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1

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...

2

The Energetics of Hematite Dissolution in Iron Ore Melts for Assimilation in Commercial Sintering Processes: In Situ High Temperature Calorimetric Studies  

Microsoft Academic Search

Melting and crystallization of iron ores in mining applications are determined by the thermodynamic properties of the crystals and liquids in equilibrium. Iron ores are widely used for sinter production in Japan, Korea Russia, and Australia. In these sinter production plants, multiple ores can be blended together. Sintering is the second stage of a two step process in which iron

A. A. Navrotsky; R. Morcos; B. Ellis

2006-01-01

3

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

4

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

5

Effect of Fuel Characteristics on the Thermal Processes in an Iron Ore Sintering Bed  

NASA Astrophysics Data System (ADS)

Coke in an iron ore sintering process is being replaced in part by powdered anthracite; less expensive fuel. In this study, influence of the different fuel characteristics on the thermal condition in the sintering bed has been investigated using a mathematical model. Numerical simulation along with experiments in a lab-scale sintering pot has been performed. The mathematical model is based on the assumption that the sintering bed can be treated as homogeneous medium, through which a reacting flow passes. Temperature distribution and flue gas composition are predicted for various kinds of solid fuel and various particle sizes of anthracite. The simulation results show that propagation of combustion zone is faster in the case of using coke than the case of using anthracite. Results also show that the reactivity of the anthracite can be improved by decreasing the size of fuel particles.

Yang, Won; Yang, Kwangheok; Choi, Sangmin

6

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

7

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

8

Influence of gangue existing states in iron ores on the formation and flow of liquid phase during sintering  

NASA Astrophysics Data System (ADS)

Gangue existing states largely affect the high-temperature characteristics of iron ores. Using a micro-sintering method and scanning electron microscopy, the effects of gangue content, gangue type, and gangue size on the assimilation characteristics and fluidity of liquid phase of five different iron ores were analyzed in this study. Next, the mechanism based on the reaction between gangues and sintering materials was unraveled. The results show that, as the SiO2 levels increase in the iron ores, the lowest assimilation temperature (LAT) decreases, whereas the index of fluidity of liquid phase (IFL) increases. Below 1.5wt%, Al2O3 benefits the assimilation reaction, but higher concentrations proved detrimental. Larger quartz particles increase the SiO2 levels at the local reaction interface between the iron ore and CaO, thereby reducing the LAT. Quartz-gibbsite is more conductive to assimilation than kaolin. Quartz-gibbsite and kaolin gangues encourage the formation of liquid-phase low-Al2O3-SFCA with high IFL and high-Al2O3-SFCA with low IFL, respectively.

Zhang, Guo-liang; Wu, Sheng-li; Chen, Shao-guo; Su, Bo; Que, Zhi-gang; Hou, Chao-gang

2014-10-01

9

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

10

Correcting the gas and particle partitioning of PCDD/F congeners in the flue gas of an iron ore sinter plant.  

PubMed

This study was aimed at developing an approach for correcting the gas and particle partitioning of PCDD/F congeners for samples collected from the flue gas of an iron ore sinter plant. An iron ore sinter plant equipped with an electrostatic precipitator (EP) and a selective catalytic reduction (SCR) was selected. Flue gas samples were collected at EP inlet, EP outlet and SCR outlet. Both particle- and gas-phase PCDD/Fs were analyzed for each collected sample. PCDD/F contents in EP ashes (EP(ash)) were also analyzed and used to correct the gas and particle partitioning of PCDD/F congeners of the collected flue gas samples. Results show that PCDD/Fs in the flue gas were dominated by the gas-phase. Before correction, the removal efficiencies for the gas- and particle-phase PCDD/Fs for EP were -58.1% and 64.3%, respectively, and SCR were 39.4% and 83.9%, respectively. The above results were conflict with the expected results for both EP and SCR indicating the need for correcting the gas and particle partitioning of PCDD/F congeners for all collected flue gas samples. After correction, the removal efficiencies become more reasonable for EP (=4.22% and 97.7%, respectively), and SCR (=54.7% and 62.0%, respectively). The above results confirm the effectiveness of the approach developed by this study. PMID:22305603

Kuo, Yu-Chieh; Chen, Yu-Cheng; Yang, Jeng-How; Tsai, Perng-Jy; Wang, Lin-Chi; Chang-Chien, Guo-Ping

2012-03-30

11

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

12

The sources of our iron ores. II  

USGS Publications Warehouse

In this instalment** the iron ore deposits of the Lake Superior States, which normally furnish about 80 per cent, of the annual output of the United States, are described together with historical notes on discovery and transportation of ore. Deposits in the Mississippi Valley and Western States are likewise outlined and the sources of imported ore are given. Reviewing the whole field, it is indicated that the great producing deposits of the Lake Superior and southern Appalachian regions are of hematite in basin areas of sedimentary rocks, that hydrated iron oxides and iron carbonates are generally found in undisturbed comparatively recent sediments, and that magnetite occurs in metamorphic and igneous rocks; also that numerical abundance of deposits is not a criterion as to their real importance as a source of supply. Statistics of production of iron ore and estimates of reserves of present grade conclude the paper.

Burchard, E.F.

1933-01-01

13

Characterisation and Processing of Some Iron Ores of India  

NASA Astrophysics Data System (ADS)

Lack of process characterization data of the ores based on the granulometry, texture, mineralogy, physical, chemical, properties, merits and limitations of process, market and local conditions may mislead the mineral processing entrepreneur. The proper implementation of process characterization and geotechnical map data will result in optimized sustainable utilization of resource by processing. A few case studies of process characterization of some Indian iron ores are dealt with. The tentative ascending order of process refractoriness of iron ores is massive hematite/magnetite < marine black iron oxide sands < laminated soft friable siliceous ore fines < massive banded magnetite quartzite < laminated soft friable clayey aluminous ore fines < massive banded hematite quartzite/jasper < massive clayey hydrated iron oxide ore < manganese bearing iron ores massive < Ti-V bearing magnetite magmatic ore < ferruginous cherty quartzite. Based on diagnostic process characterization, the ores have been classified and generic process have been adopted for some Indian iron ores.

Krishna, S. J. G.; Patil, M. R.; Rudrappa, C.; Kumar, S. P.; Ravi, B. P.

2013-10-01

14

Extracting phosphoric iron under laboratorial conditions smelting bog iron ores  

NASA Astrophysics Data System (ADS)

In recent years it has been indicated by archaeometric investigations that phosphoric-iron (P-iron, low carbon steel with 0,5-1,5wt% P), which is an unknown and unused kind of steel in the modern industry, was widely used in different parts of the world in medieval times. In this study we try to explore the role of phosphorus in the arhaeometallurgy of iron and answer some questions regarding the smelting bog iron ores with high P-content. XRF analyses were performed on bog iron ores collected in Somogy county. Smelting experiments were carried out on bog iron ores using a laboratory model built on the basis of previously conducted reconstructed smelting experiments in copies of excavated furnaces. The effect of technological parameters on P-content of the resulted iron bloom was studied. OM and SEM-EDS analyses were carried out on the extracted iron and slag samples. On the basis of the material analyses it can be stated that P-iron is usually extracted but the P-content is highly affected by technological parameters. Typical microstructures of P-iron and of slag could also be identified. It could also be established that arsenic usually solved in high content in iron as well.

Török, B.; Thiele, A.

2013-12-01

15

26 CFR 1.272-1 - Expenditures relating to disposal of coal or domestic iron ore.  

Code of Federal Regulations, 2011 CFR

... Expenditures relating to disposal of coal or domestic iron ore. 1.272-1 ...Expenditures relating to disposal of coal or domestic iron ore. (a) Introduction...hereafter sometimes referred to as a “coal royalty contract” or “iron ore...

2011-04-01

16

26 CFR 1.272-1 - Expenditures relating to disposal of coal or domestic iron ore.  

Code of Federal Regulations, 2010 CFR

... Expenditures relating to disposal of coal or domestic iron ore. 1.272-1 ...Expenditures relating to disposal of coal or domestic iron ore. (a) Introduction...hereafter sometimes referred to as a “coal royalty contract” or “iron ore...

2010-04-01

17

26 CFR 1.272-1 - Expenditures relating to disposal of coal or domestic iron ore.  

Code of Federal Regulations, 2012 CFR

... Expenditures relating to disposal of coal or domestic iron ore. 1.272-1 ...Expenditures relating to disposal of coal or domestic iron ore. (a) Introduction...hereafter sometimes referred to as a “coal royalty contract” or “iron ore...

2012-04-01

18

26 CFR 1.272-1 - Expenditures relating to disposal of coal or domestic iron ore.  

... Expenditures relating to disposal of coal or domestic iron ore. 1.272-1 ...Expenditures relating to disposal of coal or domestic iron ore. (a) Introduction...hereafter sometimes referred to as a “coal royalty contract” or “iron ore...

2014-04-01

19

26 CFR 1.272-1 - Expenditures relating to disposal of coal or domestic iron ore.  

Code of Federal Regulations, 2013 CFR

... Expenditures relating to disposal of coal or domestic iron ore. 1.272-1 ...Expenditures relating to disposal of coal or domestic iron ore. (a) Introduction...hereafter sometimes referred to as a “coal royalty contract” or “iron ore...

2013-04-01

20

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

21

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

22

Precise coulometric determination of iron in iron ores with electrogenerated manganese(III) fluoride.  

PubMed

Iron in Mohr's salt, electrolytic iron and iron ores has been determined by precision coulometric titration with electrolytically generated manganese (III) fluoride, with biamperometric end-point detection. The titration curve indicated the irreversibility of the electrode reaction of manganese(III) fluoride. Total iron in several standard samples of iron ores was determined with standard deviations of about 0.012%. PMID:18961613

Yoshimori, T; Tanaka, T

1975-01-01

23

A control relevant dynamic model of grate sintering Frode Martinsen, Bjarne A. Foss and Tor Arne Johansen  

E-print Network

process of sintering prepares the iron ore to form suitable feed for the blast furnace. Granulated ore into a partially fused porous sinter cake suitable for feeding to the blast furnace. Sintering is a complex process

Foss, Bjarne A.

24

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

25

Problems of Siderite Formation and Iron Ore Epochs: Communication 1. Types of Siderite-Bearing Iron Ore Deposits  

Microsoft Academic Search

It is shown that siderite is unstable during sedimentation, diagenesis, and metamorphism of sedimentary and volcanosedimentary rocks. Regularities in the distribution of siderite in Precambrian jaspilites (iron formations), metasomatic ores of the Bakal type, continental–marine coaliferous formations, and oolitic iron ores are discussed. The genesis of the Precambrian iron formations and Riphean–Lower Paleozoic elisional–hydrothermal deposits is considered. The genetic relation

V. N. Kholodov; G. Yu. Butuzova

2004-01-01

26

Effect of Microwave Treatment Upon Processing Oolitic High Phosphorus Iron Ore for Phosphorus Removal  

NASA Astrophysics Data System (ADS)

Influence of microwave treatment on the previously proposed phosphorus removal process of oolitic high phosphorus iron ore (gaseous reduction followed by melting separation) has been studied. Microwave treatment was carried out using a high-temperature microwave reactor (Model: MS-WH). Untreated ore fines and microwaved ore fines were then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thermogravimetric analysis (TGA). Thereafter, experiments on the proposed phosphorus removal process were conducted to examine the effect of microwave treatment. Results show that microwave treatment could change the microstructure of the ore fines and has an intensification effect on its gaseous reduction by reducing gas internal resistance, increasing chemical reaction rate and postponing the occurrence of sintering. Results of gaseous reduction tests using tubular furnace indicate both microwave treatment and high reduction temperature high as 1273 K (1000 °C) are needed to totally break down the dense oolite and metallization rate of the ore fines treated using microwave power of 450 W could reach 90 pct under 1273 K (1000 °C) and for 2 hours. Results of melting separation tests of the reduced ore fines with a metallization rate of 90 pct show that, in addition to the melting conditions in our previous studies, introducing 3 pct Na2CO3 to the highly reduced ore fines is necessary, and metal recovery rate and phosphorus content of metal could reach 83 pct and 0.31 mass pct, respectively.

Tang, Hui-Qing; Liu, Wei-Di; Zhang, Huan-Yu; Guo, Zhan-Cheng

2014-10-01

27

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

28

Stresses induced in iron-ore pellets by hydrogen reduction  

Microsoft Academic Search

The objectives of this investigation were (a) to determine the effect of reduction temperature on the strength of iron ore\\u000a agglomerates and (b) to develop enhanced understanding for the cracking associ-ated with reduction. Iron-ore agglomerates\\u000a from two sources (Samarco Minera??o and Bethlehem Steel) were reduced in a hydrogen atmosphere at temperatures varying from\\u000a 873 K to 1373 K at intervals

Taveesiri Tantevee

1986-01-01

29

Mineral and Elemental Composition Features of "Loose" Oolitic Ores in Bakchar Iron Ore Cluster (Tomsk Oblast)  

NASA Astrophysics Data System (ADS)

Geo-technological investigation considerations of iron ore deposits within the Bakchar ore cluster are being carried out. The mineral and elemental composition of "loose" ores have been studied, embracing such important aspects as the distribution pattern of valuable and harmful impurities, the determination of element concentrators (such as vanadium, phosphate and sulphur) in basic minerals and the analysis of ore composition varaiation in volume ore cluster. Based on investigation results the mineral and elemental composition characteristic features of "loose" ores were defined. Although hydrogoethite was the basic identified ore mineral, such minerals as goethite, lepidocrocite, leptochlorite, siderite and hisingerite were also found. The deportment of calcium phosphate (anapaite) and phosphates of rare-earth elements (monazite, killarite), which are associated with the harmful impurity- phosphorous, are described. It has been defined that the ore constituent composition contains such persistent impurities as vanadium and manganese, the content of which is 0.35% and 0.03%, respectively. The "loose" ores are continuous in mineral composition, both in area and cross-section throughout the Bakchar ore cluster. Based on the sample element composition analysis the most perspective areas for further mineral processing could be: western with the fraction of 1....0.2mm. and eastern- fraction of 1...0.1mm.

Rudmin, M.; Mazurov, A.; Bolsunovskaya, L.

2014-08-01

30

Microbial Beneficiation of Salem Iron Ore Using Penicillium purpurogenum  

NASA Astrophysics Data System (ADS)

High alumina and silica content in the iron ore affects coke rate, reducibility, and productivity in a blast furnace. Iron ore is being beneficiated all around the world to meet the quality requirement of iron and steel industries. Choosing a beneficiation treatment depends on the nature of the gangue present and its association with the ore structure. The advanced physicochemical methods used for the beneficiation of iron ore are generally unfriendly to the environment. Biobeneficiation is considered to be ecofriendly, promising, and revolutionary solutions to these problems. A characterization study of Salem iron ore indicates that the major iron-bearing minerals are hematite, magnetite, and goethite. Samples on average contains (pct) Fe2O3-84.40, Fe (total)-59.02, Al2O3-7.18, and SiO2-7.53. Penicillium purpurogenum (MTCC 7356) was used for the experiment . It removed 35.22 pct alumina and 39.41 pct silica in 30 days in a shake flask at 10 pct pulp density, 308 K (35 °C), and 150 rpm. In a bioreactor experiment at 2 kg scale using the same organism, it removed 23.33 pct alumina and 30.54 pct silica in 30 days at 300 rpm agitation and 2 to 3 l/min aeration. Alumina and silica dissolution follow the shrinking core model for both shake flask and bioreactor experiments.

Mishra, M.; Pradhan, M.; Sukla, L. B.; Mishra, B. K.

2011-02-01

31

Challenges facing the North American iron ore industry  

USGS Publications Warehouse

During the 20th century, the iron ore mining industries of Canada and the United States passed through several periods of transformation. The beginning of the 21st century has seen yet another period of transformation, with the economic failure of a number of steel companies, the acquisition of their facilities by more viable steelmakers, and the consolidation of control within the North American iron ore industry. Changes in Canadian and United States iron ore production and the market control structure involved are analysed. The consolidation of ownership, formation of foreign joint ventures within Nordi America, planned divestitures of upstream activities by steelmakers, and industry changes made to ensure availability of feedstocks will be reviewed. The ttaditional isolation of the Canadian and United States iron ore operations and their strong linkage to downstream steel production will be discussed in the context of a changing global economy. Management-labour conflicts that have taken place and agreements made during 2000 through 2004 will be discussed in the context of the economic environment leading up to these agreements. Cooperative agreements between competing Canadian and United States companies to resolve client needs in processing and blending will be examined. A joint industry-government project designed to use new technology to produce direct reduced iron nuggets of 96 - 98 per cent iron content using non-coking coals will also be assessed. Changes in iron ore transportation methods, ownership and infrastructure will be reviewed for both rail and inland waterway transport between Canadian and United States companies. A brief analysis of social and environmental issues relating to sustainable development of the Canadian-United States iron ore industry will be included.

Jorgenson, J.D.

2005-01-01

32

[Exposure to chromium compounds during processing of chromium iron ore].  

PubMed

The work verifies data gathered by Occupational Hygiene departments of Sanitary-Epidemiological Stations about workers exposure to chromium compounds in the processing of chrome iron ore. Research showed that 7 plants were involved in the processing of chrome iron ore and that the number of workers directly employed in the process amounted to 215-230. About 150 workers were exposed to high concentrations of chromium compounds which exceeded hygienic standards. All of them were employed only in metallurgical plants. The remaining 80-100 workers subjected to the study exposed to relatively low chromium concentrations were employed in chemical plants and refractory materials plants. PMID:1806757

Gromiec, J P; Romanowicz, B; Matczak, W

1991-01-01

33

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

34

Iron isotope fractionation during hydrothermal ore deposition and alteration  

NASA Astrophysics Data System (ADS)

Iron isotopes fractionate during hydrothermal processes. Therefore, the Fe isotope composition of ore-forming minerals characterizes either iron sources or fluid histories. The former potentially serves to distinguish between sedimentary, magmatic or metamorphic iron sources, and the latter allows the reconstruction of precipitation and redox processes. These processes take place during ore formation or alteration. The aim of this contribution is to investigate the suitability of this new isotope method as a probe of ore-related processes. For this purpose 51 samples of iron ores and iron mineral separates from the Schwarzwald region, southwest Germany, were analyzed for their iron isotope composition using multicollector ICP-MS. Further, the ore-forming and ore-altering processes were quantitatively modeled using reaction path calculations. The Schwarzwald mining district hosts mineralizations that formed discontinuously over almost 300 Ma of hydrothermal activity. Primary hematite, siderite and sulfides formed from mixing of meteoric fluids with deeper crustal brines. Later, these minerals were partly dissolved and oxidized, and secondary hematite, goethite and iron arsenates were precipitated. Two types of alteration products formed: (1) primary and high-temperature secondary Fe minerals formed between 120 and 300 °C, and (2) low-temperature secondary Fe minerals formed under supergene conditions (<100 °C). Measured iron isotope compositions are variable and cover a range in ?56Fe between -2.3‰ and +1.3‰. Primary hematite ( ?56Fe: -0.5‰ to +0.5‰) precipitated by mixing oxidizing surface waters with a hydrothermal fluid that contained moderately light Fe ( ?56Fe: -0.5‰) leached from the crystalline basement. Occasional input of CO 2-rich waters resulted in precipitation of isotopically light siderite ( ?56Fe: -1.4 to -0.7‰). The difference between hematite and siderite is compatible with published Fe isotope fractionation factors. The observed range in isotopic compositions can be accounted for by variable fractions of Fe precipitating from the fluid. Therefore, both fluid processes and mass balance can be inferred from Fe isotopes. Supergene weathering of siderite by oxidizing surface waters led to replacement of isotopically light primary siderite by similarly light secondary hematite and goethite, respectively. Because this replacement entails quantitative transfer of iron from precursor mineral to product, no significant isotope fractionation is produced. Hence, Fe isotopes potentially serve to identify precursors in ore alteration products. Goethites from oolitic sedimentary iron ores were also analyzed. Their compositional range appears to indicate oxidative precipitation from relatively uniform Fe dissolved in coastal water. This comprehensive iron isotope study illustrates the potential of the new technique in deciphering ore formation and alteration processes. Isotope ratios are strongly dependent on and highly characteristic of fluid and precipitation histories. Therefore, they are less suitable to provide information on Fe sources. However, it will be possible to unravel the physico-chemical processes leading to the formation, dissolution and redeposition of ores in great detail.

Markl, Gregor; von Blanckenburg, Friedhelm; Wagner, Thomas

2006-06-01

35

WATER CHEMISTRY EFFECTS IN IRON ORE CONCENTRATE AGGLOMERATION FEED  

Microsoft Academic Search

In two different iron ore processing plants, it was demonstrated that when magnetite concentrate was filtered to prepare it for use as pelletization feed, the moisture that remained in the filter cake had greatly elevated levels of cations compared to the water removed by the filtration process. In particular, calcium concentrations in the filter cake were 565 times higher than

T. C. Eisele; S. K. Kawatra; S. J. Ripke

2005-01-01

36

Challenges facing the North American iron ore industry  

USGS Publications Warehouse

Summary: This report is derived from a presentation the author presented in late September at the Iron Ore 2005 Conference sponsored by The Australasian Institute of Mining and Metallurgy and held in Fremantle, Western Australia. Some slight revisions have been made for the new audience.

Jorgenson, J.D.

2006-01-01

37

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

38

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

39

Pneumatic Drying of Iron Ore Particles in a Vertical Tube  

Microsoft Academic Search

The drying and hydrodynamic characteristics of iron ore particles in a vertical pneumatic conveying dryer (0.078 m ID × 6.0 m high) have been determined. The pressure drop decreases along the height at the acceleration region, while it remains constant irrespective of the height in the fully developed region. The degree of particle drying in the dilute pneumatic region increases with increasing

Won Namkung; Minyoung Cho

2004-01-01

40

Correlation Between Microstructure and Magnetic Properties of Porous Sintered Iron and Porous Iron Containing Composites.  

National Technical Information Service (NTIS)

The dependence of magnetic induction on the microstructure of two-phase materials is investigated. Investigations based on the microstructure-field property correlation by Ondracek are described. Sintered iron toroids show different microstructures when a...

E. Remane

1989-01-01

41

Siderite formation and evolution of sedimentary iron ore deposition in the Earth’s history  

Microsoft Academic Search

The role of siderite in Phanerozoic and Precambrian iron formations is discussed. Various types of iron formations are characterized,\\u000a and their place in the evolution of sedimentary iron ore deposition is outlined. In Precambrian iron ore deposition, siderite\\u000a is a primary mineral, whereas in Phanerozoic iron formations it becomes a secondary mineral and is commonly related to diagenetic\\u000a and catagenetic

V. N. Kholodov; G. Yu. Butuzova

2008-01-01

42

Simulation of primary-slag melting behavior in the cohesive zone of a blast furnace, considering the effect of Al{sub 2}O{sub 3}, Fe{sub t}O, and basicity in the sinter ore  

SciTech Connect

The alumina content in the iron ore imported to Japan is increasing year by year, and some problems in blast furnace operation, due to the use of the high-alumina-containing sinter, have already been reported. In order to clarify the mechanism of the harmful effect of alumina on the blast furnace operation, the behavior of the primary melt, which is formed in the sinter at the cohesive zone of the blast furnace, has been simulated by dripping slag through an iron or oxide funnel. The effects of basicity, Al{sub 2}O{sub 3}, and Fe{sub t}O contents in the five slag systems on the dripping temperature and weight of slag remaining on the funnel have been discussed. It was found that the eutectic melt formed in the sinter would play an important role in the dripping behavior of the slag in the blast furnace through the fine porosity of the reduced iron and ore particles. Al{sub 2}O{sub 3} increased the weight of the slag remaining on the funnel, and its effect became very significant in the acidic and low-Fe{sub t}O-containing slag. It was estimated that the increase of the weight of the slag remaining on the funnel by Al{sub 2}O{sub 3} in the ore could result in a harmful effect on the permeability resistance and an indirect reduction rate of the sinter in the blast furnace.

Hino, Mitsutaka; Nagasaka, Tetsuya; Katsumata, Akitoshi [Tohoku Univ., Sendai (Japan). Dept. of Metallurgy; Higuchi, Kenichi; Yamaguchi, Kazuyoshi; Kon-No, Norimitsu [Nippon Steel Corp., Futts (Japan). Process Technology Research Labs.

1999-08-01

43

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

NASA Astrophysics Data System (ADS)

The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling-Langalata iron ore deposits, Singhbhum-North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the geochemical evaluation of different iron ores. The geochemical and mineralogical characterization suggests that the massive, hard laminated, soft laminated ore and blue dust had a genetic lineage from BIFs aided with certain input from hydrothermal activity. The PAAS normalized REE pattern of Jilling BIF striking positive Eu anomaly, resembling those of modern hydrothermal solutions from mid-oceanic ridge (MOR). Major part of the iron could have been added to the bottom sea water by hydrothermal solutions derived from hydrothermally active anoxic marine environments. The ubiquitous presence of intercalated tuffaceous shales indicates the volcanic signature in BIF. Mineralogical studies reveal that magnetite was the principal iron oxide mineral, whose depositional history is preserved in BHJ, where it remains in the form of martite and the platy hematite is mainly the product of martite. The different types of iron ores are intricately related with the BHJ. Removal of silica from BIF and successive precipitation of iron by hydrothermal fluids of possible meteoric origin resulted in the formation of martite-goethite ore. The hard laminated ore has been formed in the second phase of supergene processes, where the deep burial upgrades the hydrous iron oxides to hematite. The massive ore is syngenetic in origin with BHJ. Soft laminated ores and biscuity ores were formed where further precipitation of iron was partial or absent.

Roy, Subrata; Venkatesh, A. S.

2009-12-01

44

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

45

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

46

Content and Binding Forms of Heavy Metals, Aluminium and Phosphorus in Bog Iron Ores from Poland  

Microsoft Academic Search

Bog iron ores are widespread in Polish wetland soils used as meadows or pastures. Th ey are suspected to contain high concentrations of heavy metals, which are precipitated together with Fe along a redox gradient. Th erefore, soils with bog iron ore might be important sources for a heavy metal transfer from meadow plants into the food chain. However, this

Danuta Kaczorek; Gerhard W. Brümmer; Michael Sommer

2009-01-01

47

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

48

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

49

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

50

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

51

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

52

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

53

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

54

Reduction of Sintering during Annealing of FePt Nanoparticles Coated with Iron Oxide  

E-print Network

thermal decomposition of iron pentacarbonyl and polyol reduction of platinum salt.4 How- everReduction of Sintering during Annealing of FePt Nanoparticles Coated with Iron Oxide Chao LiuVised Manuscript ReceiVed October 12, 2004 FePt/iron oxide core/shell nanoparticles are synthesized by a two step

Laughlin, David E.

55

Experimental and computational investigation of cyclic mechanical behavior of sintered iron  

Microsoft Academic Search

Sintered metals have found wide applications in mechanical design for their low manufacturing costs. The present paper deals with a sintered iron powder material (ASC 100.29) which is specially manufactured for experimental and computational investigations. The material has been tested under both monotonic and cyclic loading conditions. Fully reversed fatigue tests have been performed with different material porosities, strain loading

Markus Schneider; Huang Yuan

56

The selective carbochlorination of iron from titanlferous magnetite ore in a fluidized bed  

NASA Astrophysics Data System (ADS)

The selective chlorination of iron from titaniferous magnetite ore using solid carbon as a reducing agent was studied in a fluidized bed. The effects of chlorination temperature, chlorine gas partial pressure, ratio of ore to carbon particle sizes, and the amount of added carbon were determined. Experimental results indicate that temperatures between 900 and 1000 K were favorable for the selective chlorination of iron. The rate was found to be first order with respect to chlorine concentration, and the observed effects of particle size, temperature, and the amount of carbon added were expressed quantitatively by using a mixed-control model.

Rhee, K. I.; Sohn, H. Y.

1990-04-01

57

A further study on the interaction between one of organic active fractions of the MHA binder and iron ore surface  

Microsoft Academic Search

Binder is essential in the iron ore agglomeration. Fulvic acid (FA) is one of organic active fractions of the MHA binder. A further study of the interaction between FA and iron ore surface was conducted via elemental analysis, chemical group analysis, batch adsorption experiments, X-ray photoelectron spectroscopy (XPS) investigation, zeta potential measurements and scanning electron microscope (SEM) imaging. It is

Tao Jiang; Guihong Han; Yuanbo Zhang; Guanghui Li; Yanfang Huang

2011-01-01

58

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. PMID:23594855

Torti, Suzy V.; Torti, Frank M.

2014-01-01

59

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

60

Graphite immobilisation in iron phosphate glass composite materials produced by microwave and conventional sintering routes  

NASA Astrophysics Data System (ADS)

An investigation of microwave and conventional processing of iron phosphate based graphite glass composite materials as potential wasteforms for the immobilisation of irradiated graphite is reported. For the base iron phosphate glass, full reaction of the raw materials and formation of a glass melt occurs with consequent removal of porosity at 8 min microwave processing. When graphite is present, iron phosphate crystalline phases are formed with higher levels of residual porosity than in the sample prepared using conventional sintering under argon. It is found that graphite reacts with the microwave field when in powder form but this reaction is minimised when the graphite is incorporated into a pellet, and that the graphite also impedes sintering of the glass. Mössbauer spectroscopy indicates that reduction of iron also occurs with concomitant graphite oxidation. Conventionally sintered samples had lower porosities than the equivalent microwaved ones.

Mayzan, M. Z. H.; Stennett, M. C.; Hyatt, N. C.; Hand, R. J.

2014-11-01

61

Environmental impacts of iron ore tailings—The case of Tolo Harbour, Hong Kong  

NASA Astrophysics Data System (ADS)

Disposal of iron ore tailings along the shore of Tolo Harbour, Hong Kong has altered the adjacent environment. Due to the ever-expanding population, the vast development of various industries, and the lack of sanitary control, the existing pollution problem of Tolo Harbour is serious. The iron ore tailings consist of a moderate amount of various heavy metals, e.g., copper, iron, manganese, lead, zinc, and a lower level of macronutrients. A few living organisms have been found colonizing this manmade habitat. Higher metal contents were also found in the tissue of Paphia sp. (clam); Scopimera intermedia (crab); Chaetomorpha brychagona (green alga); Enteromorpha crinita (green alga); and Neyraudia reynaudiana (grass). The area can be reclaimed by surface amelioration using inert materials, soils, or organic substrates, and by direct seeding, using nontolerant and tolerant plant materials. Reclamation of the tailings would improve the amenity of the adjacent environment and also mitigate pollution escaping to the sea.

Wong, M. H.

1981-03-01

62

Utilization of Coke Oven Gas and Converter Gas in the Direct Reduction of Lump Iron Ore  

NASA Astrophysics Data System (ADS)

The application of off-gases from the integrated steel plant for the direct reduction of lump iron ore could decrease not only the total production cost but also the energy consumption and CO2 emissions. The current study investigates the efficiency of reformed coke oven gas (RCOG), original coke oven gas (OCOG), and coke oven gas/basic oxygen furnace gas mixtures (RCOG/BOFG and OCOG/BOFG) in the direct reduction of lump iron ore. The results were compared to that of reformed natural gas (RNG), which is already applied in the commercial direct reduction processes. The reduction of lump ore was carried out at temperatures in the range of 1073 K to 1323 K (800 °C to 1050 °C) to simulate the reduction zone in direct reduction processes. Reflected light microscopy, scanning electron microscopy, and X-ray diffraction analysis were used to characterize the microstructure and the developed phases in the original and reduced lump iron ore. The rate-controlling mechanism of the reduced lump ore was predicted from the calculation of apparent activation energy and the examination of microstructure. At 1073 K to 1323 K (800 °C to 1050 °C), the reduction rate of lump ore was the highest in RCOG followed by OCOG. The reduction rate was found to decrease in the order RCOG > OCOG > RNG > OCOG-BOF > RCOG-BOFG at temperatures 1173 K to 1323 K (900 °C to 1050 °C). The developed fayalite (Fe2SiO4), which resulted from the reaction between wüstite and silica, had a significant effect on the reduction process. The reduction rate was increased as H2 content in the applied gas mixtures increased. The rate-determining step was mainly interfacial chemical reaction with limitation by gaseous diffusion at both initial (20 pct reduction) and moderate (60 pct reduction) stages of reduction. The solid-state diffusion mechanism affected the reduction rate only at moderate stages of reduction.

Mousa, Elsayed Abdelhady; Babich, Alexander; Senk, Dieter

2014-04-01

63

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

64

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

PubMed

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, CaCO3, NaOH, and Na2CO3. 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. PMID:18556190

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

2009-01-01

65

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

66

Getting rid of the unwanted: highlights of developments and challenges of biobeneficiation of iron ore minerals-a review.  

PubMed

The quest for quality mineral resources has led to the development of many technologies that can be used to refine minerals. Biohydrometallurgy is becoming an increasingly acceptable technology worldwide because it is cheap and environmentally friendly. This technology has been successfully developed for some sulphidic minerals such as gold and copper. In spite of wide acceptability of this technology, there are limitations to its applications especially in the treatment of non-sulphidic minerals such as iron ore minerals. High levels of elements such as potassium (K) and phosphorus (P) in iron ore minerals are known to reduce the quality and price of these minerals. Hydrometallurgical methods that are non-biological involving the use of chemicals are usually used to deal with this problem. However, recent advances in mining technologies favour green technologies, known as biohydrometallurgy, with minimal impact on the environment. This technology can be divided into two, namely bioleaching and biobeneficiation. This review focuses on Biobeneficiation of iron ore minerals. Biobeneficiation of iron ore is very challenging due to the low price and chemical constitution of the ore. There are substantial interests in the exploration of this technology for improving the quality of iron ore minerals. In this review, current developments in the biobeneficiation of iron ore minerals are considered, and potential solutions to challenges faced in the wider adoption of this technology are proposed. PMID:25293513

Adeleke, Rasheed A

2014-12-01

67

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

68

RECOVERY OF Co, Ni, AND Cu FROM THE TAILINGS OF DIVRIGI IRON ORE CONCENTRATOR  

Microsoft Academic Search

In the Sivas-Divri?i Iron Ore Concentrator, 600,000 t of tailings are discarded annually. There are already 1 million t of tailings deposited in ponds from the previous production activities. The presence of Co, Ni, and Cu in the tailings makes the beneficiation of those tailings attractive. In the experimental work, sulphide concentrates were produced from these two types of tailings by

A. A. Sirkeci; A. Gül; G. Bulut; F. Arslan; G. Onal; A. E. Yuce

2006-01-01

69

Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon  

Microsoft Academic Search

Background, aim, and scope  In water systems, water quality and geochemical properties of sediments determine the speciation of trace metals, metal transport,\\u000a and sediment–water exchange, influencing metal availability and its potential effects on biota. Studies from temperate climates\\u000a have shown that iron-ore mining and tailing wastewaters, besides being a source of trace metals, usually show high levels\\u000a of dissolved ions and

Adriana Alves Pereira; Bert van Hattum; Abraham Brouwer; Peter Michiel van Bodegom; Carlos Eduardo Rezende; Wim Salomons

2008-01-01

70

Experimental evaluation of sorptive removal of fluoride from drinking water using iron ore  

NASA Astrophysics Data System (ADS)

High concentrations of fluoride in drinking water is a public health concern globally and of critical importance in the Rift Valley region. As a low-cost water treatment option, the defluoridation capacity of locally available iron ore was investigated. Residence time, pH, agitation rate, particle size of the adsorbent, sorbent dose, initial fluoride concentration and the effect of co-existing anions were assessed. The sorption kinetics was found to follow pseudo-first-order rate and the experimental equilibrium sorption data fitted reasonably well to the Freundlich model. The sorption capacity of iron ore for fluoride was 1.72 mg/g and the equilibrium was attained after 120 min at the optimum pH of 6. The sorption study was also carried out at natural pH conditions using natural ground water samples and the fluoride level was reduced from 14.22 to 1.17 mg/L (below the WHO maximum permissible limit). Overall, we concluded that iron ore can be used in water treatment for fluoride removal in the Rift Valley region and beyond.

