prospecting can be divided into three periods, each of them preceded by a revolution of sorts. The first one occurred in 1910 when the German scientist Schmidt developed an optic mechanical magnetometre which came to be known in Russia as M-2 or "Fanzelau". The second revolution came about in 1936 with the invention by the Russian scientist A.Logachov of an AM-9L aeromagnetometre. The third revolution happened in 1953 when Pickard in the Unuted States (and Tsyrell in 1957 in the Soviet Union) invented a proton and quantum magnetometre. But, having examined the fundam

Emelianenko, T. I.; Tachaytdinov, R. S.; Sarichev, V. F.; Kotov, B. V.; Susoeva, G. N.

384

Sintering behaviour improvement of a low Cr–Mo prealloyed powder steel through Mn additions and others liquid phase promoters  

Microsoft Academic Search

Although its good hardenability, chromium has being avoided in powder metallurgy (PM) steels because of its high oxygen affinity and difficulties in sintering. For this purpose, a prealloyed iron powder Fe–3Cr–0.5Mo Astaloy CrM® grade, with different carbon content and some alloying elements additions have been studied. Mixtures were uniaxially compacted at 700MPa. Sintering process was carried out at 1120° in

M Campos; D Sanchez; J. M Torralba

2003-01-01

385

Bioinformatics and Genomics of Iron and Sulfur-Oxidizing Acidophiles  

Microsoft Academic Search

\\u000a Important protagonists in geomicrobiology are the “biomining” microorganisms which are used to recover valuable metals from\\u000a mineral ores and concentrates. These microorganisms either convert insoluble metal sulfides to soluble metal sulfates, a process\\u000a referred to as bioleaching, or weaken the ore by removing iron and\\/or sulfur making the valuable metal accessible to subsequent\\u000a chemical treatment, a process known as biooxidation

Violaine Bonnefoy

386

The role of volatiles in the reduction of iron oxides  

Microsoft Academic Search

With iron ore reduction processes using coal-ore pellets or mixtures, it is possible that volatiles from the coals can contribute to the overall reduction. By identifying the possible reducing species in the volatiles as H2\\/CO and simulating these constituents, the rates for H2 and CO were investigated in the temperature and reduction range of interest where hydrogen was the major

Il Sohn

2005-01-01

387

Distribution of ore deposits and spectrographic analyses of some rocks and ores on the Colorado Plateau  

USGS Publications Warehouse

The geographic pattern of known igneous rocks and ore deposits on the Colorado Plateau suggests a zonal arrangement of several types of ore deposits around centers of igneous activity. Spectrographic analyses of rocks and ores on the Plateau have been obtained in an effort to determine the distribution of elements and to examine the relationships between types of ore deposits and between the ore deposits and igneous rocks. Over 170 analyses of rocks and ores are given in this report. A preliminary study of these analyses suggests that the proportion of uranium, vanadium, copper, and silver in the uranium ores varies geographically, and that the pattern of variation may be in part concentric about some of the major laccolithic intrusions. It is also suggested that the following ratios of metals contained in the uranium ores are possible guides to larger-than-average ore deposits: (1) lead/uranium greater than 1, (2) lead/zinc greater than 10, and (3) zinc/geometric mean of cobalt and nickel less than 10.

Riley, Leonard Benjamin; Shoemaker, Eugene Merle

1952-01-01

388

Computations for Mine Ore/Mineral Rock.  

National Technical Information Service (NTIS)

Several calculations of the Mineral Rock event (which duplicated MINE ORE) were performed on Physics International's ELK code. Each of the calculations utilized a different, plausible model of in-situ rock. Peak displacements and velocity histories were c...

J. E. Reaugh

1972-01-01

389

Extraction of Molybdenum from Ores by Electrooxidation.  

National Technical Information Service (NTIS)

Extraction of molybdenum from molybdenite ore by an electrolytic oxidation procedure was investigated by the Bureau of Mines. Various parameters affecting molybdenum extraction, such as salt concentration, temperature, treatment rate, current density, and...

B. J. Scheiner R. E. Lindstrom

1972-01-01

390

Borehole Mining of Deep Phosphate Ore.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. The feasibility was tested of hydraulic borehole mining for the recovery of phosphate ore from the deep, water-saturated deposits of northeastern Florida. Hydraulic ...

1983-01-01

391

Process for Recovering Copper from Oxidized Ores.  

National Technical Information Service (NTIS)

The patent application relates generally to the hydrometallurgical recovery of metals from their source materials. More particularly, the present invention relates to the hydrometallurgical recovery of copper from its oxidized ores by using alkaline leach...

P. R. Haskett

1975-01-01

392

Recovery of Uranium from Refractory Ores.  

National Technical Information Service (NTIS)

Uranium is recovered from refractory carbonaceous-sulfidic ores or concentrates by leaching with nitric acid, followed by sorption on an ion exchange resin. In addition, the nitric acid leach solution is regenerated and recycled.

T. G. Carnahan K. P. V. Lei

1977-01-01

393

Flotation of Rare Earths from Bastnaesite Ore.  

National Technical Information Service (NTIS)

As part of its efforts to maximize process efficiency and decrease energy requirements in mineral processes, the Federal Bureau of Mines has investigated methods for beneficiating bastnasite ores from Mountain Pass, Calif. The results of a bench-scale stu...

E. Morrice, M. M. Wong

1982-01-01

394

New Techniques in Processing Tungsten Ore Slimes.  

National Technical Information Service (NTIS)

New methods of beneficiation of wolframite ore slimes in China are described. A relatively high level of metal recovery has been maintained by the separate treatment of all plant slimes. Satisfactory results were gained with a centrifugal separator, a new...

