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By Donald R. Sadoway

Fused salt electrolysis is used extensively in the primary extraction of metals (electrowinning), in the refining of metals (electrorefining), and in the formation of coatings (electroplating). In the case of rare earths, fused salt electrolysis competes with nonelectrochemical processes to make the same products. However, fused salt electrolysis has the potential to produce these metals in a variety of technologically useful forms: thin films and epitaxial layers, powders, and a variety of nonequilibrium structures. The theory and practice of fused salt electrolysis as it applies to the extraction, refining and plating of rare earth metals are described. The potential of fused salt electrolysis to synthesize advanced materials containing the rare earth elements is assessed.

Jan 1, 1989

By Graeme Miller

The geotechnical characteristics of the ore are important in understanding the kinetics of a copper heap leach. These characteristics can indicate potential problems and can be used to determine the semi-quantitative changes in field kinetics as compared with column kinetics. The application of this approach allows a more rigorously based determination of ?scale up factors? than has been the case the date. The shrinking core model has been shown to be a poor predictor of leach kinetics based on the crushed ore size distribution. However the model itself is a very useful tool to analyse commercial heap data. Significant geotechnical parameters such as: bulk density / stress characteristic, limit moisture capacity and particle density are used to determine the effect of changes on the diffusion controlled leach rate. By consideration of the geotechnical reaction of the ore mass the leach rate changes are related to changes in these variables. Analysis of commercial heap data has indicated effective diffusion lengths of up to ten times the largest particle size.

Jan 1, 2003

By C. Anderson

Most applications of copper metallurgy are geared towards primary production. However, as recycling of materials is a growing industry, one future facility will rely on copper metallurgy as a means of processing precious metals. This paper will discuss the derivation of the proposed copper pyrometallurgical and electrometallurgical unit operations to be utilized in industrial recycling of secondary precious metals.

Jan 1, 1999

By T. V. Swaminathan

Monazite sand is normally processed by, the caustic soda route to produce mixed rare earths chloride, thorium hydroxide and trisodium phosphate. Bulk of the mixed rare earths chloride is used for the preparation of FC catalysts. Recently some of the catalyst producers have shown preference to cerium depleted (lanthanum enriched) rare earths chloride rather than the natural rare earths chloride obtained from monazite. Therefore, a process for producing cerium depleted rare earths chloride, cerium p thorium and uranium from Rare earths + thorium hydroxide obtained by treating monazite based on stepwise hydrochloric acid extraction, was developed in our laboratory. The process involves drying of the mixed rare earths-thorium hydroxide cake obtained by monazite-caustic soda process followed by stepwise extraction of the dried cake with hydrochloric acid under specified conditions.

Jan 1, 1989

By H. Aminian

Copper electrowinning (EW) is an important process in connection with the solvent extraction to produce pure and marketable copper cathodes. A phenomenological model was developed to simulate the copper electrowinning process. The simulator is used to predict the operation of the Mines Gaspe pilot plant electrowinning cells put in operation in 1996. Results confirm the potential of the simulator that would subsequently be used for student training, process optimization and assessing the performances of control strategies.

Jan 1, 1999

By Murray Johnston

New measurements have been made on the equilibrium distribution of selenium and tellurium between molten slag and metal phases. Distribution coefficients of Se and Te between magnesia-saturated calcium ferrite slag and copper or silver alloys were measured over the temperature range 1473 and 1673 K under controlled oxygen patrial pressures of 10-11 to 10-0.68atm. The results demonstrate that the minor elements are present in the calcium ferrite slag as the selenide (Se2-) and telluride (Te2-) respectively, up to a PO2 of 10-6 atm. As conditions become more oxidising, Te undergoes a transition to the divalent oxide whereas Se does not. Increasing the temperature was found to enhance partitioning of the minor elements to the slag. In terms of activities, at 1573 K, Se showed strong negative deviation from the ideal behaviour in the slag, while Te showed only slight positive deviation.

Jan 1, 2006

By R. E. Molnar

A number of flowsheets have been designed and operated, or are currently being considered, to extract copper from leach solutions having much more copper than the 4 g/L levels typically found in heap leach liquors. Dealing with these solutions has required that the envelope for ?normal? copper solvent extraction be pushed beyond the usually considered limits. Others have published information on flowsheets to recover copper from leach liquors containing over 25 g/L copper. Secondary solvent extraction circuits are often required to attain satisfactory overall recoveries. This paper reviews some of the issues faced in three pilot plant circuits that were operated by SGS Lakefield Research to produce cathode copper from solutions containing 8 to 20 g/L Cu. The primary objective was to maximize copper extraction using one solvent extraction circuit. The role of feed acidity and the disposition of impurities such as iron and chloride are considered. The challenges of running short SX piloting campaigns are discussed.