Kebede, Beekam; Beyene, Abebe; Fufa, Fekadu; Megersa, Moa; Behm, Michael

2014-06-01

71

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

72

POLLUTION EFFECTS OF ABNORMAL OPERATIONS IN IRON AND STEEL MAKING. VOLUME II. SINTERING, MANUAL OF PRACTICE  

EPA Science Inventory

The report is one 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. Pollution standards, generall...

73

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

74

26 CFR 1.631-3 - Gain or loss upon the disposal of coal or domestic iron ore with a retained economic interest.  

Code of Federal Regulations, 2012 CFR

...false Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...631-3 Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...c) apply to an owner who disposes of coal (including lignite), or iron...

2012-04-01

75

26 CFR 1.631-3 - Gain or loss upon the disposal of coal or domestic iron ore with a retained economic interest.  

Code of Federal Regulations, 2010 CFR

...true Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...631-3 Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...c) apply to an owner who disposes of coal (including lignite), or iron...

2010-04-01

76

26 CFR 1.631-3 - Gain or loss upon the disposal of coal or domestic iron ore with a retained economic interest.  

Code of Federal Regulations, 2013 CFR

...false Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...631-3 Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...c) apply to an owner who disposes of coal (including lignite), or iron...

2013-04-01

77

26 CFR 1.631-3 - Gain or loss upon the disposal of coal or domestic iron ore with a retained economic interest.  

Code of Federal Regulations, 2011 CFR

...true Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...631-3 Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...c) apply to an owner who disposes of coal (including lignite), or iron...

2011-04-01

78

26 CFR 1.631-3 - Gain or loss upon the disposal of coal or domestic iron ore with a retained economic interest.  

...true Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...631-3 Gain or loss upon the disposal of coal or domestic iron ore with a retained economic...c) apply to an owner who disposes of coal (including lignite), or iron...

2014-04-01

79

Chelatometric determination of calcium and magnesium in iron ores, slags, anorthosite, limestone, copper-nickel-lead-zinc ores and divers materials.  

PubMed

Chelatometric methods for the determination of calcium and magnesium in iron ores, slags, anorthosite, copper-nickel-lead-zinc ores and various other materials are described. Potential interfering elements are masked with triethanolamine and potassium cyanide. In one aliquot calcium is titrated at pH > 12, with calcein and thymolphthalein mixed indicator and in another aliquot calcium and magnesium are titrated in ammonia buffer, with o-cresolphthalein complexone screened with Naphthol Green B as indicator. The results compare favourably with certified values for reference materials of diverse nature. PMID:18962661

Hitchen, A; Zechanowitsch, G

1980-03-01

80

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

81

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

82

Effect of Sintering Temperature on Dielectric Properties of Iron Deficient Nickel-Ferrite  

SciTech Connect

Nickel Ferrite among all the magneto ceramic materials have been studied very much due to its large number of applications. But there is a large scope of modification of its properties. Thus people still working on it for improvisation of its properties via compositional and structural modifications. Present paper reporting the preparation and characterization of iron deficient Nickel ferrite for different sintering temperature. Ferrite samples having the general formula NiFe1.98O{sub 4} were prepared using the standard ceramic method. The phase formation was confirmed by X-ray diffraction technique. The effect of sintering temperature on the electrical properties and resistivity was studied. The data shows that dielectric properties are highly dependent on the sintering temperature.

Rani, Renu [Electroceramics Research Lab, GVM Girls College, Sonepat-131001 (India); School of Physics and Material Science, Thapar University, Patiala-147004 (India); Singh, Sangeeta [Department of Physics, GVM Girls College, Sonepat-131001 (India); Juneja, J. K. [Department of Physics, Hindu College, Sonepat-131001 (India); Prakash, Chandra [Directorate of ER and IPR, DRDO, DRDO Bhawan, New Delhi-110105 (India); Raina, K. K. [School of Physics and Material Science, Thapar University, Patiala-147004 (India)

2011-11-22

83

Uranium–lead ages of apatite from iron oxide ores of the Bafq District, East-Central Iran  

Microsoft Academic Search

Iron oxide–apatite (IOA) deposits, often referred to as Kiruna-type iron ore deposits, are known to have formed from the Proterozoic\\u000a to the Tertiary. They are commonly associated with calc–alkaline volcanic rocks and regional- to deposit-scale metasomatic\\u000a alteration. In the Bafq District in east Central Iran, economic iron oxide–apatite deposits occur within felsic volcanic tuffs\\u000a and volcanosedimentary sequences of Early Cambrian

Heinz-Günter Stosch; Rolf L. Romer; Farahnaz Daliran; Dieter Rhede

2011-01-01

84

Pressurized chemical-looping combustion of coal with an iron ore-based oxygen carrier  

SciTech Connect

Chemical-looping combustion (CLC) is a new combustion technology with inherent separation of CO{sub 2}. Most of the previous investigations on CLC of solid fuels were conducted under atmospheric pressure. A pressurized CLC combined cycle (PCLC-CC) system is proposed as a promising coal combustion technology with potential higher system efficiency, higher fuel conversion, and lower cost for CO{sub 2} sequestration. In this study pressurized CLC of coal with Companhia Valedo Rio Doce (CVRD) iron ore was investigated in a laboratory fixed bed reactor. CVRD iron ore particles were exposed alternately to reduction by 0.4 g of Chinese Xuzhou bituminous coal gasified with 87.2% steam/N{sub 2} mixture and oxidation with 5% O{sub 2} in N{sub 2} at 970 C. The operating pressure was varied between 0.1 MPa and 0.6 MPa. First, control experiments of steam coal gasification over quartz sand were performed. H{sub 2} and CO{sub 2} are the major components of the gasification products, and the operating pressure influences the gas composition. Higher concentrations of CO{sub 2} and lower fractions of CO, CH{sub 4}, and H{sub 2} during the reduction process with CVRD iron ore was achieved under higher pressures. The effects of pressure on the coal gasification rate in the presence of the oxygen carrier were different for pyrolysis and char gasification. The pressurized condition suppresses the initial coal pyrolysis process while it also enhances coal char gasification and reduction with iron ore in steam, and thus improves the overall reaction rate of CLC. The oxidation rates and variation of oxygen carrier conversion are higher at elevated pressures reflecting higher reduction level in the previous reduction period. Scanning electron microscope and energy-dispersive X-ray spectroscopy (SEM-EDX) analyses show that particles become porous after experiments but maintain structure and size after several cycles. Agglomeration was not observed in this study. An EDX analysis demonstrates that there is very little coal ash deposited on the oxygen carrier particles but no appreciable crystalline phases change as verified by X-ray diffraction (XRD) analysis. Overall, the limited pressurized CLC experiments carried out in the present work suggest that PCLC of coal is promising and further investigations are necessary. (author)

Xiao, Rui; Song, Min; Zhang, Shuai; Shen, Laihong [School of Energy and Environment, Southeast University, Sipailou No. 2, Nanjing 210096 (China); Song, Qilei [School of Energy and Environment, Southeast University, Sipailou No. 2, Nanjing 210096 (China); Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Lu, Zuoji [School of Energy and Environment, Southeast University, Sipailou No. 2, Nanjing 210096 (China); GCL Engineering Limited, Zhujiang No. 1, Nanjing 210008 (China)

2010-06-15

85

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

86

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

87

Mineralogical and Beneficiation Studies of a Low Grade Iron Ore Sample  

NASA Astrophysics Data System (ADS)

Investigations were carried out, to establish its amenability for physical beneficiation on a low grade siliceous iron ore sample by magnetic separation. Mineralogical studies, with the help of microscope as well as XRD, SEM-EDS revealed that the sample consists of magnetite, hematite and goethite as major opaque oxide minerals where as quartz and kaolinite form the gangue minerals in the sample. Processes involving combination of classification, dry magnetic separation and wet magnetic separation were carried out to upgrade the low grade siliceous iron ore sample to make it suitable as a marketable product. The sample was first ground and each closed size sieve fractions were subjected to dry magnetic separation and it was observed that limited upgradation is possible. The ground sample was subjected to different finer sizes and separated by wet low intensity magnetic separator. Dry beneficiation studies by Permaroll separator indicated that it is possible to get a product with 60.2 % Fe at 22 % weight recovery. It is possible to get an over all concentrate with 54 % Fe at 32.4 % weight recovery by combination of size reduction followed by LIMS and WHIMS.

Dwari, R. K.; Rao, D. S.; Reddy, P. S. R.

2014-10-01

88

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

89

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

90

Multiple reaction fronts in the oxidation-reduction of iron-rich uranium ores  

SciTech Connect

When a container of radioactive waste is buried underground, it eventually corrodes, and leakage of radioactive material to the surrounding rock occurs. Depending on the chemistry of the rock, many different reactions may occur. A particular case concerns the oxidation and reduction of uranium ores by infiltrating groundwater, since UO[sub 3] is relatively soluble (and hence potentially transportable to the water supply), whereas UO[sub 2] is essentially insoluble. It is therefore of concern to those involved with radioactive waste disposal to understand the mechanics of uranium transport through reduction and oxidation reactions. This paper describes the oxidation of iron-rich uranium-bearing rocks by infiltration of groundwater. A reaction-diffusion model is set up to describe the sequence of reactions involving iron oxidation, uranium oxidation and reduction, sulfuric acid production, and dissolution of the host rock that occur. On a geological timescale of millions of years, the reactions occur very fast in very thin reaction fronts. It is shown that the redox front that separates oxidized (orange) rock from reduced (black) rock must actually consist of two separate fronts that move together, at which the two separate processes of uranium oxidation and iron reduction occur, respectively. Between these fronts, a high concentration of uranium is predicted. The mechanics of this process are not specific to uranium-mediated redox reactions, but apply generally and may be used to explain the formation of concentrated ore deposits in extended veins. On the long timescales of relevance, a quasi-static response results, and the problem can be solved explicitly in one dimension. This provides a framework for studying more realistic two-dimensional problems in fissured rocks and also for the future study of uraninite nodule formation.

Dewynne, J.N. (Univ. of Southampton (United Kingdom). Faculty of Mathematical Studies); Fowler, A.C. (Oxford Univ. (United Kingdom). Mathematical Inst.); Hagan, P.S. (Los Alamos National Lab., NM (United States))

1993-08-01

91

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

Code of Federal Regulations, 2013 CFR

...considered a gain or loss from the sale or exchange...applies to the gain or loss; (3) From the disposal of iron ore mined in the United...applies to the gain or loss; and (4) From the...who owns a grocery store, had a net profit...

2013-04-01

92

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

...considered a gain or loss from the sale or exchange...applies to the gain or loss; (3) From the disposal of iron ore mined in the United...applies to the gain or loss; and (4) From the...who owns a grocery store, had a net profit...

2014-04-01

93

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

Code of Federal Regulations, 2011 CFR

...considered a gain or loss from the sale or exchange...applies to the gain or loss; (3) From the disposal of iron ore mined in the United...applies to the gain or loss; and (4) From the...who owns a grocery store, had a net profit...

2011-04-01

94

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

Code of Federal Regulations, 2010 CFR

...considered a gain or loss from the sale or exchange...applies to the gain or loss; (3) From the disposal of iron ore mined in the United...applies to the gain or loss; and (4) From the...who owns a grocery store, had a net profit...

2010-04-01

95

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

Code of Federal Regulations, 2012 CFR

...considered a gain or loss from the sale or exchange...applies to the gain or loss; (3) From the disposal of iron ore mined in the United...applies to the gain or loss; and (4) From the...who owns a grocery store, had a net profit...

2012-04-01

96

Origin and significance of aromatic hydrocarbons in giant iron ore deposits of the late Archean Hamersley Basin,  

E-print Network

Origin and significance of aromatic hydrocarbons in giant iron ore deposits of the late Archean for revision 18 November 2002) Abstract Late Archean to earliest Paleoproterozoic shales associated with two reserved. 1. Introduction Minimally metamorphosed (200­300 C) shales of the late Archean Hamersley

Brocks, Jochen J.

97

Iron ore beneficiation using roll-type high-intensity electric field separators  

SciTech Connect

This paper aims to demonstrate that high-intensity electric fields can be employed for the separation of artificial magnetite processed from an iron mineral containing siderite FeCO{sub 3} and ankerite (FeCaMg)CO{sub 3}. All the tests were carried out on a roll-type laboratory separator (roll diameter: 250 mm; roll speed: 175 r/min), provided with an over-tray heater, to ensure the thermal conditioning of the samples at +120 C, and a system of high-voltage electrodes, consisting of a needle-type corona electrode and either a second corona electrode or a tubular (electrostatic) electrode. The samples were collected from the technological process presently employed for the beneficiation of the iron ore deposit at Teliuc, Romania. The grain size was typically in the 0.09--0.315-mm range. Separation in high-intensity electric field ensured the increase of the Fe content in the samples from about 35--55%, for an iron recovery of up to 80%. This paper discusses these results in relation to the mineralogical characteristics of the samples and concludes that electrostatic separation could be employed either as an additional operation in an existing technological process, or as an alternative to the currently employed magnetic separation. Pilot-plant tests are needed prior to industry application.

Morar, R.; Iuga, A.; Muntean, O. [Technical Univ. of Cluj-Napoca (Romania). Electrical Engineering Dept.] [Technical Univ. of Cluj-Napoca (Romania). Electrical Engineering Dept.; Cuglesan, I. [Inst. of Research and Development for the Mining Industry, Cluj-Napoca (Romania)] [Inst. of Research and Development for the Mining Industry, Cluj-Napoca (Romania); Dascalescu, L. [Inst. Univ. de Technologie d`Angouleme (France). Lab. de Technologies Electriques et Electroniques Avancees] [Inst. Univ. de Technologie d`Angouleme (France). Lab. de Technologies Electriques et Electroniques Avancees

1999-01-01

98

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. PMID:10097051

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

1999-01-01

99

Changes in diffusivity due to sintering in metallized iron oxide pellets  

NASA Astrophysics Data System (ADS)

The work discussed in this communication forms part of a much larger study aimed at the mathematical and experimental simulation of direct reduction processes occurring in shaft furnaces of the Midrex, HyL III, Purofer, and Nippon Steel Corporation types. In these processes, iron oxide burdens are subjected to environments in which both the temperature and gas compositions change continuously. Previous work1 showed that reduction under such non-isothermal conditions caused iron oxide pellets initially to swell by up to 10 pct and then shrink to give overall pellet contractions of up to 15 pct by the latter stages of reduction. Microstructural examination indicated that the pellet contractions were due to sintering of the porous, high surface-area iron formed in the initial stages of reduction. The sintering reaction is advantageous in that it tends to increase the strength of the metallized pellets;2 however, the accompanying structural changes can also impede the diffusion of reacting gases into and out of the pellets and thus retard the reaction rates.

Wright, J. K.; Morrison, A. L.

1982-09-01

100

Introduction HIGH-GRADE (60 wt % Fe) hematite iron ore deposits that are  

E-print Network

, and testing proposed models for, the genesis of hard high-grade hematite ore de- posits is illustrated by two.S. Geological Survey, 2007). Many high-grade hematite ore- bodies consist of "soft" martite-hematite ore, which). It is, however, the so- called "hard" high-grade hematite ores, which consist of mar- tite

101

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

102

BULLETIN OF THE UNITED STATES FISH COMMISSION. 13 the bays are more or less lined with bog iron ore which has been depos-  

E-print Network

all over the peninsula. Sulphur almost always is found combined with all iron ores, and arsenic, as their present food is rather incon- venientto furnish. The so-calledartificial hatching of lobsters has often

103

A circulatory system and method of slurry delivery in long-distance pipeline transportation of iron ore  

NASA Astrophysics Data System (ADS)

Long-distance pipeline transportation of iron ore is a very good method to solve the iron ore delivering outside, and also suitable for the western complicated terrain and convenient traffic. Before the pipeline transporting the slurry, you need a low concentration of slurry (slurry concentration of less than 68%) that is concentrated and then transport to the mixing tank to mix uniformly. There will be a small amount of selected birth to mine in the upper reaches of the production process, which resulting concentration of slurry concentrated pool is low, and thus it can not meet the requirements that we have set concentration of slurry concentration, so the slurry can not be sent to the mixing tank, and the production is affected ultimately. Therefore, this paper presents a method of circulatory system and slurry delivery to solve such problems. It has been proved in practice that the system effectively improve the production and generalization efficiently.

Li, Youling; Wang, Hua

2011-10-01

104

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

Microsoft Academic Search

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

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

2008-01-01

105

Utilization of waste polyethylene terephthalate as a reducing agent in the reduction of iron ore composite pellets  

NASA Astrophysics Data System (ADS)

The increasing consumption of plastics inevitably results in increasing amounts of waste plastics. Because of their long degradation periods, these wastes negatively affect the natural environment. Numerous studies have been conducted to recycle and eliminate waste plastics. The potential for recycling waste plastics in the iron and steel industry has been underestimated; the high C and H contents of plastics may make them suitable as alternative reductants in the reduction process of iron ore. This study aims to substitute plastic wastes for coal in reduction melting process and to investigate their performance during reduction at high temperature. We used a common type of waste plastic, polyethylene terephthalate (PET), because of its high carbon and hydrogen contents. Composite pellets containing PET wastes, coke, and magnetite iron ore were reduced at selected temperatures of 1400 and 1450°C for reduction time from 2 to 10 min to investigate the reduction melting behavior of these pellets. The results showed that an increased temperature and reduction time increased the reduction ratio of the pellets. The optimum experimental conditions for obtaining metallic iron (iron nuggets) were reduction at 1450°C for 10 min using composite pellets containing 60% PET and 40% coke.

Polat, Gökhan; Birol, Burak; Sar?dede, Muhlis Nezihi

2014-08-01

106

Determination of titanium and iron in ilmenite ores by cerate titrimetry  

E-print Network

-0. 25 gram sample of most ilmenite ores. If platinum or palladium flasks are available, then the addition of a small amount of sodium fluoride will aid the attack of the silica-containing ores by the potassium bisulfate. One gram of boric acid should...-0. 25 gram sample of most ilmenite ores. If platinum or palladium flasks are available, then the addition of a small amount of sodium fluoride will aid the attack of the silica-containing ores by the potassium bisulfate. One gram of boric acid should...

Gainer, Alvis Beryl

2012-06-07

107

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

108

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

109

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

Microsoft Academic Search

The rate of reduction of iron ore-graphite composite pellets in a packed-bed reactor under controlled atmosphere (inert and\\u000a reducing) has been studied through experiments and modeling exercises. A customized high-mass, high-temperature thermogravimetric\\u000a setup was constructed to carry out reduction experiments in a packed-bed reactor. A very low overall apparent activation energy\\u000a estimated from experimental data indicates that the packed-bed reduction

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

2008-01-01

110

Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajás Mineral Province (Brazil)  

Microsoft Academic Search

The Carajás Mineral Province in northern Brazil containsa variety of world-class (>100 Mt ore) iron oxide copper-gold(IOCG) deposits, including the only Archean examples of thisdeposit class (e.g., the Igarapé Bahia\\/Alemãoand Salobo deposits). Tourmaline of schorl-dravite composition,a common gangue mineral in these deposits, precipitated shortlyprior to and after the ore assemblage. A boron isotope studyof texturally different tourmaline from three IOCG

Roberto Perez Xavier; Michael Wiedenbeck; Robert B. Trumbull; Ana M. Dreher; Lena V. S. Monteiro; Dieter Rhede; Carlos E. G. de Araújo; Ignacio Torresi

2008-01-01

111

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

112

Reaction of iron and aluminium phosphate ores with sulphuric acid and various salts  

Microsoft Academic Search

A study has been made of the reaction of ore containing high Fe and Al phosphates (crandallite (CaAl3(PO4)2OH5·H2O)), millisite (Na, K)CaAl6(PO4)4(OH)9·3H2O) and minor minerals) with sulphuric acid. The products are deliquecent, poorly crystalline solids which contain polymeric aluminium phosphate. The deliquecence was greatly reduced by adding enough ammonium, potassium or sodium sulphate to form compounds of the type M(Al, -Fe)(SO4)2.

G. S. Walker

1988-01-01

113

Monitoring Sintering Burn-Through Point Using Infrared Thermography  

PubMed Central

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, Ruben; Molleda, Julio; Garcia, Daniel F.; Bulnes, Francisco G.

2013-01-01

114

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

115

Iron Ore Solubilization by Penicillium restrictum: Effect of Carbon Source and Incubation Days  

Microsoft Academic Search

An experiment was carried out to evaluate the Fe solubilising properties of P. restrictum when grown in different carbon source and incubation period. Addition of 1% sucrose and manitol enhanced the iron solubilization upto 30 days. Dextrose and starch were most preferred carbon source and exhibited 24.40 µg\\/ml\\/g and 28.64 µg\\/ml\\/g Fe content with in 15 days of incubation period.

J. Sabat; N. Gupta

116

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

117

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

118

Sintering of powder mixtures and the growth of ferrous powder metallurgy  

Microsoft Academic Search

Advances in the understanding of sintering of powder mixtures contributed significantly to the growth of ferrous powder metallurgy industry. Solid-state sintering and liquid-phase activated sintering play an important role in the sintering of powder mixtures. In this paper, sintering of iron powder with graphite; iron powder with copper and graphite; iron powder with nickel and graphite; iron powder with phosphorus;

K. S Narasimhan

2001-01-01

119

Double-pulse laser-induced breakdown spectroscopy for trace element analysis in sintered iron oxide ceramics  

NASA Astrophysics Data System (ADS)

Double-pulse laser-induced breakdown spectroscopy (LIBS) is an emerging technique for accurate compositional analysis of many different materials. We present a systematic study of collinear double-pulse LIBS for analysis of the trace and side elements boron, manganese, copper, aluminum, titanium, silicon, chromium, nickel, potassium, and calcium in sintered iron oxide targets. The samples were ablated in air by single-pulse and double-pulse Nd:YAG laser radiation (6 ns pulse duration, laser wavelength of 532 nm) and spectra were recorded with an Echelle spectrometer equipped with an ICCD camera. We investigated the evolution of atomic and ionic line emission intensities for different interpulse delay times between the laser pulses (from 100 ns to 50 ?s) and gate delays after the second laser pulse. We also varied the energy partition between the first and second laser pulse and the size of the irradiated spot at the sample surface. For the trace and side elements, we observed double-pulse LIBS signals that were enhanced as compared to single-pulse measurements depending on the interpulse delay time, the energy partition between the pulses, and the spot size. For the elements boron, copper, aluminum, titanium, chromium, potassium, and calcium limits of detection below 10 ppm were achieved.

Heilbrunner, H.; Huber, N.; Wolfmeir, H.; Arenholz, E.; Pedarnig, J. D.; Heitz, J.

2012-01-01

120

Ore Minerals  

NSDL National Science Digital Library

This three part lab introduces sulfides and other ore minerals. Part one - Ore Minerals: Students fill in a table giving the metal, formula, and mineral group of several ore minerals. Part two - Box of Rocks: Students examine trays of ore minerals and record their physical properties, composition, habit, occurence, economic value, and use and answer questions about color, luster, density, transparency, and availability. Part three - Famous Digs: Students answer a series of questions related to famous ore deposits.

Perkins, Dexter

121

Geochemistry of sedimentary ore deposits  

SciTech Connect

A text providing a sedimentological treatment of a study on ore deposits, and especially as related to geochemistry. Excellently documented (about 5000 citations). Well indexed with the index of deposits and localities separated. Contents, Iron. Copper and silver. Aluminum and nickel. Manganese. Uranium. Lead and zinc. Volcanic-sedimentary ores. Appendix. Indexes.

Maynard, J. B.

1983-01-01

122

Ore sorter  

SciTech Connect

This invention relates to apparatus for and a method of sorting ore having a radioactive component. The method includes the steps of passing a stream of ore particles through a ring detector to detect ore in the stream having a radioactive emission intensity above a predetermined level and then sorting this ore from the remainder of the ore in the stream. Preferably the invention includes the step of determining the mass of each ore particle and correlating the mass and radioactive emission measurements of the particle to determine its grade.

Bohme, R.C.; Kealy, W.A.

1982-11-30

123

Tourmaline B-isotopes fingerprint marine evaporites as the source of high-salinity ore fluids in iron oxide copper-gold deposits, Carajás Mineral Province (Brazil)  

NASA Astrophysics Data System (ADS)

The Carajás Mineral Province in northern Brazil containsa variety of world-class (>100 Mt ore) iron oxide copper-gold(IOCG) deposits, including the only Archean examples of thisdeposit class (e.g., the Igarapé Bahia/Alemãoand Salobo deposits). Tourmaline of schorl-dravite composition,a common gangue mineral in these deposits, precipitated shortlyprior to and after the ore assemblage. A boron isotope studyof texturally different tourmaline from three IOCG deposits(Igarapé Bahia, Salobo, and Sossego) using secondaryion mass spectrometry (SIMS) provides new evidence in the long-standingdebate of magmatic versus non-magmatic sources for the highsalinity (up to 50 wt% NaCl equiv.) of ore fluids in these deposits.Values of {delta}11B from 14{per thousand} to 26.5{per thousand} for the Igarapé Bahia andSalobo deposits confirm marine evaporite-derived brinesin the ore fluids, whereas lower {delta}11B values for the IgarapéBahia deposit (5.8{per thousand} to 8.8{per thousand}) suggest that these fluids may havemixed with an isotopically different hydrothermal fluid, orone that had a mixed boron source. More variable and isotopicallylighter boron in tourmaline from the Sossego deposit (-8{per thousand}to 11{per thousand}) is attributed to mixed sources, including light boronleached from felsic intrusive and volcanic host rocks, and heavyboron derived from marine evaporites. The boron isotope dataindicate that the characteristic high salinity of the ore fluidsin the Carajás Mineral Province was acquired by the interactionof hydrothermal fluids with marine evaporites. For IOCG depositsthat contain tourmaline as a common gangue mineral, boron isotopesoffer a valuable tool to constrain the high-salinity sourceproblem, which is a critical issue in metallogenesis of IOCGdeposits worldwide.

Perez Xavier, Roberto; Wiedenbeck, Michael; Trumbull, Robert B.; Dreher, Ana M.; Monteiro, Lena V. S.; Rhede, Dieter; de Araújo, Carlos E. G.; Torresi, Ignacio

2008-09-01

124

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

125

Photosynthetic changes and oxidative stress caused by iron ore dust deposition in the tropical CAM tree Clusia hilariana  

Microsoft Academic Search

The effect of iron solid particulate matter (SPMFe) deposited onto soil and leaves on photosynthesis and oxidative stress was evaluated in Clusia hilariana, a CAM tropical tree of high occurrence in Brazilian restingas. Significant increases in iron content were found in plants\\u000a exposed to SPMFe applied onto leaf and soil surfaces. However, only the application of SPMFe on leaves of

Eduardo Gusmão Pereira; Marco Antonio Oliva; Kacilda Naomi Kuki; José Cambraia

2009-01-01

126

Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide-copper-gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis  

NASA Astrophysics Data System (ADS)

The Alvo 118 iron oxide-copper-gold (IOCG) deposit (170 Mt at 1.0 wt.% Cu, 0.3 g/t Au) lies in the southern sector of the Itacaúnas Shear Belt, Carajás Mineral Province, along a WNW-ESE-striking, 60-km-long shear zone, close to the contact of the ~2.76-Ga metavolcano-sedimentary Itacaiúnas Supergroup and the basement (~3.0 Ga Xingu Complex). The Alvo 118 deposit is hosted by mafic and felsic metavolcanic rocks and crosscutting granitoid and gabbro intrusions that have been subjected to the following hydrothermal alteration sequence towards the ore zones: (1) poorly developed sodic alteration (albite and scapolite); (2) potassic alteration (biotite or K-feldspar) accompanied by magnetite formation and silicification; (3) widespread, pervasive chlorite alteration spatially associated with quartz-carbonate-sulphide infill ore breccia and vein stockworks; and (4) local post-ore quartz-sericite alteration. The ore assemblage is dominated by chalcopyrite (~60%), bornite (~10%), hematite (~20%), magnetite (10%) and subordinate chalcocite, native gold, Au-Ag tellurides, galena, cassiterite, F-rich apatite, xenotime, monazite, britholite-(Y) and a gadolinite-group mineral. Fluid inclusion studies in quartz point to a fluid regime composed of two distinct fluid types that may have probably coexisted within the timeframe of the Cu-Au mineralizing episode: a hot (>200°C) saline (32.8‰ to 40.6 wt.% NaCl eq.) solution, represented by salt-bearing aqueous inclusions, and a lower temperature (<200°C), low to intermediate salinity (<15 wt.% NaCl eq.) aqueous fluid defined by two-phase (LH2O + VH2O) fluid inclusions. This trend is very similar to those defined for other IOCG systems of the Carajás Mineral Province. ? 18OH2O values in equilibrium with calcite (-1.0‰ to 7.5‰ at 277°C to 344°C) overlap the lower range for primary magmatic waters, but the more 18O-depleted values also point to the involvement of externally derived fluids, possibly of meteoric origin. Furthermore, sulphide ? 34S values (5.1‰ to 6.3‰), together with available boron isotope and Cl/Br-Na/Cl data provide evidence for a significant component of residual evaporative fluids (e.g., bittern fluids generated by seawater evaporation) in this scenario that, together with magma-derived brines, would be the main sources of the highly saline fluids involved in the formation Alvo 118 IOCG deposit. The restricted high temperature sodic alteration, the pervasive overprinting of the potassic alteration minerals by chlorite proximal to the ore zones, ore breccias with open-space filling textures in brittle structures, microthermometric and stable isotope data indicate, collectively, that the Alvo 118 IOCG system developed at structurally high levels and may be considered the shallower representative of the IOCG systems of the CMP.

Torresi, Ignacio; Xavier, Roberto Perez; Bortholoto, Diego F. A.; Monteiro, Lena V. S.

2012-03-01

127

Caractérisation minéralogique et microtexturale du vieillissement anthropique du minerai de fer lorrainMineralogical and microtextural characterisation of the anthropic-origin ageing of iron ore in Lorraine (France)  

NASA Astrophysics Data System (ADS)

The abandoned pillars in iron mines in Lorraine show that the oolitic ore underwent several chemical-mineralogical transformations. The first one is a rapid alteration of the diagenetic siderite and berthierine cement promoted by a bacterial flora. The oolites of goethite pack down and get loaded by deviatory-type stresses; they desquamate, get deformed and become powdery; the ore looses its cohesion. A second step, featuring recrystallisation-neoformation of berthierine in the previously formed micro-cavities, then the formation of a cavernous goethite-hematite crust, leads to a low cohesion to the crumbled ore; this anthropic-origin ageing may be one cause of mine collapsing. To cite this article: G. Dagallier et al., C. R. Geoscience 334 (2002) 455-462.

Dagallier, Guy; Grgic, Dragan; Homand, Françoise

128

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

129

Mineral chemistry of ore and hydrothermal alteration at the Sossego iron oxide–copper–gold deposit, Carajás Mineral Province, Brazil  

Microsoft Academic Search

The Sossego iron oxide–copper–gold deposit in the Carajás Mineral Province comprises two major orebodies, Sequeirinho and Sossego. Sodic alteration (albite–hematite) and sodic–calcic alteration zones represented by albite, ferro-edenite\\/hastingsite (up to 3.8 wt.% Cl), actinolite\\/magnesiohornblende, magnetite, titanite, epidote, and calcite are predominant at Sequeirinho. Magnetite bodies with envelopes of apatite-rich actinolitite were formed with the sodic–calcic event at high temperatures (~500 °C at

Lena Virgínia Soares Monteiro; Roberto Perez Xavier; Murray W. Hitzman; Caetano Juliani; Carlos Roberto de Souza Filho; Emerson de R. Carvalho

2008-01-01

130

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

131

Voidage and pressure profile characteristics of sand-iron ore-coal-FCC single-particle systems in the riser of a pilot plant circulating fluidized bed  

SciTech Connect

Hydrodynamic behaviors of single system of particles were investigated in a circulating fluidized bed (CFB) unit. Particles belonging to Geldart groups A and B like sand of various sizes (90, 300, 417, 522, 599, and 622 mu m), FCC catalyst (120 mu m), iron ore (166 and 140 {mu} m), and coal (335 and 168 {mu} m) were used to study the hydrodynamic characteristics. Superficial air velocity used in the present study ranged between 2.01 and 4.681 m/s and corresponding mass fluxes were 12.5-50 kg/(m{sup 2} s). A CFB needs the creation of some special hydrodynamic conditions, namely a certain combination of superficial gas velocity, solids circulation rate, particle diameter, density of particle, etc. which can give rise to a state wherein the solid particles are subjected to an upward velocity greater than the terminal or free fall velocity of the majority of the individual particles. The hydrodynamics of the bed was investigated in depth and theoretical analysis is presented to support the findings. Based on gas-solid momentum balance in the riser, a distinction between apparent and real voidage has been made. The effects of acceleration and friction on the real voidage have been estimated. Results indicated a 0.995 voidage for higher superficial gas velocity of 4.681. m/s.

Das, M.; Meikap, B.C.; Saha, R.K. [Indian Institute for Technology, Kharagpur (India). Dept. for Chemical Engineering

2008-06-15

132

Stability of the association fayalite + calcite within metamorphosed banded iron formations: the case of the magnetite ores of Edough massif (N-E  

E-print Network

. The main minerals of the ore bodies are magnetite, hematite, siderite, quartz, calcite, fayalite, hedenbergite and garnet, resulting from the metamorphism of siderite + calcite + quartz rocks containing

Paris-Sud XI, Université de

133

Heap bioleaching of a complex sulfide ore  

Microsoft Academic Search

The effect of pH on the bioleaching of a low-grade, black schist ore from Finland containing pyrrhotite, pyrite, pentlandite, chalcopyrite and other mineral sulfides was studied using columns containing 9.0 kg of agglomerated ore that was irrigated with nutrient supplemented surface water from the deposit at ambient temperature. Iron and sulfur-oxidizing enriched culture was used to inoculate the columns. Iron oxidation

Anna-Kaisa Halinen; Nelli Rahunen; Anna H. Kaksonen; Jaakko A. Puhakka

2009-01-01

134

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

135

Iron  

MedlinePLUS

... shows that giving iron intravenously can improve some symptoms of heart failure. It is not yet known if taking an iron supplement by mouth would help.Attention deficit-hyperactivity disorder (ADHD). Developing research shows that taking iron sulfate ( ...