S. Sun, Q. Chen, Y. Yang

1987-01-01

395

Recovery of Mercury from Ores and Concentrates.  

National Technical Information Service (NTIS)

Mercury is recovered from ores, concentrates, or wastes by means of a process comprising leaching with an aqueous solution of cupric chloride to form mercuric chloride and cuprous chloride. In addition, an additie such as calcium chloride is preferably us...

G. Atkinson

1981-01-01

396

Research of Geochemical Associations of Nephelin Ores  

NASA Astrophysics Data System (ADS)

The instant paper concerns research of distribution petrogenic chemical members in urtit ore body of Kia-Shaltyrsk deposit. Rocks of the deposit are ore for producing alum earth. Actuality of the subject based on outlooks of detection noble metal ore-bearing (Au, Pt, Pd, Rh, Ru) in alkaline rocks of Siberia, including rocks of Kia-Shaltyrsk deposit (Kuznetsk Alatau). The main purpose of analysis of distribution of members is directed to detection of a non-uniformity of distribution of substance and segments enriched with alum earth and noble members. The basic solved problems are following: o Creation regression models of ore body; o Definition of cumulative distribution functions of members in a contour of ore body; o The analysis of the obtained outcomes in geologic terms. For construction regression models the full-scale data was used, which was presented by the results of the spectral and silicate analyses of gold and petrogenic members containing 130 assays arranged in ore body. A non-linear multiparameter model of the ore body based on components of nephelin ore using neural net approach was constructed. For each member the corresponding distribution function is produced. The model is constructed on the following members: Au, Al2O3, SiO2, Fe2O3, CaO, MgO, SO3, R2O ((Na2O+K2O) -1) and losses of burning. The error of model forecasting membersS concentrations was from 0.02 up to 20%. Large errors basically connected with assays located near contact of ore body and ad- jacent strata or with very high concentrations of members; also they can be connected with different genesis of rocks or superposition of other processes. The analysis of concentrations of members and normalised absolute errors of the fore- cast has shown, that all members can be sectioned into two groups: first: Al2O3, SiO2, R2O, Fe2O3 and second: Au, losses of burning, CaO, MgO, SO3. The distribution of 1 gold is tightly connected with calcium and losses of burning and spatially linked with zones of contact of ore body and adjacent wall rocks. Also it is possible to point, that the segments enriched with gold do not coincide with segments of high-alumna rocks but they are phase-opposite. High concentrations of alum earth, earth silicon, alkalis and low contents of ferric oxide, calcium and sulphur determine high-alumina rocks. Thus, one group of members determines high quality of nephelin ore, and the sec- ond U noble metal ore-bearing bound with members aggravating quality of nephelin ore. Therefore, it is possible to draw a conclusion, that the preliminary enrichment of nephelin ore with the help of flotation will allow to receive two kinds of high quality concentrate: aluminous and noblemetal. The research also allows developing ways of a practical solution of a problem of de- terioration quality of nephelin ore with increasing depth and, accordingly, increases its cost price. These problems apparently connected with economical planning of a production activity of the ore mine and the financial state of the alumnus plant. 2

Vulf, M.; Simonov, K.; Sazonov, A.

397

8. EAST ELEVATION OF SKIDOO MILL AND UPPER ORE BIN, ...  

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

8. EAST ELEVATION OF SKIDOO MILL AND UPPER ORE BIN, LOOKING WEST FROM ACCESS ROAD. THE ROADWAY ON THIS LEVEL (CENTER) WAS USED FOR UNLOADING ORE BROUGHT ON BURROWS INTO THE ORE BIN AT THE TOP LEVEL OF THE MILL. THE ORE BIN IN THE UPPER LEFT WAS ADDED LATER WHEN ORE WAS BROUGHT TO THE MILL BY TRUCKS. - Skidoo Mine, Park Route 38 (Skidoo Road), Death Valley Junction, Inyo County, CA

398

On the drying rates of individual iron oxide pellets  

Microsoft Academic Search

After agglomeration, iron oxide pellets are sintered in continuous furnaces to develop the mechanical properties required by iron making plants. In the first zones of the furnace, pellets are dried by the hot recycled gas. The objective of the study is to model their drying kinetics. For that purpose, individual pellets, instrumented for temperature measurement, are dried in a laboratory

T. Tsukerman; C. Duchesne; D. Hodouin

2007-01-01

399

Unlocking refractory gold ores and concentrates  

NASA Astrophysics Data System (ADS)

The successful treatment of gold and silver ores is always a matter of economics, but it is not always a matter of grade, or metal content. Although the photograph accompanying this article depicts the notion that the scale of gold recovery is increasingly disproportionate to the amount of earth that must be processed, the economics of gold production nonetheless provide incentives attractive enough to justify greater investment in the development of effective treatments for refractory gold ores and concentrates.

McClincy, R. J.

1990-09-01

400

Silicon carbide material sintered bodies manufacturing  

NASA Technical Reports Server (NTRS)

A method is described for producing a high density silicon carbide sintering substance which contains aluminum oxide. The sintering is done in CO gas atmosphere, which is kept at 2 to 20 atmospheric pressures.

Suzuki, K.; Shinohara, N.

