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By L. A. Neumeier

The Bureau of Mines, U.S. Department of the Interior, is investigating the feasibility of partitioning complex sulfide minerals to simpler sulfide .phases by sulfldation reactions. Such partitioning can afford opportunity to improve selective extraction of mineral constituents of value. This report describes initial research involving sulfidation partitioning of chalcopyrite concentrates. Small chalcopyrite samples were sulfidized with elemental sulfur in glass capsules sealed after evacuating and backfilling with helium, by heating for 1 to 24 h at specific temperatures in the range of 250° to 500° C. which extends from below to above the boiling point of sulfur (-445° C). Above the boiling point of sulfur, the overall reaction with adequate sulfur (13.9 wt pct of CuFeS2) is 5CuFeS2 + 4S g ? Cu5FeS6 + 4FeS2.

Jan 1, 1989

By C. J. Malek

The CONTOP® smelting cyclone technology is a large-scale and time-proven method which in combination with other technologies (grinding, drying, pyrolysis, etc.) provides for a cost- efficient and ecological disposal of a wide range of waste materials from industry and households. In this report the basic principle of smelting cyclone technology will be explained first. Subsequently, the paper will discuss substantial concepts for the recovery of various remainders.

Jan 1, 1996

By Hongli Wen, Guangkun Shen, Qiong Deng, Shoujian Huang, Min Gan, Xiaohui Fan

"Due to the low iron grade and high sulfur content, pyrite cinder is difficult to be directly used for iron-making. In this paper, technology of magnetic roasting -grinding and magnetic separation -acid leaching was put forward for reclamation of pyrite cinder. For pyrite cinder of TFe53.51%, S2.20 %, studies showed that good magnetic effect can be achieved at roasting temperature 650~7000, reducing atmosphere CO/(CO + C02) 10~20% and roasting time 10~30 minutes. In separation conditions of grinding size -0.045mm accounting for 96.09% and magnetic field intensity of 1240 GS, iron concentrate of TFe64.81 %, S0.18% and iron recovery rate 91.44% was achieved. Acid leaching was studied to strengthen desulfurization. Results showed that high-quality iron ore concentrate of TFe66.3 l %, S0.10% was obtained under the conditions of hydrochloric acid mass fraction of 5%, pulp density of30%, leaching temperature of70? and leaching time of2 hours.IntroductionPyrite cinder is produced as a by-product of sulfuric acid industry [1] Domestic production is more than 12 million tons every year and occupied area is over 10 million square meters [2,3]. The pyrite cinder outdoor not only pollutes air but also damages surrounding surface [4] It after treatment used for iron-making is an ideal reclamation approach for its rich iron which is commonly 40-60% [5]. But pyrite cinder gets low utilization for its low iron grade and high sulfur content in China [6]. Therefore, comprehensive utilization of pyrite cinder has profound significance to environmental protection and the development of domestic iron and steel industry."

Jan 1, 2013

By M. Krishna, Jayagopal Uchi1, Shanta Sastry, B. M. Satish

"A well-considered composite of ZA-27 reinforced with weight percentage 0, 2, 4, and 6% of alwninite particulate has been made by compocasting technique. The elastic properties of ZA- 27 /alwniniute particulate composite were determined by using U1M. The results showed that the modulus of elasticity and UTS of the composite gradually increases with increase in the wt.% of reinforcement. However, the overall ductility decreased monotonically with an increase in reinforcement. The results of these tests· as well as the predictions of several model~ for composite strengthening available in the literature were compared with experimental results. The data observed from Young's modulus by measurements studies were compared with theoretical results predicted by Eshelby model.IntroductionMetal matrix composites (MMCs) have received increasing attention in _the recent decades as engineering materials. The introduction of a ceramic reinforcement into a metal matrix produces a composite material resulting in an attractive combination of physical and mechanical properties that cannot be obtained with monolithic alloys. Particulate reinf9rced MMCs among the discontinuously reinforced MMCs have attracted quite a lot of attention both in the industrial sectors and the academic communities. There is an increasing need for knowledge about the processing techniques and mechanical behavior of particulate MMCs in view of their production getting enhanced and their commercial applications becoming wider [I]. Interest in particulate reinforced MMCs is mainly due to easy availability of particles and economical processing techniqu"