Jan 1, 2003

By Katsutoshi Komeya

Aluminum nitride(A1N) is a theoretically high thermal conductive ceramic, but is a poor sinterable one because of its covalent bond structure. The densification of A1N had to be done first. It was found in 1968 that rare earth compounds as yttria were an excellent sintering aids. Recently more improvement of conductivity was attained by following effects of yttria: (1) trapping of oxygen in A1N sources to form yttrium aluminates, (2)elimination of the aluminates by heating in carbo-reductive atmosphere. Consequently very high thermal conductivity of up to 270W/mK has been developed. Thus A1N applications for substrates and packages have been opened.

Jan 1, 1992

By Xiaorong Liu

Interfacial emulsion generated in copper solvent extraction is an inhomogeneous O/W emulsion that consists of organic phase, aqueous phase and solid particles. In order to determine what kind of components in organic phase promotes the emulsion, the organic phase separated from the interfacial crud provided by Dexing Copper Mine in Jiangxi, China was analyzed for its components by combined gas chromatography-mass spectroscopy. It was found that many kinds of emphiphiles containing such hydrophilic groups as carbonyl, carboxyl, or acylamine existed in organic phase, most of which were originated from the reagent degradation. Conclusively, Lix984N would degrade gradually during a long-term contact with the acidic aqueous feed and strip reagents. Lix84 and nonylphenol, as effective components of Lix984N, degraded almost completely after long-term recycling. As a result, the effective components of Lix984N were far lower in concentration than the dense-aromatic impurities derived from the diluent and the degradation products in total. The degradation of Lix984N would deteriorate solvent extraction, disengagement performance and result in more serious interfacial emulsion.

Jan 1, 2006

By Barry T. Kilbourn

There is a continuous quest for better-performing materials, for example, to withstand higher temperatures, to resist more efficiently degradation or to be electrically conductive under extreme conditions. The oxides, and similar compounds, of the lanthanides and yttrium can, in some cases, help provide such behavior. Other advanced materials, such as hydrocarbon catalysts, optical ceramics or sensitive phosphors, may also require these oxides for some essential function. The role of the oxides in a wide variety of technologies, some novel and developing, will be reviewed and the underlying physico-chemical principles, the common threads, between several less well-known and apparently unrelated uses discussed.

Jan 1, 1989

By Malcolm J. Harrison

The problems associated with the flow control of abrasive slurries and solids laden fluids creates reliability problems in many mining operations. Conventional valves such as pinch, knife gate and plug types cannot always function reliably in such harsh operating environments. Due to the technological advances in the hard coating industry, ball valves can now be produced with internal surfaces protected from the erosive effects of these applications. Pressures well in excess of the capability of conventional 1000 kPa working pressure valves can now be handled reliably. The significant advantages of minimizing down-time and lowering maintenance costs can now be realized with metal seated ball valves.

Jan 1, 1999

By B. S. Boyanov

The hydrometallurgical technology for zinc production in Bulgaria is characterized by the use of considerable quantities of imported zinc concentrates and several kinds of Bulgarian ones which are quite different in chemical, phase and granulometric compositions. In this connection, 7 sulfide zinc concentrates (Bulgarian and imported ones) were investigated by chemical analysis, DTA, TGA, X-ray diffraction analysis, sieve analysis. The accomplishment of optimal mixing of concentrates and providing stabile mix composition for a long period of time of roasting in fluid bed furnace is a task of primary importance in the technological process control in zinc hydrometallurgy. This can be achieved using mathematical optimization methods.

Jan 1, 2006

By B. Wan

The process of synthesizing silica nanopowder by the gas phase thermal oxidation of tetraethylorthosilicate (TEOS) in a diffusion flame reactor was simulated using a commercial computational fluid dynamic (CFD) code. The fuel combustion process and silica particle formation and growth in the flame are modeled. The temperature, velocity and particle size distribution (PSD) fields inside the reactor are computed. Chemical reaction rate and population balance model (PBM) were used to calculate the particle formation and growth and PSD.

