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By William Petruk

The capabilities of SEM/image analyzers for determining quantitative mineral data which have a bearing on extractive metallurgy have given applied mineralogy a new dimension. The capabilities include automatic mineral identification, unattended operation, search for rare minerals, and measurements of (1) mineral quantities, (2) grain and particle size distributions, (3) liberation characteristics of minerals in ground ores, and (4) mineral associations. Data on mineral quantities define the distributions of elements among minerals, provide background information on characteristics of the samples, and provide a data base for a mineral-materials balance. Size analysis data of the minerals in unbroken ores are used to predict the grind required to liberate minerals. Data on liberation analysis can be used in many ways. One application is to process the image analysis data for feed, concentrate and tails by a materials balancing technique to calculate the recovery of liberated and unliberated grains at each point in a circuit. The calculated recovery data define the behaviour of an ore in a concentrator, pilot plant or bench test, and indicate whether recovery improvements are possible and/or feasible for a particular ore.

Jan 1, 1991

By Ph. Cauwe

This paper presents the experience that NESA and MECHIM have gained about recovery of non ferrous and precious metals from complex sulfide materials. Processed materials are from natural deposits or metallurgical by-products or residues. Roasting of these materials is closely related to the pyro or hydrometallurgical processes used downstream of the roasting. Conditions of a first step of roasting the SELECTIVE ROASTING, are analyzed and explained. The roasted products so obtained are characterised by an extended elimination of volatile sulfides (AS, Bi, Sb, Sn, Pb, Hg, ?? ) and are readily available for the pyrometallurgical recovery of non ferrous and precious metals. After the SELECTIVE ROASTING, thanks to. the high porosity obtained in the "selective calcine", the SULFATE ROASTING is per-formed in excellent conditions. Hydrometallurgical tests performed for the final calcine show a high recovery of non ferrous and precious? metals and require only simple and well known processes. Many experimental and commercial data are given.

Jan 1, 1983

By H. J. Roorda

With an increasing need to obtain metals by processing complex fine intergrown ores, the use of electron-optical techniques will become more important as a tool for mineralogical studies. Electron images enable a higher spacial resolution than can be obtained by optical microscopy and thus provide a powerful and necessary aid for the examination of small grains and finely locked particles. In this paper the mineralogy of Meggen ore was investigated. Both light-optical and electron-optical techniques were used to evaluate the mill feed and products of the concentrator. Detailed examination by reflected-light microscopy to assess the comportment of galena in the complex pyritic ore was inconclusive in establishing the cause for low lead recovery of only forty percent of the ore's lead content. Electron microprobe analyses indicated that the majority of the lead lost to the tailings was accounted for by extreme fine (often smaller than one micron) and complex intergrowths of galena in pyrite. The remainder was lost as fine free galena grains.

Jan 1, 1987

By D. B. Dreisinger, V. van der Pas

Zinc sulphate electrolyte used for zinc electrowinning must be purified for cObalt ions. The cobalt is removed in a cementation stage by the addition of zinc dust. Copper arid antimony are frequently used additives which enhance the cementation of cobalt. This paper aims at a better understanding of how copper and antimony promote the removal of cobalt. Initial experiments were done in a batch cementation reactor. Copper and antimony precipitated in the early stages of cementation indicating that a preferential substrate was formed. The individual role of copper and antimony was further investigated in an electrochemical cell. On a microsca1e, the , growth process, morphology and the composition of the precipitates were examined with SEM and XRD. It was found that cobalt could not be deposited in its pure form but as a cobalt-zinc alloy with zinc as the prime constituent. Copper increases the cathodic surface area of zinc dust by precipitating as numerous dendrites. Antimony acts as a cathodic surface onto which a cobalt-zinc alloy with an increased cobalt content is deposited.

Jan 1, 1997

By S. L. Kher

The Singhbhum Copper Belt located in the state of Bihar in Eastern India bears evidence of ancient workings and indicates the existence of a civilized habitation in this region in the past. It was in 1833. how- ever, that the first official announcement of the occurrence of copper in the district was made. Although the occurrence was confirmed in 1847, it was not until 1857 that the first company was formed to exploit the deposits. This Company was dissolved in 1859 and from then until 1920, there were many unsuccessful attempts to develop and exploit the copper deposits in the Singhbhum area. In 1920. the Cordoba Copper Co. took an option on the Mosaboni area, which is nearly 10 km away from the present works located at Moubhandar, Ghatsila and exercising the option in 1924, purchased the mining rights from the Cape Copper Company. The Cordoba Copper Co. was then converted into Indian Copper Corporation Ltd. This was subsequently taken over by the Government of India in March 1972 and is now known as Indian Copper Complex (ICC), forming one of the two smelting units of Hindustan Copper Ltd.