136

Tracking hydrothermal alteration and mineralization in rock-forming and accessory minerals from the Lyon Mountain Granite and related iron oxide apatite (IOA) ores from the Adirondack Mountains, New York State  

NASA Astrophysics Data System (ADS)

The Lyon Mountain granite (LMG) is located in the northeastern Adirondack Mountains in New York State and hosts several low-titanium iron oxide apatite (IOA) ore deposits. The ores are predominately hosted by perthite bearing granite, which has been extensively altered to albite and microcline granite by Na and K metasomatism. This alteration results in several distinct groups of rocks that are dominated by either K or Na addition and a group composed of mixed Na and K addition. The different groups of altered perthite also lie on a trend suggestive of addition of Fe to each, consistent with a secondary mineralization origin. Previous work showed that the host rocks of the IOA ores have zircon with ~1150 Ma cores and 1060-1050 Ma rims and whole grains. This study aims to further constrain the timing of LMG emplacement, subsequent hydrothermal alteration, and Fe mineralization through geochemical analysis of the major, minor, and accessory phases and geochronology of accessory phases. SIMS analyses of zircon from several of the IOA ores reveal at least two periods of growth after LMG magmatism, at 1039 +/- 4.4 Ma and 1016 +/- 7 Ma to 1000 +/- 9 Ma. In situ EMPA and LA-ICPMS trace element analyses of the zircon rims and cores reveal that in two samples the zircon rims are enriched in rare earth elements (REE) compared to their cores, potentially pointing to a hydrothermal origin. Apatite has unusually high REE and Y concentrations (some total REE2O3 > 20 wt. % oxide and up to 8 wt. % oxide Y2O3), as does titanite, which allowed for the in situ analysis of Sm-Nd in apatite and titanite by LA-MC-ICP-MS. Initial Nd isotopic composition of both ore and host rock apatite and host rock titanite are consistent with published Adirondack initial Nd whole rock data, suggesting a local source for REE in these ores. EMPA and LA-ICPMS trace-element analyses of the major rock-forming minerals indicate that the feldspar have undergone Na-metasomatism and are depleted in REEs, perhaps signifying the "local source" and the mechanism of the REE enrichment in the LMG apatite in the IOA ores and host rocks. In contrast, the minor- and trace-element compositions of the other major rock-forming minerals (e.g., clinopyroxene and fayalite) as well as the zircon, and fluorite in the LMG have average igneous granitic trace- and minor-element compositions. To better understand the timing and origin of these post ~1050 Ma events, U-Pb ID-TIMS dating of apatite and titanite, and in situ LA-MC-ICPMS Sm-Nd analysis were done on the ore and host rock samples. Apatite dates range from 1050 to 850 Ma and titanite dates range from ~1015 to 970 Ma. There is significant age variation within samples and within grains. Titanite does not have sufficient spread for accurate Sm-Nd isochron dating and two ore-apatite samples have homogenous initial Nd isotopic and Sm-Nd elemental ratios, precluding calculation of Sm-Nd dates. A third ore sample shows a large spread in Sm-Nd and yields a Sm-Nd isochron date of ~850 Ma, in close agreement with U-Pb apatite dates. The Sm-Nd isochron and U-Pb apatite dates may reflect cooling recorded in these minerals or a younger hydrothermal mineralization event.

Buchanan, A.; Hanchar, J. M.; Steele-MacInnis, M. J.; Crowley, J. L.; Valley, P. M.; Fisher, C. M.; Fedo, C.; Piccoli, P. M.; Fournelle, J.

2012-12-01

137

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.

138

Geology of the Eymir iron mine, Edremit, Turkey  

USGS Publications Warehouse

The Eymir mine near Edremit on Turkey's Aegean coast (long 27?30'E.,1at 39?36'N.) was investigated as part of the Maden Tetkik ve Arama Enstitutsu (MTA)-U. S. Geological Survey (USGS) mineral exploration and training project, for the purpose of increasing the known mineral reserves. Geologic mapping of the mine area indicates that hematite is restricted to argillized, silicified, and pyritized dacite and possibly andesite. Hematite is present as massive replacements, impregnations, disseminations, and fracture fillings. Most of the upper part of the iron deposit consists of a breccia composed mostly of silicifiled dacite fragments in a hematite matrix. The iron deposit was apparently formed in three steps: 1. Argillation, silicification, and pyritization of the andesitic lava and dacite units as a result of a regional intrusion. 2. Intrusion of the Dere Oren dacite stock, with associated faulting, fracturing, and breccia formation at the surface. 3. Deposition of hematite by oxidation of pyrite, and transfer of iron via fractures and faults by hydrothermal or meteoric fluids. The Eymir iron deposit is a blanketlike deposit on the crest of the Sivritepe-Eymir ridge. It is 1300 meters long, 80 to 450 meters wide, and has an average thickness of 18.6 meters. Drill holes in the deposit show the iron content to range from 32.0 to 57.6 percent, and to average 46.5 percent. Most of the gangue is silica, and an arsenic impurity averaging 0.39 percent is present. Most of the deposit cannot be utilized as iron ore because of low iron content, high silica content, and high arsenic content. Ore-dressing tests have shown that it is feasible to concentrate the low-grade material, producing a concentrate having increased iron content and reduced silica content. Tests have shown also that the arsenic content of the ore can be reduced substantially by sintering. Further tests and economic feasibility studies are necessary to determine whether an economic marketable iron ore can be produced. If such studies indicate the technical and economic feasibility of utilizing all the Eymir iron deposit, detailed additional studies are recommended including: 1. A detailed drilling and sampling program to include 60 drill holes averaging 40 meters in depth and detailed sampling of mine dumps. 2. Pilot-plant testing of concentration and sintering procedures. 3. A detailed pre-investment economic feasibility study.

Jacobson, Herbert Samuel; Turet, Erdogan

1972-01-01

139

Ferronickel enrichment by fine particle reduction and magnetic separation from nickel laterite ore  

NASA Astrophysics Data System (ADS)

Ferronickel enrichment and extraction from nickel laterite ore were studied through reduction and magnetic separation. Reduction experiments were performed using hydrogen and carbon monoxide as reductants at different temperatures (700-1000°C). Magnetic separation of the reduced products was conducted using a SLon-100 cycle pulsating magnetic separator (1.2 T). Composition analysis indicates that the nickel laterite ore contains a total iron content of 22.50wt% and a total nickel content of 1.91wt%. Its mineral composition mainly consists of serpentine, hortonolite, and goethite. During the reduction process, the grade of nickel and iron in the products increases with increasing reduction temperature. Although a higher temperature is more favorable for reduction, the temperature exceeding 1000°C results in sintering of the products, preventing magnetic separation. After magnetic separation, the maximum total nickel and iron concentrations are 5.43wt% and 56.86wt%, and the corresponding recovery rates are 84.38% and 53.76%, respectively.

Tang, Xiao-hui; Liu, Run-zao; Yao, Li; Ji, Zhi-jun; Zhang, Yan-ting; Li, Shi-qi

2014-10-01

140

Ore Melting and Reduction in Silicomanganese Production  

NASA Astrophysics Data System (ADS)

The charge for silicomangansese production consists of manganese ore (often mixed with ferromanganese slag) dolomite or calcite, quartz, and in some cases, other additions. These materials have different melting properties, which have a strong effect on reduction and smelting reactions in the production of a silicomanganese alloy. This article discusses properties of Assman, Gabonese, and Companhia Vale do Rio Doce (CVRD) ores, CVRD sinter and high-carbon ferromanganese (HC FeMn) slag, and their change during silicomanganese production. The melting and reduction temperatures of these manganese sources were measured in a carbon monoxide atmosphere, using the sessile drop method and a differential thermal analysis/thermogravimetric analysis. Equilibrium phases were analyzed using FACTSage (CRCT, Montreal, Canada and GTT, Aachen, Germany) software. Experimental investigations and an analysis of equilibrium phases revealed significant differences in the melting behavior and reduction of different manganese sources. The difference in smelting of CVRD ore and CVRD sinter was attributed to a faster reduction of sinter by the graphite substrate and carbon monoxide. The calculation of equilibrium phases in the reduction process of manganese ores using FACTSage correctly reflects the trends in the production of manganese alloys. The temperature at which the manganese oxide concentration in the slag was reduced below 10 wt pct can be assigned to the top of the coke bed in the silicomanganese furnace. This temperature was in the range 1823 K to 1883 K (1550 °C to 1610 °C).

Ringdalen, Eli; Gaal, Sean; Tangstad, Merete; Ostrovski, Oleg

2010-12-01

141

Evolution of ore deposits on terrestrial planets  

NASA Technical Reports Server (NTRS)

Ore deposits on terrestrial planets materialized after core formation, mantle evolution, crustal development, interactions of surface rocks with the hydrosphere and atmosphere, and, where life exists on a planet, the involvement of biological activity. Core formation removed most of the siderophilic and chalcophilic elements, leaving mantles depleted in many of the strategic and noble metals relative to their chondritic abundances. Basaltic magma derived from partial melting of the mantle transported to the surface several metals contained in immiscible silicate and sulfide melts. Magmatic ore deposits were formed during cooling, fractional crystallization and density stratification from the basaltic melts. Such ore deposits found in earth's Archean rocks were probably generated during early histories of all terrestrial planets and may be the only types of igneous ores on Mars. Where plate tectonic activity was prevalent on a terrestrial planet, temporal evolution of ore deposits took place. Repetitive episodes of subduction modified the chemical compositions of the crust and upper mantles, leading to porphyry copper and molybdenum ores in calc-alkaline igneous rocks and granite-hosted tin and tungsten deposits. Such plate tectonic-induced mineralization in relatively young igneous rocks on earth may also have produced hydrothermal ore deposits on Venus in addition to the massive sulfide and cumulate chromite ores associated with Venusian mafic igneous rock. Sedimentary ore deposits resulting from mechanical and chemical weathering in reducing atmospheres in Archean earth included placer deposits (e.g., uraninite, gold, pyrite ores). Chromite, ilmenite, and other dense unreactive minerals could also be present on channel floors and in valley networks on Mars, while banded iron formations might underlie the Martian northern plains regions. As oxygen evolved in earth's atmosphere, so too did oxide ores. By analogy, gossans above sulfide ores probably occur on Mars, but not submarine ferromanganese nodules and crusts which have precipitated in oxygenated seawater on earth.

Burns, R. G.

1991-01-01

142

Iron  

MedlinePLUS

... several factors [ 1 , 3 , 8 , 11-15 ]. Storage levels of iron have the greatest influence on iron ... RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL). The RDA recommends the average daily intake ...

143

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

144

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

145

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

146

Modelling the long-term evolution of groundwater's quality in a flooded iron-ore mine using a reactive transport pipe network model  

E-print Network

of cases, the complexity of the mine structure and the lack of information on its hydrodynamic parameters modelling was carried out on the so-called South Basin (fig. 1). the lorraine iron-bearing deposit (10­65 m) with marly intercalations. Five mineralised levels were mined in the South Basin. the iron-bearing succession

Paris-Sud XI, Université de

147

Sources of ores of the ferroalloy metals  

USGS Publications Warehouse

Since all steel is made with the addition of alloying elements, the record of the metallic raw materials contributory to the steel industry would be far from complete without reference to the ferroalloy metals. This paper, therefore, supplements two preceding arvicles on the sources of our iron ores. The photographs, with the exception of those relating to molybdenum and vanadium, are by the author.

Burchard, E.F.

1933-01-01

148

Comparison of first order analysis and Monte Carlo methods in evaluating groundwater model uncertainty: a case study from an iron ore mine in the Pilbara Region of Western Australia  

NASA Astrophysics Data System (ADS)

The expansion of mining in the Pilbara region of Western Australia is resulting in the need to develop better water strategies to make below water table resources accessible, manage surplus water and deal with water demands for processing ore and construction. In all these instances, understanding the local and regional hydrogeology is fundamental to allow sustainable mining; minimising the impacts to the environment. An understanding of the uncertainties of the hydrogeology is necessary to quantify the risks and make objective decisions rather than relying on subjective judgements. The aim of this paper is to review some of the methods proposed by the published literature and find approaches that can be practically implemented in an attempt to estimate model uncertainties. In particular, this paper adopts two general probabilistic approaches that address the parametric uncertainty estimation and its propagation in predictive scenarios: the first order analysis and Monte Carlo simulations. A case example application of the two techniques is also presented for the dewatering strategy of a large below water table open cut iron ore mine in the Pilbara region of Western Australia. This study demonstrates the weakness of the deterministic approach, as the coefficients of variation of some model parameters were greater than 1.0; and suggests a review of the model calibration method and conceptualisation. The uncertainty propagation into predictive scenarios was calculated assuming the parameters with a coefficient of variation higher than 0.25 as deterministic, due to computational difficulties to achieve an accurate result with the Monte Carlo method. The conclusion of this case study was that the first order analysis appears to be a successful and simple tool when the coefficients of variation of calibrated parameters are less than 0.25.

Firmani, G.; Matta, J.

2012-04-01

149

3D Inversion of airborne gravity gradiomentry for iron ore exploration in Brazil Cericia Martinez,Yaoguo Li, Richard Krahenbuhl, Marco Braga  

E-print Network

of Geophysics, Colorado School of Mines Companhia Vale do Rio Doce, Brazil SUMMARY We present the 3D inversion distribution and increased information provided by multicomponent data, we expect improved con- straints, with gold and iron being two major resources produced from the region (Dor- r, 1969). The focus

150

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

151

Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide-copper-gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis  

Microsoft Academic Search

The Alvo 118 iron oxide-copper-gold (IOCG) deposit (170 Mt at 1.0 wt.% Cu, 0.3 g\\/t Au) lies in the southern sector of the Itacaúnas Shear Belt, Carajás Mineral Province, along a WNW-ESE-striking, 60-km-long shear zone, close to the contact of the ~2.76-Ga metavolcano-sedimentary Itacaiúnas Supergroup and the basement (~3.0 Ga Xingu Complex). The Alvo 118 deposit is hosted by mafic

Ignacio Torresi; Roberto Perez Xavier; Diego F. A. Bortholoto; Lena V. S. Monteiro

2011-01-01

152

Hydrothermal alteration, fluid inclusions and stable isotope systematics of the Alvo 118 iron oxide–copper–gold deposit, Carajás Mineral Province (Brazil): Implications for ore genesis  

Microsoft Academic Search

The Alvo 118 iron oxide–copper–gold (IOCG) deposit (170 Mt at 1.0 wt.% Cu, 0.3 g\\/t Au) lies in the southern sector of the\\u000a Itacaúnas Shear Belt, Carajás Mineral Province, along a WNW–ESE-striking, 60-km-long shear zone, close to the contact of the\\u000a ~2.76-Ga metavolcano-sedimentary Itacaiúnas Supergroup and the basement (~3.0 Ga Xingu Complex). The Alvo 118 deposit is hosted\\u000a by mafic and felsic metavolcanic

Ignacio Torresi; Roberto Perez Xavier; Diego F. A. Bortholoto; Lena V. S. Monteiro

153

In situ X-ray diffraction of pyrolite to 40 GPa using Kawai-type apparatus with sintered diamond anvils: possibility for the existence of iron-rich metallic particles in the lower mantle  

SciTech Connect

We investigated phase relations in pyrolite at -33--40 GPa and -1800--2150 K by in situ X-ray diffraction using Kawai-type apparatus with sintered diamond anvils. The results demonstrated that MgSiO{sub 3}-rich orthorhombic perovskite (mpv), CaSiO{sub 3}-rich cubic perovskite (cpv) and (Mg,Fe)O ferropericlase (fp) are the stable phases in pyrolite bulk composition at the conditions corresponding to the lower mantle. However, chemical analyses of a run product recovered from -34 GPa by an analytical transmission electron microscope showed the coexistence of metallic iron particles with mpv, fp, and SiO{sub 2}-rich amorphous phase. Also, Fe/Mg partitioning coefficient between mpv and fp was found to be 0.66(31), which is consistent with previous results for pyrolite bulk composition at 26--30 GPa and -1900 K. These results indicate that iron-rich metallic particles can exist in the lower mantle as a stable phase to the depth of at least -900 km.

Kubo, A.; Ito, E.; Katsura, T.; Fujino, K.; Funakoshi, K. (Hokkaido); (JASRI); (UC); (Okayama)

2008-11-12

154

Sintered soft magnetic materials. Properties and applications  

NASA Astrophysics Data System (ADS)

A comparison is presented of the characteristics and production requirements of a variety of materials used to produce sintered soft magnetic parts. These include pure iron, phosphorous-iron, silicon-iron, nickel-iron, and cobalt-iron, together with new coated materials based on encapsulated iron powders. In these bonded materials an organic and/or inorganic insulator is used to coat the metallic powder particles giving a magnetic composite. The suitability of the different materials for use in both direct and alternating current applications is reviewed, and examples are provided of their application in both the automotive and other sectors. The results of a comparative study of motors using stators and rotors based on both conventional laminated materials and the insulated iron powders are presented, in which the new materials show advantages of reduced hysteresis losses at high frequencies, and isotropy of magnetic properties. Nevertheless, the applications of these materials in electrical motors requires the modification of existing designs.

Bas, J. A.; Calero, J. A.; Dougan, M. J.

2003-01-01

155

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

156

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.  

PubMed

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 degree of separation than the DB5MS column. Polychlorinated dibenzofurans are present in significantly larger amounts in both the dust and stack emissions, and are the main contributors to the I-TEQ. Analysis using the SP2331 column for dioxins show considerable similarity to those of Bacher et al. for soot from a wood-burning fire, but differ markedly from those of Addink et al. for simulation of waste incineration. The similarities to Bacher's results are less for the dibenzofurans. Comparison of absolute concentrations with reported vapour pressures shows the retention of significant dioxin in the dust to involve mechanisms other than pure condensation. PMID:12615113

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

2003-05-01

157

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

158

The connection between iron ore formations and "mud-shrimp" colonizations around sunken wood debris and hydrothermal sediments in a Lower Cretaceous continental rift basin, Mecsek Mts., Hungary  

NASA Astrophysics Data System (ADS)

In the Early Cretaceous, the continental rift basin of the Mecsek Mts. (Hungary), was situated on the southern edge of the European plate. The opening of the North Atlantic Ocean created a dilatational regime that expanded to the southern edge of the European plate, where several extensional basins and submarine volcanoes were formed during the Early Cretaceous epoch. Permanent seaquake activity caused high swell events during which a large amount of terrestrial wood fragments entered into submarine canyons from rivers or suspended woods which had sunk into the deep seafloor. These fragments created extended wood-fall deposits which contributed large-scale flourishing of numerous burrowing thalassinid crustaceans. Twelve different thalassinid coprolite ichnospecies can be found in the Berriasian-Hauterivian volcano-sedimentary formations. According to the seladonitic crustacean burrows which associated with framboidal pyrite containing Zoophycos and Chondrites ichnofossils (i.e. a "fodinichnia" trace fossil association), the bottom water was aerobic and the pore water was anaerobic; in the latter sulfate reduction occurred. The preservation of wood fragments around thalassinid burrows can be explained by rapid sedimentation related to turbidity currents. Due to the low temperature hydrothermal circulations of seawater, large amounts of iron were released from intrusive, pillowed basaltic sills; these sills intruded into soft, water-saturated sediments containing large amounts of thalassinid excrement. In the coprolites can be found idiomorphic mineral particles originating from the basalts, and coprolites can often be found in peperitic interpillow sediments. This indicates that the life-activity of the decapoda crustaceans in many Lower Cretaceous occurrences initially preceded the first magmatic eruptions. The paroxysm of the rift volcanism took place during the Valanginian age, when some submarine volcanoes emerged above sea level, reaching a maximum height of 300 m (above sea level); from these volcanoes further terrestrial plant debris got into the basin. Hydrothermal vents, which periodically occurred around basaltic bodies until the Hauterivian, could have contributed to the creation of favourable temperature or nutritional conditions for some decapoda crustaceans - e.g the recently described new callianassid (Nihonotrypaea thermophila), which is known only from hydrothermally infuenced habitats. Around the intrusive pillow basalts, hydrothermal circulation of oxygenated seawater occured and thick seladonitic and goethitic fills formed along the cracks and cavities of pillowed basalts. When oxidized, sulfate-rich fluids passed into the crustacean coprolite-rich, reductive and anaerobic interpillow sediments, these fluids underwent an intensive sulfate reduction. This was primarily due to termophil sulfate reducers which as proved by the negative sulfur isotope values (- 35.9‰ and - 28.0‰ ? 34S) of sulfidic hydrothermal chimneys which contain framboidal pyrite and which were formed between the pillow basalts. The largest chimney structure reached a height of 1 m, with a mass of about 150 kg. The sulfide phase is characterized by Mo enrichments up to 511 ppm. The fluid inclusion measurements from the calcitic precipitations of the sulfide chimneys indicate low temperature (~ 129 °C) hydrothermal activity, and the salinity of the primary fluid inclusions proves the seawater origin of the hydrothermal fluids. In some thalassinid crustacean coprolite rich interpillow sediments and in the cracks of some hydrothermal calcite, there is the presence of black, lustrous bitumine (gilsonite) which is the distillation product of hydrothermal petroleum formed mainly by the coprolites. Hydrothermal circulations of oxygenated seawater caused subsequent oxidation of the sulfidic, interpillow sediments and chimneys; these were altered to form goethite. Due to the short-period of the hydrothermal activity among the intrusive pillowed basalts, sulfidized interpillow sediments could not be oxidized completely. The text

Jáger, Viktor; Molnár, Ferenc; Buchs, David; Kod?ra, Peter

2012-09-01

159

Magmatogenic manganese ores of the South Minusa Intermontane Trough  

NASA Astrophysics Data System (ADS)

The first data on the mineral composition and formation conditions of manganese ore at the Chapsordag and Malosyrsky deposits in the Askiz ore district of Khakassia are integrated and systematized. The detailed mineralogical mapping of the deposits has been carried out. The identification of minerals and examination of the ore microstructure were performed with optical microscopy in transmitted and reflected light and using SEM/EDS, EMPA, XRD, IRS, and other methods. It was established that the ore mineralization is spatially and genetically related to the Early Devonian magmatism and accompanying hydrothermal activity and metasomatism. Syngenetic braunite was detected for the first time in elevated amounts reaching an economic level in the devitrified groundmass of volcanic rocks, in cement of lava breccia, and in fragments in pyroclastic rocks. By analogy with iron deposits, this magmatogenic type of manganese mineralization is regarded as ore lavas and tuffs combined with metasomatic and hydrothermal mineral assemblages into a strata-bound orebearing complex and as a source of hydrothermal metasomatic ore. The elevated Mn content in magmatic melts of the Early Devonian trachybasalt-trachyandesite-trachydacite association is caused by assimilation of Riphean and Lower Cambrian high-Mn carbonate sequences in crustal magma chambers. In contours of economic orebodies, the hydrothermal economic ore is recognized as sites of massive, patchy and impregnated, brecciated, stringer-disseminated, and disseminated varieties. High-grade massive ore occurs as stratiform and branching bodies up to 1.5 m thick and a few tens of meters long and as smaller pocketlike bodies. Braunite and pyrolusite (polianite) are major ore minerals varying in size, degree of crystallinity, and character of intergrowths with associating minerals. Gangue minerals include carbonates, sulfates, albite, quartz, chlorite, actinolite, piemontite, and okhotskite, a Mn-pumpellyite identified in Russia for the first time and studied in detail in this paper. The veined hydrothermal ore is classified as a calcite-barite-pyrolusite type. The crystallization temperature of hydrothermal metasomatic ore is estimated at 350-180°C; oxygen fugacity is above the hematite-magnetite buffer. The surface of high-grade ore is encrusted with supergene goethite-hydrogoethite, chalcedony-hematite, and pyrolusite-psilomelane crusts and veinlets (less than 1% of the bulk ore mass). The data obtained facilitate prospecting for high-quality manganese ore at walls of superimposed rifts in fold regions, including large economic manganese concentrations in the form of ore lavas and tuffs as products of solidification of metalliferous melt.

Kassandrov, E. G.; Mazurov, M. P.

2009-10-01

160

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

161

METALLURGICAL PROCESSING OF URANIUM ORES  

Microsoft Academic Search

A process for concentrating U values in ores before processing for U ; recovery is offered. Raw ore is crushed in rubber-lined equipment and wetted to ; prevent dust loss. The crushed ore passes then to an attrition mill where it is ; conditioned for the first flotation (coal tar creosote collector-pine derivative ; frothing reagent) to remove carbonaceous material.

Dering

1959-01-01

162

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

163

Sintering of Tin Powder  

Microsoft Academic Search

MOST powdered metals will sinter together appreciably when heated to a temperature which, in the absence of extraneous factors, is about three-quarters of their absolute melting point; metals of low melting point tend to be exceptions, however, to this generalization in that they can be heated nearly to their melting point before sintering takes place. There is no evidence, in

R. F. Smart; E. C. Ellwood

1958-01-01

164

Ore-fluid evolution at the Getchell Carlin-type gold deposit, Nevada, USA  

USGS Publications Warehouse

Minerals and fluid-inclusion populations were examined using petrography, microthermometry, quadrupole mass-spectrometer gas analyses and stable-isotope studies to characterize fluids responsible for gold mineralization at the Getchell Carlin-type gold deposit. The gold-ore assemblage at Getchell is superimposed on quartz-pyrite vein mineralization associated with a Late-Cretaceous granodiorite stock that intruded Lower-Paleozoic sedimentary rocks. The ore assemblage, of mid-Tertiary age, consists of disseminated arsenian pyrite that contains submicrometer gold, jasperoid quartz, and later fluorite and orpiment that fill fractures and vugs. Late ore-stage realgar and calcite enclose ore-stage minerals. Pre-ore quartz trapped fluids with a wide range of salinities (1 to 21 wt.% NaCl equivalent), gas compositions (H2O, CO2, and CH4), and temperatures (120 to >360??C). Oxygen- and hydrogen-isotope ratios indicate that pre-ore fluids likely had a magmatic source, and were associated with intrusion of the granodiorite stock and related dikes. Ore-stage jasperoid contains moderate salinity, aqueous fluid inclusions trapped at 180 to 220??C. Ore fluids contain minor CO2 and trace H2S that allowed the fluid to react with limestone host rocks and transport gold, respectively. Aqueous inclusions in fluorite indicate that fluid temperatures declined to ~175??C by the end of ore-stage mineralization. As the hydrothermal system collapsed, fluid temperatures declined to 155 to 115??C and realgar and calcite precipitated. Inclusion fluids in ore-stage minerals have high ??D(H2O) and ??18O(H2O) values that indicate that the fluid had a deep source, and had a metamorphic or magmatic origin, or both. Late ore-stage fluids extend to lower ??D(H2O) values, and have a wider range of ??18O(H2O) values suggesting dilution by variably exchanged meteoric waters. Results show that deeply sourced ore fluids rose along the Getchell fault system, where they dissolved carbonate wall rocks and deposited gold-enriched pyrite and jasperoid quartz. Gold and pyrite precipitated together as H2S in the ore fluids reacted with iron in the host rocks. As ore fluids mixed with local aquifer fluids, ore fluids became cooler and more dilute. Cooling caused precipitation of ore-stage fluorite and orpiment, and late ore-stage realgar. Phase separation and/or neutralization of the ore fluid during the waning stages of the hydrothermal ore system led to deposition of late ore-stage calcite.

Cline, J.S.; Hofstra, A.A.

2000-01-01

165

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

166

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

167

Geology, geochemistry and sulfur isotope composition of the Late Proterozoic Jingtieshan (Superior-type) hematite-jasper-barite iron ore deposits associated with stratabound Cu mineralization in the Gansu Province, China  

Microsoft Academic Search

The Jingtieshan deposit occurs in a Precambrian tectonic-stratigraphic terrane within the Northern Qilian Caledonian Orogen,\\u000a and is generally considered as a Superior-type iron formation. The deposit is characterized by Fe-Si-Ba and Cu mineralization\\u000a and consists of two types of orebodies, an upper jasper-barite-iron deposit and a lower copper sulfide deposit. The iron orebodies\\u000a occur as independent stratigraphic layers concordant within

H. Sun; J. Wu; P. Yu; J. Li

1998-01-01

168

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

169

Hydrothermal Mobilization and Enrichment of Iron in the Iron Deposits of the Middle-Lower Yangtze Valley District.  

National Technical Information Service (NTIS)

There are two main types of iron deposits in the Middle-Lower Yangtze Valley district. Both of them underwent post-magmatic hydrothermal processes during ore formation. Iron in the hydrothermal ore bodies was derived largely through mobilization from subs...

L. Gu H. Ruan

1994-01-01

170

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

171

OBLIQUE/EXTERIOR VIEW, LOOKING NORTHEAST, WITH SINTERING PLANT RUINS AND TRACES ...  

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

OBLIQUE/EXTERIOR VIEW, LOOKING NORTHEAST, WITH SINTERING PLANT RUINS AND TRACES OF L. & N. RAILROAD EXTENDING THROUGH GRACE'S GAP TOWARD THE BIRMINGHAM CITY CENTER. - Republic Steel, Spaulding Red Ore Mine (Ruins), Spanning Grace's Pass at Louisville & Nashville Railroad, Birmingham, Jefferson County, AL

172

Effect of attrition milling on the reaction sintering of silicon nitride  

NASA Technical Reports Server (NTRS)

Silicon powder was ground in a steel attrition mill under nitrogen. Air exposed powder was compacted, prefired in helium, and reaction sintered in nitrogen-4 v/o hydrogen. For longer grinding times, oxygen content, surface area and compactability of the powder increased; and both alpha/beta ratio and degreee of nitridation during sintering increased. Iron content remained constant.

Herbell, T. P.; Glasgow, T. K.; Yeh, H. C.

1978-01-01

173

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

174

Sintering Theory and Practice  

NASA Astrophysics Data System (ADS)

Although sintering is an essential process in the manufacture of ceramics and certain metals, as well as several other industrial operations, until now, no single book has treated both the background theory and the practical application of this complex and often delicate procedure. In Sintering Theory and Practice, leading researcher and materials engineer Randall M. German presents a comprehensive treatment of this subject that will be of great use to manufacturers and scientists alike. This practical guide to sintering considers the fact that while the bonding process improves strength and other engineering properties of the compacted material, inappropriate methods of control may lead to cracking, distortion, and other defects. It provides a working knowledge of sintering, and shows how to avoid problems while accounting for variables such as particle size, maximum temperature, time at that temperature, and other problems that may cause changes in processing. The book describes the fundamental atomic events that govern the transformation from particles to solid, covers all forms of the sintering process, and provides a summary of many actual production cycles. Building from the ground up, it begins with definitions and progresses to measurement techniques, easing the transition, especially for students, into advanced topics such as single-phase solid-state sintering, microstructure changes, the complications of mixed particles, and pressure-assisted sintering. German draws on some six thousand references to provide a coherent and lucid treatment of the subject, making scientific principles and practical applications accessible to both students and professionals. In the process, he also points out and avoids the pitfalls found in various competing theories, concepts, and mathematical disputes within the field. A unique opportunity to discover what sintering is all about--both in theory and in practice What is sintering? We see the end product of this thermal process all around us--in manufactured objects from metals, ceramics, polymers, and many compounds. From a vast professional literature, Sintering Theory and Practice emerges as the only comprehensive, systematic, and self-contained volume on the subject. Covering all aspects of sintering as a processing topic, including materials, processes, theories, and the overall state of the art, the book Offers numerous examples, illustrations, and tables that detail actual processing cycles, and that stress existing knowledge in the field Uses the specifics of various consolidation cycles to illustrate the basics Leads the reader from the fundamentals to advanced topics, without getting bogged down in various mathematical disputes over treatments and measurements Supports the discussion with critically selected references from thousands of sources Examines the sintering behavior of a wide variety of engineered materials--metals, alloys, oxide ceramics, composites, carbides, intermetallics, glasses, and polymers Guides the reader through the sintering processes for several important industrial materials and demonstrates how to control these processes effectively and improve present techniques Provides a helpful reference for specific information on materials, processing problems, and concepts For practitioners and researchers in ceramics, powder metallurgy, and other areas, and for students and faculty in materials science and engineering, this book provides the know-how and understanding crucial to many industrial operations, offers many ideas for further research, and suggests future applications of this important technology. This book offers an unprecedented opportunity to explore sintering in both practical and theoretical terms, whether at the lab or in real-world applications, and to acquire a broad, yet thorough, understanding of this important technology.

German, Randall M.

1996-01-01

175

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

176

Sintering of Lunar and Simulant Glass  

NASA Technical Reports Server (NTRS)

Most oxygen-extraction techniques are temperature-dependent, with higher temperatures resulting in higher oxygen yield. An example is hydrogen reduction, in which the optimum process temperature is 1050 C. However, glass-rich lunar soil begins to show the effects of sintering at temperatures of 900 C or lower. Sintering welds particles together due to viscous relaxation of the glass in the sample. One approach to avoid problems related to sintering, such as difficulty in removing waste material from the reactor, is to keep the soil in motion. One of several methods being studied to accomplish this is fluidized-bed processing techniques, in which the grains are kept in motion by the action of flowing reductant gas. The spent material can be removed from the chamber while still fluidized, or the fluidizing motion can continue until the material has cooled below approx. 500 C. Until end-to-end prototypes are built that can remove the heated soil, the most practical option is to keep the bed fluidized while cooling the waste material. As ISRU technology advances, another option will become valuable, which is to intentionally sinter the material to a great enough extent that it becomes a brick. The free iron in lunar soil is magnetic, and ferromagnetic bricks can be manipulated by robotic systems using electromagnetic end effectors. Finally, if an electromagnetic field is applied to the soil while the brick is being formed, the brick itself will become a magnet. This property can be used to create self-aligning bricks or other building materials that do not require fasteners. Although sintering creates a challenge for early lunar surface systems, knowledge gained during prototype development will be valuable for the advanced lunar outpost.

Cooper, Bonnie L.

2007-01-01

177

Sintering of Synroc D  

SciTech Connect

Sintering has been investigated as a method for the mineralization and densification of high-level nuclear defense waste powder. Studies have been conducted on Synroc D composite powder LS04. Optimal densification has been found to be highly dependent on the characteristics of the starting material. Powder subjected to milling, which was believed to reduce the level of agglomeration and possibly particle size, was found to densify better than powder not subjected to this milling. Densities of greater than 95% of theoretical could be achieved for samples sintered at 1150 to 1200/sup 0/C. Mineralogy was found to be as expected for Synroc D for samples sintered in a CO/sub 2//CO atmosphere where the Fe/sup +2//Fe/sup +3/ ratio was maintained at 1.0 to 5.75. In a more oxidizing, pure CO/sub 2/ atmosphere a new phase, not previously identified in Synroc D, was found.

Robinson, G.

1982-06-01

178

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

179

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

180

Sintered metal sand screen  

SciTech Connect

This patent describes a well screen for separating unconsolidated material out of inflowing well fluid in water, oil, gas and recovery wells. It comprises a tubular, porous body of sintered powdered metal, the tubular well screen body having an external surface which has been smoothed by electropolishing.

Arterbury, B.A.; Spangler, J.E.

1992-02-18

181

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  

Microsoft Academic Search

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

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

2008-01-01

182

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...

183

Sintered composite filter  

DOEpatents

A particulate filter medium formed of a sintered composite of 0.5 micron diameter quartz fibers and 2 micron diameter stainless steel fibers is described. Preferred composition is about 40 vol.% quartz and about 60 vol.% stainless steel fibers. The media is sintered at about 1100/sup 0/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/sup 0/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, W.

1986-05-02

184

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

185

A Visual Insight into the Oxidation of Sulfide Minerals During Bioleaching and Chemical Leaching of a Complex Ore  

Microsoft Academic Search

A scanning electron microscope (SEM) study was performed to provide a visual insight into the oxidation patterns of sulfide minerals during chemical and bacterial leaching of a complex ore for 3 days. The mineral grains were studied under SEM before and after bacterial and chemical leaching with or without the addition of ferrous iron to generate ferric iron in situ

H. Deveci; T. Ball

2010-01-01

186

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

187

Reactive sintering of SiC  

NASA Technical Reports Server (NTRS)

Investigation of the sintering processes involved in the sintering of SiC revealed a connection between the types and quantities of sintering additives or catalysts and densification, initial shrinkage, and weight loss of the sintered SiC material. By sintering processes, is meant the methods of mass transport, namely solid vapor transport and grain boundary diffusion.