Jan 1, 2006

By Akira Yazawa

Oxidic dissolution loss of metal in slag is discussed thermodynamically in terms of oxygen potential, activity coefficient and equilibrium constant. To understand basic principle, regular solution model is applied for model calculation of the activity behaviour of metal oxide in FeO-SiO2-CaO slag, and effects of slag composition, temperature, and basicity of oxide on dissolution loss are demonstrated. As: a simplified but practical conclusion, the dissolved metal loss in slag is inversely proportional to activity coefficient of metal oxide, and also to FeO content in slag when amount of slag is taken account.

Jan 1, 1994

By P. T. Velu

Light weight aluminum alloys are the major construction materials for a number of structures in automobile and aerospace industries. Higher cost of production is the key impediment which restricts the usage of these alloys. A new electrochemical process route for the low cost production of aluminum alloys is being investigated, in which alloying elements are obtained from the dissolved compound. In the present investigation, solubility of lithium compound has been determined by measuring the EMF, when it is dissolved in the electrolyte. The solubility of Li2CO3 increased with temperature from 2.95 wt pct at 1063 K to 7.57 wt pct at 1093 K. Activities of the compound in the electrolyte were deduced using Temkin's ideal solution approach.

Jan 1, 1995

By O. Nakai

In the copper electrorefining process, the quality of the starting sheet is one of the basic factors for producing high quality copper cathodes. A highly automated and advanced facility for the production of copper starting sheets was constructed at the Toyo Copper Refinery in 1992, bringing various improvements into an automatic stripping system using stainless steel mother blanks. In 1998, the refinery expanded the tankhouse by another 128 commercial cells, and introduced 64 polymer concrete cells in a first stage conversion. As a result, the Toyo Copper Refinery now has the capacity to produce 103,200 t/y of cathode copper. Construction has led to great improvements in the materials handling facilities and computer associated short-circuit detection technology. This report summarizes the improvements made in the quality of the cathodes and in plant productivity.

Jan 1, 1999

By L. L. Ludwig, S. E. James, B. L. Motycka

Significant modifications to the electrolytic zinc plant operated by Big River Zinc Corporation were made at the end of the 1990's resulting in increased capacity and improved efficiencies. A new cell room, with the innovative use of acid-resistant concrete cells and a modern ventilation system, was installed to raise the capacity from 80,000 tonne/y to 106,000 tonne/y of finished zinc. Improvements to the leaching section include the conversion from a single to a two-step process, with associated equipment changes, to improve the quality of the residues produced. Another key change is the construction of a facility to allow the use of zinc oxides from secondary sources as a feed to the plant. This paper describes these improvements and the current operations.

Jan 1, 2000

By A. A. Shook

For relatively little capital outlay, the metal delivery control system in the BHP Copper Rod Plant at San Manuel' was significantly upgraded using the UNAC process simulation and control system (CICS Automation, Newcastle, Australia). An accurate simulation of the metal delivery process was developed with UNAC, which was then used to design a robust controller capable of dealing with plant complexities such as noise, time delays, and nonlinearities. This controller was implemented online using UNAC. Thanks to the extensive preparatory simulation, the controller worked immediately and required no additional online "tuning". Operator response has been favorable, and the UNAC control system has become part of the standard operation of the plant.

Jan 1, 1999

By Marilda Macagnan, Rosana de Cassia de Souza Schneider, Valeriano Corbellini, Tiago Bjerk, Mariela de Souza Vieira

The great potential of Brazil for the agricultural production makes our country a generator of agro industrial residues. In this context, the solid-state fermentation appears as a technology that shows alternative ways for those residues, adding values to these raw materials, through the production of substances of industrial interest, besides reducing the possible environmental problems. The main objective of this study was to apply the bovine fat residue associated to the garden grass for the fungal lipase production. Initially, 75 microbial cultures were isolated from garden grass samples after incubation of the mixture with bovine fat. From these cultures were selected the filamentous fungi, whose lipase production abilities were evaluated. The isolation and the selection were accomplished by using a differential culture medium containing Tween 80 as inducer substrate of lipase production. The colonies with lipolytic potential were detected by the presence of white precipitation haloes on the agar. With agro industrial residues the best lipase producer fungus was identified as Penicillium sp in 6 days of solid state fermentation. The crude enzyme obtained was tested in transesterification process for the biodiesel production.

Jan 1, 2008

By Peter J. Hancock

The pyrometallurgical .processing of non-ferrous, complex materials and wastes will be surveyed. Pyrometallurgy offers the most versatile way of processing a large variety of such materials because of its high temperatures, closely-controlled oxidation potential and the availability of commercially-proven reactor configurations. Some current industrial applications will be reviewed and possible new applications as well as future trends will be outlined.

Jan 1, 1994