Jan 1, 1976

By Yoshisada Michiura, Junko Umeda, Katsuyoshi Kondoh

Rice husks or straws, one of the main agricultural wastes in South-east Asia, have a large possibility to be employed as usefully renewable resources to produce energy and high-purity silica (SiO2), because they consist of about 70% organics such as cellulose or hemi-cellulose, and 20% amorphous SiO2. The former is utilized as bio-mass energy; for example, thermal or electric energy, and bio-mass ethanol. High-purity silica can be used as raw materials in the industrial uses. It would be possible to extract silica elements from rice husks and straws by burning them in air because their main contents are organics. In the previous studies, a strong acid leaching treatment on rice husks before burning was carried out by using H2SO4, HCl and HNO3 to prepare high-purity silica materials. This was available to accelerate the hydrolysis of celluloses and hemicelluloses contained in rice husks, and remove the above metallic impurities. A strong acid leaching treatment, however, is significantly hazardous to environment and human life, and causes an increase of the process cost. In this study, the environmentally benign, harmless to human and economically effective process to produce high-purity amorphous SiO2 materials from rice husks has been established without using strong acids. From a viewpoint of the harmless influence on human body, the carboxylic acids were used in the leaching treatment on rice husks. TG-DTA measurement and GCMS analysis indicated that the leaching was effective for the hydrolysis of celluloses and hemicelluloses contained in rice husks at 473K~873K, which produced the same results in using the conventional sulfuric acid. The metallic impurities could be also removed from the husks via a chelate reaction between carboxyl groups (-COOH) and the metal elements. In particular, it was clarified that cadmium (Cd) were completely removed from rice straws by this reaction. Concerning the burning conditions of rice husks after the acid leaching, it was necessary to supply a suitable amount of air to completely combust organics; for example it required air supplement of 50 ml/min. or more. The burning temperature should be less than 1273K to obtain amorphous structured silica. High-purity amorphous silica materials with 99% or more were prepared from rich husks by applying the citric acid leaching treatment and burning process at 1073K in air.

Jan 1, 2008

By T. C. Goel, A. Venna, R. G. Mendiratta

"Processing of ferrites has gained tremendous importance in recent times to meet the high performance demands on ferrites in keeping with the fast emerging· technologies. The quality of ferrite powders has strong influence on ·the performance of final device. Fabrication· of high performing ferrite components requires starting ferrite powders of precise stoichiometry, purity and microstructure. It is difficult to obtain these attributes by the conventional ceramic method. The key to obtaining quality powders lies in the· solution techniques. With this in view soft ferrites have been prepared by a wet chemical process, known as the citrate precursor method, which involves the formation of citrate complexes of the constituent cations. The advantages of this process are the ease of preparation and close control of composition, homogeneity, purity and particle size. Electrical and magnetic measurements on lithium ferrites have shown resistivity higher by more than two orders of magnitude compared to that observed for samples prepared by the conventional ceramic method, and low magnetic losses, making the ferrites specially suitable for high frequency applications.IntroductionProperties of ferrites are known to be sensitive to .their processing technique. A small deviation in the compositional stoichiometry of the ferrite affects its properties greatly. Soft ferrites such as Ni-Zn, Mn-Zn and Mg-Mn. are well known ferrites covering wide-ranging applications [1,2]. Lithiiim ferrites have also assumed technological importance for microwave applications and are potential substitutes for the expensive garnets [3]. Lithium ferrites are often doped with zinc to tailor the saturation magnetization required at high frequencies. Lithium and lithium-zinc ferrites, however, present difficulty to processing due to the volatile nature of both the cation components, namely Li and Zn. These ions are volatile at temperatures > 1000°C which makes their processing difficult. One of the main considerations of high frequency performance of ferrites is the high eddy current losses which prevent the interaction of the magnetic field with the ferrite component and hence impair device performance. These losses can be reduced by having a material of high resistivity. Electrical conductivity in lithium ferrite has been attributed to electron hopping [4] between the two vaience states of iron, Fe2+ <=> Fe3+, on octahedral sites. Maintaining the + 3 valence state of otahedral- Fe ions is thus a prerequisite for achieving high resistivity. The resistivity of ferrites is normally found to be low when processed by the conventional solid-state or the ceramic method [5]. This is attributed to (a) extensive ball-milling employed in the method to mix the component oxides results in non-stoichiometric compositions due to introduction of additional Fe ions on abrasion of steel balls during milling, (b) high processing temperatures involved which result in significant volatilization of Li and Zn ions creating thereby oxygen non-stoichiometry which results in reduction of Fe3 + to Fe2 +, (c) large and non-uniform grain sizes. In the present work, preparation of Li and Li-Zn ferrites by a non-conventional method known as a citrate precursor method [6, 7] which requires lower processing temperatures and duration is reported. The method gives stoichiometric compositions on account of homogeneous atomic-scale mixing of the constituent cations via the formation of metal-citrate complexes mixed in solution state. The method is also capable of giving small grain size which aids the oxidation ofFe2+ ions."