Jan 1, 2000

By Yuanbo Zhang, Zhixiong You, Daoxian Duan, Guanghui Li, Tao Jiang

"Manganese is mainly consumed by steel and battery industries. In recent years, it is essential to utilize the low-grade manganese oxide ores with total manganese grade below 25%, as the high quality manganese ore resources are becoming scarce with the rapid development of the steel industry. Conventional pyro-metallurgical processes for utilizing manganese oxide ores are characterized by high production cost and energy consumption, low productivity, serious environmental pollution, etc. In this study, reduction thermodynamic of MnO2 reduced by sulfur was firstly carried out. Then, a novel process of reduction roasting with sulfur followed by acid leaching was developed to recover manganese from the very low-grade manganese oxide ores. Effects of main factors, including temperature, reduction time and S/Mn mole ratio, were investigated, and a high leaching efficiency of Mn above 95% was obtained under optimal conditions.IntroductionHigh/middle-grade manganese oxide ores are generally used in the metallurgical industries, particularly in steel plants and ferro-alloy units. The consumption of metal manganese in the ferro-alloy industry accounts for 85- 90% of the total Mn demanded [1]. Therefore, high quality manganese ore resources are becoming scarce with the rapid development of steel industry. It is essential to make good use of large quantity of low-grade manganese ores (TMn < 25%) presently available."

Jan 1, 2012

By H. D. Freeman

The occurrence of gold in refractory gold ores varies widely and affects the recovery process. The determination of gold and the composition of the associated minerals are important in selecting an appropriate processing scheme. However, locating the gold in an ore sample is a difficult task which requires perseverance, luck, and experience. Our experience has led to the development of a relatively fast and reliable means of deter-mining the mineralogy of ore samples through analysis combining an energy-dispersive x-ray analyser coupled to a scanning electron microscope (SEM). In some cases, a wave length dispersive spectrometer or microprobe is used to further quantify the various mineral compositions. The SEM/microprobe analysis identifies the source of problems that may arise during the recovery of gold from refractory gold ores.

Jan 1, 1981

By Cissé Kane, Klaus Hieronymi, Mathias Schluep, Gerry Newson, Susanne Dittke

"E-waste is currently the fastest growing waste stream in South Africa as well as in many other African countries. Informal collectors, dismantlers and recyclers based in Africa play an increasingly larger role in the processing of e-waste under generally unacceptable social and environmental conditions. In direct response to this trend, and as part of Hewlett Packard’s international Extended Producer Responsibility, the project “e-Waste Management in Africa” was started in 2007 in cooperation with the Global Digital Solidarity Fund (DSF) and the Swiss Federal Laboratories for Materials Testing and Research (Empa). This project is investigating the e-Waste situation in various African Countries, including South Africa, while actively supporting the development of practical, socially just and environmentally acceptable local e-waste management solutions. To this end, the project has been funding the development of a pilot project in Cape Town, South Africa since February 2008, supporting the start-up of a low tech/highly labour intensive material dismantling and recovery facility (MRF) for the pre-processing of e-waste. The aim is to test the feasibility of an integrated value adding local e-Waste management system, designed to maximize the potential of refurbishment, repair, re-use, dismantling and recycling of equipment, with environmentally responsible disposal as a last resort only. The project also seeks to incorporate the current informal e-waste processing activities, by transforming them into sustainable and environmentally sound operations. The MRF acts as a nucleus, raising awareness, and providing training and education to previously disadvantaged individuals as a means of creating opportunities for entrepreneurship in the technical maintenance, dismantling and waste-to-art project sectors."