1984-01-01

401

Microstructures of binderless tungsten carbides sintered by spark plasma sintering process  

Microsoft Academic Search

Pure WC was sintered by spark plasma sintering (SPS) process for a binderless cemented carbide application. The relative density of spark plasma sintered WC was over 98% when the SPS temperature was 1700°C under 50 MPa pressure. Grain growth of WC could be suppressed with full densification by shortening sintering time. When the initial WC powder size was varied from

Seung I. Cha; Soon H. Hong

2003-01-01

402

Direct laser sintering of a silica sand  

Microsoft Academic Search

As an application study of rapid prototyping, commercially available silica sand was successfully direct-laser-sintered in a self-developed high-temperature laser sintering equipment. The mechanism of powder-state sand becoming a solid state block during the laser sintering process was disclosed by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis on sand particles and sintered samples. The effect of process parameters

Y. Tang; J. Y. H. Fuh; H. T. Loh; Y. S. Wong; L. Lu

2003-01-01

403

Low Temperature Sintering Semiconductive Barium Strontium Titanate  

Microsoft Academic Search

Low temperature sintering has become a very important research area in ceramics processing and sintering as a promising process to obtain grain size below 100nm. For electronic ceramics, low temperature sintering is particularly difficult, because not only the required microstructure but also the desired electronic properties should be obtained.\\u000aIn this dissertation, the effect of liquid sintering aids and particle

Wenzhong Wu

2007-01-01

404

Grain growth in zirconium diboride during sintering  

Microsoft Academic Search

The results are presented of an investigation into the growth of zirconium diboride grains during sintering. It is assumed that, during the initial period of sintering, grain growth is effected by a mechanism of grain displacement under the influence of surface tension forces, when grain matching occurs on polygonized boundaries. At sintering time of more than 30 min, grain growth

M. A. Kuzenkova; P. S. Kislyi

1966-01-01

405

Wear characteristics of laser sintered molding tools  

Microsoft Academic Search

Some characteristics of the direct metal laser sintering process, a layered manufacturing technology, which is already successfully being used for rapid tolling applications, are presented. Particular micro-structural and mechanical characterization of the sintered parts is included with the aim to find the proper surface finishing and coatings to improve the wear characteristics of the laser sintered products. Consequently, wear resistance

Slavko Dolinšek

2005-01-01

406

Oil shales, evaporites and ore deposits  

NASA Astrophysics Data System (ADS)

The relationships between oil shales, evaporites and sedimentary ore deposits can be classified in terms of stratigraphic and geochemical coherence. Oil shale and black shale deposition commonly follows continental red beds and is in turn followed by evaporite deposition. This transgressive-regressive sequence represents an orderly succession of depositional environments in space and time and results in stratigraphic coherence. The amount of organic carbon of a sediment depends on productivity and preservation, both of which are enhanced by saline environments. Work on Great Salt Lake. Utah, allows us to estimate that only 5% of TOC originally deposited is preserved. Inorganic carbonate production is similar to TOC production, but preservation is much higher. Oil shales and black shales commonly are enriched in heavy metals through scavenging by biogenic particles and complexation by organic matter. Ore deposits are formed from such rocks through secondary enrichment processes, establishing a geochemical coherence between oil shales and ore deposits. The Permian Kupferschiefer of N. Europe is used as an example to define a Kupferschiefer type (KST) deposit. Here oxygenated brines in contact with red beds become acidified through mineral precipitation and acquire metals by dissolving oxide coatings. Oxidation of the black shale leads to further acid production and metal acquisition and eventually to sulfide deposition along a reducing front. In order to form ore bodies, the stratigraphic coherence of the red bed-black shale-evaporite succession must be joined by the geochemical coherence of the ore body-evaporite-black shale association. The Cretaceous Cu-Zn deposits of Angola, the Zambian Copperbelt as well as the Creta, Oklahoma, deposits are other KST examples. In the Zambian Copperbelt, evaporites are indicated by the carbonate lenticles thought to be pseudomorphs after gypsum-anhydrite nodules. MVT deposits are also deposited by acid brines, but at more elevated temperatures and with carbonates as principal host rocks. The Pine Point deposits are cited for their close association with evaporites. Alkaline, metal-rich brines are postulated for the HYC deposit of McArthur River, Australia. Such brines are known from the Green River Formation and deposits formed from such brines constitute the GRT class. They can be recognized by the presence of Magadi-type cherts and zeolite-analcime-K-spar tuffs. The Cu-Co ore bodies of Outokumpu, Finland, might also belong to this type. A new classification of sedimentary ore deposits is proposed, based on their geochemical environment. KST and MVT are formed from acid ore fluids, while GRT and CT (Creede type) are derived from basic ore fluids. pH of the fluids is best evaluated not from the ores themselves, but from their effect on the host-rocks.

Eugster, Hans P.

1985-03-01

407

Microwave sintering of boron carbide  

Microsoft Academic Search

A method for forming boron carbide into a particular shape and densifying the green boron carbide shape. Boron carbide in powder form is pressed into a green shape and then sintered, using a microwave oven, to obtain a dense boron carbide body. Densities of greater than 95% of theoretical density have been obtained. 1 tab.

R. D. Blake; J. D. Katz; J. J. Petrovic; H. Sheinberg

1988-01-01

408

Sintering of Nascent Calcium Oxide.  

National Technical Information Service (NTIS)

The paper discusses the measurement of the sintering rate of CaO in a nitrogen atmosphere at temperatures of 700-1100 C. CaO prepared from ultrapure CaCO3 was compared with an impure CaO derived from limestone. Both materials yielded an initial surface ar...

R. H. Borgwardt

1989-01-01

409

Iron impurities in Si3N4 processing  

NASA Technical Reports Server (NTRS)

The atomic environment of iron impurities is investigated during the processing cycle of reaction-bonding silicon nitride (RBSN). Several analysis techniques are utilized, including X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and electron spin resonance (ESR), to examine iron impurities in the starting silicon powder, in sintered silicon compacts, and in RBSN materials. Results indicate that iron impurities in as-received metallurgical grade silicon powder are incorporated in the silicon bulk as a highly distorted FeSi2 compound. No surface iron or iron-based particulate is observed in the starting material. Upon sintering, the iron environment becomes an ordered FeSi2 structure. In the RBNS material, the FeSi2 structure is again distorted, as observed by both EXAFS and ESR.