Jan 1, 2000

By N. A. Barcza

DC plasma-arc technology using a hollow graphite electrode (cathode) has been successfully implemented in the primary metallurgical industry in South Africa up to the 30 MW scale. Mintek has applied its expertise base, established over the past fifteen years, to testing the treatment of metallurgical wastes such as carbon- and stainless-steel plant dusts, lead- and zinc-containing slags, and residues from the base-metal industry. Favourable results have been achieved, and disposable products were produced. The evaluation of numerous wastes indicates that recovery of zinc as metal gives the best economic return from these sources. Direct recovery via a splash condenser or electrolytic zinc extraction from fume are the two preferred alternatives under review. In both instances dehalogenation is an important issue, but can be achieved by suitable treatment processes. The Enviroplas technology provides a flexible, commercially viable approach to the treatment of a wide variety of wastes. Mintek, together with its associate Pyromet CC, are installing a plasma- arc pilot-plant facility with both an ISP lead-splash condenser of about 5 t/d condensed zinc capacity and a combustion chamber to burn zinc vapour to zinc oxide. This will demonstrate the suitability of the Enviroplas technology for treating specific metallurgical wastes, so that customized industrial plants can be engineered based on large-scale testwork.

Jan 1, 1994

By M. A. Kader, M. A. Islam, P. J. Hazell, M. Saadatfar, J. P. Escobedo, A. D. Brown

The present study investigates the dynamic deformation mechanisms of closed-cell aluminium foams during low velocity drop weight impact with experimental analyses and finite element (FE) simulation.The evolution of foam collapse was explored with FE simulation using ABAQUS/Explicit. X-ray computed tomography (XRT) based geometry was reconstructed to understand the actual microstructural changes during impact. The experimenta lstress-strain response was compared with FE simulation with reasonably good agreement observed between FE prediction and experimental data. A vertical cross-sectional XRT slice was analysed at different strains from FE simulation to understand the pore collapse mechanisms.

Mar 1, 2017

By R. R. Beebe

"Laboratory and pilot-scale tests are almost invariably required before metallurgical development can proceed. Difficulties with sampling, as well as with classical chemical and physical scaleups, are normally anticipated and relatively well-understood, but more subjective factors also come into play, including misunderstandings of the operating scheme chosen, wrong ""lessons"" learned from similar operations, failures to handle data appropriately, and even arbitrary intervention by management. The paper examines some of these subjective factors and suggests ways to guard against them. Several anecdotal case studies are used as examples, including when and where to heap leach or to mill specific types of gold ore.When the Romans first exploited the gold-rich gossans at Rio Tinto, they were guided by analyses and tests that delineated the ore deposits, identified the richer portions, and measured the gold recoveries achieved. There is little evidence, however, to suggest that test data were used to develop improved methods of metallurgical extraction. Indeed, it is likely that ores too difficult to treat were simply passed by, at least until improvements in full-scale operations could deal with them. For example, it is not difficult to imagine that an early metallurgist might test a tin ore by placing some in a fire; a smallscale emulation of the method actually used in practice."

Jan 1, 1997

By R. Altman

A Brookfield viscometer fitted with a stainless steel bob was used to measure the viscosity of industrial lead blast furnace slags between 1126 and 1298°c. Slag oxidation state was characterized by first annealing the? slag samples at 750°c in sealed copper tubes in order to precipitate magnetite crystals. The magnetite concentration was then measured on an Outokumpu Saturated Magnetic Analyzer. Using an Arrhenius-type equation, a viscosity model was developed by regression. The equation below accounted for 75% of the variability in the data used to generate the regression coefficients and, on average, could predict viscosity within ± 12% of the measured value. The greatest difficulty encountered in measuring viscosity was due to the occasional presence of solids in the slag which caused, at times, erroneously high viscosity measurements. Precautions to minimize this problem are outlined in the text.