Jan 1, 2008

By David J. Kinneberg, Barbara E. Mangion, Arnold M. Savolainen

Analytical laboratories require a qualitative or semi-qualitative method of determining major and minor constituents in "unknown" samples to select optimal analytical techniques. This is exceedingly important in precious metal assay laboratories where the precision and accuracy requirements are exacting (routinely within 0.02%, absolute basis). This paper describes the use of an x-ray fluorescence spectrometer with a specially designed software package to select optimal analytical procedures and specify relevant analytical parameters. A wavelength dispersive XRF spectrometer is capable of quick and accurate analyses of properly prepared samples without extensive standardization. When coupled with a specially designed software package, this preliminary assay system is applicable to a wide variety of sample types including gold and silver bullion, karat gold and karat PGM alloys, high silver and high copper metallic samples as well as particulate samples of ores and sweeps. The system relieves the assayer of tedious calculations for silver inquartation and proofing, minimizes human error and standardizes selections over time. Most importantly, the system allows for independent verification of final assay results.

Jan 1, 1999

By C. A. Pickles

Microwave processing is a relatively new technology that has been successfully applied in a number of industries. However, in the field of metal extraction, there is a paucity of success, despite considerable hype in the early years. Increased reaction rates, lowered reaction temperatures and higher energy efficiencies were some of the advantages claimed. Even with over almost two decades of research and some pilot plant studies, microwave metal extraction remains essentially a laboratory technique. In this paper, the research performed over the last few decades will be reviewed and some reasons for the lack of success in developing microwave metal extraction processes will be discussed. Based on the knowledge gained from these experiences, a more informed view of microwave heating can lead to the realization that there is still some untapped potential for this heating technique in metal extraction processes.

By Zhen Zhang, Jiang Diao, Tao Zhang, Yi Ren, Lu Jiang, Xiao-Man Yan, Bing Xie

The precipitation behavior of phosphorus enrichment phase was investigated by slag modification with Al2O3. The mineral phase of the original slag and modified slags were measured by mineral phase microscope, SEM+EDS and XRD. The mechanism of Al2O3 modification was discussed according to the thermodynamic theory analysis software (Factsage version 6.3). The results show that the high phosphorus solid solution (nˊ2CaO·SiO2-3CaO·P2O5) was generated by the continuous reaction of nC2S-C3P (nˊ＜n) solid solution and Al2O3 under 1350℃. The amount of initially precipitated solid solution (nC2S-C3P) was reduced and even disappeared with the increasing of Al2O3. If the addition of Al2O3 is enough in the slag, the high phosphorus solid solution (nˊC2S-C3P) that generated by the above mentioned reaction will continue to react with Al2O3 to produce Ca2Al2SiO7 and even C3P, which was demonstrated that the addition of Al2O3 has a positive influence on the precipitation of phosphorus enrichment phase.

Jan 1, 2015

By Yimin Ruan

"An inverse design method is developed to obtain the optimal cooling conditions for the continuous quenching of precipitation hardenable sheet alloys to achieve the required yield strength. The yield strength of a precipitation hardenable alloy is obtained by allowing solute to enter into solid solution at a proper temperature and rapidly cooling the alloy to retain the solute in the solid solution. An aging process may be needed for the alloy to develop the final mechanical properties.The objective of the design is to optimize the quenching process so that the required yield strength can be achieved. With the inverse design method, the required yield strength is specified and the sheet thermal profile at the exit of the quenching chamber can also be specified. The conjugate gradient method is used to optimize the cooling boundary condition during quenching. The adjoint system is developed to compute the gradient of the objective functional. An aluminum sheet quenching problem is presented to demonstrate feasibility of the inverse design method.IntroductionQuenching is a critical step in metal production to achieve desired material properties, such as yield strength, hardness, etc., for precipitation hardenable alloys. In most cases, rapid quenching from the solution heat treatment temperature is necessary to obtain the required material properties, but rapid quenching may cause other problems such as excessive distortions of the quenched materials.In a solution heat treatment, the alloy is heated to a suitable temperature, held at that temperature to allow the soluble alloying elements to enter into the solid solution, and cooled rapidly (quenching) to retain the alloy elements in the solid solution. An aging process, which controls precipitation of fine particles at room (natural aging) or elevated temperatures (artificial aging), is generally followed after the quenching process to develop the final mechanical properties of the heat treated alloys."