Bouldin, C. E.; Stern, E. A.; Donley, M. S.; Stoebe, T. G.

1985-01-01

410

Effect of calcination on sintering of hydroxyapatite.  

PubMed

Four different temperatures (700-1000 degrees C) were chosen for calcination treatment of as-received hydroxyapatite powder before press forming and sintering to study the effect of calcination on the sintering behaviours. The results show that calcination treatment increases the average particle size and distribution, which changes from trimodal to monomodal. The sintering behaviours were investigated by dilatometry and density measurement. Fluidity of powder and driving force for sintering were found to dominate the properties. Calcining at 900 degrees C and sintering 1250 degrees C results in a higher bending strength (about 55 MPa) with finer grain size. PMID:8902238

Juang, H Y; Hon, M H

1996-11-01

411

Recovery of Rare Earths, Niobium, and Thorium from the Tailings of Giant Bayan Obo Ore in China  

NASA Astrophysics Data System (ADS)

The recovery of rare earths, niobium, and thorium from Bayan Obo's tailings has been investigated because the Bayan Obo ore is rich in rare earths and rich in niobium and thorium, but it is mined mainly as an iron ore and will be used up soon. By carbochlorination between 823 K (550 °C) and 873 K (600 °C) for 2 hours, 76 to 93 pct of rare earths were recovered from the tailings, which were much higher than those from Bayan Obo's rare earth concentrate, together with 65 to 78 pct of niobium, 72 to 92 pct of thorium, 84 to 91 pct of iron, and 81 to 94 pct of fluorine. This suggests a cooperative reaction mechanism that carbochlorination of iron minerals (and carbonates) in the tailings enhances that of rare earth minerals, which is supported by a thermodynamic analysis. Subsequently, niobium separation from the low-volatile, ultrahigh iron chloride mixture was achieved efficiently by selective oxidation with Fe2O3. This process, combined with the best available technologies for separation of rare earths and thorium from the involatile chloride mixture and for comprehensively using other valuable elements, allows the ore to minimize radioactive waste and to use rare metal resources sustainably in the future.

Yu, Xiu-Lan; Bai, Li; Wang, Qing-Chun; Liu, Jia; Chi, Ming-Yu; Wang, Zhi-Chang

2012-06-01

412

Speciation and Characterization of Arsenic in Gold Ores and Cyanidation Tailings Using X-ray Absorption Spectroscopy  

SciTech Connect

The knowledge of mineralogy and molecular structure of arsenic is needed to better understand the stability of As in wastes resulting from processing of gold ores. In this study, optical microscopy, scanning electron microscopy, electron microprobe, X-ray diffraction and X-ray absorption spectroscopy (XAFS) techniques were employed to determine the mineralogical composition and local coordination environment of arsenic in gold ores and process tailings from a bench-scale testwork designed to mimic a common plant practice. Arsenic -bearing minerals identified in the ores and tailings include Fe oxyhydroxides, scorodite, ferric arsenates, arseniosiderite, Ca-Fe arsenates, pharmacosiderite, jarosite and arsenopyrite. Iron oxyhydroxides contain variable levels of As from trace to about 22 wt % and Ca to approximately 9 %.

Paktunc, Dogan; Foster, Andrea; Heald, Steve M.; Laflamme, Gilles

2004-03-25

413

Spark plasma sintering of aluminum matrix composites  

NASA Astrophysics Data System (ADS)

Aluminum matrix composites make a distinct category of advanced engineering materials having superior properties over conventional aluminum alloys. Aluminum matrix composites exhibit high hardness, yield strength, and excellent wear and corrosion resistance. Due to these attractive properties, aluminum matrix composites materials have many structural applications in the automotive and the aerospace industries. In this thesis, efforts are made to process high strength aluminum matrix composites which can be useful in the applications of light weight and strong materials. Spark Plasma Sintering (SPS) is a relatively novel process where powder mixture is consolidated under the simultaneous influence of uniaxial pressure and pulsed direct current. In this work, SPS was used to process aluminum matrix composites having three different reinforcements: multi-wall carbon nanotubes (MWCNTs), silicon carbide (SiC), and iron-based metallic glass (MG). In Al-CNT composites, significant improvement in micro-hardness, nano-hardness, and compressive yield strength was observed. The Al-CNT composites further exhibited improved wear resistance and lower friction coefficient due to strengthening and self-lubricating effects of CNTs. In Al-SiC and Al-MG composites, microstructure, densification, and tribological behaviors were also studied. Reinforcing MG and SiC also resulted in increase in micro-hardness and wear resistance.

Yadav, Vineet

414

Pollution Effects of Abnormal Operations in Iron and Steel Making. Volume 1. Technical Report.  

National Technical Information Service (NTIS)

The report is the first in a six-volume series considering abnormal operating conditions (AOCs) in the primary section (sintering, blast furnace ironmaking, open hearth, electric furnace, and basic oxygen steelmaking) of an integrated iron and steel plant...