Kim, Y. W.; Lee, J. G.

1984-01-01

188

Low-temperature sintering of Ni?Zn?Cu ferrite and its permeability spectra  

NASA Astrophysics Data System (ADS)

The low-temperature sintering of Ni?Zn?Cu ferrite was investigated using the usual ceramic technique. We found that the post-sintering density and the permeability of the sintered ferrite are strongly affected by the size of the starting oxide powders and the pre-sintering temperature. The most effective method of preparing high-permeability ferrite is to utilize fine particles of iron oxide and to calcine at about 800°C. Sintered ferrite with a density greater than 4.5 g/cc and a permeability at 10 MHz greater than 200 can be obtained at a relatively low sintering temperature (about 900°C). This condition is suitable for producing multilayer chip inductors. Additionally, the complex permeability of sintered ferrite was well-described as the summation of the spin rotational contribution and the domain wall motion component. The permeability in the 100 MHz region was determined mainly by the spin rotation magnetizing mechanism and then it depended only on the ferrite volume loading, i.e. the post-sintering density. However, the contribution of the domain wall motion was not negligible in the 10 MHz region and the domain wall contribution was controlled both by altering the post-sintering density and by varying the ferrite grain size.

Nakamura, T.

1997-04-01

189

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. PMID:24723798

Wang, Xingrun; Zhang, Fengsong; Nong, Zexi

2014-01-01

190

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

191

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...

192

Ore Potential of the Olkiluoto District (Finland).  

National Technical Information Service (NTIS)

The criticalness of potential future ore occurrences and ore mining in and around the area of the planned Olkiluoto repository for low- and medium-level radioactive waste was analysed. Judging by the theories of ore formation and the statistics based on t...

P. Ilveskivi, H. Niini

1985-01-01

193

Towards Zero CO2 Continuous Steelmaking Directly from Ore  

NASA Astrophysics Data System (ADS)

In-line continuous processing of high-grade hematite ore (crushed ore or fines) with a pure hydrogen reductant is assessed. An appraisal is made of the rate controlling mechanisms involved in the reduction of a pure layer of molten wustite being transported by floating on a molten carrier iron carbon-free medium at temperatures just in excess of the iron melting point. Published research clearly indicates that under these conditions the kinetics are principally controlled by molecular gaseous diffusion. Thus, the rate is essentially not influenced by total gas pressure above 1 atmosphere. Accordingly, on safety grounds it is recommended that high pressure should not be used for hydrogen steelmaking in the future, but the operation should be conducted close to atmospheric pressure with low pressure steam encapsulation of the plant items involved. Using hydrogen as the reductant means that sub-surface nucleation of CO bubbles cannot disrupt continuous processing. The operation is then no different to processing a normal liquid phase. The off-gases from the reduction zone of a melt circulation loop are super-clean and only contaminated with iron vapor. Accordingly, the best available technology becomes available for energy conservation without risk of non-fusible solids deposition. The net result is that the energy requirements are expected to be superior to other potential processes.

Warner, Noel A.

2014-08-01

194

Ore Geology and Mineral Resources  

Microsoft Academic Search

Analysis of research work on Ore geology and mineral resources, during the report period (2004-2008) reveals equitable outputs for the precious metals (Au, Ag, PGE), atomic minerals (U), and base metals (Cu, Pb, Zn), modest efforts made for Cr, Sn, W and some rare metals, with less emphasis on Fe and Mn. Again, like the previous reports, the non metals

BISWAJIT MISHRA; MIHIR DEB

195

DETERMINATION OF THORIUM IN ORES  

Microsoft Academic Search

A procedure for the determination of thorium in ores is as follows: The ; sample is decomposed with perchloric and hydrofluoric acids and is dissolved in ; hydrochloric acid. The residue is reserved. Sodium hydroxide precipitation is ; made and the precipitate is dissolved in nitric acid (solution A). The reserved ; residue is then used with sodium peroxide and

S. Sekine; T. Mochizuki

1961-01-01

196

Gaseous reduction of laterite ores  

NASA Astrophysics Data System (ADS)

Lateritic nickel ores have been reduced under laboratory conditions. The reduction experiments were carried out at temperatures from 500 °C to 1100 °C in a horizontal tube furnace using various mixtures of H2 and CO2. The hydrogen evolution method was used to measure the degree of metallization of the reduced ore. It was found that the rate of reduction was very low at 500 °C but then increased rapidly upon heating the ore to 600 °C. The percent metallics increased with increasing H2 to CO2 ratios in the reducing gas. At temperatures between 600 °C and 1100 °C, a H2 to CO2 ratio of 3 leads to the formation of 5 to 6 pct metallics in the reduced calcine was shown. Heating the ore in air or nitrogen prior to reduction does not affect the degree of metallization. A H2 to CO2 ratio of at least 4 is required to obtain a ferronickel product analyzing 36 pct nickel if no further reduction is carried out during the subsequent smelting operation.

Utigard, T.; Bergman, R. A.

1993-04-01

197

Computer simulation of nanoparticle sintering  

NASA Astrophysics Data System (ADS)

Molecular Dynamics techniques were used to simulate Cu nanoparticle arrays at different temperatures. New potential was modified to provide the reliable representation of Cu nanoparticle systems. Different sets of simulation arrays were used to study the different stages of nanoscale sintering. The results are summarized as follows: (1) Three new mechanisms were found to contribute significantly to the early stage sintering. They are plastic deformation, mechanical rotation and amorphisation-recrystallization. Mechanical rotation, caused by large atomic forces relative to the particle masses, appeared to be almost independent of temperature. Plastic deformation was found to involved via dislocation generation and transmission and appeared almost athermal as well. Amorphisation of sub-critical grains was found to significantly increase the diffusion rates in the affected regions and dramatically accelerate the sintering kinetics and grain boundary kinetics. A high-speed plastic deformation, twinning, was found in the nanosphere sintering and resulted in sintered clusters with multiply twinned particles. (2) Only two of the six classical mechanisms (surface diffusion and grain boundary diffusion) were found to be important for nanoscale sintering. However, the processes were considerably accelerated by strong interatomic attractions, and depended only weakly on temperature. These "force-driven" diffusions are different from the standard "random walk" ones, and need to be treated quite differently. (3) Large array simulations are made possible by using pressure clamp technique. The effect of grain size distribution, temperature and pressure were investigated. Residual pores were found playing important role in fully densification. (4) Classical sintering laws, such as Herring's law, were found invalid to describe nanoscale sintering due to the facts that a series of mechanisms co-exists and come intro play in an overlapping manner in a short period of time. (5) Sintering Diagrams, estimated from the simulation results, appear to be differently from the ones that are predicted by the classical theory.

Zeng, Pei

198

[Structural changes in mineral phases and environmental release behavior of arsenic during sintering of arsenic-containing waste].  

PubMed

An experimental work was carried out to investigate the effect of sintering temperature on arsenic volatility, arsenic leaching of the sinter and structural changes in mineral phases of arsenic in the sinter. The raw materials were shaped under the pressure of 10 MPa and sintered at 1 000-1 350 degrees C for 60 min with the air flow rate of 2 000 mL x min(-1). The results showed that there was little impact between the volatilization of arsenic before and after sintering, and arsenic fixed-rate remained above 90%, however, the sintering temperature had an important influence on the leaching concentration of arsenic. When sintering temperature was lower than 1 000 degrees C, FeAsS was oxidized into calcium arsenate, aluminum arsenate, and iron-arsenate. Ca3 (AsO4)2 was the main compound, and the release of arsenic leaching was high. When sintering temperature was up to 1 200 degrees C, the arsenic was surrounded by a glass matrix and became chemically bonded inside the matrix. Arsenates can be converted into silicoarsenates during sintering, which led to the leaching of arsenic was significantly lower. Considering the product's environmental safety, the best sintering temperature was 1 200 degrees C. PMID:23379173

Wang, Xing-Run; Nong, Ze-Xi; Wang, Qi

2012-12-01

199

Effect of anions on selective solubilization of zinc and copper in bacterial leaching of sulfide ores.  

PubMed

Bacterial leaching of sulfide ores using Thiobacillus ferrooxidans, Thiobacillus thiooxidans, or a combination of the two was studied at various concentrations of specific anions. Selective zinc and copper solubilization was obtained by inhibiting iron oxidation without affecting sulfur/sulfide oxidation. Phosphate reduced iron solubilization from a pyrite (FeS(2))-sphalerite (ZnS) mixture without significantly affecting zinc solubilization. Copper leaching from a chalcopyrite (CuFeS(2))-sphalerite mixture was stimulated by phosphate, whereas chloride accelerated zinc extraction. In a complex sulfide ore containing pyrite, chalcopyrite, and sphalerite, both phosphate and chloride reduced iron solubilization and increased copper extraction, whereas only chloride stimulated zinc extraction. Maximum leaching obtained was 100% zinc and 50% copper. Time-course studies of copper and zinc solubilization suggest the possibility of selective metal recovery following treatment with specific anions. PMID:10861398

Harahuc, L; Lizama, H M; Suzuki, I

2000-07-20

200

Method for beneficiating coal ore  

SciTech Connect

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 beneficiated using a water-trichlorofluoromethane emulsion as the parting medium in a sink-float separation process.

Irons, S.D.

1983-03-15

201

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

202

Iron and Iron Deficiency  

MedlinePLUS

... other types of foods eaten at the same meal. Foods containing heme iron (meat, poultry, and fish) ... heme iron absorption when eaten at the same meal. Substances (such as polyphenols, phytates, or calcium) that ...

203

Compacted graphite iron: Cast iron makes a comeback  

NASA Astrophysics Data System (ADS)

Although compacted graphite iron has been known for more than four decades, the absence of a reliable mass-production technique has resulted in relatively little effort to exploit its operational benefits. However, a proven on-line process control technology developed by SinterCast allows for series production of complex components in high-quality CGI. The improved mechanical properties of compacted graphite iron relative to conventional gray iron allow for substantial weight reduction in gasoline and diesel engines or substantial increases in horsepower, or an optimal combination of both. Concurrent with these primary benefits, CGI also provides significant emissions and fuel efficiency benefits allowing automakers to meet legislated performance standards. The operational and environmental benefits of compacted graphite iron together with its low cost and recyclability reinforce cast iron as a prime engineering material for the future.

Dawson, S.

1994-08-01

204

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

205

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

206

Rare earth-iron-boron-permanent magnets  

SciTech Connect

This patent describes a neodymium-iron-boron permanent magnet containing added rare earth oxide. It is prepared by the method of comprising the steps of: mixing together components: a particulate alloy consisting essentially of neodymium, iron, cobalt, and boron; and a particulate rare earth oxide selected from the group consisting of gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, and mixtures thereof; aligning magnetic domains of the mixture in a magnetic field; compacting the aligned mixture to form a shape; sintering the compacted shape; and annealing the sintered shape.

Ghandehari, M.H.

1990-08-28

207

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

208

Iron versus Copper II. Principles and Applications in Bioinorganic Chemistry.  

ERIC Educational Resources Information Center

Discusses the differences between iron and copper. Describes various aspects of the behaviors of these two elements, including those of biological and environmental significance. Addresses the evolution of the atmosphere and sedimentary ore formation, the phylogeny of iron and copper, and some anthropological notes regarding the use of the metals.…

Ochiai, Ei-Ichiro

1986-01-01

209

Optimization of flotation variables for the recovery of hematite particles from BHQ ore  

NASA Astrophysics Data System (ADS)

The technology for beneficiation of banded iron ores containing low iron value is a challenging task due to increasing demand of quality iron ore in India. A flotation process has been developed to treat one such ore, namely banded hematite quartzite (BHQ) containing 41.8wt% Fe and 41.5wt% SiO2, by using oleic acid, methyl isobutyl carbinol (MIBC), and sodium silicate as the collector, frother, and dispersant, respectively. The relative effects of these variables have been evaluated in half-normal plots and Pareto charts using central composite rotatable design. A quadratic response model has been developed for both Fe grade and recovery and optimized within the experimental range. The optimum reagent dosages are found to be as follows: collector concentration of 243.58 g/t, dispersant concentration of 195.67 g/t, pH 8.69, and conditioning time of 4.8 min to achieve the maximum Fe grade of 64.25% with 67.33% recovery. The predictions of the model with regard to iron grade and recovery are in good agreement with the experimental results.

Rath, Swagat S.; Sahoo, Hrushikesh; Das, B.

2013-07-01

210

The origin of Cu/Au ratios in porphyry-type ore deposits.  

PubMed

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. PMID:12052953

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

2002-06-01

211

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

212

The room temperature fracture strength of sintered UO 2 rings containing deliberately introduced impurities  

Microsoft Academic Search

A ring test has been used to measure the room temperature fracture strength of sintered UO2 and of UO2 deliberately doped with either silica, calcium oxide or iron oxide. The maximum observed flaw size and the minimum measured fracture strength in a group of nominally identical specimens was found to be related for some of the materials tested. It is

J. B. Ainscough; P. F. Messer

1976-01-01

213

An investigation into the prospects of arsenic(v) removal from contaminated groundwater using untreated bauxite ore  

Microsoft Academic Search

Steady-state experiments were conducted on arsenic (V) removal from contaminated groundwater using two different grades of bauxite ore. The materials considered were refractory grade bauxite (RB) with high alumina and low iron content and feed bauxite (FB) with moderate alumina and high iron content. Adsorption studies were carried out for different parameters such as pH, adsorbent dosage, As(V) concentration and

Debasish Mohapatra; Debaraj Mishra; Gautam Roy Chaudhury; Radhanath Prasad Das

2007-01-01

214

Low temperature sintering of PNSZT.  

SciTech Connect

Pb-based ferroelectrics are useful because of their large dielectric constants, high polarization values, and strong piezoelectric coefficients, but typically require sintering temperatures >1200 C, which leads to loss of the volatile Pb cation and necessitates the use of Pt electrodes for cofired parts. Reduced sintering temperatures can minimize lead loss and enable the use of cheaper electrodes, but must not sacrifice electrical performance. A systematic study of dopants to lower the sintering temperature of PNSZT (Pb0.992 (Zr0.815 Ti0.05 Sn0.135)0.9845 Nb0.155 O3) led to densities greater than 98.5% of theoretical at temperatures as low as 1100 C with as little as 0.2 wt% of a Pb glass additive or as high as 98% at 900 C with Cu2O additions with equivalent electrical properties to undoped materials.

Young, Amanda L.; Zschiesche, Dale J.; Moore, Roger Howard; Roesler, Alexander William; Hutchinson, Michael Andrew

2009-01-01

215

Radiometric Sorting of Rio Algom Uranium Ore.  

National Technical Information Service (NTIS)

An ore sample of about 0.2 percent uranium from Quirke Mine was subjected to radiometric sorting by Ore Sorters Limited. Approximately 60 percent of the sample weight fell within the sortable size range: -150 + 25 mm. Rejects of low uranium content (<0.01...

M. A. Cristovici

1983-01-01

216

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

217

Rb-Sr dating of sphalerites from Tennessee and the genesis of Mississippi Valley type ore deposits  

Microsoft Academic Search

MISSISSIPPI Valley type (MVT) ore deposits commonly consist of some combination of lead, zinc and iron sulphides accompanied by barite, fluorite, dolomite and calcite. They are thought to form by fluid expulsion from sedimentary successions1-3,but their exact origin has remained controversial because of the scarcity of reliable geochronological data. In a recent and widely quoted model the MVT deposits of

Shun'ichi Nakai; Alex N. Halliday; Stephen E. Kesler; Henry D. Jones

1990-01-01

218

Measuring Elastic Modulus of Sintered Metal  

NASA Technical Reports Server (NTRS)

Technique minimizes effect of substrate on thin sintered coating. Uniaxial tension test yields approximate value for elastic modulus of sintered material on thin substrate. Electrode composed of central perforated nickel plated steel sheet about 4 mils (0.1mm) thick, coated on each face by porous sintered nickel about 8 mils (0.2mm) thick.

Fedors, R. F.; Eastman, A. F.

1983-01-01

219

Effect of calcination on sintering of hydroxyapatite  

Microsoft Academic Search

Four different temperatures (700–1000 °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

Horng Yih Juang; Min Hsiung Hon

1996-01-01

220

SINTERING OF NASCENT CALCIUM OXIDE  

EPA Science Inventory

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 area of 104 sq m/g. The rat...

221

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

222

Effect of microstructure changes on magnetic properties of spark plasma sintered Nd-Fe-B powders  

NASA Astrophysics Data System (ADS)

In this study the SPS method was applied for low RE content (8,5% at.) and high RE content (13,5 % at.) MQ powders. The powders were sintered in a wide range of temperature, for 5 min., under pressure of 35 MPa. The low RE content grade, densified reluctantly and gained the density close to the theoretical value only for 850 °C. The coercivity decreased gradually with increasing sintering temperature. On the other hand, the densification of the higher RE content grade powder occurred much easier and the coercivity, close to the theoretical value, was achieved already at 650 °C. The coercivity of this material also decreased with increasing sintering temperature. Microstructural studies revealed that the SPS sintering process leads to partial decomposition of the Nd2Fe14B phase. The proportion of the RE-rich and iron phases increases parallel to the increasing sintering temperature. On the basis of the current results one can conclude that fabrication of high density MQ powders based magnets by the SPS method is possible, however the powders having higher RE content should be used for this purpose and the sintering temperature as low as possible, related to density, should be kept.

Kaszuwara, W.; Leonowicz, M.; Michalski, B.; Lis, M.

2013-01-01

223

Studies on sintering process of synthetic hydroxyapatite.  

PubMed

In this study the effect of sintering process in different temperatures on microstructure and morphological properties of sintered hydroxyapatite (HAp) was investigated. HAp powder was prepared by wet precipitation method from following reagents: Ca(OH)2 + H3PO4 in an alkaline conditions. Thermal analysis (TA), X-Ray diffraction method (XRD), FT-IR spectrometry (FT-IR) and scanning electron microscopy (SEM) were used to elaborate the phase composition and properties of sintered HAp samples and raw HAp powder as well. The total and apparent density and total porosity of sintered compacts, shrinkage and weight loss during the sintering were also measured. The results show that there is a difference in sintering behavior of synthetic hydroxyapatites depending on sintering temperature. The main differences refer to the loss of mass, shrinkage, changes in porosity and density of the investigated materials. PMID:24432345

Malina, Dagmara; Biernat, Kamila; Sobczak-Kupiec, Agnieszka

2013-01-01

224

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

225

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

226

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

227

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

228

Non-Sintered Nickel Electrode  

DOEpatents

A non-sintered nickel electrode contains a conductive support and a paste comprising an electrochemically active material containing nickel hydroxide and a binder which is a mixture of an elastomer and a crystalline polymer. The proportion of the elastomer is in the range 25% to 60% by weight of the binder and the proportion of the crystalline polymer is in the range 40% to 75% by weight of the binder.

Bernard, Patrick (Massy, FR); Dennig, Corinne (Asnieres sur Seine, FR); Cocciantelli, Jean-Michel (Bordeaux, FR); Alcorta, Jose (Bordeaux, FR); Coco, Isabelle (Dax, FR)

2002-01-01

229

Energy Consumption and Potential for Energy Conservation in the Steel Industry  

E-print Network

, April 22-25, 1979 IRON ORE REDUCTION STEELMAKING PRIMARY CONVERSION HOT ROLLING FINISHING SIMPLIFIED FLOW SHEET STEEL PRODUCTION PROCESSES Iron Ore & Wastes , Agg lomerating Pellets Ore & Flux Coal ~ " Sinter - Blast ~ Coke Furnaces... in the world are identical. In the iron-ore reduction process there are three separate operations: blast furnaces, ore agglomerating facilities other than the mine-site preparation previously mentioned, and coke ovens -- the blast furnaces being the central...

Hughes, M. L.

1979-01-01

230

Method for preparing rare earth-iron-boron permanent magnets  

SciTech Connect

This patent describes a method for producing a permanent magnet. It comprises: mixing together the components; a particulate alloy consisting essentially of neodymium, iron, and boron; particulate aluminum; and a particulate rare earth oxide selected from the group consisting of gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, and mixtures thereof; aligning magnetic domains of the mixture in a magnetic field; compacting the aligned mixture to form a shape; sintering the compacted shape; and annealing the sintered shape.

Ghandehari, M.H.

1989-11-07

231

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

232

Electrical resistivity of low temperature sintered perovskites  

Microsoft Academic Search

Lanthanum–Manganese perovskites are suitable for application as a cathode contact layer in SOFC-stacks. This work describes the resistivity of Lanthanum–Manganese samples which were pre-sintered at different temperatures before annealing at 850 °C in air. Due to the different degrees of sintering, measured resistivity values of low temperature sintered perovskites are higher than resistivity values reported in the literature. For a low

Stefan Megel; Klaus Eichler; Nikolai Trofimenko; Soeren Hoehn

2006-01-01

233

Selective laser sintering of amorphous metal powder  

Microsoft Academic Search

For the first time, selective sintering of amorphous PtCuNiP powder with a pulsed Nd:YAG laser has been studied. Upon pulsed interaction, the grains melt only superficially to build necks between the grains. Depending on the laser parameters, the sintered material can be crystallized or retained amorphous. By contrast with crystalline powder, laser sintering of amorphous powder is achieved at substantially

P. Fischer; A. Blatter; V. Romano; H. P. Weber

2005-01-01

234

On the sintering of silicon carbide  

NASA Technical Reports Server (NTRS)

This document deals with the sintering of silicon carbide using pressureless sintering. This technique makes it possible to sinter a primarily covalent material to usable densities up to over 98% thD without having to use a high amount of sinter additives as is the case with other non-oxide ceramic materials. The process takes place rapidly, and it is also possible to produce relatively thick-walled structural parts without major problems. This sheds more light on the true characteristics of silicon carbide in one structural part, since there is no second or nearly no second phase. Heat pressing has improved stability.

Gugel, E.

1986-01-01

235

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

236

How many ore-bearing asteroids?  

NASA Astrophysics Data System (ADS)

A simple formalism is presented to assess how many asteroids contain ore, i.e., commercially profitable material, and not merely a high concentration of a resource. I apply this formalism to two resource cases: platinum group metals (PGMs) and water. Assuming for now that only Ni-Fe asteroids are of interest for PGMs, then 1% of NEOs are rich in PGMs. The dearth of ultra-low delta-v (<4.5 km s-1) NEOs larger than 100 m diameter reduces the ore-bearing fraction to only 1 in 2000 NEOs. As 100 m diameter NEOs are needed to have a value ?US$1B and the population of near-Earth objects (NEOs) larger than 100 m diameter is 20,000 (Mainzer et al., 2011) the total population of PGM ore-bearing NEOs is roughly 10. I stress that this is a conservative and highly uncertain value. For example, an order of magnitude increase in PGM ore-bearing NEOs occurs if delta-v can be as large as 5.7 km s-1. Water ore for utilization in space is likely to be found in 1/1100 NEOs. NEOs as small as 18 m diameter can be water-ore-bodies because of the high richness of water ( 20%) expected in 25% of carbonaceous asteroids, bringing the number of water-ore-bearing NEOs to 9000 out of the 10 million NEOs of this size. These small NEOs are, however, hard to find with present surveys. There will be 18 water-ore-bearing NEOs >100 m diameter. These estimates are at present highly imprecise and sensitive to small changes, especially in the maximum delta-v allowed. Nonetheless the low values found here mean that much improved determinations of each of the terms of the formalism are urgently needed. If better estimates still find small numbers of ore-bearing NEOs then thorough surveys for NEA discovery and, especially, characterization are needed. Strategies for the two classes are likely to be different.

Elvis, Martin

2014-02-01

237

Machine vision system for ore sizing  

NASA Astrophysics Data System (ADS)

A machine vision systelu has been developed to size and count ore as it passes down a conveyor belt. The imaging system consists of a line scan camera a zoom lens and a structured lighting arrangenient. The structured lighting produces a line of light which is projected onto the conveyor belt at an angle with respect to the caniera. When a piece of ore is present the line of light covering the piece is displaced out of the field of view of the camera. This method is used to overcome the poor contrast between the ore and the conveyor belt. Iniages are acquired using an iiaage processor which performs real-tiiae thresholding of the iraage before it is passed to a frame buffer. A coniputer progrant locates the ore pieces in the image and identifies the boundaries between those pieces which are touching. Chords corresponding to the approximate major and minor axes of each piece are calculated. Using these measurements the size distribution for a population of ore is determined. 1.

Eichelberger, Christopher L.; Blair, Steven M.; Khorana, Brij M.

1991-03-01

238

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. PMID:17053079

Müller, Daniel B.; Wang, Tao; Duval, Benjamin; Graedel, T. E.

2006-01-01

239

Photochemical changes in cyanide speciation in drainage from a precious metal ore heap  

USGS Publications Warehouse

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.

Johnson, C.A.; Leinz, R.W.; Grimes, D.J.; Rye, R.O.

2002-01-01

240

The indirect electrochemical refining of lunar ores  

NASA Technical Reports Server (NTRS)

Recent work performed on an electrolytic cell is reported which addresses the implicit limitations in various approaches to refining lunar ores. The cell uses an oxygen vacancy conducting stabilized zirconia solid electrolyte to effect separation between a molten salt catholyte compartment where alkali metals are deposited, and an oxygen-evolving anode of composition La(0.89)Sr(0.1)MnO3. The cell configuration is shown and discussed along with a polarization curve and a steady-state current-voltage curve. In a practical cell, cathodically deposited liquid lithium would be continuously removed from the electrolytic cell and used as a valuable reducing agent for ore refining under lunar conditions. Oxygen would be indirectly electrochemically extracted from lunar ores for breathing purposes.

Semkow, Krystyna W.; Sammells, Anthony F.

1987-01-01

241

DESULFURIZATION OF STEEL MILL SINTER PLANT GASES  

EPA Science Inventory

The report gives results of an evaluation of the technical and economic feasibility of using limestone scrubbing technology to control sinter plant emissions. Data from Soviet and Japanese sinter plants employing limestone scrubbing technology were used to develop a realistic des...

242

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

243

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

244

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

245

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

246

Manufacture of high-density ceramic sinters  

NASA Technical Reports Server (NTRS)

High density ceramic sinters are manufactured by coating premolded or presintered porous ceramics with a sealing material of high SiO2 porous glass or nitride glass and then sintering by hot isostatic pressing. The ceramics have excellent abrasion and corrosion resistances. Thus LC-10 (Si3N2 powder) and Y2O3-Al2O3 type sintering were mixed and molded to give a premolded porous ceramic (porosity 37%, relative bulk density 63%). The ceramic was dipped in a slurry containing high SiO2 porous glass and an alcohol solution of cellulose acetate and dried. The coated ceramic was treated in a nitrogen atmosphere and then sintered by hot isostatic pressing to give a dense ceramic sinter.

Hibata, Y.

1986-01-01

247

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...

248

Long term sealing ability of butyl o-rings  

SciTech Connect

This article reports on accelerated aging tests carried out to anticipate the long term performance of o-rings in the Galileo spacecraft during its mission to Jupiter. This topics discussed include the impetus for the investigation, the operating conditions for the o-rings, the conditions leading to degradation of performance of the o-rings, and a prediction of the ability of the o-rings to complete their intended mission.

Ytterboe, S.N.; Catsiff, E.H.; Kelchner, R.E.

1991-10-01

249

Long term sealing ability of butyl o-rings  

Microsoft Academic Search

This article reports on accelerated aging tests carried out to anticipate the long term performance of o-rings in the Galileo spacecraft during its mission to Jupiter. This topics discussed include the impetus for the investigation, the operating conditions for the o-rings, the conditions leading to degradation of performance of the o-rings, and a prediction of the ability of the o-rings

S. N. Ytterboe; E. H. Catsiff; R. E. Kelchner

1991-01-01

250

Enumeration and characterization of microorganisms associated with the uranium ore deposit at Cigar Lake, Canada; Informal report  

SciTech Connect

The high-grade uranium deposit at Cigar Lake, Canada, is being investigated as a natural analog for the disposal of nuclear fuel waste. Geochemical aspects of the site have been studied in detail, but the microbial ecology has not been fully investigated. Microbial populations in an ore sample and in groundwater samples from the vicinity of the ore zone were examined to determine their effect on uranium mobility. Counts of the total number of bacteria and of respiring bacteria were obtained by direct microscopy, and the viable aerobic and anaerobic bacteria were assessed as colony forming units (CFUs) by the dilution plating technique. In addition, the population distribution of denitrifiers, fermenters, iron- and sulfur-oxidizers, iron- and sulfate-reducers, and methanogens was determined by the most probable number (MPN) technique.

Francis, A.J.; Joshi-Tope, G.; Gillow, J.B.; Dodge, C.J.

1994-03-01

251

Platinum metals magmatic sulfide ores.  

PubMed

Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. PMID:17796685

Naldrett, A J; Duke, J M

1980-06-27

252

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

253

3. EAGLE MILL, DETAIL OF CRUDE ORE BIN FROM NORTH, ...  

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

3. EAGLE MILL, DETAIL OF CRUDE ORE BIN FROM NORTH, c. 1908-10. SHOWS EXPOSED CRUSHER HOUSE IN FRONT OF (SOUTH) CRUDE ORE BIN AND SNOW SHED ADDED OVER TRAM TRACKS. NOTE LACK OF EAST OR WEST CRUDE ORE BINS. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

254

Viton B O-Ring Resilience Study.  

National Technical Information Service (NTIS)

The Challenger accident in January 1986 was attributed to failure of the pressure seal in the aft field joint of the solid rocket motor. It was concluded that the elastomeric O-ring seals did not perform their sealing function because of the low temperatu...

T. W. Giants

2001-01-01

255

Production of uranium ore in capitalist countries  

Microsoft Academic Search

The uranium deposits of the USA are concentrated in the sedimentary rocks of the Colorado plateau [2, 12]. The ore bodies are adapted to arkosic sandstones, conglomerates, limestones, and argillites. The reserves are distributed into a rather small number of large deposits and a large number of small deposits. Large deposits, each with reserves of from 50 to 100 thousand

N. I. Chesnokov; V. G. Ivanov

1973-01-01

256

Detecting and Sorting Disseminated Native Copper Ores.  

National Technical Information Service (NTIS)

The report describes and evaluates a detector-sorting device to separate copper-bearing and non-copper-bearing rock in native Cu ore. Results of small-scale sorting tests on four Michigan native copper samples showed 60 to 85 pct of the copper was recover...

V. R. Miller, R. W. Nash, A. E. Schwaneke

1974-01-01

257

Metalliferous black shales and related ore deposits  

SciTech Connect

This book comprises papers and extended abstracts dealing with a variety of topics including the geochemistry and organic geochemistry of several black shale formations: the nature of modern Black Sea sediments: metal- organic complexes in ore fluids; black shales related to disseminated gold deposits; vanadium concentrations and molybdenum-nickel deposits; and the problem of defining metalliferous black shales.

Grauch, R.I. (Geological Survey, Reston, VA (United States)); Huyck, H.L.O. (Cincinnati Univ., OH (United States))

1990-01-01

258

Iron overdose  

MedlinePLUS

Iron is an ingredient in many mineral and vitamin supplements. Iron supplements are also sold by themselves. Types include: Ferrous sulfate (Feosol, Slow Fe) Ferrous gluconate (Fergon) Ferrous fumarate (Femiron, Feostat) Note: This list may not be all-inclusive.

259

Nondestructive evaluation of sintered ceramics  

NASA Technical Reports Server (NTRS)

Radiography and several acoustic and thermoacoustic microscopy techniques are investigated for application to structural ceramics for advanced heat engines. A comparison is made of the results obtained from the use of scanning acoustic microscopy (SAM), scanning laser acoustic microscopy (SLAM), and thermoacoustic microscopy (TAM). These techniques are evaluated on research samples of green and sintered monolithic silicon nitrides and silicon carbides in the form of modulus-of-rupture (MOR) bars containing deliberately introduced flaws. Strengths and limitations of the techniques are described, with the emphasis being on statistics of detectability of flaws that constitute potential fracture origins. Further, it is shown that radiographic evaluation and guidance helped develop uniform high-density Si3N4 MOR bars with improved four-point flexural strength (875, 544, and 462 MPa at room temperature, 1200 C, 1370 C, respectively) and reduced scatter in bend strength.

Baaklini, George Y.; Klima, Stanley J.; Sanders, William A.

1988-01-01

260

Tribological properties of sintered polycrystalline and single crystal silicon carbide  

NASA Technical Reports Server (NTRS)

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 indicate that there is a significant temperature influence on both the friction properties and the surface chemistry of silicon carbide. The main contaminants on the as received sintered polycrystalline silicon carbide surfaces are adsorbed carbon, oxygen, graphite, and silicon dioxide. The surface revealed a low coefficient of friction. This is due to the presence of the graphite on the surface. At temperatures of 400 to 600 C graphite and copious amount of silicon dioxide were observed on the polycrystalline silicon carbide surface in addition to silicon carbide. At 800 C, the amount of the silicon dioxide decreased rapidly and the silicon carbide type silicon and carbon peaks were at a maximum intensity in the XPS spectra. The coefficients of friction were high in the temperature range 400 to 800 C. Small amounts of carbon and oxygen contaminants were observed on the as received single crystal silicon carbide surface below 250 C. Silicon carbide type silicon and carbon peaks were seen on the silicon carbide in addition to very small amount of graphite and silicon dioxide at temperatures of 450 to 800 C.

Miyoshi, K.; Buckley, D. H.; Srinivasan, M.

1982-01-01

261

Microwave Sinterator Freeform Additive Construction System (MS-FACS)  

NASA Technical Reports Server (NTRS)

The harmful properties of lunar dust, such as small size, glass composition, abnormal surface area, and coatings of imbedded nanophase iron, lead to a unique coupling of the dust with microwave radiation. This coupling can be exploited for rapid sintering of lunar soil for use as a construction material that can be formed to take on an infinite number of shapes and sizes. This work describes a system concept for building structures on the lunar surface using lunar regolith (soil). This system uses the ATHLETE (All-Terrain Hex- Limbed Extra-Terrestrial Explorer) mobility system as a positioning system with a microwave print head (similar to that of a smaller-scale 3D printer). A processing system delivers the lunar regolith to the microwave print head, where the microwave print head/chamber lays down a layer of melted regolith. An arm on the ATHLETE system positions the layer depending on the desired structure.

Howe, Alan S.; Wilcox, Brian H.; Barmatz, Martin B.; Mercury, Michael B.; Siebert, Michael A.; Rieber, Richard R.

2013-01-01

262

Iron Range Research Center Archival Collections  

NSDL National Science Digital Library

For many people, Minnesota's Iron Range isn't just a geographic region, it is a way of life. Stretching across the northeastern section of the state, the Iron Range includes everything from vast bands of iron ore to counties with piquant names, like Koochiching. It is a largely rural area, where people's winter pastimes tend to involve skiing, snowmobiles, and ice fishing. This digital collection from the Minnesota Discovery Center preserves the culture and folkways of this area via photographs, oral histories, government records, and manuscripts. Within the Oral History Collection, visitors can look over memories of this region captured and preserved for all time. Visitors can explore labor struggles, internecine political battles in the region, and recreational pursuits. Additionally, the Map Collection is a great way to learn about forest distribution, geological landforms, and iron deposits across the area. All in all, it is a wonderful resource and one that may serve as a model to other institutions.

263

Eat Iron?!!  

NSDL National Science Digital Library

To gain an understanding of mixtures and the concept of separation of mixtures, students use strong magnets to find the element of iron in iron-fortified breakfast cereal flakes. Through this activity, they see how the iron component of this heterogeneous mixture (cereal) retains its properties and can thus be separated by physical means.