Jan 1, 1985

By B. R. Westphal

The Integral Fast Reactor (IFR) concept being developed by Argonne National Laboratory is based on the pyrometallurgical processing of spent nuclear metallic fuel with subsequent fabrication into new reactor fuel by an injection casting process. During fabrication, a dilute scrap stream containing uranium alloy fines and broken quartz (Vycor) molds is produced. Waste characterization of this stream, developed by using present operating data and chemical analysis, was used to evaluate different uranium recovery methods and possible process variations for the return of the recovered metal. Two methods, comminution with size separation and electrostatic separation, have been tested and can successfully recover over 94% of the metal. Recycling the recovered metal to the injection casting process was evaluated for the different economic and process impacts. The physical waste parameters and the important separation process variables are discussed relative to their effects on the viability of recycling the material. A discussion of the criteria that is being used to establish the acceptable operating limits is also presented.

Jan 1, 1992

By Marco Olper

After two years of extensive research a new and innovative modification to the CX-EW process has been exploited. This process, called CX-EWS, avoids completely all the critical aspects of the previous process which affected the cost of the energy, of the chemicals and of The maintenance of the insoluble anodes. All these benefits reflect a saving of about 30% of The operating costs compared to the present traditional production and allow for a total operating costs of less than 6.5 cts/lb. lead (net of raw material cost). With this new technology it is allowed for the first time the treatment in the same plant facilities of both primary lead sulphide concentrate and spent batteries. The paper describes the technical and economical aspect of the new process with a feasibility study for 150,000 t/y spent battery facility throughput.

Jan 1, 1995

By R. D. Pehlke

The history and present status of continuous casting of steel are reviewed, including a genera 1 description of current processes. Plant layout, process development and elements of machine component design are outlined, and key steps in integration into a stee-1 production system are detailed. Recent productivity advances and improvements in quality are described. Process developments are reviewed, and some future avenues for this technology are considered.

Jan 1, 1985

By J. L. Johnson

The U.S. Department of the Interior, Bureau of Mines, investigated recovery of concentrates containing tin, tantalum, and niobium from the Kougarok deposit on the Seward Peninsula, AK. To date, 25 million lb of tin has been delineated in occurrences containing 0.36 to 1.32 pct Sn, and the resource potential is estimated to be as high as 25 million short tons at average grades of 0.75 pct Sn, 0.025 pct Ta, and 0,025 pct Nb. Deslimed ore was concentrated to 54 pct Sn, 0.3 pct Ta, and 0.3 pct Nb, with recoveries of 74 pct Sn and 44 pct Ta/Nb using a Humphrey&apos;s* spiral followed by a Deister shaking table. Tin values in the slimes were upgraded to a 5-pct-Sn concentrate using a Bartles-Mozley separator followed by flotation. The 5- pct-Sn was further upgraded by fuming to give a concentrate containing approximately 60 pct Sn. The recovery of the two products combined was 80 pct Sn and 46 pct Ta/Nb, A flowsheet with mill-design parameters resulted from the metallurgical testing. An economic analysis was made based on the proposed process.

Jan 1, 1990

By Yongbin Yang, Meixia Cai, Yufeng Guo, Guanzhou Qiu, Tao Jiang, Jianjun Fan

"A series of sintering and metallurgical experiments were carried out to optimize the blast furnace burden structure in this study. The results indicated that the sinter disintegrated seriously with basicity around 1.4, and after this “turning point”, the sintering properties were improved gradually with the increase of basicity of sinter. Based on the results, an idea was put forward which focused on producing two different kinds of sinter with different basicity. Different with the original burden structure of 85% sinter with basicity 1.4-1.5 + 15% pellets, an alternative new BF burden structure was proposed by the following structure?44% sinter with basicity 1.05 + 44% sinter with basicity 1.87 + 12% pellets. This new alternative BF burden structure has been adopted by some steel plants.IntroductionIn recent years, conventional blast furnace (BF) process was put into operation to produce hot metal in “A” steel plant. “A” steel plant owns two sets of sinter strands at present. Because the sinter production capacity exceeds the actual requirements of BF, a burden structure with 85-90% self-made sinter + 10-15% purchased pellets is adopted to take advantage of the low–cost sinter. But the serious problems encountered with the BF operators are that the sinter disintegrated easily during transportation and storage process. Therefore, the rate of return fines is very high after sinter being screened."