Jan 1, 1998

By Teixeira

An experimental investigation on the kinetics of oxidation of As(III) with H202 in synthetic effluent solutions followed by precipitation of Fe/As (V) compounds was carried out. The variables investigated were: As concentration (200 -3000 mg/l) , oxidation pH (2.0 -11.0), oxidation temperature (25 -800C) , H202 stoichiometric excess (50% -100%), precipitation pH (5.0 -7.0), precipitation agent (Fe2+ -Fe3+). Fixed conditions were, Fe/As molar ratio (6:1) and stirring speed (560 rpm). The results were empirically modelled. The precipitates obtained were amorphous. The precipitates were checked upon their environmental stability according to the United States Environmental Protection Agency (U.S.E.P.A.) Toxicity Test, and were considered to be adequate for deposition in impermeable waste dumps. The combined Fe/H202 detoxification process, in selected conditions, was able to reduce the As contents of effluents containing 1600 mg/l As to 0.1 mg/l, in about 2 1/2 hours of total processing time.

Jan 1, 1990

By I. C. Howard, E. J. Palmiere

"Heat transfer and friction in hot flat rolling have traditionally been characterised by an average heat transfer coefficient (h) and an average friction coefficient (p.). However, the presence of oxide scales and asperities at the interface question the use of such averages. The apparent irregularity and lack of pattern of interactions at the interface has prompted this present investigation to move away from averaged h and 11 values, and to study their local evolution based on probabilistic rules. The approach is based on the probability of finding the workpiece surface in a specific configuration at a particular instance of time in the roll gap. These rules are based on observations of surface phenomena such as scale behaviour during hot rolling. The model is implemented using user-subroutines integrated with the commercially available finite element program ABAQUS™. The results show the strong dependence of h and u on the local scale interactions. In particular, the effect of scale thickness, material behaviour and processing conditions on the evolution of hand 11 are discussed. Finally, the development of a Cellular Automata based Finite Element (CAFE) model is proposed to model the combined interfacial phenomenon of friction and heat transfer at the tool-work piece interface.IntroductionIntricate interactions between process variables in hot rolling of steels make it a challenge to the modelling community. For a given material and geometry combination, reducing interfacial power losses can increase the efficiency of the rolling process. The roll-strip interface, therefore, forms the critical zone and is currently the domain of intense investigation, especially to characterize interfacial frictionl • 2 and heat transfer3 • 4 . These interfacial phenomena are inter-related and cannot be studied in isolation. However, very few mathematical models4 • 5 combine an analysis of friction and heat transfer and deformation of the strip-roll interface taking into account the role of asperities and oxide scales."

Jan 1, 2001

By C. S. Ek

As a continuation of previous work, further tests have been carried out to recover silver from the residues obtained in a zinc jarosite process. Selective flotation has been performed with different reagents, and ?cleaning steps have been introduced to upgrade the silver concentrate. Leaching of crude residues, as well as flotation tailings, has been carried out with cyanide and thiourea. Finally, the different beneficiation methods are compared, and the industrial aspects? of their application are reviewed.

Jan 1, 1990

By M. S. Moats

Galvanic stripping, in conjunction with solvent extraction, has been proposed as a technical option to the challenging problem of iron removal in certain hydrometallurgical processes. The galvanic stripping process is based on the ability of a solid metal to directly reduce ferric ion to the ferrous state in an organic media. Stripping the iron into the aqueous phase is then easily accomplished. Previous work has shown the reaction kinetics and efficiency are affected by such operating parameters as water and oxygen contents, temperature, time and metal reductant. In this study, the optimum operating range for some of these variables was determined. Both zinc and iron metal were used in the separate stripping of iron from D2EHP A. Reasons for the differences in the extent of the reaction obtained using the various conditions are discussed.