NSF GK-12 and Research Experience for Teachers (RET) Programs,

264

Conditions for making direct reduced iron, transition direct reduced iron and pig iron nuggets in a laboratory furnace - Temperature-time transformations  

SciTech Connect

The pig iron nugget process is gaining in importance as an alternative to the traditional blast furnace. Throughout the process, self-reducing-fluxing dried greenballs composed of iron ore concentrate, reducing-carburizing agent (coal), flux (limestone) and binder (bentonite) are heat-treated. During the heat treatment, dried greenballs are first transformed into direct reduced iron (DRI), then to transition direct reduced iron (TDRI) and finally to pig iron nuggets. The furnace temperature and/or residence time and the corresponding levels of carburization, reduction and metallization dictate these transformations. This study involved the determination of threshold furnace temperatures and residence times for completion of all of the transformation reactions and pig iron nugget production. The experiments involved the heat treatment of self-reducing-fluxing dried greenballs at various furnace temperatures and residence times. The products of these heat treatments were identified by utilizing optical microscopy, apparent density and microhardness measurements.

Anameric, B.; Kawatra, S.K. [Michigan Technological University, Houghton, MI (United States). Dept. of Chemical Engineering

2007-02-15

265

Enery Efficient Press and Sinter of Titanium Powder for Low-Cost Components in Vehicle Applications  

SciTech Connect

This is the final technical report for the Department of Energy NETL project NT01931 Energy Efficient Press and Sinter of Titanium Powder for Low-Cost Components in Vehicle Applications. Titanium has been identified as one of the key materials with the required strength that can reduce the weight of automotive components and thereby reduce fuel consumption. Working with newly developed sources of titanium powder, Webster-Hoff will develop the processing technology to manufacture low cost vehicle components using the single press/single sinter techniques developed for iron based powder metallurgy today. Working with an automotive or truck manufacturer, Webster-Hoff will demonstrate the feasibility of manufacturing a press and sinter titanium component for a vehicle application. The project objective is two-fold, to develop the technology for manufacturing press and sinter titanium components, and to demonstrate the feasibility of producing a titanium component for a vehicle application. The lowest cost method for converting metal powder into a net shape part is the Powder Metallurgy Press and Sinter Process. The method involves compaction of the metal powder in a tool (usually a die and punches, upper and lower) at a high pressure (up to 60 TSI or 827 MPa) to form a green compact with the net shape of the final component. The powder in the green compact is held together by the compression bonds between the powder particles. The sinter process then converts the green compact to a metallurgically bonded net shape part through the process of solid state diffusion. The goal of this project is to expand the understanding and application of press and sinter technology to Titanium Powder applications, developing techniques to manufacture net shape Titanium components via the press and sinter process. In addition, working with a vehicle manufacturer, demonstrate the feasibility of producing a titanium component for a vehicle. This is not a research program, but rather a project to develop a process for press and sinter of net shape Titanium components. All of these project objectives have been successfully completed.

Thomas Zwitter; Phillip Nash; Xiaoyan Xu; Chadwick Johnson

2011-03-31

266

Liquid phase sintering of silicon carbide  

DOEpatents

Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1,600 C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase. 4 figs.

Cutler, R.A.; Virkar, A.V.; Hurford, A.C.

1989-05-09

267

Liquid phase sintering of silicon carbide  

DOEpatents

Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1600.degree. C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase.

Cutler, Raymond A. (Bountiful, UT); Virkar, Anil V. (Salt Lake City, UT); Hurford, Andrew C. (Salt Lake City, UT)

1989-01-01

268

Comparison of rapid and slow sintered pulverised fuel ash  

Microsoft Academic Search

This study has investigated the properties of sintered PFA using conventional (20°C\\/min) and rapid heating rates. Rapid heating was achieved by directly placing pressed PFA samples into a furnace preset at the sintering temperature. Slow sintered PFA samples show an increase in shrinkage and fired density and a reduction in water absorption as the sintering temperature increases, with maximum density

V. Adell; C. R. Cheeseman; A. Doel; A. Beattie; A. R. Boccaccini

2008-01-01

269

DETAIL VIEW OF LOWER TRAM TERMINAL, SECONDARY ORE BIN, CRUSHER ...  

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

DETAIL VIEW OF LOWER TRAM TERMINAL, SECONDARY ORE BIN, CRUSHER FOUNDATION, AND BALL MILL FOUNDATIONS, LOOKING NORTH NORTHWEST. ORE FROM THE MINES WAS DUMPED FROM THE TRAM BUCKETS INTO THE PRIMARY ORE BIN UNDER THE TRAM TERMINAL. A SLIDING CONTROL DOOR INTRODUCED THE INTO THE JAW CRUSHER (FOUNDATIONS,CENTER). THE CRUSHED ORE WAS THEN CONVEYED INTO THE SECONDARY ORE BIN AT CENTER LEFT. A HOLE IN THE FLOOR OF THE ORE BIN PASSED ORE ONTO ANOTHER CONVEYOR THAT BROUGHT IT OUT TO THE BALL MILL(FOUNDATIONS,CENTER BOTTOM). THIS SYSTEM IS MOST LIKELY NOT THE ORIGINAL SET UP, PROBABLY INSTALLED IN THE MINE'S LAST OCCUPATION IN THE EARLY 1940s. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

270

Degradation Characteristics of O-rings on Highly Aged GIS  

NASA Astrophysics Data System (ADS)

Owing to increasing number of highly aged GIS, the investigation of the remaining lifetimes of those systems are becoming more important. Because a lot of O-rings are used in GIS, the study of degradation mechanism and lifetime estimation method of O-ring is essential. In this paper, the information about O-ring degradation mechanism is described, and the statistical method for estimating the remaining lifetime of O-ring is proposed. The degradation of O-ring is mainly subject to chemical reactions triggered by oxygen. Because there are many factors influencing those chemical reactions, the dispersion of degradation rates of O-rings in GIS is very large. Consequently the statistical analysis is one of the effective techniques for lifetime estimation of O-rings in GIS.

Minagawa, Tadao; Nagao, Eiichi; Tsuchie, Ei; Yonezawa, Hiroshi; Takayama, Daisuke; Yamakawa, Yutaka

271

Oxide Transformation in Cr-Mn-Prealloyed Sintered Steels: Thermodynamic and Kinetic Aspects  

NASA Astrophysics Data System (ADS)

The main obstacle for utilization of Cr and Mn as alloying elements in powder metallurgy is their high oxygen affinity leading to oxidation risk during powder manufacturing, handling, and especially during further consolidation. Despite the high purity of the commercially available Cr- and Mn-prealloyed iron powder grades, the risk of stable oxide formation during the sintering process remains. Thermodynamic and kinetic simulation of the oxide formation/transformation on the former powder surface during heating and sintering stages using thermodynamic modeling tools (Thermo-Calc and HSC Chemistry) was performed. Simulation is based on the results from the analysis of amount, morphology, and composition of the oxide phases inside the inter-particle necks in the specimens from interrupted sintering trials utilizing advanced analysis tools (HRSEM + EDX and XPS). The effect of the processing parameters, such as sintering atmosphere composition, temperature profile as well as graphite addition on the possible scenarios of oxide reduction/formation/transformation for Fe-Cr-Mn-C powder systems, was evaluated. Results indicate that oxide transformation occurs in accordance with the thermodynamic stability of oxides as follows: Fe2O3 ? FeO ? Fe2MnO4 ? Cr2FeO4 ? Cr2O3 ? MnCr2O4 ? MnO/MnSiO x ? SiO2. Spinel MnCr2O4 was identified as the most stable oxide phase at applied sintering conditions up to 1393 K (1120 °C). Controlled conditions during the heating stage minimize the formation of stable oxide products and produce oxide-free sintered parts.

Hryha, Eduard; Nyborg, Lars

2014-04-01

272

Nd-Isotopic and Rare-Earth Element Geochemical Constraints on the Origin of the Wenduermiao Iron Deposit, Inner Mongolia, China  

Microsoft Academic Search

The Wenduermiao deposit, a large, low-grade iron ore deposit, occurs in the upper Proterozoic metavolcanic-sedimentary sequences of the Wenduermiao Group in south-central Inner Mongolia. The Wenduermiao Group consists mainly of metabasaltic rock, greenschist, marble, finely crystalline quartzite, and related metachemical sediments. Most of the iron ore occurs as stratiform and podiform deposits, or as massive lenses, along the transition zone

Feng-Jun Nie; Arne Bjørlykke

1994-01-01

273

Coble Creep, Cavity Sintering, and Cavity Growth.  

National Technical Information Service (NTIS)

The close relationships between Coble creep, cavity sintering and cavity growth are discussed. The measurement of size distributions of crack-like cavities is useful for determining grain boundary and surface diffusivities. In nickel aluminide (Ni3Al) int...

J. H. Schneibel, L. Martinez

1988-01-01

274

Microwave sintering of multilayer ceramic capacitors.  

National Technical Information Service (NTIS)

Multilayer ceramic capacitors of several compositions (both Z5U and NPO types) were sintered in air in both conventional and microwave furnaces. Several casketing and insulation techniques were used to improve temperature uniformity and minimize dopant lo...

R. J. Lauf, C. E. Holcombe, C. Hamby

1992-01-01

275

Sintered electrode for solid oxide fuel cells  

DOEpatents

A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation.

Ruka, Roswell J. (Pittsburgh, PA); Warner, Kathryn A. (Bryan, TX)

1999-01-01

276

Pressureless sintering of whiskered-toughened ceramic composites  

DOEpatents

A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method.

Tiegs, Terry N. (Lenoir City, TN)

1994-01-01

277

Pressureless sintering of whisker-toughened ceramic composites  

DOEpatents

A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method.

Tiegs, T.N.

1993-05-04

278

Pressureless sintering of whisker-toughened ceramic composites  

DOEpatents

A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method.

Tiegs, Terry N. (Lenoir City, TN)

1993-01-01

279

Sintering Behavior of Diboride Based Materials  

NASA Technical Reports Server (NTRS)

A brief history of diboride research, an overview of processing, and sintering studies are covered in this viewgraph presentation. UHTCs are a family of ceramic materials, including diborides of Hf and Zr, with extremely high melting temperatures. Spark Plasma Sintering (SPS) is a novel processing technique useful in consolidating difficult materials. The presentation also contains microphotographs of the microstructure of HfB2 and ZrB2 processed in different ways.

Gasch, Matt; Gusman, Michael; Irby, Edward; Ellerby, Don; Beckman, Sarah; Johnson, Sylvia

2003-01-01

280

Hydrothermal manganese mineralization in the Peterbourgskoye ore field (North Atlantic)  

NASA Astrophysics Data System (ADS)

The manganese crust covered by pelagic sediment was recovered from the 3 km depth from the Peterbourgskoye ore field located on the eastern flank of the Mid-Atlantic Ridge. The crust comprises a platy brittle aggregate 1-5 cm thick made of black heterogeneous and partly porous material. The inner structure consists of aggregated parallel microplaits several micrometers to 0.2 mm thick consisting of well-crystallized bisnessite with a minor admixture of colloform vernadite. The chemical composition of the crust is dominated by manganese (more than 60% MnO) with minor iron (1.7% Fe2O3) and somewhat notable sodium and sulfur. The trace element composition is characterized by very high molybdenum, moderate gallium and uranium, and very low values of 40 other trace elements. Compared to previous publications, the composition of this crust is fairly different from the average values previously defined for hydrothermal crusts. On the other hand, it is rather close to some crusts recovered from subsea volcanoes in the Sea of Japan.

Baturin, G. N.; Dobretsova, I. G.; Dubinchuk, V. T.

2014-03-01

281

Sintered silicon nitrode recuperator fabrication  

NASA Technical Reports Server (NTRS)

The preliminary design and a demonstration of the feasibility of fabricating submodules of an automotive Stirling engine recuperator for waste heat recovery at 370 C are described. Sinterable silicon nitride (Sialon) tubing and plates were fabricated by extrusion and hydrostatic pressing, respectively, suitable for demonstrating a potential method of constructing ceramic recuperator-type heat exchangers. These components were fired in nitrogen atmosphere to 1800 C without significant scale formation so that they can be used in the as-fired condition. A refractory glass composition (Al2O3 x 4.5 CaO.MgO x 11SiO2) was used to join and seal component parts by a brazing technique which formed strong recuperator submodules capable of withstanding repeated thermal cycling to 1370 C. The corrosion resistance of these materials to Na2SO4 + NaCl carbon mixtures was also assessed in atmospheres of air, hydrogen and CO2-N2-H2O mixtures at both 870 C and 1370 C for times to 1000 hours. No significant reaction was observed under any of these test conditions.

Gatti, A.; Chiu, W. S.; Mccreight, L. R.

1980-01-01

282

Effects of Heating Rate and Sintering Temperature on 316 l Stainless Steel Powders Sintered Under Multi-Physical Field Coupling  

Microsoft Academic Search

This paper presents an approach to fabricate micro components using multi-physical field sintering technique. In this study, 316 L stainless steel powders were sintered at different heating rates and sintering temperatures to produce cylindrical compacts with diameters of 1.0 mm, and heights of 1.0 mm. The effects of heating rates and sintering temperatures on sintering densification were studied. It shows that both heating

Ankang Du; Yi Yang; Yi Qin; Gang Yang

2012-01-01

283

Theory and method of genetic-neural optimizing cut-off grade and grade of crude ore  

Microsoft Academic Search

Cut-off grade for ore drawing is a kind of technological method used to control the process of drawing in sublevel caving with no sill pillar. The cut-off grade for ore drawing means the grade of ore in the last time (current time) of ore drawing. Grade of crude ore is the grade of ore entering the milling workshop after ore

Yong He; Kejun Zhu; Si-wei Gao; Ting Liu; Yue Li

2009-01-01

284

Comparison of effect of induction and classical sintering to mechanical properties of powder metal components  

NASA Astrophysics Data System (ADS)

Because of solidifying to component, sintering is the most important step of the production of powder metal parts. Generally it is made classical furnace. Alternatively sintering furnace, it is done that induction sintering studies. Induction sintering provide a grand time and energy savings since components hot up rapidly and sintering time is lower than classical sintering in furnace. Because of that induction sintering is an important alternative at sintering process. In this study, mechanical properties of induction sintered Fe based components included Cu and Graphite were compared with classical sintered components. Parameters of same mechanical properties of induction sintered and classical sintered components were identified.

Çivi, Can; Atik, Enver

2012-09-01

285

Effects of Sintering Conditions on Mechanical Properties of Biomedical Porous Ti Produced by Spark Plasma Sintering  

NASA Astrophysics Data System (ADS)

Because of its excellent biocompatibility, good corrosion resistance and relatively lower Young's modulus, Ti was suitable for biomaterial. It, however, showed still bigger Young's modulus comparing to the living bone. It was necessary to decrease the Young's modulus in order to avoid adversely affect to the bone, such as stress sheilding. In this study, porous Ti were fablicated to decrease the Young's modulus by space holder method from Ti/NaCl composites sintered using spark plasma sintering (SPS) method. The sintering condition and the size of NaCl affected to the porous structure and mechanical properties. According to the scanning electron microscope (SEM) observation and the relative density measurement of specimens sintered with several sintering conditions, the desirable sintering condition was concluded as 973 K of sintering temperature and 1.2 ks of sintering time. The specimens made from NaCl powder whose size were from 106 to 214 µm showed almost opened and connected pores. The Young's modulus was decreased with increasing the porosity.

Hasebe, Tatsuya; Kobayashi, Equo; Tezuka, Hiroyasu; Sato, Tatsuo

2013-01-01

286

Solid-state sintering of tungsten heavy alloys  

SciTech Connect

Solid-state sintering is a technologically important step in the fabrication of tungsten heavy alloys. This work addresses practical variables affecting the sinterability: powder particle size, powder mixing, and sintering temperature and time. Compositions containing 1 to 10 micrometer ({mu}M) tungsten (W) powders can be fully densified at temperatures near the matrix solidus. Blending with an intensifier bar provided good dispersion of elemental powders and good as-sintered mechanical properties under adequate sintering conditions. Additional ball milling increases powder bulk density which primarily benefits mold and die filling. Although fine, 1 {mu}m W powder blends have high sinterability, higher as-sintered ductilities are reached in shorter sintering times with coarser, 5 {mu}m W powder blends; 10{mu}m W powder blends promise the highest as-sintered ductilities due to their coarse microstructural W.

Gurwell, W.E.

1994-10-01

287

Raman spectroscopy of efflorescent sulfate salts from Iron Mountain Mine Superfund Site, California.  

PubMed

The Iron Mountain Mine Superfund Site near Redding, California, is a massive sulfide ore deposit that was mined for iron, silver, gold, copper, zinc, and pyrite intermittently for nearly 100 years. As a result, both water and air reached the sulfide deposits deep within the mountain, producing acid mine drainage consisting of sulfuric acid and heavy metals from the ore. Particularly, the drainage water from the Richmond Mine at Iron Mountain is among the most acidic waters naturally found on Earth. The mineralogy at Iron Mountain can serve as a proxy for understanding sulfate formation on Mars. Selected sulfate efflorescent salts from Iron Mountain, formed from extremely acidic waters via drainage from sulfide mining, have been characterized by means of Raman spectroscopy. Gypsum, ferricopiapite, copiapite, melanterite, coquimbite, and voltaite are found within the samples. This work has implications for Mars mineralogical and geochemical investigations as well as for terrestrial environmental investigations related to acid mine drainage contamination. PMID:23464669

Sobron, Pablo; Alpers, Charles N

2013-03-01

288

A circulation mud system used in long-distance ore pipeline transportation  

NASA Astrophysics Data System (ADS)

The long-distance ore pipeline transportation is a new and high-tech industry, which is non-polluting, zero emissions, and in line with the strategy needs of national low-carbon economy and energy demand reduction. The long-distance ore transport needs multi-station pumping station transportation, however, the low concentration slurry that does not match the technological requirements, such as slurry head and so on. This paper designs a circulation mud system used in long-distance pipeline transportation, which solves the following issues: (1) the technical pool can't storage water during the period of cleaning mine, so can't meet the needs of non-suspension production; (2) slurry spot cool dry easy to bring serious environmental pollution; (3) the refined iron dug out from the process pool need transport to iron and steel industry, trucking transportation needs a huge costs. Experience has shown that the system effectively improve the production efficiency and propagate.

Li, Youling; Wang, Hua

2011-10-01

289

Liquid phase sintering in microgravity  

NASA Astrophysics Data System (ADS)

Liquid Phase Sintering (LPS) experiments have been conducted on four suborbital rockets, six Space Shuttle missions and two missions to the Mir Space Station by our research group. These missions began in 1989, spanning over 10 years. This paper will overview the many separate and interesting research and technical challenges faced in these missions and review the many published models developed to date by our group. The principle finding is that microgravity materials made using typical liquid phase sintering approaches are inferior to those made on earth. This results from pressing the green, presintered compact from their constituent powders, Fe and Co base materials with a Cu additive phase, producing composites that have solid volume fractions of 70-80%, with the balance either vacuum filled pores or entrapped gas. During LPS, the compact is processed above the melting point of the additive phase, producing a three-phase system. On earth, the entrapped gas is rapidly eliminated, and particle rearrangement is principally by buoyancy driven convection. In microgravity, this is not the case. In microgravity systems, all three phases exist concurrently, and the gas phase is not eliminated by buoyancy driven convection. Instead, the gas phase alters the free energy of the composite producing a variety of transport processes not typically seen in the earth based experiments, a positive result. Microgravity experiments slow down the typically fast acting rearrangement phase, permitting detailed study of the rapid processes taking place on earth in the first few seconds to minutes of LPS. Results from space processing have lead to a reconsideration of unit gravity models during the rearrangement stage. It has lead to a new model to explain the initiation of pore metamorphosis in LPS sample processed in microgravity, where pore breakup, coalescence and filling were found. Diffusion controlled grain growth in mutually soluble alloy phase systems, such as Co-Cu, was observed for the first time and a shrinking core model developed that successfully modeled this aspect of grain growth. In the absence of gravity, the grain coarsening model should follow the Lifshitz-Slyozov and Wagner (LSW) theory. Our extensive analysis of over 200 samples has shown that, contrary to expectation, there was an enhancement in particle coarsening with a decrease in the volume fraction of solid. The agglomerated microstructures exhibited a higher grain growth constant consistent with their higher 3D coordination number. Though buoyancy driven convection is eliminated, Brownian motion is not and becomes dominate in microgravity. This driving force leads to agglomeration and the need to use the Lifshitz-Slyozov Encounter Modified (LSEM) model to correctly model the results. Many papers on these phenomena h ve appeared in the literature and will be summarized anda presented along with a discussion of systems and subsystems needed to successfully conduct high temperature microgravity research on the fundamental mechanisms associated with LPS.

Smith, J.; Lundquist, C.; Riley, M.; Robinson, R.

290

Ore zoning and dynamics of ore-forming processes of Yinshan polymetallic deposit in Dexing, Jiangxi  

Microsoft Academic Search

The Yinshan deposit, one of the large-scale Cu-Pb-Zn-Au-Ag polymetallic deposits, may be named a middle-low temperature subvolcanic\\u000a hydrothermal deposit and referred to as the“transitional deposit” linking mineralization of the epithermal and porphyry copper\\u000a types. In this paper, the characteristics and structures of ore zoning are briefly described. On the basis of the dynamics\\u000a of ore-forming processes and applying computer numerical

Zhang Dehui; Yu Chongwen; Bao Zhengyu; Tang Zhonghua

1997-01-01

291

Iron refractory iron deficiency anemia  

PubMed Central

Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. PMID:23729726

De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U.; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

2013-01-01

292

N. MATR. ESITO DATA PROVA ORALE 1 1157595 ammesso 22 SETTEMBRE 2014 -ORE 9.00  

E-print Network

2014 - ORE 9.00 16 1627766 ammesso 22 SETTEMBRE 2014 - ORE 9.00 17 361424 ammesso 22 SETTEMBRE 2014 1198362 ammesso 24 SETTEMBRE 2014 - ORE 15.00 57 362906 ammesso 24 SETTEMBRE 2014 - ORE 15.00 58 1203397N. MATR. ESITO DATA PROVA ORALE 1 1157595 ammesso 22 SETTEMBRE 2014 - ORE 9.00 2 1199682 ammesso 22

Di Pillo, Gianni

293

OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE ...  

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

OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE BIN, LOOKING NORTHEAST. REMAINS OF A BLACKSMITH'S FORGE AND WORK CAN BE SEEN JUST BELOW THE ORE BIN (SEE CA-291-32 FOR DETAIL). ROCK FOUNDATIONS LOCATED JUST ABOVE THE ORE BIN AND ALONG THE FIRST RIDGELINE ARE TENT PADS. SEE CA-291-49 (CT) FOR IDENTICAL COLOR TRANSPARENCY. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

294

OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE ...  

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

OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE BIN, LOOKING NORTHEAST. REMAINS OF A BLACKSMITH'S FORGE AND WORK CAN BE SEEN JUST BELOW THE ORE BIN (SEE CA-291-32 FOR DETAIL). ROCK FOUNDATIONS LOCATED JUST ABOVE THE ORE BIN AND ALONG THE FIRST RIDGELINE ARE TENT PADS. SEE CA-291-24 FOR IDENTICAL B&W NEGATIVE. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

295

37. VIEW NORTH FROM EAST CRUDE ORE BIN TO CRUSHER ...  

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

37. VIEW NORTH FROM EAST CRUDE ORE BIN TO CRUSHER ADDITION AND CRUSHED OXIDIZED ORE BIN. VISIBLE ARE DINGS MAGNETIC PULLEY (CENTER), THE 100-TON STEEL CRUSHED UNOXIDIZED ORE BIN, AND UPPER PORTION OF THE STEPHENS-ADAMSON 25 TON/HR BUCKET ELEVATOR. THE UPPER TAILINGS POND LIES BEYOND THE MILL WITH THE UPPER TAILINGS DAM UNDER THE GRAVEL ROAD IN THE UPPER RIGHT CORNER. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

296

Room Temperature Aging Study of Butyl O-rings  

Microsoft Academic Search

During testing under the Enhanced Surveillance Campaign in 2001, preliminary data detected a previously unknown and potentially serious concern with recently procured butyl o-rings. All butyl o-rings molded from a proprietary formulation throughout the period circa 1999 through 2001 had less than a full cure. Tests showed that sealing force values for these suspect o-rings were much lower than expected

Mark Wilson

2009-01-01

297

Degradation Characteristics of O-rings on Highly Aged GIS  

Microsoft Academic Search

Owing to increasing number of highly aged GIS, the investigation of the remaining lifetimes of those systems are becoming more important. Because a lot of O-rings are used in GIS, the study of degradation mechanism and lifetime estimation method of O-ring is essential. In this paper, the information about O-ring degradation mechanism is described, and the statistical method for estimating

Tadao Minagawa; Eiichi Nagao; Ei Tsuchie; Hiroshi Yonezawa; Daisuke Takayama; Yutaka Yamakawa

2005-01-01

298

Predicting and confirming the lifetime of o-rings  

Microsoft Academic Search

We derive an empirical method for estimating the equilibrium sealing force appropriate to o-rings under their application (e.g., squeezed) conditions. Another empirical approach allows us to estimate the equilibrium compression set for o-rings once they have been released from their compressed state. Comparing the two equilibrium values for three different butyl o-ring materials aged under both laboratory accelerated aging conditions

K. T. Gillen; R. Bernstein; M. H. Wilson

2005-01-01

299

Calculation of O-ring failure due to material aging  

Microsoft Academic Search

Applications where O-rings are used to isolate atmospheric environments within a structure are critical to weapon reliability. Failure occurs when gases are able to travel from one side of the O-ring to the other. The anticipated cause of failure is the relaxation of the rubber over decades, the reduction in closure force, and the O-ring`s consequent inability to offer a

D. Segalman; L. Weingarten; R. Chambers

1997-01-01

300

Effect of sintering process on the magnetic and mechanical properties of sintered Nd-Fe-B magnets  

NASA Astrophysics Data System (ADS)

The magnetic and mechanical properties of sintered Nd-Fe-B magnets prepared by different sintering processes were investigated. The results showed that the intrinsic coercivity and fracture toughness of sintered Nd-Fe-B magnets first increased, and then declined with increasing annealing temperature. The optimum magnetic properties and fracture toughness of sintered Nd-Fe-B magnets were obtained at the annealing temperature of 540 °C. Sintering temperature increasing from 1047 °C to 1071 °C had hardly effect on the magnetic properties of sintered Nd-Fe-B magnets. The variation of Vickers hardness and fracture toughness was not the same with increasing sintering temperature, and the effect of sintering temperature on the mechanical properties was complex and irregular. The reasons for the variation on magnetic and mechanical properties were analyzed, and we presumed that the effect of microstructure on the mechanical properties was more sensitive than the magnetic properties through analyzing the microstructure of sintered Nd-Fe-B magnets.

Hu, Z. H.; Qu, H. J.; Zhao, J. Q.; Yan, C. J.; Liu, X. M.

2014-11-01

301

Field assisted sintering of ceramic materials  

NASA Astrophysics Data System (ADS)

The objective of this dissertation is to provide an understanding of the processing mechanisms of ceramic materials under an electrical field. Different parameters of the process, such as the electrical field, the heating rate, the holding time, and the precursor powder characteristics are studied in connection with their individual effect on the microstructural evolution and properties. The work reviews the fundamentals of sintering in the presence and in the absence of an electrical field, electrical conductivity in ceramics, precursor powder preparation methods for ceramic processing, as well as the relationship between the thermal properties and the neck formation in the first sintering stage. The ceramic materials that are chosen for the sintering studies are: Al2O3, TiO2, Al2TiO5 and MoSi2. Two type of precursors are used for the studies on Al 2TiO5: an amorphous sol-gel nanosize, and a crystalline coprecipitated micron size powder. Comparative studies on the effect of the heating rates in FAST on the conductive MoSi2 versus non-conductive Al2 O3 are also presented. The initial sintering stages of alpha-Al 2O3, which displays the maximum sintering activity under electrical field, are studied by a thermo-optical measurement method (TOM). The TOM method measures in-situ the thermal diffusivity of the powder. All the materials are characterized after sintering by XRD, FTIR, SEM, TEM, density and thermal diffusivity by TOM. The results show that the electrical field application enhances the kinetics of non-conductive oxide ceramics (Al2TiO5) formation by reaction sintering of the individual oxides. It also increases the rate of the neck formation during first sintering stage, and reduces porosity, thus improving the final density of non-conductive Al2O3. The sol-gel precursor powders with nanosize particles and a higher degree of homogeneity result in improved densification of the final consolidated part as compared to micron size or mechanically mixed precursors. A rapid heating rate (such as in field sintering) retards grain growth for materials with a higher driving force for coarsening than for densification (Al 2O3) and has no effect on the grain coarsening behavior of conductive MoSi2.

Stanciu, Lia Antoaneta

2003-06-01

302

34. VIEW OF VIVIANNA WORKS ORE SORTING AND CRUSHING PLATFORM ...  

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

34. VIEW OF VIVIANNA WORKS ORE SORTING AND CRUSHING PLATFORM LOOKING EAST, NORTHEAST. NOTICE RAIL TIES EMBEDDED IN CONCRETE. - Mariscal Quicksilver Mine & Reduction Works, Terlingua, Brewster County, TX

303

Experimenting With Ore: Creating the Taconite Process; flow chart of ...  

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

Experimenting With Ore: Creating the Taconite Process; flow chart of process - Mines Experiment Station, University of Minnesota, Twin Cities Campus, 56 East River Road, Minneapolis, Hennepin County, MN

304

4. TROJAN MILL, DETAIL OF CRUDE ORE BINS FROM NORTH, ...  

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

4. TROJAN MILL, DETAIL OF CRUDE ORE BINS FROM NORTH, c. 1912. SHOWS TIMBER FRAMING UNDER CONSTRUCTION FOR EAST AND WEST CRUDE ORE BINS AT PREVIOUS LOCATION OF CRUSHER HOUSE, AND SNOW SHED PRESENT OVER SOUTH CRUDE ORE BIN WITH PHASE CHANGE IN SNOW SHED CONSTRUCTION INDICATED AT EAST END OF EAST CRUDE ORE BIN. THIS PHOTOGRAPH IS THE FIRST IMAGE OF THE MACHINE SHOP, UPPER LEFT CORNER. CREDIT JW. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

305

Calculation of O-ring failure due to material aging  

SciTech Connect

Applications where O-rings are used to isolate atmospheric environments within a structure are critical to weapon reliability. Failure occurs when gases are able to travel from one side of the O-ring to the other. The anticipated cause of failure is the relaxation of the rubber over decades, the reduction in closure force, and the O-ring`s consequent inability to offer a barrier to gas transport. A predictive model with tractable complexity has been developed to predict the time over which an O-ring is able to maintain an acceptable value of closure force.

Segalman, D.; Weingarten, L.; Chambers, R.

1997-09-01

306

Impact fracture toughness of porous iron and high-strength steels  

Microsoft Academic Search

The impact fracture toughness of sintered iron and high-strength sintered steels, with densities between 7.0 and 7.25 g\\/cm3, have been investigated by means of instrumented impact testing on fatigueprecracked as well as 0.17-mm-notched specimens.\\u000a Experimental results show that the fracture behavior is controlled by the properties of the resisting necks at the crack\\/notch\\u000a tip. The materials with impact yield strengths

Giovanni Straffelini

2000-01-01

307

Discrimination of Ore-Bearing and Barren Porphyries in the Yulong Porphyry Copper Ore Belt, Eastern Tibet  

Microsoft Academic Search

The Yulong porphyry copper ore belt is the largest belt of porphyry copper deposits in China. Detailed geological and geochemical comparison indicates that ore-bearing and barren porphyries in this belt were derived by progressive partial melting of veins of phlogopite-garnet clinopyroxenite in lherzolitic lithosphere. Ore-bearing porphyry represents the earliest melt derived by partial melting of accessory phases such as apatite,

Yao-Hui Jiang; Shao-Yong Jiang; Bao-Zhang Dai; Hong-Fei Ling

2008-01-01

308

Mixing from below in hydrothermal ore deposits  

NASA Astrophysics Data System (ADS)

Unconformity-related hydrothermal ore deposits typically show indications of mixing of two end-member fluids: (a) hot, deep, rock-buffered basement brines and (b) colder fluids derived from the surface or overlying sediments. The hydromechanics of bringing these fluids together from above and below remain unclear. Classical percolative Darcy-flow models are inconsistent with (1) fluid overpressure indicated by fracturing and brecciation, (2) fast fluid flow indicated by thermal disequilibrium, and (3) strong fluid composition variations on the mm-scale, indicated by fluid inclusion analyses (Bons et al. 2012; Fusswinkel et al. 2013). We propose that fluids first descend, sucked down by desiccation reactions in exhumed basement. Oldest fluids reach greatest depths, where long residence times and elevated temperatures allow them the extensively equilibrate with their host rock, reach high salinity and scavenge metals, if present. Youngest fluids can only penetrate to shallower depths and can (partially) retain signatures from their origin, for example high Cl/Br ratios from the dissolution of evaporitic halite horizons. When fluids are released from all levels of the crustal column, these fluids mix during rapid ascent to form hydrothermal ore deposits. Mixing from below provides a viable hydromechanical mechanism to explain the common phenomenon of mixed shallow and deep fluids in hydrothermal ore deposits. Bons, P.D., Elburg, M.A., Gomez-Rivas, E. 2012. A review of the formation of tectonic veins and their microstructures. J. Struct. Geol. doi:10.1016/j.jsg.2012.07.005 Fusswinkel, T., Wagner, T., Wälle, M., Wenzel, T., Heinrich, C.A., Markl, M. 2013. Fluid mixing forms basement-hosted Pb-Zn deposits: Insight from metal and halogen geochemistry of individual fluid inclusions. Geology. doi:10.1130/G34092.1

Bons, Paul D.; Gomez-Rivas, Enrique; Markl, Gregor; Walter, Bejamin

2014-05-01

309

The Idaho cobalt belt, northwestern United States — A metamorphosed Proterozoic exhalative ore district  

NASA Astrophysics Data System (ADS)

In the Idaho cobalt belt, originally exhalative, stratiform mineralization within the Proterozoic Yellow-jacket Formation has become increasingly coarse-grained and remobilized toward the northwest in the direction of increasing regional metamorphic grade. The Idaho cobalt belt is located about 40 km west of Salmon, Idaho in the northwestern United States. The most important deposit in the district is the Blackbird mine which produced copper-cobalt ore sporadically from the early 1900's until about 1960. The Iron Creek deposit at the southeast end of the belt has undergone greenschist fades, biotite zone metamorphism; zones of disseminated, veinlet and massive sulfides lie more or less parallel to bedding of quartzites and phyllites. The main ore minerals are chalcopyrite and cobaltiferous pyrite. Toward the northwest at the Blackpine mine, remobilization has concentrated most of the mineralization into relatively thin concordant and discordant veins containing chalcopyrite, pyrite and arsenopyrite. The cobalt is reported to occur within arsenopyrite. Further northwest at the Blackbird mine where the Yellowjacket formation has been metamorphosed to the lower amphibolite facies, zones of disseminated and coarse-grained vein ores lie approximately along the same stratigraphic zone. Chalcopyrite, cobaltite, arsenopyrite, pyrite and pyrrhotite are the dominant ore minerals. Up to 0.22 oz. Au/ton was present in some of the ore. In addition, tourmaline-bearing sedimentary rocks (tourmalinites) are associated with some of the Blackbird ores. The Salmon Canyon deposit at the northwest end of the belt has undergone upper amphibolite facies, sillimanite zone metamorphism. In these garnet-sillimanite gneisses, chalcopyrite is found as coarse blebs and cobaltite as large porphyroblastic crystals. Gold occurs in amounts up to 0.02 oz. Au/ton. Elsewhere in the world the two most similar districts are the cobalt-bearing portion of the Zambian-Zairian Copperbelt of central Africa where Proterozoic Roan sedimentary rocks contain stratiform copper-cobalt ore-bodies over a distance of more than 500 kilometers, and the Sheep Creek district of Meagher County, Montana, which contains strata-bound copper-cobalt mineralization. The Idaho cobalt belt is a strata-bound copper-cobalt district hosted by the Proterozoic Yellowjacket Formation and located in east-central Idaho within Lemhi County, approximately 40 kilometers west of Salmon, Idaho, northwestern United States (Fig. 1). Of the four main deposits described here (from southeast to northwest, the Iron Creek, Blackpine, Blackbird, and the Salmon Canyon deposits), the Blackbird mine is the most important in the district. It was discovered in 1893 and sporadically produced copper and cobalt until about 1960. The Yellowjacket Formation has undergone an increasing degree of metamorphism toward the northwest. The deposits are largely strata-bound in a belt over 50 km in length, strongly suggesting a syngenetic mode of origin. However, the proximity of the district to satellitic granitic plutons of the Idaho batholith has prompted many investigators to suggest an epigenetic hydrothermal origin (Anderson 1947 and Purdue 1975). Remobilization of some of the mineralization into veins at the Blackbird mine, where most of the previous work has been concentrated, has also suggested an epigenetic origin. A more district-wide view of the mineralization points to a strong degree of stratigraphic control.