Jan 1, 2012

By Qingchun Yu, Bin Yang, Yong Deng, Heng Xiong, Fei Wang, Minxiu Chen

"Metal aluminum produced by non-electrolysis process received much attention due to its lower energy consumption. In this paper, carbothermic reduction and carbothermic-chlorination of alumina in normal pressure and vacuum were studied. The products were examined by means of XRD, EDS and SEM. During the carbothermic reduction process using carbon reductant in normal pressure, no metal aluminum was found. However, when coal was used as reductant, a mixture containing metallic aluminum, A14C3, and silicon was obtained, but metallic aluminum couldn't be separated from the mixture. During the carbothermic-chlorination process in vacuum, Al404C and Al4C3 were produced by the reaction between alumina and carbon, and Al Ch gas reacted with Al404C and Al4C3 to produce Al Cl gas. Metallic aluminum was produced due to the disproportionation of A!Cl gas and condensed on the collecting plate. Meanwhile, the initial temperature of carbothermic reduction of alumina reduced in vacuum compared with that in normal pressure.IntroductionIndustrial production of primary aluminum is carried out in alumina cell by the so-called Hall- Heroult process, necessitating the use of very high currents of low voltage. The alumina from which metallic aluminum is gained must be chemically pure, otherwise impure metal results. The main drawbacks of the electrolytic production are its very high energy consumption, the release ofperfluorocarbons, and the high specific C02 emissions [1]. During the past years, there were a lot of attempts to produce metallic aluminum by carbothermic reduction of A1203 [2, 3]. Cox [4] determined the vapor pressure over the A1203-C system and performed X-ray diffraction analysis of condensed products. It was demonstrated that an increase in the carbon content in the system leaded to the sequence of transitions: A1203~Al404C~A1zoc~A14C3 ~AI [5]. In any carbothermic reduction process for aluminum, extremely high temperatures (2000 °C ) were required [6]. In spite of considerable effort, the carbothermic reduction of alumina to aluminum remains a formidable technical challenge, due to the high temperatures required, and to the formation of aluminum carbide and oxycarbide byproducts [7]."

Jan 1, 2013

By S. Seetharaman

In the processing of molten metals, it is extremely important to monitor continuously the concentration levels of various minor elements, In the production of common metals like copper, iron and aluminium electrochemical sensors involving solid, as well as liquid electrolytes are being increasingly used to measure the concentrations of minor elements The present paper deals with the electrochemical principles underlying these measurements and the possible errors involved. One of the major difficulties in the case of the solid electrolytes is to correct for the consequences oldie electronic contribution to the conduction of the electrolyte. The application of the electrochemical sensors for molten metals processing involves designing of these probes to withstand the industrial operating conditions. In this respect, significant achievements have been made with respect to the design of oxygen probes for liquid metals in general and liquid copper in particular. Some of the salient design features are discussed in the paper, The application of auxiliary electrodes for impurities in molten metals like phosphorus in copper and silicon in iron are taken up. The development of oxygen sensors for slags is given special attention. Recent developments&apos; in the field of sensor technology, as applied to metals processing are highlighted.

Jan 1, 1996

By Lionel Ryan

In 1996, the Dominican Republic operation of Falconbridge (Falcondo) developed a 5-year Process Control Plan in conjunction with the corporate Process Control group located in Sudbury, Ontario, Canada. This plan was further refined into an analysis of the areas of the highest potential economic return for the company with the reduction shaft furnace operation being the most promising. Historically, the reduction plant, which comprises 12 shaft furnaces, has been the bottleneck of ferronickel production. Since 1996 there has been a history of control development, and the current status is that all 12 furnaces are using advanced model-based multi- variable predictive control. The combination of advanced process control (APC), improved control system performance and improved process information management has resulted in an increased throughput of 6% per shaft furnace and a reduction in operating costs of 4.5 US cent/lb of Ni. This paper reviews some of the major milestones that have been achieved in this development Keywords: Advanced Process Control; Model Based Predictive Control; Connoisseur, Reduction Shatt Furnace; Nickel Laterite Ore; Ferronickel; MonitorMV

Jan 1, 2004

By Randall M. Gennan

Generally sintering is focused on the bonding of particles at high temperatures; possibly with simultaneous densification. However, an important aspect of sintering occurs during heating at relatively low temperatures where polymer processing aids are removed via control of the atmosphere, heating rate, or hold time at intennediate temperatures. New insights into burnout processes show impact from the polymenype, particle size, amount of polymer, atmosphere, part geometry, and thermal profile. This presentation focuses on the key parameters to demonstrate improved mechanical property levels are available in traditional powder metallurgy alloys by proper selection of the processing polymer and proper care in its thermal extraction. The focus is on mechanical property, where gains up to 40% are demonstrated due 10 changes in the processing polymer. Further, atmosphere control during polymer burnout provides a benefit by allowing formation of desirable carbonitrides, giving strength levels over 3 GPa (over 400 kpsi). Insight is? gleaned from powder injection molding, where high polymer contents mandate proper processing control.

Jan 1, 1996