B. H. Carpenter D. W. VanOsdell D. W. Coy R. Jablin

1978-01-01

415

Mortality among sulfide ore miners  

SciTech Connect

Lung cancer mortality was studied during 1965-1985 in Outokumpu township in North Karelia, where an old copper mine was located. Age-specific lung cancer death rates (1968-1985) were higher among the male population of Outokumpu than among the North Karelian male population of the same age excluding the Outokumpu district (p less than .01). Of all 106 persons who died from lung cancer during 1965-1985 in Outokumpu township, 47 were miners of the old mine, 39 of whom had worked there for at least three years and been heavily exposed to radon daughters and silica dust. The study cohort consisted of 597 miners first employed between 1954 and 1973 by a new copper mine and a zinc mine, and employed there for at least 3 years. The period of follow-up was 1954-1986. The number of person-years was 14,782. The total number of deaths was 102; the expected number was 72.8 based on the general male population and 97.8 based on the mortality of the male population of North Karelia. The excess mortality among miners was due mainly to ischemic heart disease (IHD); 44 were observed, the expected number was 22.1, based on the general male population, and the North Karelian expected number was 31.2 (p less than .05). Of the 44 miners who died from IHD, 20 were drillers or chargers exposed to nitroglycerin in dynamite charges, but also to several simultaneous stress factors including PAHs, noise, vibration, heavy work, accident risk, and working alone. Altogether 16 tumors were observed in the cohort. Ten of these were lung cancers, the expected number being 4.3. Miners who had died from lung cancer were 35-64 years old, and had entered mining work between 1954 and 1960. Five of the ten lung cancer cases came from the zinc mine (1.7 expected). Three of them were conductors of diesel-powered ore trains.

Ahlman, K.; Koskela, R.S.; Kuikka, P.; Koponen, M.; Annanmaeki, M. (Department of Epidemiology and Biometry, Institute of Occupational Health, Helsinki (Finland))

1991-01-01

416

Photochemical changes in cyanide speciation in drainage from a precious metal ore heap.  

PubMed

In drainage from an inactive ore heap at a former gold mine, the speciation of cyanide and the concentrations of several metals were found to follow diurnal cycles. Concentrations of the hexacyanoferrate complex, iron, manganese, and ammonium were higher at night than during the day, whereas weak-acid-dissociable cyanide, silver, gold, copper, nitrite, and pH displayed the reverse behavior. The changes in cyanide speciation, iron, and trace metals can be explained by photodissociation of iron and cobalt cyanocomplexes as the solutions emerged from the heap into sunlight-exposed channels. At midday, environmentally significant concentrations of free cyanide were produced in a matter of minutes, causing trace copper, silver, and gold to be mobilized as cyanocomplexes from solids. Whether rapid photodissociation is a general phenomenon common to other sites will be important to determine in reaching a general understanding of the environmental risks posed by routine or accidental water discharges from precious metal mining facilities. PMID:11918005

Johnson, Craig A; Leinz, Reinhard W; Grimes, David J; Rye, Robert O

2002-03-01

417

The physical hydrogeology of ore deposits  

USGS Publications Warehouse

Hydrothermal ore deposits represent a convergence of fluid flow, thermal energy, and solute flux that is hydrogeologically unusual. From the hydrogeologic perspective, hydrothermal ore deposition represents a complex coupled-flow problem—sufficiently complex that physically rigorous description of the coupled thermal (T), hydraulic (H), mechanical (M), and chemical (C) processes (THMC modeling) continues to challenge our computational ability. Though research into these coupled behaviors has found only a limited subset to be quantitatively tractable, it has yielded valuable insights into the workings of hydrothermal systems in a wide range of geologic environments including sedimentary, metamorphic, and magmatic. Examples of these insights include the quantification of likely driving mechanisms, rates and paths of fluid flow, ore-mineral precipitation mechanisms, longevity of hydrothermal systems, mechanisms by which hydrothermal fluids acquire their temperature and composition, and the controlling influence of permeability and other rock properties on hydrothermal fluid behavior. In this communication we review some of the fundamental theory needed to characterize the physical hydrogeology of hydrothermal systems and discuss how this theory has been applied in studies of Mississippi Valley-type, tabular uranium, porphyry, epithermal, and mid-ocean ridge ore-forming systems. A key limitation in the computational state-of-the-art is the inability to describe fluid flow and transport fully in the many ore systems that show evidence of repeated shear or tensional failure with associated dynamic variations in permeability. However, we discuss global-scale compilations that suggest some numerical constraints on both mean and dynamically enhanced crustal permeability. Principles of physical hydrogeology can be powerful tools for investigating hydrothermal ore formation and are becoming increasingly accessible with ongoing advances in modeling software.

Ingebritsen, Steven E.; Appold, M. S.

2012-01-01

418

Properties of nano- and microparticles emitted into the environment from open-pit mining of iron deposits  

NASA Astrophysics Data System (ADS)

The properties of nano- and microparticles (60 nm-200 ?m) of the dust formed by mass blasting in the iron ore open pit of the Lebedinsky Mining and Concentrating Combine have been studied. Data on the morphology of particles, their magnetic properties, mineralogy, and dimensions have been obtained. Quartz, magnetite, and mica were identified among these particles. The dust mostly consisted of fragmented iron ore formation from the rock massif involved in the blasting.

Adushkin, V. V.; Weidler, P. G.; Dubovskoi, A. N.; Pernik, L. M.; Popel, S. I.; Friedrich, F.

2010-10-01

419

Sintered composite medium and filter  

DOEpatents

A particulate filter medium is formed of a sintered composite of 0.5 micron diameter quartz fibers and 2 micron diameter stainless steel fibers. A preferred composition is about 40 vol. % quartz and about 60 vol. % stainless steel fibers. The media is sintered at about 1100.degree. C. to bond the stainless steel fibers into a cage network which holds the quartz fibers. High filter efficiency and low flow resistance are provided by the smaller quartz fibers. High strength is provided by the stainless steel fibers. The resulting media has a high efficiency and low pressure drop similar to the standard HEPA media, with tensile strength at least four times greater, and a maximum operating temperature of about 550.degree. C. The invention also includes methods to form the composite media and a HEPA filter utilizing the composite media. The filter media can be used to filter particles in both liquids and gases.