Nold, J. L.

1990-07-01

310

Determination of sintering parameters for liquid phase sintering of silicon nitride  

NASA Astrophysics Data System (ADS)

The sintering parameters of silicon nitride were determined during the second stage of liquid phase sintering via interrupted sinter forging tests under compressive uniaxial load. The silicon nitride with an yttria-alumina rich secondary phase (Saint-Gobain composition NB D300) was submitted to seven level of stress (from 0.24MPa to 9.41MPa) at three different temperatures (1500°C, 1550°C and 1600°C) with continuous monitoring of the axial and longitudinal shrinkage during all experiments to directly obtain the sintering stress, Poisson's ratio and bulk viscosity. The sintering stress measured in the first 1.5 minutes after reaching temperature was 7.5MPa at 1500°C (˜60% theoretical density), 21.5 MPa at 1550°C (˜70% dense) and 11.5MPa at 1600°C (˜80% dense). The bulk viscosity also peaks at the intermediate density at about 48GPas. This variation is largely attributed to the noticeable changes of microstructure during the second stage of liquid phase sintering, especially the overall pore size distribution as well as the degree to which the liquid phase is fully melted and partially or fully fills the smallest pores. The experimental data were then inserted into a numerical model developed by Abouaf. Proper fit of the model could not be obtained without considering the rearrangement stage of sintering. Considering both the rearrangement and solution-precipitation stages of densification, it was possible to determine the variation during sintering of different parameters that influences the liquid phase sintering and therefore the microstructure development.

Theron, Claire

311

Sedimentary exhalative nickel-molybdenum ores in south China  

USGS Publications Warehouse

Unique bedded Ni-Mo ores hosted by black shales were discovered in localized paleobasins along the Yangzte platform of southern China in 1971. Textural evidence and radiometric dates imply ore formation during sedimentation of black shales that grade into readily combustible beds, termed stone coals, which contain 10 to 15 percent organic carbon. Studies of 427 fluid inclusions indicate extreme variation in hydrothermal brine salinities that were contained by Proterozoic dolostones underlying the ore zone in Hunan and Guizhou. Variations of fluid inclusion salinities, which range from 0.1 to 21.6 wt percent NaCl equiv, are attributed to differences in the compositions of brines in strata underlying the ore bed, complicated by the presence of seawater and dilute fluids that represent condensates of vapors generated by boiling of mineralizing fluids or Cambrian meteoric water. The complex processes of ore deposition led to scattered homogenization temperatures ranging from 100??to 187??C within the Hunan ore zone and from 65??to 183??C within the Guizhou ore zone. While living organisms probably did not directly accumulate metals in situ in sufficient amounts to explain the unusually high grades of the deposits, sulfur isotope ratios indicate that bacteria, now preserved as abundant microfossils, provided sufficient sulfide for the ores by reduction of seawater sulfate. Such microbiota may have depended on vent fluids and transported organic matter for key nutrients and are consistent with a sedex origin for the ores. Vent fluids interacted with organic remains, including rounded fragments of microbial mats that were likely transported to the site of ore deposition by the action of waves and bottom currents prior to replacement by ore minerals.

Lott, D. A.; Coveney, Jr. , R. M.; Murowchick, J. B.; Grauch, R. I.

1999-01-01

312

Process for microwave sintering boron carbide  

DOEpatents

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Holcombe, C.E.; Morrow, M.S.

1993-10-12

313

Process for microwave sintering boron carbide  

DOEpatents

A method of microwave sintering boron carbide comprises leaching boron carbide powder with an aqueous solution of nitric acid to form a leached boron carbide powder. The leached boron carbide powder is coated with a glassy carbon precursor to form a coated boron carbide powder. The coated boron carbide powder is consolidated in an enclosure of boron nitride particles coated with a layer of glassy carbon within a container for microwave heating to form an enclosed coated boron carbide powder. The enclosed coated boron carbide powder is sintered within the container for microwave heating with microwave energy.

Holcombe, Cressie E. (440 Sugarwood Dr., Knoxville, TN 37922); Morrow, Marvin S. (Rte. #3, Box 113, Kingston, TN 37763)

1993-01-01

314

40 CFR 440.20 - Applicability; description of the aluminum ore subcategory.  

Code of Federal Regulations, 2012 CFR

... Applicability; description of the aluminum ore subcategory. 440.20 Section...AND DRESSING POINT SOURCE CATEGORY Aluminum Ore Subcategory § 440.20 Applicability; description of the aluminum ore subcategory. The...

2012-07-01

315

40 CFR 440.60 - Applicability; description of the tungsten ore subcategory.  

Code of Federal Regulations, 2011 CFR

... Applicability; description of the tungsten ore subcategory. 440.60 Section...AND DRESSING POINT SOURCE CATEGORY Tungsten Ore Subcategory § 440.60 Applicability; description of the tungsten ore subcategory. The...

2011-07-01

316

40 CFR 440.40 - Applicability; description of the mercury ore subcategory.  

Code of Federal Regulations, 2011 CFR

... Applicability; description of the mercury ore subcategory. 440.40 Section...AND DRESSING POINT SOURCE CATEGORY Mercury Ore Subcategory § 440.40 Applicability; description of the mercury ore subcategory. The...

2011-07-01

317

40 CFR 440.40 - Applicability; description of the mercury ore subcategory.  

Code of Federal Regulations, 2013 CFR

... Applicability; description of the mercury ore subcategory. 440.40 Section...AND DRESSING POINT SOURCE CATEGORY Mercury Ore Subcategory § 440.40 Applicability; description of the mercury ore subcategory. The...

2013-07-01

318

40 CFR 440.40 - Applicability; description of the mercury ore subcategory.  

Code of Federal Regulations, 2010 CFR

... Applicability; description of the mercury ore subcategory. 440.40 Section...AND DRESSING POINT SOURCE CATEGORY Mercury Ore Subcategory § 440.40 Applicability; description of the mercury ore subcategory. The...

2010-07-01

319

40 CFR 440.40 - Applicability; description of the mercury ore subcategory.  

Code of Federal Regulations, 2012 CFR

... Applicability; description of the mercury ore subcategory. 440.40 Section...AND DRESSING POINT SOURCE CATEGORY Mercury Ore Subcategory § 440.40 Applicability; description of the mercury ore subcategory. The...

2012-07-01

320

40 CFR 440.70 - Applicability; description of the nickel ore subcategory.  

Code of Federal Regulations, 2010 CFR

... Applicability; description of the nickel ore subcategory. 440.70 Section...MINING AND DRESSING POINT SOURCE CATEGORY Nickel Ore Subcategory § 440.70 Applicability; description of the nickel ore subcategory. The...

2010-07-01

321

Sintered-reaction Bonded Silicon Nitride Densified by a Gas Pressure Sintering Process Effects of Rare Earth Oxide Sintering Additives  

SciTech Connect

Reaction-bonded silicon nitrides containing rare-earth oxide sintering additives were densified by gas pressure sintering. The sintering behavior, microstructure and mechanical properties of the resultant specimens were analyzed. For that purpose, Lu2O3-SiO2 (US), La2O3-MgO (AM) and Y2O3-Al2O3 (YA) additive systems were selected. Among the tested compositions, densification of silicon nitride occurred at the lowest temperature when using the La2O3-MgO system. Since the Lu2O3-SiO2 system has the highest melting temperature, full densification could not be achieved after sintering at 1950oC. However, the system had a reasonably high bending strength of 527 MPa at 1200oC in air and a high fracture toughness of 9.2 MPa m1/2. The Y2O3-Al2O3 system had the highest room temperature bending strength of 1.2 GPa

Lee, S. H. [Korea Institute of Materials Science; Ko, J. W. [Korea Institute of Materials Science; Park, Y. J. [Korea Institute of Materials Science; Kim, H. D. [Korea Institute of Materials Science; Lin, Hua-Tay [ORNL; Becher, Paul F [ORNL

2012-01-01

322

TYPES AND ORE RESERVES OF CANADIAN RADIOACTIVE DEPOSITS  

Microsoft Academic Search

Figures for production of uranium in Canada and for reserves of ; radioactive ores are summarized. A revised classification and a short discussion ; of geological types of productive and nonproductive radioactive deposits are ; presented. Low-grade thorium deposits are known to occur in large tonnages, ; particularly at Blind River. The ores of this region as a whole, although

J. W. Grittith; A. H.. Lang

1959-01-01

323

DETAIL OVERHEAD VIEW OF SECONDARY ORE BIN, CONVEYOR PLATFORM TRAM ...  

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

DETAIL OVERHEAD VIEW OF SECONDARY ORE BIN, CONVEYOR PLATFORM TRAM TRESTLE, AND LOADING PLATFORM, LOOKING SOUTHWEST. THE HOLE IN THE ORE BIN FLOOR CAN BE SEEN, AND BALL MILL FOUNDATION AT LOWER LEFT CORNER. SEE CA-291-13 FOR IDENTICAL B&W NEGATIVE. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

324

25. DETAIL OF STRUCTURAL TIMBERS, ORE BIN, AND STAIRWAY TO ...  

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

25. DETAIL OF STRUCTURAL TIMBERS, ORE BIN, AND STAIRWAY TO TOP FLOOR OF MILL, LOOKING SOUTH FROM SECOND FLOOR OF MILL. PORTION OF ORE BIN ON RIGHT, STAIRS ON LEFT. - Skidoo Mine, Park Route 38 (Skidoo Road), Death Valley Junction, Inyo County, CA

325

15. NORTH ELEVATION OF UPPER ORE BIN, CHUTE, AND JAW ...  

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

15. NORTH ELEVATION OF UPPER ORE BIN, CHUTE, AND JAW CRUSHER, LOOKING SOUTH FROM END OF CONVEYOR PLATFORM. NOTICE THE THREE ORE BIN CONTROL DOORS, CORRESPONDING TO SEPARATE COMPARTMENTS OF THE BIN. - Skidoo Mine, Park Route 38 (Skidoo Road), Death Valley Junction, Inyo County, CA

326

LOOKING WEST ALONG PASSAGE BETWEEN CRUSHING ROOM AND FINE ORE ...  

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

LOOKING WEST ALONG PASSAGE BETWEEN CRUSHING ROOM AND FINE ORE BIN AREA. NOTE STEEL CUSTOM ORE CHUTES IN BACKGROUND. THE FARTHEST BINS WERE LAST USED FOR STORAGE OF BALL MILL BALLS. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

327

25. View looking southwest from furnaces shows the ore end ...  

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

25. View looking southwest from furnaces shows the ore end limestone storage bins. Ore and limestone were carried by conveyor, seen at far left, to the tripper car, which in turn distributed them into the trestle bins. - Central Furnaces, 2650 Broadway, east bank of Cuyahoga River, Cleveland, Cuyahoga County, OH

328

14. OBLIQUE VIEW OF UPPER ORE BIN AND LOADING DECK, ...  

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

14. OBLIQUE VIEW OF UPPER ORE BIN AND LOADING DECK, LOOKING WEST. DETAIL OF SUPPORTING TIMBERS. THE LOCATION OF THIS ORE BIN IN RELATION TO THE MILL CAN BE SEEN IN MANY OF THE MILL OVERVIEWS. (CA-290-4 THROUGH CA-290-8). - Skidoo Mine, Park Route 38 (Skidoo Road), Death Valley Junction, Inyo County, CA

329

19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ...  

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

19. VIEW OF CRUDE ORE BINS FROM EAST. EAST CRUDE ORE BIN IN FOREGROUND WITH DISCHARGE TO GRIZZLY AT BOTTOM OF VIEW. CONCRETE RETAINING WALL TO LEFT (SOUTH) AND BOTTOM (EAST EDGE OF EAST BIN). - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

330

64. NORTH WALL OF CRUSHED OXIDIZED ORE BIN. THE PRIMARY ...  

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

64. NORTH WALL OF CRUSHED OXIDIZED ORE BIN. THE PRIMARY MILL FEEDS AT BOTTOM. MILL SOLUTION TANKS WERE TO THE LEFT (EAST) AND BARREN SOLUTION TANK TO THE RIGHT (WEST) OR THE CRUSHED ORE BIN. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

331

27. HULETT ORE UNLOADERS TEMPORARILY IN REPOSE, AS A NEW ...  

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

27. HULETT ORE UNLOADERS TEMPORARILY IN REPOSE, AS A NEW SKIP TIES UP AT DOCK. THE UNLOADERS OPERATE ALMOST CONTINUOUSLY DURING THE SHIPPING SEASON, WHICH USUALLY RUNS FROM APRIL UNTIL LATE DECEMBER OR EARLY JANUARY. VIEW HERE IS LOOKING NORTHEAST. - Pennsylvania Railway Ore Dock, Lake Erie at Whiskey Island, approximately 1.5 miles west of Public Square, Cleveland, Cuyahoga County, OH

332

Sample preparation methods for analysis of spent chrome ores  

Microsoft Academic Search

Two methods of sample preparation were compared for analysis of total chromium in samples of spent ore. These spent ores result from the production of chromium chemicals. In the standard method used by the US Environmental Protection Agency, the sample is reacted with nitric and hydrochloric acids and hydrogen peroxide to extract the reacted chromium from the solid matrix and

O. Baturay; A. Sigerson; J. E. Shirk

2009-01-01

333

Redesigning exhaust-gas recirculation systems in sintering  

Microsoft Academic Search

The recirculation of hot gases (air from the sinter coolers or the cooling zone, sintering waste gases) permits energy conservation and environmental protection in sinter production. A benefit of gas recirculation is the reduced atmospheric emission of harmful materials (CO, CO 2 , H 2 S, SO 2 ) and dust. One common method of hot-gas recirculation is to return

A. A. Vyatkin; S. S. Skachkova; E. G. Dmitrieva; R. N. Shumilov; A. Yu. Morozov

2008-01-01

334

Stress evolution in graded materials during densification by sintering processes  

Microsoft Academic Search

A set of constitutive laws for describing functionally graded materials behaviour during entire sintering process was developed. It can be used to get stress distribution arising during sintering and cooling as well as to check various parameters on sintering of FGM (particle size, density and graded profile of concentration) to optimise the process. It was implemented in ABAQUS code as

Baosheng Zhang; Michael M. Gasik

2002-01-01

335

New Ferro Powder for Selective Laser Sintering of Dense Parts  

Microsoft Academic Search

The paper describes a new powder composition specially developed for selective laser sintering (SLS). The aim is to obtain a ferro powder that can be sintered without need for a (sacrificial) polymer binder and that results in quasi dense parts that do not need any post-processing like furnace sintering, infiltration or HIP. The powder is a mixture of different types

J. P. Kruth; L. Froyen; M. Rombouts; J. Van Vaerenbergh; P. Mercells

2003-01-01

336

Numerical simulation of selective laser sintering transient temperature field  

Microsoft Academic Search

A numerical simulation pattern based on finite element algorithm is proposed for calculation of selective laser sintering transient temperature field. The patter is based on the transient thermal radiation and the boundary conditions is concerned soundly, particularly during the transient sintering the relation between thermal conductivity and transient sintering temperature is set up on the basis of practical test to

Jian Xing; Xiaogang Sun

2009-01-01

337

The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits  

NASA Astrophysics Data System (ADS)

The ubiquity of Au-bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of Au and As in this sulfide occurs under a wide range of physico-chemical conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-ICP-MS, SIMS, and ?-PIXE analyses of As and Au in pyrite from Carlin-type Au, epithermal Au, porphyry Cu, Cu-Au, and orogenic Au deposits, volcanogenic massive sulfide (VHMS), Witwatersrand Au, iron oxide copper gold (IOCG), and coal deposits. Pyrite included in the data compilation formed under temperatures from ?30 to ?600 °C and in a wide variety of geological environments. The pyrite Au-As data form a wedge-shaped zone in compositional space, and the fact that most data points plot below the solid solubility limit defined by Reich et al. (2005) indicate that Au1+ is the dominant form of Au in arsenian pyrite and that Au-bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native Au. The analytical data also show that the solid solubility limit of Au in arsenian pyrite defined by an Au/As ratio of 0.02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal-chemical properties of pyrite and post-depositional alteration. Compilation of Au-As concentrations and formation temperatures for pyrite indicates that Au and As solubility in pyrite is retrograde; Au and As contents decrease as a function of increasing temperature from ?200 to ?500 °C. Based on these results, two major Au-As trends for Au-bearing arsenian pyrite from ore deposits are defined. One trend is formed by pyrites from Carlin-type and orogenic Au deposits where compositions are largely controlled by fluid-rock interactions and/or can be highly perturbed by changes in temperature and alteration by hydrothermal fluids. The second trend consists of pyrites from porphyry Cu and epithermal Au deposits, which are characterised by compositions that preserve the Au/As signature of mineralizing magmatic-hydrothermal fluids, confirming the role of this sulfide in controlling metal ratios in ore systems.

Deditius, Artur P.; Reich, Martin; Kesler, Stephen E.; Utsunomiya, Satoshi; Chryssoulis, Stephen L.; Walshe, John; Ewing, Rodney C.

2014-09-01

338

Room Temperature Aging Study of Butyl O-rings  

SciTech Connect

During testing under the Enhanced Surveillance Campaign in 2001, preliminary data detected a previously unknown and potentially serious concern with recently procured butyl o-rings. All butyl o-rings molded from a proprietary formulation throughout the period circa 1999 through 2001 had less than a full cure. Tests showed that sealing force values for these suspect o-rings were much lower than expected and their physical properties were very sensitive to further post curing at elevated temperatures. Further testing confirmed that these o-rings were approximately 50% cured versus the typical industry standard of > 90% cured. Despite this condition, all suspect o-rings fully conformed to their QC acceptance requirements, including their individual product drawing requirements.

Mark Wilson

2009-08-07

339

Iron deficiency  

Microsoft Academic Search

Iron deficiency remains one of the world’s greatest public health problems. Globally it is the greatest contributor to anaemia, affecting 47% of pre-school age children and 25% of school age children worldwide, and is a major contributor to both physical and neuro-developmental morbidity.Iron deficiency results from inadequate intake, excess turnover or excessive loss. Whilst inadequate intake is the commonest cause

Katrina Pettit; Jennifer Rowley; Nick Brown

2011-01-01

340

Growth and Sintering of Fullerene Nanotubes  

Microsoft Academic Search

Carbon nanotubes produced in arcs have been found to have the form of multiwalled fullerenes, at least over short lengths. Sintering of the tubes to each other is the predominant source of defects that limit the utility of these otherwise perfect fullerene structures. The use of a water-cooled copper cathode minimized such defects, permitting nanotubes longer than 40 micrometers to

D. T. Colbert; J. Zhang; S. M. McClure; P. Nikolaev; Z. Chen; J. H. Hafner; D. W. Owens; P. G. Kotula; C. B. Carter; J. H. Weaver; A. G. Rinzler; R. E. Smalley

1994-01-01

341

Direct selective laser sintering of metals  

Microsoft Academic Search

Considers efforts to date to produce parts by direct selective laser sintering (SLS) of metals, including post processing to improve structural integrity and\\/or to induce a transformation. Provides a brief overview of the basic principles of SLS machine operation, and discusses materials issues affecting direct SLS of metals and the resultant properties and microstructures of the parts. Reviews results of

Mukesh Agarwala; David Bourell; Joseph Beaman; Harris Marcus; Joel Barlow

1995-01-01

342

Effective thermal conductivity of sintered metal fibers  

Microsoft Academic Search

For the effective thermal conductivity of dry and fluid-saturated sintered metal fibers, existing correlations are compared to experimental data, and an empirical expression that compensates for the effect of the aspect ratio of the fibers is presented. It is shown that the present equation predicts the data with 10 percent deviation, while the Acton equation, which has been recommended in

W. J. Mantle; Won S. Chang

1991-01-01

343

Sintered electrode for solid oxide fuel cells  

DOEpatents

A solid oxide fuel cell fuel electrode is produced by a sintering process. An underlayer is applied to the electrolyte of a solid oxide fuel cell in the form of a slurry, which is then dried. An overlayer is applied to the underlayer and then dried. The dried underlayer and overlayer are then sintered to form a fuel electrode. Both the underlayer and the overlayer comprise a combination of electrode metal such as nickel, and stabilized zirconia such as yttria-stabilized zirconia, with the overlayer comprising a greater percentage of electrode metal. The use of more stabilized zirconia in the underlayer provides good adhesion to the electrolyte of the fuel cell, while the use of more electrode metal in the overlayer provides good electrical conductivity. The sintered fuel electrode is less expensive to produce compared with conventional electrodes made by electrochemical vapor deposition processes. The sintered electrodes exhibit favorable performance characteristics, including good porosity, adhesion, electrical conductivity and freedom from degradation. 4 figs.

Ruka, R.J.; Warner, K.A.

1999-06-01

344

Machinability of phosphorous containing sintered steels  

Microsoft Academic Search

Study of the machinability characteristics of porous sintered materials has received far less attention during the last decades, presumably due to powder metallurgy’s greatest advantage over other manufacturing methods in eliminating completely or minimising greatly machining and also perhaps due to lack of any standard test method developed for machinability studies. However, many parts because of intricate design, require machining

Mohammad Hamiuddin; Qasim Murtaza

2001-01-01

345

Reactive sintering of plutonium-bearing titanates.  

SciTech Connect

Titanate ceramics are being developed for the immobilization of weapons-grade plutonium. These multi-phase ceramics are intended to be both corrosion and proliferation resistant. Reactive sintering techniques were refined to reproducibly provide titanate ceramics for further characterization and testing. Plutonium-bearing pyrochlore-rich composites were consolidated to greater than 90% of their theoretical density.

Hash, M. C.

1999-06-24

346

Method for cleaning sinter plant gas emissions  

SciTech Connect

A method for cleaning sinter plant gas emissions using a wet electrostatic precipitator system having separate recirculating wash liquor loops for the high voltage precipitator section and the pre-scrubber section. The system is operated with acidic washing liquor to avoid scaling and deposition of solids within the system.

Herman, S.T.; Jassund, S.A.; Mazer, M.R.

1981-03-17

347

Study of Organic and Inorganic Binders on Strength of Iron Oxide Pellets  

NASA Astrophysics Data System (ADS)

Bentonite is a predominant binder used in iron ore pelletization. However, the presence of a high content of silica and alumina in bentonite is considered undesirable for ironmaking operations. The objective of this study was to identify the alternatives of bentonite for iron ore pelletization. To achieve this goal, different types of organic and inorganic binders were utilized to produce iron oxide pellets. The quality of these iron oxide pellets was compared with pellets made using bentonite. All pellets were tested for physical strength at different stages of pelletization to determine their ability to survive during shipping and handling. The results show that organic binders such as lactose monohydrate, hemicellulose, and sodium lignosulfonate can provide sufficient strength to indurated pellets.

Srivastava, Urvashi; Kawatra, S. Komar; Eisele, Timothy C.

2013-08-01

348

Pressureless sintering of whiskered-toughened ceramic composites  

DOEpatents

A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method. 6 figures.

Tiegs, T.N.

1994-12-27

349

Comparative sinterability of combustion synthesized and commercial titanium carbides  

SciTech Connect

The influence of various parameters on the sinterability of combustion synthesized titanium carbide was investigaged. Titanium carbide powders, prepared by the combustion synthesis process, were sintered in the temperature range 1150 to 1600/sup 0/C. Incomplete combustion and high oxygen contents were found to be the cause of reduced shrinkage during sintering of the combustion syntheized powders when compared to the shrinkage of commercial TiC. Free carbon was shown to inhibit shrinkage. The activation energy for sintering was found to depend on stoichiometry (C/Ti). With decreasing C/Ti, the rate of sintering increased. 29 references, 16 figures, 13 tables.

Manley, B.W.

1984-11-01

350

Constraints on the composition of ore fluids and implications for mineralising events at the Cleo gold deposit, Eastern Goldfields Province, Western Australia  

USGS Publications Warehouse

The Cleo gold deposit, 55 km south of Laverton in the Eastern Goldfields Province of Western Australia, is characterised by banded iron-formation (BIF)-hosted ore zones in the gently dipping Sunrise Shear Zone and high-grade vein-hosted ore in the Western Lodes. There is evidence that gold mineralisation in the Western Lodes (which occurred at ca 2655 Ma) post-dates the majority of displacement along the Sunrise Shear Zone, but it remains uncertain if the ore in both structures formed simultaneously or separately. Overall, the Pb, Nd, Sr, C. O and S isotopic compositions of ore-related minerals from both the Western Lodes and ore zones in the Sunrise Shear Zone are similar. Early low-salinity aqueous-carbonic fluids and late high-salinity fluids with similar characteristics are trapped in inclusions in quartz veins from both the Sunrise Shear Zone and the Western Lodes. The early CO2, CO2-H2O, and H2O- dominant inclusions are interpreted as being related to ore formation, and to have formed from a single low-salinity aqueous-carbonic fluid as a result of intermittent fluid immiscibility. Homogenisation temperatures indicate that these inclusions were trapped at approximately 280??C and at approximately 4 km depth, in the deeper epizonal range. Differences between the ore zones are detected in the trace-element composition of gold samples, with gold from the Sunrise Shear Zone enriched in Ni, Pb, Sn, Te and Zn, and depleted In As, Bi, Cd, Cu and Sb, relative to gold from the Western Lodes. Although there are differences in gold composition between the Sunrise Shear Zone and Western Lodes, and hence the metal content of ore fluids may have varied slightly between the different ore zones, no other systematic fluid or solute differences are detected between the ore zones. Given the fact that the ore fluids in each zone have very similar bulk properties, the considerable differences in gold grade, sulfide mineral abundance, and ore textures between the two ore zones most likely result from different gold-deposition mechanisms. The association of ore zones in the Sunrise Shear Zone with pyrite-replaced BIF suggests that wall-rock sulfidation was the most significant mechanism of gold precipitation, through the destabilisation of gold-bisulfide complexes. The Western Lodes, however, do not exhibit any host-rock preference and multistage veins commonly contain coarse-grained gold. Fluid-inclusion characteristics and breccia textures in veins in the Western Lodes suggest that rapid pressure changes, brought about by intermittent release of overpressured fluids and concomitant phase separation, are likely to have caused the destabilisation of gold-thiocomplexes, leading to formation of higher-grade gold ore zones.

Brown, S.M.; Johnson, C.A.; Watling, R.J.; Premo, W.R.

2003-01-01

351

Total Ore Processing Integration and Management  

SciTech Connect

This report outlines the technical progress achieved for project DE-FC26-03NT41785 (Total Ore Processing Integration and Management) during the period 01 July through 30 September of 2005. This ninth quarterly report discusses the activities of the project team during the period 1 July through 30 September 2005. Richard Gertsch's unexpected death due to natural causes while in Minnesota to work on this project has temporarily slowed progress. Statistical analysis of the Minntac Mine data set for late 2004 is continuing. Preliminary results raised several questions that could be amenable to further study. Detailed geotechnical characterization is being applied to improve the predictability of mill and agglomerator performance at Hibtac Mine.

Leslie Gertsch; Richard Gertsch

2006-01-30

352

Electrosintering of iron powder compacts  

NASA Astrophysics Data System (ADS)

The influence of a nominal external electric fieldE=3 to 10 kV/cm on the sintering of iron powder compacts for 30 minutes at 1140°C in a vacuum of ˜10-6 torr was investigated. It was found that the field reduced the porosity by as much as 29 to 73 pct compared to sintering without a field, the magnitude depending on the procedure employed to measure the density of the specimen. Optical microscopy revealed that the specimen electrosintered withE=10 kV/cm had a skin of ˜0.2 mm in thickness, where the porosity was significantly less than in the interior. This was also the depth of carburization that was obtained upon carburizing the electrosintered specimens. It is proposed that the decrease in porosity produced by the field results from a decrease in the chemical potential of vacancies at or just below the charged external surface. Vacancy flux equations employed to calculate the porosity as a function of distance below the external surface showed that the porosity becomes approximately zero at a distance ofx c=0.4 to 0.5 mm below the surface, which is in reasonable accord with the microscopy measurements. Similar values ofx c were obtained by assuming that the entire porosity decrease given by the density measurements occurred in a ring of thickness ofx c below the external surface. The difference in the density measured by two Archimedes-principle procedures and microscopy observations suggests that the cavities open to the external surface of the electrosintered specimens are smaller or narrower than those for specimens sintered without a field.

Fahmy, Yusef; Conrad, Hans

2001-03-01

353

CFB roasting for gold ore processing  

SciTech Connect

This paper describes how KTI/Dorr-Oliver applied the results from CFB boiler technology to the design for a CFB mineral processing plant built in Africa in 1992. The whole ore gold roaster plant located in Syama, Mali is presently owned and operated by Randgold of South Africa and it processes over 216 tons per hour of whole gold ore. The plant has operated continuously for over four years. The CFB reactor operates in the turbulent CFB mode of fluidization with over 40 minutes of solids residence time in the dense phase for optimum conversion of the feed material. The success of the plant after four years of operation is in large part due to the choice of the turbulent CFB mode of fluidization. This mode is very flexible in face of significant variations in feed composition and size distribution. Sulfur capture takes place in situ and the sorbent is present naturally in the feed. An electrostatic precipitator is used for particulate removal from the flue gas. The energy balance for the system requires auxiliary fuel oil burned in the CFB reactor. Energy from the 1,200--1,350 F roasted product stream is recovered and recycled back into the CFB using two fluidized bed coolers; one to directly heat the secondary air and the other to indirectly heat the primary fluidizing air. Pilot plant testing and the scale up of pilot plant results to the full scale plant is described. The plant start up including resolution of some unique start up difficulties is covered. A comparison of results for the pilot plant and commercial plant is presented.

Hubbard, G.; D'Acierno, J.P.

1999-07-01

354

Ore minerals textural characterization by hyperspectral imaging  

NASA Astrophysics Data System (ADS)

The utilization of hyperspectral detection devices, for natural resources mapping/exploitation through remote sensing techniques, dates back to the early 1970s. From the first devices utilizing a one-dimensional profile spectrometer, HyperSpectral Imaging (HSI) devices have been developed. Thus, from specific-customized devices, originally developed by Governmental Agencies (e.g. NASA, specialized research labs, etc.), a lot of HSI based equipment are today available at commercial level. Parallel to this huge increase of hyperspectral systems development/manufacturing, addressed to airborne application, a strong increase also occurred in developing HSI based devices for "ground" utilization that is sensing units able to play inside a laboratory, a processing plant and/or in an open field. Thanks to this diffusion more and more applications have been developed and tested in this last years also in the materials sectors. Such an approach, when successful, is quite challenging being usually reliable, robust and characterised by lower costs if compared with those usually associated to commonly applied analytical off- and/or on-line analytical approaches. In this paper such an approach is presented with reference to ore minerals characterization. According to the different phases and stages of ore minerals and products characterization, and starting from the analyses of the detected hyperspectral firms, it is possible to derive useful information about mineral flow stream properties and their physical-chemical attributes. This last aspect can be utilized to define innovative process mineralogy strategies and to implement on-line procedures at processing level. The present study discusses the effects related to the adoption of different hardware configurations, the utilization of different logics to perform the analysis and the selection of different algorithms according to the different characterization, inspection and quality control actions to apply.

Bonifazi, Giuseppe; Picone, Nicoletta; Serranti, Silvia

2013-02-01

355

Study on the sintering method of Terfenol-D  

NASA Astrophysics Data System (ADS)

A sintering method, which is called low-temperature instantaneous liquid-phase sintering with addition of Sn, is exploited to fabricate Terfenol-D sintered compacts. In this work, the influences of powder size, Sn content, compaction pressure, and sintering technique on the magnetic and mechanical properties have been investigated. A large magnetostriction (??) of 546 ppm at 12 kOe is obtained for the sintered compact fabricated at the following conditions: a powder size <75 ?m, a Sn content of 8:100, a compaction pressure of 1.0 GPa, and sintering at 250 °C for 150 s in the rapid thermal processor. In addition, the sintered compact fabricated by this means possesses higher oxidation resistance and its hard brittleness improves.

Zhao, Shuwen; Liu, Heyan; Han, Xiaoyan; Meng, Xiangxi; Qu, Jingping; Li, Yangxian; Li, Songtao

2006-04-01

356

Alteration mineral mapping for iron prospecting using ETM+ data, Tonkolili iron field, northern Sierra Leone  

NASA Astrophysics Data System (ADS)

The Tonkolili iron field in northern Sierra Leone has the largest known iron ore deposit in Africa. It occurs in a greenstone belt in an Achaean granitic basement. This study focused mainly on mapping areas with iron-oxide and hydroxyl bearing minerals, and identifying potential areas for haematite mineralization and banded iron formations (BIFs) in Tonkolili. The predominant mineral assemblage at the surface (laterite duricrust) of this iron field is haematitegoethite- limonite ±magnetite. The mineralization occurs in quartzitic banded ironstones, layered amphibolites, granites, schists and hornblendites. In this study, Crosta techniques were applied on Enhanced Thematic Mapper (ETM+) data to enhance areas with alteration minerals and target potential areas of haematite and BIF units in the Tonkolili iron field. Synthetic analysis shows that alteration zones mapped herein are consistent with the already discovered magnetite BIFs in Tonkolili. Based on the overlaps of the simplified geological map and the remote sensing-based alteration mineral maps obtained in this study, three new haematite prospects were inferred within, and one new haematite prospect was inferred outside the tenement boundary of the Tonkolili exploration license. As the primary iron mineral in Tonkolili is magnetite, the study concludes that, these haematite prospects could also be underlain by magnetite BIFs. This study also concludes that, the application of Crosta techniques on ETM+ data is effective not only in mapping iron-oxide and hydroxyl alterations but can also provide a basis for inferring areas of potential iron resources in Algoma-type banded iron formations (BIFs), such as those in the Tonkolili field.