Jan 1, 1996

By Robert R. Beebe

On the night of August 1&apos;9-20, 1995, seepage was seen at the toe of the Omai tailings dam in Guyana. The mill was immediately shut down, and within two hours the flow, then mostly water, was diverted into an inactive mining pit nearby. At about the same time a second more serious break occurred at a point where water and solids could flow directly into the Omai River. By the time Ii coffer dam could be completed in the early morning of August 24, some 4.2 million cubic meters of tailings water and solids had escaped from the dam, of which nearly2.9 million cubic meters had reached the Omai River. This paper outlines some initial Process considerations and operational decisions which might have contributed to the dam&apos;s failure, describes how the Government of Guyana and the operator, Omai Gold Mines Limited, cooperated in dealing with immediate problems and shows how the Government set about investigating the accident. In particular, the paper details the work of a Process Review Committee comprising Guyanese and foreign experts convened to assess the gold processing and effluent management systems at Omai, and to recommend actions where appropriate.

Jan 1, 1998

By M. J. Adam

The U.S. Bureau of Mines has investigated the partitioning of complex minerals to simpler phases using sulfidation reactions for selective extraction of mineral values. This report describes research in which thermal processing of the complex Ti-bearing mineral ilmenite (FeTi03) resulted in partitioning of the valuable Ti metal to the simpler compound rutile (TiO2). Samples of ilmenite were blended with elemental S for thermal treatment at various temperatures under controlled atmospheres in an effort to dissociate the Fe from the ilmenite complex. Product characterization revealed that the Fe was partitioned &apos;from the ilmenite, forming a rim of pyrrhotite/pyrite (FeS/FeS2) on a rut il e core. The products were agate milled and then subjected to cursory magnetic and flotation techniques in an attempt to physically separate the partitioned phases. Partitioning results and phase concentration data are reported relative to thermal treatment variables and physical separation techniques.

Jan 1, 1991

By M. J. Adam

The Bureau of Mines is investigating the feasibility of partitioning complex sulfide minerals to simpler sulfide phases by sulfidation reactions. Such partitioning can afford opportunity to improve selective extraction of mineral constituents of value. This report describes research involving sulfidation partitioning of byproduct chalcopyrite concentrates from Missouri lead ore processing, and a Utah chalcopyrite concentrate from Cu ore processing. Small chalcopyrite samples were sulfidized with elemental S in glass capsules sealed after evacuating and backfilling with He, by heating for 1 to 24 h at specific temperatures in the range of 250? to 500? C, extending from below to above the boiling point of S (-4450 C).

Jan 1, 1987

By Tim B. Vander Wood

Standard methods of determining clay mineral powder aspect ratios involve manual scanning electron microscopy analyses of shadowed particles in order to measure both platelet thickness and diameter. We present a method whereby the diameters of platelets are quickly determined by automated scanning electron microscopy and their images are recorded and digitally transferred to a transmission electron microscope equipped for parallel electron energy loss spectroscopy. Thickness&apos; of platelets whose diameters are known from the previous analyses are determined by measurement of the ratio of scattered and unscattered electrons in the beam after it has been transmitted through the platelet.

Jan 1, 1995

By C. Landolt

Inco&apos;s Copper Cliff Smelter Complex produces some 11 5,000 tonnes per year of nickel and 120,000 tonnes per year of copper. The Smelter flowsheet has changed a number of times over the years. The most recent changes were effected in the mid-1980&apos;s in response to new realities in metal markets and heightened awareness about the workplace environment. By 1994, the flowsheet will undergo yet another metamorphosis as part of Inco&apos;s SO2 Abatement Program. The paper discusses the improvements implemented during the 1980&apos;s and projects the processing in the Smelter through 1994.

Jan 1, 1993