Bergman, Werner (Pleasanton, CA)

1987-01-01

420

Sintering of nascent calcium oxide  

Microsoft Academic Search

The paper discusses the measurement of the sintering rate of CaO in a nitrogen atmosphere at temperatures of 700-1100 C. CaO prepared from ultrapure CaCOâ was compared with an impure CaO derived from limestone. Both materials yielded an initial surface area of 104 sq m\\/g. The rate of surface reduction was independent of particle size between 2 and 20 micrometers,

Robert H. Borgwardt

1989-01-01

421

Principles of laser micro sintering  

Microsoft Academic Search

Purpose – The purpose of the paper is the elucidation of certain mechanisms of laser material processing in general and laser micro sintering in particular. One major intention is to emphasize the synergism of the various effects of q-switched laser pulses upon metal and ceramic powder material and to point out the non-equilibrium character of reaction steps. Design\\/methodology\\/approach – Recent

P. Regenfuss; A. Streek; L. Hartwig; S. Klötzer; Th. Brabant; M. Horn; R. Ebert; H. Exner

2007-01-01

422

Extraction of Gold from Carbonaceous Ores: Pilot Plant Studies.  

National Technical Information Service (NTIS)

Oxidation procedures based on the chlorine-hypochlorite system were investigated for improving gold recovery from carbonaceous gold ores. The oxidation pretreatment prior to cyanidation was accomplished by: (1) Addition of sodium hypochlorite to ore pulp;...

B. J. Scheiner D. G. Peterson R. E. Lindstrom W. J. Guay

1972-01-01

423

4. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO ...  

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

4. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO EAST. - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

424

2. VIEW TO NORTHEAST (ORE RECEIVING PLATFORM OUT OF VIEW ...  

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

2. VIEW TO NORTHEAST (ORE RECEIVING PLATFORM OUT OF VIEW TO RIGHT). - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

425

3. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO ...  

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

3. DETAIL OF ORE RECEIVING PLATFORM AND GRIZZLY, VIEW TO WEST. - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

426

1. VIEW TO SOUTH (RETAINING WALL OF ORE RECEIVING PLATFORM ...  

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

1. VIEW TO SOUTH (RETAINING WALL OF ORE RECEIVING PLATFORM TO LEFT). - Vanadium Corporation of America (VCA) Naturita Mill, Sampling Building & Ore Receiving Platform, 3 miles Northwest of Naturita, between Highway 141 & San Miguel River, Naturita, Montrose County, CO

427

CONTEXT VIEW ACROSS ORE YARD AT MODERN SELFUNLOADING SHIP UNLOADING ...  

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

CONTEXT VIEW ACROSS ORE YARD AT MODERN SELF-UNLOADING SHIP UNLOADING IN FRONT OF HULETTS. LOOKING SOUTHWEST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

428

CONTEXT VIEW ACROSS ORE YARD AT MODERN SELFUNLOADING BOOM IN ...  

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

CONTEXT VIEW ACROSS ORE YARD AT MODERN SELF-UNLOADING BOOM IN FRONT OF HULETTS. LOOKING SOUTHWEST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

429

AERIAL OVERVIEW, LOOKING NORTH, WITH FORMER TCIUS STEEL ORE MINE ...  

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

AERIAL OVERVIEW, LOOKING NORTH, WITH FORMER TCI-US STEEL ORE MINE HEADQUARTERS (BOTTOM) AND SUPERINTENDENT'S AND FOREMAN HOUSING ALONG MINNESOTA AVENUE AT CREST OF RED MOUNTAIN (TOP LEFT). - Muscoda Red Ore Mining Community, Bessemer, Jefferson County, AL

430

Placement Of O-Rings In Solid Rocket Booster  

NASA Technical Reports Server (NTRS)

Brief report proposes to modify placement of O-ring seals in joints of Solid Rocket Booster of Space Shuttle. Modified joint and seal essentially "inside-out" version of old joint and seal. O-rings placed between outer side of tang and clevis. Joint rotation pushes tang harder against O-rings, thereby making even tighter seal. Proposal derived from analysis of Space Shuttle Challenger disaster, attributed to failure of these O-ring seals.

Wood, Charles

1991-01-01

431

Rajkonkoski gold-telluride ore occurrence: A new high prospective type of complex noble metal mineralization in the Karelian Proterozoic  

NASA Astrophysics Data System (ADS)