Mansaray, Lamin R.; Liu, Lei; Zhou, Jun; Ma, Zhimin

2013-10-01

357

Mercury ores from the New Idria Mining District, California: geochemical and stable isotope studies  

SciTech Connect

The mercury ores of the New Idria Mining District are composed of metacinnabar and cinnabar with minor amounts of stibnite and iron disulfides. Metacinnabar from the main ore zone at the New Idria Mine contains Fe as a major impurity, whereas that from the CO veins contains both Se and Fe in solid solution. The impurity content varies within the same specimen and within individual crystals as well and demonstrates lack of chemical equilibrium. Most of the pyrite and marcasite crystallized earlier than cinnabar and in rare cases contain nuclei of framboidal pyrite. Pyrite and marcasite crystallized as discrete phases, and the latter does not show evidence of transition to pyrite. Dolomite shows normal marine carbonate delta/sup 18/O and delta/sup 13/C values. Quartz displays delta/sup 18/O ranging from 18.5 to 21.5 per thousand, distinctly lower than the associated dolomites, suggesting that the two minerals may have formed at two different stages. The range of delta/sup 34/S values for metacinnabar overlaps with that of cinnabar. The delta/sup 34/S for pyrite ranges from 3.1 to 13.0 per thousand; pyrite with framboidal nuclei shows the highest delta/sup 34/S values. The sulfur isotope data also suggest the lack of isotopic equilibrium. The source of C in the ore-forming fluids was marine carbonates leached from the Franciscan sediments. The source of S is uncertain because of lack of knowledge of the isotopic composition of total sulfur. It is likely that mixed sources of sulfur leached from sulfides in the host rocks and magmatic sulfur are involved.

Boctor, N.Z.; Shieh, Y.N.; Kullerud, G.

1987-06-01

358

Sulfur isotope geochemistry of ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type ore district, Poland  

USGS Publications Warehouse

Studies of the sulfur isotopic composition of ore and gangue minerals from the Silesian-Cracow Zn-Pb district were conducted to gain insights into processes that controlled the location and distribution of the ore deposits. Results of this study show that minerals from the Silesian-Cracow ore district have the largest range of sulfur isotope compositions in sulfides observed from any Mississippi Valley-type ore district in the world. The ??34S values for sulfide minerals range from +38 to -32 per mil for the entire paragenetic sequence but individual stages exhibit smaller ranges. There is a well developed correlation between the sulfur isotope composition and paragenetic stage of ore deposition. The first important ore stage contains mostly positive ??34S values, around 5 per mil. The second stage of ore formation are lower, with a median value of around -5 to -15 per mil, and with some values as low as -32 per mil. Late stage barite contains isotopically heavy sulfur around +32 per mil. The range in sulfur isotope compositions can be explained by contributions of sulfur from a variety of source rocks together with sulfur isotope fractionations produced by the reaction paths for sulfate reduction. Much of the variation in sulfur isotope compositions can be explained by bacterial reduction of sedimentary sulfate and disequilibrium reactions by intermediate-valency sulfur species, especially in the late-stage pyrite and sphalerite. Organic reduction of sulfate and thermal release of sulfur from coals in the Upper Silesian Coal Basin may have been important contributors to sulfur in the ore minerals. The sulfur isotopic data, ore mineral textures, and fluid inclusion data, are consistent with the hypothesis that fluid mixing was the dominant ore forming mechanism. The rather distinct lowering of ?? 34S values in sulfides from stage 2 to stage 3 is believed to reflect some fundamental change in the source of reduced sulfur and/or hydrology of the ore-forming environment. A change in the hydrology of the ore forming environment could be accomplished by extensional faulting that was coeval with ore formation. Late stage barite contains high values of ??34S which may reflect the final collapse of the hydrothermal system.

Leach, D. L.; Vets, J. G.; Gent, C. A.

1996-01-01

359

SGA Biennial Meeting Let's Talk Ore Deposits  

E-print Network

of the hydrothermal alteration and mineralization features, their timing and spatial relations with respect Hydrothermal alteration and mineralization in Santo Domingo Sur Iron Oxide (-Cu-Au) (IOCG) deposit, Atacama refined the main geological features and provided insight into the time-space evolution

Barton, Mark D.

360

Radon emanation from low-grade uranium ore.  

PubMed

Estimation of radon emanation in uranium mines is given top priority to minimize the risk of inhalation exposure due to short-lived radon progeny. This paper describes the radon emanation studies conducted in the laboratory as well as inside an operating underground uranium mine at Jaduguda, India. Some of the important parameters, such as grade/(226)Ra activity, moisture content, bulk density, porosity and emanation fraction of ore, governing the migration of radon through the ore were determined. Emanation from the ore samples in terms of emanation rate and emanation fraction was measured in the laboratory under airtight condition in glass jar. The in situ radon emanation rate inside the mine was measured from drill holes made in the ore body. The in situ(222)Rn emanation rate from the mine walls varied in the range of 0.22-51.84 × 10(-3) Bq m(-2) s(-1) with the geometric mean of 8.68 × 10(-3) Bq m(-2) s(-1). A significant positive linear correlation (r = 0.99, p < 0.001) between in situ(222)Rn emanation rate and the ore grade was observed. The emanation fraction of the ore samples, which varied in the range of 0.004-0.089 with mean value of 0.025 ± 0.02, showed poor correlation with ore grade and porosity. Empirical relationships between radon emanation rate and the ore grade/(226)Ra were also established for quick prediction of radon emanation rate from the ore body. PMID:23974076

Sahu, Patitapaban; Mishra, Devi Prasad; Panigrahi, Durga Charan; Jha, Vivekanand; Patnaik, R Lokeswara

2013-12-01

361

Dry sintering of refractory oxides at elevated temperatures  

NASA Astrophysics Data System (ADS)

Recent efforts to explore the possibility of extending the service of alumina-based refractories into basic steelmaking operations have involved the application of a basic oxide veneer to both fireclay and high-alumina substrates. Because these investigations used a mineralogically complex system consisting of mixtures of commercial refractories and coatings, the nature of the chemical/mineralogical changes that occurred due to the presence of various metal oxides was often difficult to determine. Thus, the present work was undertaken to establish the extent of chemical/mineralogical reaction that might be expected when dissimilar pellets of high-purity single oxides were placed in pressureless contact for known reaction times at known temperatures. Results for the systems , and MgO-Fe showed significant diffusion of chromium into both Fe, as well as iron into MgO after 3 h at 1450 °C. Also, for mixtures of Al and MgO, over 29% spinel formation was evident, even at 1200 °C for 3 h. However, because most couples in the solid state did not remain joined on cooling in spite of the extensive reaction, it would appear that to achieve good bonding, liquid or transient liquid sintering is a prerequisite to the formation of an adherent oxide veneer on a commercial refractory.

Cameron, J.; Caley, W. F.

1993-10-01

362

Water leaching of titanium from ore flotation residue  

SciTech Connect

Copper ore tailings were tested for the stability of titanium submitted to water leaching in three different reactor systems (agitated vessel, bioreactor and percolated fixed-bed column). For each of these systems, titanium extraction did not exceed 1% of the available metal. Biomass removed from ore residue adsorbed a small part of the titanium with sorption capacities below 20-30 mg g{sup -1}, but most of this biomass was sequestered in the ore residue. Oxygen and carbon dioxide concentrations were monitored and changes in concentration correlated with bacteria development at the initial stage of the process and to fungal development in the latter stages.

Jaworska, Malgorzata M.; Guibal, Eric

2003-07-01

363

Agronomic use of calcined christmas island iron\\/aluminium phosphates i. field trials  

Microsoft Academic Search

Christmas Island “C” ore when calcined at 550°C contains up to 24% aluminium and iron and 15% phosphorus which is not water-soluble but is up to 95% soluble in neutral ammonium citrate. Samples vary in total phosphorus content and in the percentage of phosphorus soluble in neutral ammonium citrate, depending on the proportions of crandallite, millisite, and apatite in the

F. B. Muller

1970-01-01

364

DEWATERING AT THE CAPÃO XAVIER IRON OPEN PIT MINE (MINAS GERAIS, BRAZIL)  

Microsoft Academic Search

Highly detailed hydrological and hydrogeological studies of the areas surrounding the Capão Xavier iron orebody, south of the city of Belo Horizonte (MG, Brazil), began in 1993. Dewatering of the aquifer in which the mineralization is located started in September, 2003, in advance of mining. Open pit mining of 220 million tonnes of ore, most of it below groundwater level,

RAFAEL FERNÁNDEZ RUBIO; CÉSAR GRANDCHAMP; LOBO DE REZENDE; DAVID LORCA FERNÁNDEZ

365

Taking iron supplements  

MedlinePLUS

... levels. You may also need to take iron supplements as well to rebuild iron stores in your ... ABOUT IRON SUPPLEMENTS Iron supplements may be taken as capsules, tablets, chewable tablets, and liquids. The most common tablet size is ...

366

Chemolithotrophic bacteria in copper ores leached at high sulfuric Acid concentration.  

PubMed

Extensive bacterial growth was observed when copper sulfide ores were leached with 0.6 N sulfuric acid. The bacterial population developed in this condition was examined by characterization of the spacer regions between the 16S and 23S rRNA genetic loci obtained after PCR amplification of the DNA extracted from the leached ore. The spacers observed had the sizes found in strains of "Leptospirillum ferrooxidans" and Thiobacillus thiooxidans, except for a larger one, approximately 560 bp long, that was not observed in any of the strains examined, including those of Thiobacillus ferrooxidans. The bacteria with this last spacer were selected after culturing in mineral and elemental sulfur media containing 0.7 N sulfuric acid. The spacer and the 16S ribosomal DNA of this isolate were sequenced and compared with those in species commonly found in bioleaching processes. Though the nucleotide sequence of the spacer showed an extensive heterologous region with T. thiooxidans, the sequence of its 16S rDNA gene indicated a close relationship (99.85%) with this species. These results indicate that a population comprised of bacterial strains closely related to T. thiooxidans and of another strain, possibly related to "L. ferrooxidans," can develop during leaching at high sulfuric acid concentration. Iron oxidation in this condition is attributable to "L. ferrooxidans" and not T. ferrooxidans, based on the presence of spacers with the "L. ferrooxidans" size range and the absence of spacers characteristic of T. ferrooxidans. PMID:16535497

Vasquez, M; Espejo, R T

1997-01-01

367

Development of Continuous, Direct Feedback Control Systems for Sintering of Metallic Components  

SciTech Connect

N,N.-Ethylenebisstearimide (EBS) is one of the most commonlyused lubricants in the powder metallurgy (PM) industry in the sintering process. During sintering, the lubricated powder compacts are heat-treated to temperatures in excess of 1,200 °C thus fusing adjacent particles and yielding a part with improved mechanical strength. Delubrication commonly is achieved in the first zone of a sintering furnace by heating the part to temperatures in the 500-600 °C temperature range at a fixed rate and under controlled atmospheric conditions; this strategy minimizes defects, carbon contamination, and compact deformation. The de-lubricated part then enters the second zone (commonly in the 1200-1300 °C temperature range) for sintering. The third zone cools the sintered part at a desired rate to obtain the requisite micro-structural properties. Controlled delubrication is imperative towards achieving high quality parts for the following reasons: the elevated thermal gradient at the transition between the first and second zones can cause parts to expand rapidly and develop microscopic fissures (.blistering.); improper gas flows and belt speeds can lead to carbon deposition on the part and at the grain boundaries (sooting); delubrication products deposit throughout the furnace, even in the coolers, which are far removed from the preheating chamber, leading to significant maintenance costs; pollutants emitted in the exhaust stream of furnaces operating inefficiently are increasingly of environmental concern. In practice, lubricant removal is difficult to control, which often leads to reduced yields in PM manufacturing processes. Throughput is another important issue: process control ideally should lead to a delubrication cycle that yields defect-free parts in a minimum of furnace time, thereby increasing productivity and reducing the net energy consumption. Efficient process control requires rapid monitoring of suitable indicators, preferably gasphase products of delubrication. EBS thermolyzes relatively cleanly in a range of furnace atmospheres, but the mechanism governing the pyrolysis of EBS, compacted with iron powder, is not known and needs to be investigated to determine the parameters important for industrial control, as well as the optimal conditions of delubrication. In addition, a thorough understanding of the pre-sintering chemistry will enable the development of a process control sensor.

Diran Apelian; Marc M. Baum

2006-09-18

368

46 CFR 97.12-1 - Bulk ores and similar cargoes.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Bulk ores and similar cargoes. 97.12-1...OPERATIONS Cargo Stowage § 97.12-1 Bulk ores and similar cargoes. (a) The...operators of general cargo vessels which carry bulk cargoes such as ore, ore...

2010-10-01

369

Thermoluminescence properties of sintered ZnO  

NASA Astrophysics Data System (ADS)

New pellet-shaped ZnO phosphors were synthesized using a controlled chemical reaction. Some samples were sintered at 1123, 1173 or 1223 K during 24 h in air, and then exposed to beta particle irradiation in the dose range from 25 to 800 Gy to investigate their thermoluminescence (TL) properties. By considering their sensitivity, reproducibility, and fading features, samples sintered at 1173 K exhibit the best dosimetric characteristics. From computerized glow curve deconvolution that was carried out using a general order equation, the kinetics parameters were computed, and it was found that the glow curves are composed by six individual TL peaks with kinetics order ranging from 1.2 to 1.8.

Borbón-Nuñez, H. A.; Cruz-Vázquez, C.; Bernal, R.; Kitis, G.; Furetta, C.; Castaño, V. M.

2014-11-01

370

Ceramic components manufacturing by selective laser sintering  

Microsoft Academic Search

In the present paper, technology of selective laser sintering\\/melting is applied to manufacture net shaped objects from pure yttria–zirconia powders. Experiments are carried out on Phenix Systems PM100 machine with 50W fibre laser. Powder is spread by a roller over the surface of 100mm diameter alumina cylinder. Design of experiments is applied to identify influent process parameters (powder characteristics, powder

Ph. Bertrand; F. Bayle; C. Combe; P. Goeuriot; I. Smurov

2007-01-01

371

Iron and infection  

Microsoft Academic Search

Iron and infection. Intravenous iron therapy maintains iron stores and decreases erythropoietin demand in patients undergoing regular dialysis therapy. Microbiology studies show a close relationship between the availability of iron and bacterial virulence. Iron is also an essential requirement of bacteria for multiplication in the host. Therefore, clinical conditions associated with iron excess in the host may increase the risk

SANDA I. PATRUTA; WALTER H. HORL

1999-01-01

372

Thermoelectric Coolers with Sintered Silver Interconnects  

NASA Astrophysics Data System (ADS)

The fabrication and performance of a sintered Peltier cooler (SPC) based on bismuth telluride with sintered silver interconnects are described. Miniature SPC modules with a footprint of 20 mm2 were assembled using pick-and-place pressure-assisted silver sintering at low pressure (5.5 N/mm2) and moderate temperature (250°C to 270°C). A modified flip-chip bonder combined with screen/stencil printing for paste transfer was used for the pick-and-place process, enabling high positioning accuracy, easy handling of the tiny bismuth telluride pellets, and immediate visual process control. A specific contact resistance of (1.4 ± 0.1) × 10-5 ? cm2 was found, which is in the range of values reported for high-temperature solder interconnects of bismuth telluride pellets. The realized SPCs were evaluated from room temperature to 300°C, considerably outperforming the operating temperature range of standard commercial Peltier coolers. Temperature cycling capability was investigated from 100°C to 235°C over more than 200 h, i.e., 850 cycles, during which no degradation of module resistance or cooling performance occurred.

Kähler, Julian; Stranz, Andrej; Waag, Andreas; Peiner, Erwin

2014-06-01

373

Processing of sintered alpha SiC  

NASA Technical Reports Server (NTRS)

Processing methods of sintered alpha SiC for engine applications are developed in a cost effective manner, using a submicron sized powder blended with sintering aids (boron and carbon). The processes for forming a green powder compact, such as dry pressing, cold isostatic pressing and green machining, slip casting, aqueous extrusion, plastic extrusion, and injection molding, are described. Dry pressing is the simplest route to component fabrication, and is carried out at approximately 10,000 psi pressure, while in the cold isostatic method the pressure could go as high as 20,000 psi. Surfactants are added to control settling rates and casting characteristics in the slip casting. The aqueous extrusion process is accomplished by a hydraulic ram forcing the aqueous mixture through a die. The plastic forming processes of extrusion and injection molding offer the potential of greater diversity in shape capacity. The physical properties of sintered alpha SiC (hardness, Young's modulus, shear modulus, and thermal diffusivity) are extensively tested. Corrosion resistance test results of silicon carbide are included.

Storm, R. S.

1984-01-01

374

Preservation of Microbial Lipids in Geothermal Sinters  

NASA Astrophysics Data System (ADS)

Lipid biomarkers are widely used to study the earliest life on Earth and have been invoked as potential astrobiological markers, but few studies have assessed their survival and persistence in geothermal settings. Here, we investigate lipid preservation in active and inactive geothermal silica sinters, with ages of up to 900 years, from Champagne Pool, Waiotapu, New Zealand. Analyses revealed a wide range of bacterial biomarkers, including free and bound fatty acids, 1,2-di-O-alkylglycerols (diethers), and various hopanoids. Dominant archaeal lipids include archaeol and glycerol dialkyl glycerol tetraethers (GDGTs). The predominance of generally similar biomarker groups in all sinters suggests a stable microbial community throughout Champagne Pool's history and indicates that incorporated lipids can be well preserved. Moreover, subtle differences in lipid distributions suggest that past changes in environmental conditions can be elucidated. In this case, higher archaeol abundances relative to the bacterial diethers, a greater proportion of cyclic GDGTs, the high average chain length of the bacterial diethers, and greater concentrations of hopanoic acids in the older sinters all suggest hotter conditions at Champagne Pool in the past.

Kaur, Gurpreet; Mountain, Bruce W.; Hopmans, Ellen C.; Pancost, Richard D.

2011-04-01

375

RUSTING ORE TRAIN, ONCE PART OF NEW YORK ELEVATED LINE ...  

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

RUSTING ORE TRAIN, ONCE PART OF NEW YORK ELEVATED LINE (TWO LOCOMOTIVES, SHOWING RAILROAD TRUCKS IN FOREGROUND) - Council City & Solomon River Railroad, Locomotives, Nome Vicinity, Nome, Nome Census Area, AK

376

44. PHOTOCOPY OF DRAWING OF THE MINE ORE BIN AND ...  

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

44. PHOTOCOPY OF DRAWING OF THE MINE ORE BIN AND LOADING TERMINAL, CROSS SECTION AND SIDE ELEVATION - Kennecott Copper Corporation, On Copper River & Northwestern Railroad, Kennicott, Valdez-Cordova Census Area, AK

377

43. PHOTOCOPY OF DRAWING OF THE MINE ORE BIN AND ...  

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

43. PHOTOCOPY OF DRAWING OF THE MINE ORE BIN AND LOADING TERMINAL, CROSS SECTION AND SIDE ELEVATION - Kennecott Copper Corporation, On Copper River & Northwestern Railroad, Kennicott, Valdez-Cordova Census Area, AK

378

VIEW FACING EAST. ORE TRESTLE WINDS AROUND THE INGOT MOLD ...  

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

VIEW FACING EAST. ORE TRESTLE WINDS AROUND THE INGOT MOLD CONDITIONING BUILDING IN FOREGROUND. PITTSBURGH & LAKE ERIE TRACKS WIND THROUGH TOWN TOWARDS PITTSBURGH AT RIGHT. - Pittsburgh Steel Company, Monessen Works, Donner Avenue, Monessen, Westmoreland County, PA

379

53. VIEW OF CRUSHED OXIDIZED ORE BIN FROM EAST. SHOWS ...  

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

53. VIEW OF CRUSHED OXIDIZED ORE BIN FROM EAST. SHOWS ACCESS STAIR TO FEED LEVEL; DUST COLLECTOR ON LEFT. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

380

Froth Flotation of Insoluble Slimes from Sylvinite Ores.  

National Technical Information Service (NTIS)

Sylvinite ores are treated for removal of insoluble slimes by a froth flotation technique which includes flocculating the slimes with nonionic or polyacrylamide flocculants and thereafter utilizing a nonionic or an anionic flotation collector including a ...

P. Thompson, J. L. Huiatt, D. C. Seidel

1980-01-01

381

Froth Flotation of Insoluble Slimes from Sylvinite Ores.  

National Technical Information Service (NTIS)

Sylvinite ores are treated for removal of insoluble slimes by a froth flotation technique which includes flocculating the slimes with nonionic or polyacrylamide flocculants and thereafter using a nonionic or an anionic flotation collector including a mixt...

P. Thompson, J. L. Huiatt, D. C. Seidel

1978-01-01

382

Effect of shelf aging on O-ring materials  

NASA Technical Reports Server (NTRS)

Commercial O-rings made from 13 different rubber compounds were tested for physical properties after 7 and 12 years of shelf aging. No gross changes were observed in tensile strength, elongation, or compression deflection characteristics.

Wood, T. E.; Stone, W. P.

1978-01-01

383

O-ring coping attachments for removable partial dentures.  

PubMed

Clinical experiences for the past 9 years have demonstrated the practicability of the O-ring coping attachment, a modification of the telescopic crown-and-sleeve coping retainers, for removable partial dentures. A circumferential groove placed in the primary coping receives an elastomeric O-ring that fits into a corresponding groove made in the internal surface of the telescopic crown. The O-ring not only provides controllable retention but also acts as a shock absorber. Long-term retention of the prostheses can be easily maintained by periodic replacements of the O-rings. Sophisticated procedures and expensive machines are not required to make the prostheses. Excellent patient acceptance and the versatility in clinical applications make this system one of the winning designs for removable partial prosthodontics. PMID:7473276

Lee, M W; Baum, L; Pence, B; Hererra, W

1995-09-01

384

OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE ...  

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

OVERVIEW OF UPPER TRAM TERMINAL, TRAM TRESTLE, AND PRIMARY ORE BIN, LOOKING NORTHEAST. REMAINS OF A PRIVY ARE LOCATED IN BOTTOM RIGHT CORNER. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

385

Sitalls from beneficiation wastes of phosphorite ores  

Microsoft Academic Search

llass thermal treatment of the model glasses showed that in the noniron glasses (series P) strengthening of the opacification of the specimens is observed. X-ray analysis fixes the formation of a small amount of crystalline phase -- tetracalcium phosphate 4CaO.P2Os but only in the high-phosphate (3-4%* P205) glasses. In the nonphosphate iron-containing glasses (series F), with an increase in the

S. V. Mulevanov; V. Z. Bliskovskii

1987-01-01

386

Comprehensive Utilization of Complex Titania Ore  

Microsoft Academic Search

To fully utilize Panzhihua titanium resources, a new process was proposed. In the process, Panzhihua ilmenite concentrate was first reduced in a rotary hearth furnace (RHF) to produce a titanium-rich material and iron. The titanium-rich material was then used in a new chlorination process to produce TiCl4. The comparison of different groups of experimental results or calculation results showed that

Zhang-fu YUAN; Yi-fang PAN; E ZHOU; Cong XU; Shu-qing LI

2007-01-01

387

Micromachined rubber O-ring micro-fluidic couplers  

Microsoft Academic Search

In this paper, we present a novel type of a “quick-connect” for micro-fluidic devices realized by a simple silicone-rubber O-ring MEMS coupler. As shown in this work, the proposed O-ring couplers are easy to fabricate and utilize, reusable, can withstand high pressure (>60 psi), and provide good seals. In the paper, results from both the leak rate test and pull-out

Tze-Jung Yao; Sangwook Lee; Weileun Fang; Yu-Chong Tai

2000-01-01

388

Making Reliable Large-Diameter O-Rings  

NASA Technical Reports Server (NTRS)

Vacuum curing yields joint-free, voidless elastomer seals. Method for manufacturing large-diameter O-rings produces them in single pieces, without bonded joints. Reduces probability trapped gases form flaws. O-rings produced, having diameters as much as 144 in. (3.66m), reliable and of high quality. Nesting upper and lower halves of mold hold elastomer rings for curing. Oil flowing through upper and lower cavities heats elastomer to cure it.

Larsen, Glade L.; Harvey, Albert R.

1989-01-01

389

Predicting the lifetime of fluorosilicone O-rings  

Microsoft Academic Search

Long-term (up to 1000 days) accelerated oven-aging studies on a commercial fluorosilicone o-ring seal are used to predict the sealing lifetime at room temperature (23 C). The study follows force decay (relaxation) on squeezed o-ring material using isothermal compression stress relaxation (CSR) techniques. The relaxation is normally a complex mix of reversible physical effects and non-reversible chemical effects but we

Kenneth Todd Gillen; Robert Bernstein

2008-01-01

390

Accelerated thermal ageing studies on nitrile rubber O-rings  

Microsoft Academic Search

Poly(acrylonitrile-butadiene) rubber (NBR) O-rings have been aged in air whilst under 12.5% compression at temperatures up to 110 °C. The compression set properties together with oxygen uptake of the O-rings under the applied load conditions were measured and results analysed using time-temperature superposition and Arrhenius kinetics. The compression set results suggest a single degradation process with an activation energy of

P. R. Morrell; M. Patel; A. R. Skinner

2003-01-01

391

Predicting the lifetime of fluorosilicone o-rings  

Microsoft Academic Search

Long-term (up to 1000 days) accelerated oven-aging studies on a commercial fluorosilicone o-ring seal are used to predict the sealing lifetime at room temperature (23 °C). The study follows force decay (relaxation) on squeezed o-ring material using isothermal compression stress relaxation (CSR) techniques. The relaxation is normally a complex mix of reversible physical effects and non-reversible chemical effects but we utilize

R. Bernstein; K. T. Gillen

2009-01-01

392

AGING PERFORMANCE OF MODEL 9975 PACKAGE FLUOROELASTOMER O-RINGS  

Microsoft Academic Search

The influence of temperature and radiation on Viton{reg_sign} GLT and GLT-S fluoroelastomer O-rings is an ongoing research focus at the Savannah River National Laboratory. The O-rings are credited for leaktight containment in the Model 9975 shipping package used for transportation of plutonium-bearing materials. At the Savannah River Site, the Model 9975 packages are being used for interim storage. Primary research

E. Hoffman; W. Daugherty; E. Skidmore; K. Dunn; D. Fisher

2011-01-01

393

Genetics Home Reference: Iron-refractory iron deficiency anemia  

MedlinePLUS

... Genetic disorder catalog Conditions > Iron-refractory iron deficiency anemia On this page: Description Genetic changes Inheritance Diagnosis ... July 2014 What is iron-refractory iron deficiency anemia? Iron-refractory iron deficiency anemia is one of ...

394

Potential for cobalt recovery from lateritic ores in Europe  

NASA Astrophysics Data System (ADS)

Cobalt is one of the 'critical metals' identified under the EU Raw Materials Initiative. Annually the global mine production of cobalt is around 55,000 tonnes,with Europe's industries consuming around 30% of that figure. Currently Europe produces around 27 tonnes of cobalt from mines in Finland although new capacity is planned. Co-bearing nickel laterite ores being mined in Greece, Macedonia and Kosovo where the cobalt is currently not being recovered (ores have typical analyses of 0.055% Co and >1% Ni,). These ores are currently treated directly in pyrometallurgical plants to recover the contained nickel and this process means there is no separate cobalt product produced. Hydrometallurgical treatment of mineralogically suitable laterite ores can recover the cobalt; for example Cuba recovers 3,500 tonnes of cobalt from its laterite mining operations, which are of a similar scale to the current European operations. Implementation of hydrometallurgical techniques is in its infancy in Europe with one deposit in Turkey planning to use atmospheric heap leaching to recover nickel and copper from oxide-dominated ores. More widespread implementation of these methods to mineralogically suitable ore types could unlock the highly significant undeveloped resources (with metal contents >0.04% Co and >1% Ni), which have been defined throughout the Balkans eastwards into Turkey. At a conservative estimate, this region has the potential to supply up to 30% of the EU cobalt requirements.

Herrington, R.

2012-04-01

395

IN-SITU MINING OF PHOSPHATE ORES  

SciTech Connect

Presently the mining of Florida phosphate requires the movement of over a 100-ton of materials (overburden, sand, clay) for every ton of phosphate concentrate recovered. Not only is this energy intensive, but it also causes significant stress on the environment. In 2003, the Department of Energy solicited ideas for innovative mining ideas that could significantly improve the efficiency of mining. An award was made to the University of Florida Engineering Research Center to evaluate the in situ mining of phosphates using an aqueous CO{sub 2} solution. Tests were carried out in a 15.2 cm (6-inch) diameter column, 1.83 meter (6 feet) long at pressures up to 117.2 kg/cm{sup 2} (40 psi). Results to date demonstrate that initially the MgO is leached from the ore and then the phosphate. While the tests are continuing, so far they have not demonstrated P{sub 2}O{sub 5} concentrations that are economically attractive.

H. El-Shall; R. Stana; A. El-Midany; S. Malekzadah

2004-12-17

396

Iron pentacarbonyl decomposition over grafoil. Production of small metallic iron particles  

SciTech Connect

Mossbauer spectroscopy was the principal technique used to study the adsorption and thermal decomposition of iron pentacarbonyl on a high surface area, oriented graphite (Grafoil). The iron carbonyl physisorbs on the graphite at temperatures less than ca. 300 K, whereas decomposition of the carbonyl occurs upon heating to 378 K. The Mossbauer spectra of the decomposition product are sextuplets indicative of metallic iron. However, the room-temperature magnetic hyperfine splitting (ca. 300 kOe) is smaller and the peak widths (ca. 1.5 mm s-/sup 1/) are larger than those corresponding spectral parameters for bulk metallic iron (330 kOe and 0.28 mm s-/sup 1/, respectively). Computer simulations suggest that these differences are due to magnetic relaxation and to a distribution of magnetic hyperfine fields. For consistency with the Mossbauer spectra, it is proposed that the iron particles are present as thin rafts on the graphite surface. Transmission electron microscopy shows that these rafts are preferentially located along edges and steps on the graphite. Heating to 450 K leads to significant sintering of the iron particles.

Phillips, J.; Clausen, B.; Dumesic, J.A.

1980-07-10

397

In vitro study on newly designed biodegradable Fe-X composites (X = W, CNT) prepared by spark plasma sintering.  

PubMed

Early in vivo animal test on pure iron coronary stent had proved that it is a promising candidate material as biodegradable metal, despite a faster degradation rate and uniform degradation mode is expected. In this work, Fe-X (X= W, CNT) composites were prepared from powders of pure iron and the additive secondary phase X using the spark plasma sintering (SPS) method, aiming to obtain a higher corrosion rate and a more uniform corrosion mode in physiological environment. The microstructures, mechanical properties, corrosion behaviors, and in vitro biocompatibility of these Fe-X composites were investigated. It was found that the additives were uniformly distributed in the iron matrix and relatively high dense Fe-X composite bulk samples were obtained after sintering by SPS. Both the yield strength and ultimate compressive strength increased when compared with that of as-cast pure iron. The corrosion mode of Fe-X composites turned out to be uniform corrosion instead of localized corrosion. Electrochemical measurements and immersion tests indicated that the addition of W and CNT could increase the corrosion rate of the iron matrix. From the results of cytotoxicity evaluation, it was found that all the Fe-X composites extracts induced no obvious cytotoxicity to L929 cells and ECV304 cells whereas significantly decreased cell viabilities of VSMC cells. The hemocompatibility tests showed that all the hemolysis percentage of Fe-X composites were less than 5%, and no sign of thrombogenicity was observed. It might be concluded that Fe composited with suitable second phase can exhibit higher strength, faster degradation rate, and uniform degradation mode than those of pure iron and are promising candidates for future development of new degradable metallic stents. PMID:23359385

Cheng, J; Zheng, Y F

2013-05-01

398

VERIFYING THE MASTER SINTERING CURVE ON AN INDUSTRIAL FURNACE  

Microsoft Academic Search

The Master Sintering Curve is a simple means of predicting density evolution during sintering. This model relies on the work-of-sintering concept, a time-temperature integral, to predict the degree to which a compact has approached the theoretical density limit. The model is characterized through a series of constant heating rate dilatometry experiments. In this paper, we verify that although the model

Deborah C. Blaine; Seong-Jin Park; Randall M. German; Jerry LaSalle; Hill Nandi

399

Application of Work-of-sintering concepts in powder metals  

Microsoft Academic Search

One of the current challenges facing the particulate materials industry is developing simple, accurate models to predict sintered\\u000a properties. Work-of-sintering concepts, where time-temperature integrals are used in such models, offer a solution to this\\u000a problem. In this study, the master sintering curve concept is applied to several powder metal systems: 17 to 4PH stainless\\u000a steel, 316L stainless steel, nickel, niobium,

Deborah C. Blaine; Seong Jin Park; Randall M. German; Pavan Suri

2006-01-01

400

Iron-refractory iron deficiency anemia (IRIDA).  

PubMed

Iron deficiency anemia is a common global problem whose etiology is typically attributed to acquired inadequate dietary intake and/or chronic blood loss. However, in several kindreds multiple family members are affected with iron deficiency anemia that is unresponsive to oral iron supplementation and only partially responsive to parenteral iron therapy. The discovery that many of these cases harbor mutations in the TMPRSS6 gene led to the recognition that they represent a single clinical entity: iron-refractory iron deficiency anemia (IRIDA). This article reviews clinical features of IRIDA, recent genetic studies, and insights this disorder provides into the regulation of systemic iron homeostasis. PMID:25064705

Heeney, Matthew M; Finberg, Karin E

2014-08-01

401

Nanocrystalline gadolinium iron garnet for circulator applications  

NASA Astrophysics Data System (ADS)

Due to high resistivity and low microwave losses, gadolinium iron garnets (GdIG) are useful materials for non-reciprocal devices such as circulators or isolators. Keeping the miniaturization and cost reduction in mind, the trend is to modify the conventional methods of preparation of samples. In this connection we have synthesized nanocystalline GdIG by using the Microwave Hydrothermal method at 160 °C/45 min. As synthesized powders were characterized by using X-ray diffraction (XRD), transmission electron microscopy and Fourier Transform Infrared Spectroscopy. XRD patterns show the formation of a garnet phase with crystallite size varying between 19 nm and 40 nm. Differential Thermal Analysis studies were also carried out on the nanopowders. The powders were densified at a lower sintering temperature of 1100 °C/45 min using a microwave sintering method. The sintered samples were characterized by XRD and atomic force microscopy. The frequency dependence of complex permittivity and ferromagnetic resonance were measured in the Ka band frequency (27-40 GHz). Magnetic properties were also measured at room temperature.

Ramesh, T.; Shinde, R. S.; Murthy, S. R.

2012-11-01

402

An innovative method for nondestructive analysis of cast iron artifacts at Hopewell Furnace National Historic Site, Pennsylvania  

USGS Publications Warehouse

Iron ore containing elevated concentrations of trace metals was smelted at Hopewell Furnace during its 113 years of operation (1771-1883). For this study, we sampled iron ore, cast iron furnace products, slag, soil, groundwater, streamflow, and streambed sediment to determine the fate of trace metals released into the environment during the iron-smelting process. Standard techniques were used to sample and analyze all media except cast iron. We analyzed the trace-metal content of the cast iron using a portable X-ray fluorescence spectrometer, which provided rapid, on-site, nondestructive analyses for 23 elements. The artifacts analyzed included eight cast iron stoves, a footed pot, and a kettle in the Hopewell Furnace museum. We measured elevated concentrations of arsenic, copper, lead, and zinc in the cast iron. Lead concentrations as great as 3,150 parts per million were measured in the stoves. Cobalt was detectable but not quantifiable because of interference with iron. Our study found that arsenic, cobalt, and lead were not released to soil or slag, which could pose a significant health risk to visitors and employees. Instead, our study demonstrates these heavy metals remained with the cast iron and were removed from the site.