The Rajkonkoski ore occurrence is located within the region of the Karelian craton (AR2) and the Svecofennian folded belt (PR1) conjugation. It is presented by quartz-carbonate veins in metadoleriles and a zone of brecciation, crumple, and silification of carbonaceous shales within the volcanites of the Soanlakhtinsky suite (PR1). Ore mineralization in black shales and quartz veins has features of genetic similarity presenting different levels of the ore system controlled by different range strike-slip fault dislocations. At the Rajkonkoski ore occurrence, 41 ore minerals have been identified: 12 tellurides (native tellurium, hedleyite, pilsenite, tsumoite, tellurobismuthite, hessite, stuetzite, radclidzhite, joseite-B, altaite, volynskite, petzite); 4 bismuth-tellurides of the following compositions Bi3Te, Bi3Te2, BiTe4, PbBiTe; 3 selenides (clausthalite, tellurolaitakarite, native selenium); and 12 native metals (gold, silver, electrum, copper, iron, lead, tin, bismuth, osmiridium). The contents of the main ore minerals in places exceed 10%, and the concentrations of elements reach as follows: Cu and Pb, 5%; Zn, Bi, 1%; Se, 219 ppm; Te, 171 ppm; Sb, 3 ppm; As, 5 ppm; Ag, >0.1%; Au, 35.28 ppm. Ore mineralization is formed during the temperature interval from 550°C up to <170oC in the conditions of high activity of Se and Te, and beginning from medium temperatures (>300°C) complete miscibilities galenite-clausthalite and galenite-altaite are observed. In aggregate with a wide temperature interval (>400°C) of ore process evolution and mineral specia variety of telluride and native metal mineralizations, the original “torsion” of different temperature mineralizations makes it possible to determine the affiliation of the Rajkonkoski ore occurrence to the xenothermal type deposits or epithermal “alkaline,” gold-telluride A-type characterized by a close connection with magmatism of increased alkalinity and the original geochemical (Te-V-F) and mineral (tellurides of gold, silver and other metals, fluorite, roscoelite, vanadium-containing sulfides) associations. Taking into consideration that many of the xenothermal and epithermal A-type gold and silver deposits are large commercial objects, the prospects of the Rajkonkoski ore occurrence and the region of the Karelian craton and Svecofennian folded belt conjugation seem to be significant for noble metal mineralization.

Ivashchenko, V. I.; Sundblad, K.; Toritsin, A. N.; Golubev, A. I.; Lavrov, O. B.

2008-11-01

432

TREATMENT OF HEXAVALENT CHROMIUM IN CHROMITE ORE PROCESSING SOLID WASTE USING A MIXED REDUCTANT SOLUTION OF FERROUS SULFATE AND SODIUM DITHIONITE  

EPA Science Inventory

We developed a method for disseminating ferrous iron in the subsurface to enhance chemical reduction of hexavalent chromium (Cr(VI)) in a chromite ore processing solid waste derived from the production of ferrochrome alloy. The method utilizes ferrous sulfate (FeSO4) in combinati...

433

17. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN ...  

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

17. ORE DOCK, LOOKING EAST FROM HULETT NO. 1. WHEN BUILT IN 1911-1912, THIS WAS THE LARGEST ORE-UNLOADING DOCK ON THE GREAT LAKES. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

434

Copper Artifacts: Correlation with Source Types of Copper Ores  

Microsoft Academic Search

Six out of eight minor chemical elements, determined by spectroscopic and neutron-activation techniques, were found to be critical in computing a probability that a given copper artifact was derived from one of three types of copper ore: native metal, oxidized ore, reduced ore. Two elements, gold and tin, were apparently alloyed deliberately in many artifacts from both the Old World

A. M. Friedman; M. Conway; M. Kastner; J. Milsted; D. Metta; P. R. Fields; E. Olsen

1966-01-01

435

18. VIEW OF CRUDE ORE BINS FROM WEST. WEST CRUDE ...  

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

18. VIEW OF CRUDE ORE BINS FROM WEST. WEST CRUDE ORE BIN AND TRESTLE FROM TWO JOHNS TRAMLINE TO SOUTH, CRUDE ORE BIN IN FOREGROUND. MACHINE SHOP IN BACKGROUND. THE TRAM TO PORTLAND PASSED TO NORTH OF MACHINE SHOP. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

436

Beneficiation Technology of Copper-Nickel Sulphide Ores in China.  

National Technical Information Service (NTIS)

A review is given of the procesing of copper--nickel sulfide ores in China with particular emphasis on the Jinchuan copper--nickel ores. The innovation and application in beneficiation technology of copper--nickel ores in China are introduced and recent d...

W. Xing J. Yu

1994-01-01

437

Spark plasma sintering on nanometer scale WC–Co powder  

Microsoft Academic Search

Nanometer scale WC–11Co powder was sintered by spark plasma sintering (SPS) process in order to improve the properties of the cemented carbides. Properties such as density and hardness were measured. The microstructures of sintered WC–11Co cemented carbides were observed. The grain size of WC in alloys was also obtained. The results showed that spark plasma sintering could lower the sintering

Cheng-Chang Jia; Hua Tang; Xue-Zhen Mei; Fa-Zhang Yin; Xuan-Hui Qu

2005-01-01

438

Behavior of uranium under conditions of interaction of rocks and ores with subsurface water  

NASA Astrophysics Data System (ADS)