Sloto, R. A.; Helmke, M. F.

2011-01-01

403

POLLUTION EFFECTS OF ABNORMAL OPERATIONS IN IRON AND STEEL MAKING. VOLUME 1. TECHNICAL REPORT  

EPA Science Inventory

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. Pollution standards, ge...

404

Ultrasonic imaging of porosity variations produced during sintering  

NASA Technical Reports Server (NTRS)

A silicon carbide disk was sintered from 2090 to 2190 C in 25-C steps. After each sintering step, the disk was examined using a precision acoustic scanning system to determine acoustic attenuation and velocity. The bulk density was found to vary nonmonotonically with sintering temperature. The density varied as much as 10 percent from its value at 2090 C during the sintering process. Local density fluctuations occurred in an organized and history-dependent way. These local density fluctuations varied up to + or - 7 percent of the bulk density and were made visible by acoustic attenuation and velocity mapping.

Generazio, Edward R.; Roth, Don J.; Stang, David B.

1989-01-01

405

Mechanism of fatigue performance enhancement in a laser sintered superhard nanoparticles reinforced nanocomposite followed by laser shock peening  

NASA Astrophysics Data System (ADS)

This study investigates the fundamental mechanism of fatigue performance enhancement during a novel hybrid manufacturing process, which combines laser sintering of superhard nanoparticles integrated nanocomposites and laser shock peening (LSP). Through laser sintering, TiN nanoparticles are integrated uniformly into iron matrix to form a nanocomposite layer near the surface of AISI4140 steel. LSP is then performed on the nanocomposite layer to generate interaction between nanoparticles and shock waves. The fundamental mechanism of fatigue performance enhancement is discussed in this paper. During laser shock interaction with the nanocomposites, the existence of nanoparticles increases the dislocation density and also helps to pin the dislocation movement. As a result, both dislocation density and residual stress are stabilized, which is beneficial for fatigue performance.

Lin, Dong; Ye, Chang; Liao, Yiliang; Suslov, Sergey; Liu, Richard; Cheng, Gary J.

2013-04-01

406

Accuracy in Powder Diffraction IV NIST, Gaithersburg MD, USA  

E-print Network

Austenite) Intermediate products Sinter, blast furnace Pellets, DRI Steel plant #12;Mining of iron ore, magnetite Fe3O4, goethite FeOOH) ­ Al content (increases viscosity of the slag in blast furnace) ­ Plus

Magee, Joseph W.

407

Development of a characterization approach for the sintering behavior of new thermoplastics for selective laser sintering  

Microsoft Academic Search

Currently the standard thermoplastic powders for selective laser sintering are based on polyamide12. This leads to restrictions for many applications e.g. in the industrial or medical field. Thus, research on further polymers with enhanced chemical or higher thermal stability plays a major role for applying additive manufacturing to serial production of individual components. Currently, great efforts are made to process

Dietmar Drummer; Dominik Rietzel; Florian Kühnlein

2010-01-01

408

Fluorosilicone and silicone o-ring aging study.  

SciTech Connect

Fluorosilicone o-ring aging studies were performed. These studies examined the compressive force loss of fluorosilicone o-rings at accelerated (elevated) temperatures and were then used to make predictions about force loss at room temperature. The results were non-Arrhenius with evidence for a lowering in Arrhenius activation energies as the aging temperature was reduced. The compression set of these fluorosilicone o-rings was found to have a reasonably linear correlation with the force loss. The aging predictions based on using the observed curvature of the Arrhenius aging plots were validated by field aged o-rings that yielded degradation values reasonably close to the predictions. Compression set studies of silicone o-rings from a previous study resulted in good correlation to the force loss predictions for the fluorosilicone o-rings from this study. This resulted in a preliminary conclusion that an approximately linear correlation exists between compression set and force decay values for typical fluorosilicone and silicone materials, and that the two materials age at similar rates at low temperatures. Interestingly, because of the observed curvature of the Arrhenius plots available from longer-term, lower temperature accelerated exposures, both materials had faster force decay curves (and correspondingly faster buildup of compression set) at room temperature than anticipated from typical high-temperature exposures. A brief study on heavily filled conducting silicone o-rings resulted in data that deviated from the linear relationship, implying that a degree of caution must be exercised about any general statement relating force decay and compression set.

Bernstein, Robert; Gillen, Kenneth T.

2007-10-01

409

Master sintering curves for UO2 and UO2-SiC composite processed by spark plasma sintering  

NASA Astrophysics Data System (ADS)

Master sintering curve (MSC) theory has been applied successfully to UO2 and UO2-SiC composite ceramics processed using spark plasma sintering (SPS). By applying the constant heating rate method, where the powder compact was heated at a constant rate to a specified maximum temperature and then cooled naturally, the apparent activation energies for sintering have been determined to be 140 kJ/mol for UO2 and 420 kJ/mol for UO2-SiC composite. The ability of the derived MSCs to control and predict final density in the sintered compact was demonstrated by additional experimental runs using the isothermal heating method, in which the powder is held for a specified time at the maximum sintering temperature. It is shown that the master sintering curve is an effective tool to characterize the densification and sinterability behavior of a given nuclear powder compact during spark plasma sintering. The reason for significantly lower activation energy in SPS processed UO2 pellets compared to conventional sintering has been rationalized on the basis of field activation in SPS process.

Chen, Zhichao; Subhash, Ghatu; Tulenko, James S.

2014-11-01

410

Selective laser sintering in biomedical engineering.  

PubMed

Selective laser sintering (SLS) is a solid freeform fabrication technique, developed by Carl Deckard for his master's thesis at the University of Texas, patented in 1989. SLS manufacturing is a technique that produces physical models through a selective solidification of a variety of fine powders. SLS technology is getting a great amount of attention in the clinical field. In this paper the characteristics features of SLS and the materials that have been developed for are reviewed together with a discussion on the principles of the above-mentioned manufacturing technique. The applications of SLS in tissue engineering, and at-large in the biomedical field, are reviewed and discussed. PMID:23250790

Mazzoli, Alida

2013-03-01

411

Fabrication Of Metal Chloride Cathodes By Sintering  

NASA Technical Reports Server (NTRS)

Transition-metal chloride cathodes for use in high-temperature rechargeable sodium batteries prepared by sintering transition-metal powders mixed with sodium chloride. Need for difficult and dangerous chlorination process eliminated. Proportions of transition metal and sodium chloride in mixture adjusted to suit specific requirements. Cathodes integral to sodium/metal-chloride batteries, which have advantages over sodium/sulfur batteries including energy densities, increased safety, reduced material and thermal-management problems, and ease of operation and assembly. Being evaluated for supplying electrical power during peak demand and electric vehicles.

Bugga, Ratnakumar V.; Di Stefano, Salvador; Bankston, C. Perry

1992-01-01

412

Geological reconnaissance of some Uruguayan iron and manganese deposits in 1962  

USGS Publications Warehouse

Three mineralized areas lie in an area near the town of Minas de Corrales in the Departamento de Rivera; they are the Cerro Amelia, the Cerro de Papagayo, and the Cerro Iman. The Cerro Amelia is composed of small bands of iron-rich rock separated by an amphibolitic or mafic rock. Selective mining would be necessary to extract the 31,000 tons per meter of depth of iron-rich rock that ranges from 15 to 40 percent metallic iron. The Cerro de Papagayo district contains many small, rich deposits of ferruginous manganese ore. The ratio of Mn to Fe varies widely within each small deposit as well as from deposit to deposit. Some ferruginous manganese ore contains 50-55 percent manganese dioxide. Although there are many thousands of tons of ore in the district, small-scale mining operations are imperative. One deposit, the Cerro Avestuz manganese mine, was visited. The manganese ore body lies within contorted highly metamorphosed itabirite that contains both hard low grade and soft high grade ferruginous manganese ores estimated to average 40 percent Mn. About 38,000 tons of manganese ore is present in this deposit. The Cerro Iman is a large block of itabirite that contains about 40 percent Fe. The grade is variable and probably runs from less than 35 percent Fe to more than 50 percent Fe. No exploration has been done on this deposit. It is recommended that the Cerro de Iman area be geologically mapped in detail, and that a geological reconnaissance be made of the area that is between the Cuchilla de Corrales and the Cuchilla de Areycua/Cuchilla del Cerro Pelado area.

Wallace, Roberts Manning

1976-01-01

413

Pharmacology of Iron Transport  

PubMed Central

Elucidating the molecular basis for the regulation of iron uptake, storage, and distribution is necessary to understand iron homeostasis. Pharmacological tools are emerging to identify and distinguish among different iron transport pathways. Stimulatory or inhibitory small molecules with effects on iron uptake can help characterize the mechanistic elements of iron transport and the roles of the transporters involved in these processes. In particular, iron chelators can serve as potential pharmacological tools to alleviate diseases of iron overload. This review focuses on the pharmacology of iron transport, introducing iron transport membrane proteins and known inhibitors. PMID:23020294

Byrne, Shaina L.; Krishnamurthy, Divya; Wessling-Resnick, Marianne

2013-01-01

414

Disorders of iron metabolism. Part II: iron deficiency and iron overload  

Microsoft Academic Search

Main disorders of iron metabolismIncreased iron requirements, limited external supply, and increased blood loss may lead to iron deficiency (ID) and iron deficiency anaemia. In chronic inflammation, the excess of hepcidin decreases iron absorption and prevents iron recycling, resulting in hypoferraemia and iron restricted erythropoiesis, despite normal iron stores (functional iron deficiency), and finally anaemia of chronic disease (ACD), which

Manuel Muñoz; José Antonio García-Erce; Ángel Francisco Remacha

2010-01-01

415

Microstructure and magnetic properties of low-temperature sintered CoTi-substituted barium ferrite for LTCC application  

NASA Astrophysics Data System (ADS)

In this article, the influences of the BaCu(B 2O 5) (BCB) additive on sintering behavior, structure and magnetic properties of iron deficient M-type barium ferrite Ba(CoTi) xFe 11.8-2 xO 19 (BaM) have been investigated. It is found that the maximum sintered densities of BaM change from 86% to 94% as the BCB content varies from 1 to 4 wt%. Single-phase BaM can be detected by the XRD analysis in the sample with 3 wt% BCB sintered at 900 °C, and the microstructure is hexagonal platelets with few intragranular pores. This is attributed to the formation of the BCB liquid phase. Meanwhile, the experimental results illuminate that the CoTi ions prefer to occupy the 4f2 and 2b sites and the magnetic properties depend on the amount of CoTi-substitution. In addition, the chemical compatibility between BaM and silver paste is also investigated; it can be seen that BaM is co-fired well with the silver paste and no other second phase is observed. Especially, the 3 wt% BCB-added Ba(CoTi) 0.9Fe 11O 19 sintered at 900 °C has good properties with the sintered density of 4.9 g/cm 3, saturation magnetization of 49.7 emu/g and coercivity of 656.6 Oe. These results indicate that it is cost effective in the production of Low Temperature Co-fired Ceramics (LTCC) multilayer devices.

Chen, Daming; Liu, Yingli; Li, Yuanxun; Zhong, Wenguo; Zhang, Huaiwu

2011-11-01

416

Serpentinization of sintered olivine during seawater percolation experiments  

NASA Astrophysics Data System (ADS)

Hydration of the mantle lithosphere exposed along detachment faults at slow-spreading ridges leads to strong modification of rock rheological, geophysical and geochemical properties, and to the emission of large amounts of H2 and CH4, and of complex carbon molecules that support primitive ecosystems. The sustainability and efficiency of this hydration process, serpentinisation, and of associated reactions, requires penetration and renewal of fluids at the mineral-fluid interface. However, precipitation of material along flow paths will affect porosity and permeability that, in turn, will have feedbacks effects on the reactions. It is thus necessary to investigate the sustainability of flow paths, and the evolution of reaction rates for a dynamic system under representative conditions. We investigate these processes by percolation experiments carried out under P, T representative conditions, using the ICARE Microlab experimental bench. We present the preliminary results of seawater percolation within samples of sintered San Carlos olivine. The experiments were carried out under a confined pressure of 190 bars and a temperature of 190° C and water flow was set at a constant specific discharge of 0.06 ml/h.. The experiments were performed at very slow flow rate to be more representative of natural systems. ICARE Microlab allows measuring continuously the permeability changes during the percolation experiment and sampling the brine at the outlet of the sample. After 20 days of experiments, poorly crystallized serpentine and iron oxide formed within the micro-cracks while permeability strongly decreases. Such rapid precipitation of serpentine results in clogging of fluid paths. The chemical composition of the outlet fluid is dominated by Si and is depleted in Mg relative to stoechiometric dissolution of olivine during the whole experiment suggesting that brucite possibly formed. SEM and AEM/TEM are used to characterize the reactive interfaces and the neoformed materials.

Luquot, Linda; Andreani, Muriel; Godard, Marguerite; Gouze, Philippe; Gibert, Benoit

2010-05-01

417

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 at a reasonable cost. A primary example of this is copper heap leaching, where there are no binders currently encountered in this acidic environment process. 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. The active involvement of our industrial partners will help to ensure rapid commercialization of any agglomeration technologies developed by this project.

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

2005-09-30

418

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. A primary example of this is copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process. As a result, operators of acidic heap-leach 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 other agglomeration applications, particularly advanced primary ironmaking.

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

2004-03-31

419

Timing and setting of skarn and iron oxide formation at the Smältarmossen calcic iron skarn deposit, Bergslagen, Sweden  

NASA Astrophysics Data System (ADS)

Abundant iron oxide deposits including banded iron formations, apatite iron oxide ores, and enigmatic marble/skarn-hosted magnetite deposits occur in the Palaeoproterozoic Bergslagen region, southern Sweden. During the last 100 years, the latter deposit class has been interpreted as contact metasomatic skarn deposits, metamorphosed iron formations, or metamorphosed carbonate replacement deposits. Their origin is still incompletely understood. At the Smältarmossen mine, magnetite was mined from a ca. 50-m-thick calcic skarn zone at the contact between rhyolite and stratigraphically overlying limestone. A syn-volcanic dacite porphyry which intruded the footwall has numerous apophyses that extend into the mineralized zone. Whole-rock lithogeochemical and mineral chemical analyses combined with textural analysis suggests that the skarns formed by veining and replacement of the dacite porphyry and rhyolite. These rocks were added substantial Ca and Fe, minor Mg, Mn, and LREE, as well as trace Co, Sn, U, As, and Sr. In contrast, massive magnetite formed by pervasive replacement of limestone. Tectonic fabrics in magnetite and skarn are consistent with ore formation before or early during Svecokarelian ductile deformation. Whereas a syngenetic-exhalative model has previously been suggested, our results are more compatible with magnetite formation at ca. 1.89 Ga in a contact metasomatic skarn setting associated with the dacite porphyry.

Jansson, Nils F.; Allen, Rodney L.

2013-03-01

420

Isothermal Dilatometric Study of Sintering in Kaolin  

NASA Astrophysics Data System (ADS)

Solid-state sintering for kaolin samples was studied by dilatometric measurements in the isothermal regime in the temperature range from 600 °C to 1100 °C. The relative expansion was measured for a period of 10h. For the temperatures up to 850 °C, we observed only a small shrinkage (less than 0.5 %), most of which took place within the first 3h of the measurements. For the temperatures above 850 °C, a significant shrinkage occurred for the whole measured time interval and reached up to 2.7 %. Anomalous behavior—a decrease in the shrinkage with the temperature—was observed in the range from 700 °C to 850 °C. The dilatometric measurements are supplemented by porosity distribution measurements. The standard spherical-grains microscopic model was applied to determine that for the initial stages of the sintering process, grain boundary diffusion was the dominant mechanism at lower temperatures (600 °C to 850 °C), whereas lattice diffusion was dominant at higher temperatures (900 °C, 1050 °C, and 1100 °C).

Ondruška, Ján; Trník, Anton; Keppert, Martin; Medved', Igor; Vozár, Libor

2014-10-01

421

Sintering of Cobalt-Rare Earth Permanent Magnets  

Microsoft Academic Search

The process sequence used to fabricate high performance cobalt-rare earth Permanent magnets is a powder metallurgy type of process with sintering as a key step. Precise control of the composition of the sintered magnet is essential if high magnetic performance is to be achieved. In this study we compare results from two approaches: 1) direct control of composition at the

M. G. Benz; D. L. Martin

1972-01-01

422

Transient liquid phase sintering conductive adhesives as solder replacements  

Microsoft Academic Search

New transient liquid phase sintering conductive adhesives, which have an interpenetrating polymer\\/metal network, have been developed to mitigate some of the deficiencies of standard particle-filled conductive adhesives. The metal network is formed in situ by a process known as transient liquid phase sintering (TLPS) and is mutually reinforcing with the polymer network. Bulk as well as interface electrical connections are

Catherine Gallagher; Goran Matijasevic; James F. Maguire

1997-01-01

423

Sintering behavior of periclase–doloma refractory mixes  

Microsoft Academic Search

Steelmaking electric arc furnaces (EAF) hearth is usually built up with dry vibratable refractory mixes. During furnace operation, the refractory mix undergoes sinterization, slag attack, and chemical interaction with steel. Material sintering is needed in the upper part of the EAF hearth, in order to develop enough mechanical strength and wear resistance during operation. Densification of the upper layer also

A. G. Tomba Martinez; M. A. Camerucci; A. L. Cavalieri; L. Martorello; P. G. Galliano

2009-01-01

424

Microwave sintering of sol-gel derived abrasive grain  

DOEpatents

A method is provided for making microwave-sintered, free flowing alpha alumina-based ceramic abrasive grain, under conditions effective to couple microwaves with calcined alpha alumina-based abrasive gain precursor and sinter it at a temperature of at least about 1150.degree. C.

Plovnick, Ross (St. Louis Park, MN); Celikkaya, Ahmet (Woodbury, MN); Blake, Rodger D. (Tuscon, AZ)

1997-01-01

425

Method for sintering fuel cell electrodes using a carrier  

DOEpatents

A carrier for conveying components of a fuel cell to be sintered through a sintering furnace. The carrier comprises a metal sheet coated with a carbon-based paint, the carbon-based paint comprising an organic binder. The carbon-based paint may be an alcohol or a solvent-based paint or a water-based paint.

Donelson, Richard (Victoria, AU); Bryson, E. S. (Downers Grove, IL)

1995-01-01

426

Sintering Behavior of Elemental Powders with FeB Addition in the Composition of Martensitic Stainless steel  

Microsoft Academic Search

The effect of sintering additive for the development of high-strength martensitic stainless steel from elemental powders was\\u000a studied. The sintering parameters investigated were: sintering temperature, sintering time, and wt.% of FeB. In vacuum sintering,\\u000a effective sintering took place between 1300 and 1350 ?C with 1-1.5 wt.% FeB addition. The maximum sintered density and ultimate\\u000a tensile strength (UTS) were achieved after sintering at

Farid Akhtar

2007-01-01

427

Iron deficiency anemia  

MedlinePLUS

... You get iron deficiency anemia when your body's iron stores run low. This can occur because: You lose ... ferrous sulfate) are needed to build up the iron stores in your body. Most of the time, your ...

428

Iron and Prochlorococcus/  

E-print Network

Iron availability and primary productivity in the oceans are intricately linked through photosynthesis. At the global scale we understand how iron addition induces phytoplankton blooms through meso-scale iron-addition ...

Thompson, Anne Williford

2009-01-01

429

Iron Recorded in Black Corals Mapped by Synchrotron Micro XRF and Raman Studies  

NASA Astrophysics Data System (ADS)

Black corals are widely distributed throughout the world's oceans and across a large range in depths from near surface to thousands of meters deep. Long-lived proteinaceous skeletons provided concentric chronological growth bands, and have become potential as ocean environmental proxy records. The role of limiting nutrient element iron is important for ocean primary productivity and environment change. In this study, black corals (Cirrhipathes sp.) were collected at 7m depth for both near Sanya and Xisha island from the South China Sea. These two samples display clear annual bands with extremely low growth rate (~10 ?m year-1 for near Sanya sample and ~15 ?m year-1 for near Xisha island sample based on 210Pb and SEM images, respectively). Synchrotron radiation scanning micro-X-ray fluorescence analyses at Shanghai Synchrotron Radiation Facility beamline BL15U1 has been mapped to reveal iron variability across the annual layers with 2.5 ?m resolution. A series of iron peak concentration appeared at 1910 to 1962 in near Sanya sample, while there was no obvious high iron concentration in mapping data from near Xisha one. A former Tiandu iron ore (mining time 1910-1962) is located at Sanya, and there is a small Damao river passed by the iron ore and then went to the near Sanya sample growing place. In contrast, there is little anthropic activities in Xisha island. The results showed in good agreement with Tiandu iron ore mining time. The same high iron peak concentration was also proved by micro-Raman mapping data with 2.5 ?m resolution too. The high spatial resolution of the synchrotron and micro-Raman mapping techniques allow trace elements measurements for future work on the environmental reconstructions.

Zhang, F.; Zhang, X.; Cai, W.; Zhang, J.

2013-12-01

430

Effect of oxygen-nitrogen ratio on sinterability of Sialons  

NASA Technical Reports Server (NTRS)

The effect of varying the sintering temperature and the oxygen to nitrogen ratio (O/N) on the sinterability of Sialons of the formula Si2.55Al0.6OyN4-0.667y was investigated for y between 0.57 and 1.92 (O/N between 0.157 and 0.706). The Sialons reached maximum density on pressureless sintering for 4 hours at about 1760 C in nitrogen. Optimum sinterability with densities up to about 98 percent of theoretical was attained with negligible X-phase in the O/N range from about 0.2 to 0.3. On sintering at approximately 1830 C the Sialons decomposed with evolution of silicon and aluminum.

Arias, A.

1979-01-01

431

Powder metallurgy: Solid and liquid phase sintering of copper  

NASA Technical Reports Server (NTRS)

Basic powder metallurgy (P/M) principles and techniques are presented in this laboratory experiment. A copper based system is used since it is relatively easy to work with and is commercially important. In addition to standard solid state sintering, small quantities of low melting metals such as tin, zinc, lead, and aluminum can be added to demonstrate liquid phase sintering and alloy formation. The Taguchi Method of experimental design was used to study the effect of particle size, pressing force, sintering temperature, and sintering time. These parameters can be easily changed to incorporate liquid phase sintering effects and some guidelines for such substitutions are presented. The experiment is typically carried out over a period of three weeks.

Sheldon, Rex; Weiser, Martin W.

1993-01-01

432

A Combined Statistical-Microstructural Model for Simulation of Sintering  

SciTech Connect

Sintering theory has been developed either as the application of complex diffusion mechanisms to a simple geometry or as the deformation and shrinkage of a continuum body. They present a model that can treat in detail both the evolution of microstructure and the sintering mechanisms, on the mesoscale, so that constitutive equations with detail microstructural information can be generated. The model is capable of simulating vacancy diffusion by grain boundary diffusion, annihilation of vacancies at grain boundaries resulting in densification, and coarsening of the microstructural features. In this paper, they review the stereological theory of sintering and its application to microstructural evolution and the diffusion mechanism, which lead to sintering. They then demonstrate how these stereological concepts and diffusion mechanisms were incorporated into a kinetic Monte Carlo model to simulate sintering. Finally, they discuss the limitations of this model.

BRAGINSKY,MICHAEL V.; DEHOFF,ROBERT T.; OLEVSKY,EUGENE A.; TIKARE,VEENA

1999-10-22

433

Virtual Atlas of Opaque and Ore Minerals in Their Associations  

NSDL National Science Digital Library

This atlas provides over 400 full colour photomicrographs of the major ore-forming mineral associations and opaque minerals in non-mineralized rocks. It describes typical examples of each mineral from many classical localities throughout the world. For each association there is a listing of the major (and important minor) primary ore minerals, alteration products and gangue, typical textures, a brief discussion of the geology of the association and a list of references. Minerals can be searched by association, country, location, mineral name, mineralogy, texture, optical property, individual plate descriptions, or via an image gallery.

Duller, Paul R.; Ixer, R. A. (Robert A.)

2007-01-28

434

Iron and Stony-iron Meteorites  

Microsoft Academic Search

Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich sampling of the deep interiors of differentiated asteroids.Iron and stony-iron

H. Haack; T. J. McCoy

2003-01-01

435

Fluid mixing and ore deposition during the geodynamic evolution of the Sierra Almagrera (Betics, Spain)  

NASA Astrophysics Data System (ADS)

Marine and continental intramountaineous basins developed during the Neogene orographic evolution of the Betico-rifan orogenic wedge, as well as the related uplifted ranges within the Sierra Almagrera Metamorphic Core Complexes (MCC). The NNE-SSW striking trans-Alboran transcurrent fault system crosscuts the MCC post-dating the extensional exhumation stages recorded in the metamorphic fabric. Iron ores (± Pb, Cu, Zn) are encountered either as stratabound ore deposits in the Neogene basins or as vein networks crosscutting the metamorphic fabric of graphitic phyllites from the Sierra Almagrera. These Late Miocene ore deposits are related to the activity of the N-S striking Palomares fault segment of the Trans-Alboran fault system. Three sets of quartz veins (V?, V?? and V?) and one set of mineralized vein (V?, siderite, barite) are distinguished. The V? and V?? respectively are totally or partially transposed into the foliation. The V? and V? veins are discordant to the foliation. The problem addressed in this study concerns the nature of the fluids involved in the metal deposits and their relationships with the main reservoir fluids, e.g. the deep metamorphic fluids, the basinal fluids, and eventually the recharge meteoric fluids. This study focuses thus on the evolution of the fluids at different stages of ductile-brittle exhumation of the metamorphic ranges (Sierras) and their role during the exhumation and later on in relation with the hydrothermalism and metal deposition at a regional scale. Paleofluids were studied as inclusions in quartz, siderite and barite from veins by microthermometry and Raman spectroscopy, and a stable isotope study is in progress. Earliest fluids recorded in (V??) quartz veins are H2O- NaCl + CaCl2 (17 wt. %) - (traces of CO2, CH4, N2) metamorphic brines trapped at the ductile brittle transition at a minimum trapping temperatures (Th) of 340 °C. Older metamorphic fluids in (V?) veins were lost during the complete recrystallization of the original quartz grains during transposition. The second fluid type is characterized by very low salinity inclusions (1.2 wt.% NaCl) found in veins discordant to the foliation (V?), and precedes brines (23 wt. % NaCl + CaCl2 with Th of 320 °C) trapped in transgranular fluid inclusion planes (FIP). The NW-SE to N-S directions of these FIP appears coherent with shortening directions related to Tortonian and Messinian basin development (Montenat, 1990). The halogen signatures of the latest brines confirm that they derive from primary brines issued from sea water evaporation. Fluid inclusions in barites and siderites from (V?) veins display a Br/Cl ratio more typical of secondary brines and a rather large range of salinities, this indicating distinct fluid movements and the dissolution of evaporates by dilute fluids may be of meteoric origin. Fluids in siderites show the lowest trapping temperature conditions around 190 °C. The existence of a sea water component in fluids was previously mentioned by Morales Ruano et al. (1995) indicate a ?34S of 22,1-23.9 ‰ for barite from Sierra Almagrera. In conclusion, during the Neogene multistage evolution of the Almagrera MCC, fluids of different origins e.g. basinal, meteoric and metamorphic fluids have circulated within the crust, and locally interacted with evaporites. The resulting brines formed Fe-(Ba, Pb, Cu) ores in discontinuities affecting both the metamorphic and sedimentary rocks. Morales Ruano, S., Both, R., and Fenoll Hach-Ali, P., 1995, Fluid evolution and mineral deposition in the Aguilas - Sierra Almagrera base metal ores, southeastern Spain.: Mineral Deposits, p. 365-368. Montenat, C., 1990, Les Bassins néogènes du domaine bétique oriental (Espagne), Documents et Travaux IGAL n°12-13, 392 p.

Dyja, Vanessa; Tarantola, Alexandre; Hibsch, Christian; Boiron, Marie-Christine; Cathelineau, Michel

2013-04-01

436

Management of Wastes Containing Radioactivity from Mining and Milling of Uranium Ores in Northern Australia.  

National Technical Information Service (NTIS)

The procedures and controls to achieve safe management of wastes containing radioactivity during the mining and processing of uranium ores are mainly site specific depending on the nature, location and distribution of the ore and gangue material. Waste ro...

J. M. Costello

1977-01-01

437

System for recycling char in iron oxide reducing kilns  

SciTech Connect

A method and means for improving the efficiency of the process for directly reducing ore 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 charred coal or char found in the discharge product is recycled into the process at the discharge end of the kiln rather than the feed end as in the prior art. In particular, the recovered char, both coarse and finer particles, are transported to a recycle bin from which they are returned at a preselected rate to the kiln process by being injected along with the coal blown into the discharge end of the kiln. Alternatively, the recycle char alone may be fed without any coal at the discharge end of the kiln.

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

1983-03-08

438

On the possibility of new discoveries in the Strel'tsovka ore field  

NASA Astrophysics Data System (ADS)

As further development of ideas stated by F.I. Wolfson on principles of uranium ore localization in the Strel’tsovka ore field, a possibility of an increase in uranium reserves in the northern portion of this ore field is substantiated. A large caldera, which is not less than the Strel’tsovka caldera in dimensions, is suggested beneath Cretaceous sediments in the northern portion of the ore field.

Shumilin, M. V.

2007-10-01

439

Chemical constituents in particulate emissions from an integrated iron and steel facility.  

PubMed

Particle emissions from four integrated iron and steel plant processes, i.e., coke making, sintering, cold forming, and hot forming, were investigated in this study. Particle compositions of 21 element species, 11 ionic species, elemental carbon (EC), organic carbon (OC) and 16 polyaromatic hydrocarbons (PAHs) were analyzed to create "fingerprints" of the particles emitted from various processes in an integrated iron and steel plant. Results indicated that element compositions (0.11-0.42 g/g), water-soluble ions (0.34-0.52 g/g), elemental carbon (0.008-0.14 g/g), organic carbon (0.02-0.06 g/g) and PAHs (0.52-6.2 mg/g) contributed to the particle mass. In general, sulfur had a higher mass contribution than the other elements, which resulted from the use of coal, flux, heavy oil, and many recycled materials in the iron and steel plant. The particle mass contribution of potassium and chlorine in the sinter plant was higher than in other processes; this may be attributed to the lower boiling point and volatility of potassium. In addition, many recycled materials were fed into the sinter plant, causing a high concentration of potassium and chlorine in the particle phase. Eight PAH compounds were analyzed in the four processes. The carcinogenic compound Benzo(a)pyrene (BaP) was detectable only in the sintering process. PMID:17276592

Tsai, Jiun-Horng; Lin, Kuo-Hsiung; Chen, Chih-Yu; Ding, Jian-Yuan; Choa, Ching-Guan; Chiang, Hung-Lung

2007-08-17

440

HEPCIDIN AND IRON HOMEOSTASIS  

PubMed Central

Despite fluctuations in dietary iron intake and intermittent losses through bleeding, the plasma iron concentrations in humans remain stable at 10–30 ?M. While most of the iron entering blood plasma comes from recycling, appropriate amount of iron is absorbed from the diet to compensate for losses and maintain nontoxic amounts in stores. Plasma iron concentration and iron distribution are similarly regulated in laboratory rodents. The hepatic peptide hepcidin was identified as the systemic iron-regulatory hormone. In the efferent arc, hepcidin regulates intestinal iron absorption, plasma iron concentrations, and tissue iron distribution by inducing degradation of its receptor, the cellular iron exporter ferroportin. Ferroportin exports iron into plasma from absorptive enterocytes, from macrophages that recycle the iron of senescent erythrocytes, and from hepatocytes that store iron. In the more complex and less well understood afferent arc, hepatic hepcidin synthesis is transcriptionally regulated by extracellular and intracellular iron concentrations through a molecular complex of bone morphogenetic protein receptors and their iron-specific ligands, modulators and iron sensors. Through as yet undefined pathways, hepcidin is also homeostatically regulated by the iron requirements of erythroid precursors for hemoglobin synthesis. In accordance with the role of hepcidin-mediated iron redistribution in host defense, hepcidin production is regulated by inflammation as well. Increased hepcidin concentrations in plasma are pathogenic in iron-restrictive anemias including anemias associated with inflammation, chronic kidney disease and some cancers. Hepcidin deficiency causes iron overload in hereditary hemochromatosis and ineffective erythropoiesis. Hepcidin, ferroportin and their regulators represent potential targets for the diagnosis and treatment of iron disorders and anemias. PMID:22306005

Ganz, Tomas; Nemeth, Elizabeta

2014-01-01

441

Spark plasma sintering of titanium aluminide intermetallics and its composites  

NASA Astrophysics Data System (ADS)

Titanium aluminide intermetallics are a distinct class of engineering materials having unique properties over conventional titanium alloys. gamma-TiAl compound possesses competitive physical and mechanical properties at elevated temperature applications compared to Ni-based superalloys. gamma-TiAl composite materials exhibit high melting point, low density, high strength and excellent corrosion resistance. Spark plasma sintering (SPS) is one of the powder metallurgy techniques where powder mixture undergoes simultaneous application of uniaxial pressure and pulsed direct current. Unlike other sintering techniques such as hot iso-static pressing and hot pressing, SPS compacts the materials in shorter time (< 10 min) with a lower temperature and leads to highly dense products. Reactive synthesis of titanium aluminide intermetallics is carried out using SPS. Reactive sintering takes place between liquid aluminum and solid titanium. In this work, reactive sintering through SPS was used to fabricate fully densified gamma-TiAl and titanium aluminide composites starting from elemental powders at different sintering temperatures. It was observed that sintering temperature played significant role in the densification of titanium aluminide composites. gamma-TiAl was the predominate phase at different temperatures. The effect of increasing sintering temperature on microhardness, microstructure, yield strength and wear behavior of titanium aluminide was studied. Addition of graphene nanoplatelets to titanium aluminide matrix resulted in change in microhardness. In Ti-Al-graphene composites, a noticeable decrease in coefficient of friction was observed due to the influence of self-lubrication caused by graphene.

Aldoshan, Abdelhakim Ahmed

442

Studies on the sintering behaviour of uranium dioxide powder compacts  

NASA Astrophysics Data System (ADS)

Uranium dioxide fuel pellets are normally made from their precursor ammonium diuranate, followed by calcination, subsequent reduction to sinterable grade powders and a post operation treatment of pressing and sintering. The low temperature calcined powders, usually exhibiting non-crystalline behaviour (under X-ray diffraction studies) progressively transforms into a crystalline variety on subsequent heat treatment at higher temperature. It is observed however that powders calcined between 800 to 900°C exhibit enhanced densification behaviour when sintered at higher temperatures. The isothermal shrinkage versus time plot of the sintered compacts are well described by a hyperbolic relationship which takes care of the observed shrinkage (?) as caused due to a cumulative effect from the initial sintering of the powder compacts at zero time (?) and that caused due to the structural transformation from a non-crystalline modification with increased thermal treatment (?). The derived equation is a modification of the sintering mechanism of the viscous flow type proposed by Frenkel, involving sintering of an amorphous phase, the viscosity of the latter is presumed to increase with increasing thermal treatment to assume the final modified form as ? = {t}/{(? +?t)}, where t = time, ? = shrinkage and ? and ? are the unknown parameters.

Das, Pranab; Chowdhury, Ranjit

1988-09-01

443

Effect of YSZ sintering temperature on mixed potential sensor performance  

SciTech Connect

In this article, the influence of Yttria-Stabilized Zirconia (YSZ) sintering temperature