The behavior of uranium during interaction of subsurface water with crystalline rocks and uranium ores is considered in connection with the problem of safe underground insulation of spent nuclear fuel (SNF). Since subsurface water interacts with crystalline rocks formed at a high temperature, the mineral composition of these rocks and uranium species therein are thermodynamically unstable. Therefore, reactions directed toward the establishment of equilibrium proceed in the water-rock system. At great depths that are characterized by hindered water exchange, where subsurface water acquires near-neutral and reducing properties, the interaction is extremely sluggish and is expressed in the formation of micro- and nanoparticles of secondary minerals. Under such conditions, the slow diffusion redistribution of uranium with enrichment in absorbed forms relative to all other uranium species is realized as well. The products of secondary alteration of Fe- and Ti-bearing minerals serve as the main sorbents of uranium. The rate of alteration of minerals and conversion of uranium species into absorbed forms is slow, and the results of these processes are insignificant, so that the rocks and uranium species therein may be regarded as unaltered. Under reducing conditions, subsurface water is always saturated with uranium. Whether water interacts with rock or uranium ore, the equilibrium uranium concentration in water is only ?10-8 mol/l. Uraninite ore under such conditions always remains stable irrespective of its age. The stability conditions of uranium ore are quite suitable for safe insulation of SNF, which consists of 95% uraninite (UO2) and is a confinement matrix for all other radionuclides. The disposal of SNF in massifs of crystalline rocks at depths below 500 m, where reducing conditions are predominant, is a reliable guarantee of high SNF stability. Under oxidizing conditions of the upper hydrodynamic zone, the rate of interaction of rocks with subsurface water increases by orders of magnitude and subsurface water is commonly undersaturated with uranium. Uranium absorbed by secondary minerals, particularly by iron hydroxides and leucoxene, is its single stable species under oxidizing conditions. The impact of oxygen-bearing water leads to destruction of uranium ore. This process is realized simultaneously at different hypsometric levels even if the permeability of the medium is variable in both the lateral and vertical directions. As a result, intervals containing uranyl minerals and relics of primary uranium ore are combined in ore-bearing zones with intervals of completely dissolved uranium minerals. A wide halo of elevated uranium contents caused by sorption is always retained at the location of uranium ore entirely destroyed by weathering. Uranium ore commonly finds itself in the aeration zone due to technogenic subsidence of the groundwater table caused by open-pit mining or pumping out of water from underground mines. The capillary and film waters that interact with rocks and ores in this zone are supplemented by free water filtering along fractures when rain falls or snow is thawing. The interaction of uranium ore with capillary water results in oxidation of uraninite, accompanied by loosening of the mineral surface, formation of microfractures, and an increase in solubility with enrichment of capillary water in uranium up to 10-4 mol/l. Secondary U(VI) minerals, first of all, uranyl hydroxides and silicates, replace uraninite, and uranium undergoes local diffusion redistribution with its sorption by secondary minerals of host rocks. The influx of free water facilitates the complete dissolution of primary and secondary uranium minerals, the removal of uranium at the sites of groundwater discharge, and its redeposition under reducing conditions at a greater depth. It is evident that the conditions of the upper hydrodynamic zone and the aeration zone are unfit for long-term insulation of SNF and high-level wastes because, after the failure of containers, the leakage of radionuclides into the environment becomes inevi

Omel'Yanenko, B. I.; Petrov, V. A.; Poluektov, V. V.

2007-10-01

439

Exploring the engine of anthropogenic iron cycles  

PubMed Central

Stocks of products in use are the pivotal engines that drive anthropogenic metal cycles: They support the lives of people by providing services to them; they are sources for future secondary resources (scrap); and demand for in-use stocks generates demand for metals. Despite their great importance and their impacts on other parts of the metal cycles and the environment, the study of in-use stocks has heretofore been widely neglected. Here we investigate anthropogenic and geogenic iron stocks in the United States (U.S.) by analyzing the iron cycle over the period 1900–2004. Our results show the following. (i) Over the last century, the U.S. iron stock in use increased to 3,200 Tg (million metric tons), which is the same order of magnitude as the remaining U.S. iron stock in identified ores. On a global scale, anthropogenic iron stocks are less significant compared with natural ores, but their relative importance is increasing. (ii) With a perfect recycling system, the U.S. could substitute scrap utilization for domestic mining. (iii) The per-capita in-use iron stock reached saturation at 11–12 metric tons in ?1980. This last finding, if applicable to other economies as well, could allow a significant improvement of long-term forecasting of steel demand and scrap availability in emerging market economies and therefore has major implications for resource sustainability, recycling technology, and industrial and governmental policy.

Muller, Daniel B.; Wang, Tao; Duval, Benjamin; Graedel, T. E.

2006-01-01

440

Exploring the engine of anthropogenic iron cycles.  

PubMed

Stocks of products in use are the pivotal engines that drive anthropogenic metal cycles: They support the lives of people by providing services to them; they are sources for future secondary resources (scrap); and demand for in-use stocks generates demand for metals. Despite their great importance and their impacts on other parts of the metal cycles and the environment, the study of in-use stocks has heretofore been widely neglected. Here we investigate anthropogenic and geogenic iron stocks in the United States (U.S.) by analyzing the iron cycle over the period 1900-2004. Our results show the following. (i) Over the last century, the U.S. iron stock in use increased to 3,200 Tg (million metric tons), which is the same order of magnitude as the remaining U.S. iron stock in identified ores. On a global scale, anthropogenic iron stocks are less significant compared with natural ores, but their relative importance is increasing. (ii) With a perfect recycling system, the U.S. could substitute scrap utilization for domestic mining. (iii) The per-capita in-use iron stock reached saturation at 11-12 metric tons in approximately 1980. This last finding, if applicable to other economies as well, could allow a significant improvement of long-term forecasting of steel demand and scrap availability in emerging market economies and therefore has major implications for resource sustainability, recycling technology, and industrial and governmental policy. PMID:17053079

Müller, Daniel B; Wang, Tao; Duval, Benjamin; Graedel, T E

2006-10-31

441

Mössbauer spectroscopic study of iron-chelate trammels  

NASA Astrophysics Data System (ADS)

Any kind of waste effluent in the Indian context and other countries contains a lot of iron in any ore. During mining, milling, extraction and purification process iron acts as contaminant towards other metal's purity. It is essential to remove iron to the maximum extent. In this case, an "IN-HOUSE" resin polyacrylamidehydroxamic acid (PHOA) has been designed and developed which is highly hydrophilic three dimensionally cross-linked. It has an excellent iron binding capacity with almost no leaching. Interaction of resin with ammonium ferrous sulphate and red-mod (Fe2O3) is studied using Mössbauer spectroscopy.

Pal, Sangita; Meena, S. S.; Ningthoujam, R. S.; Goswami, D.