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By Cashman R. S. Mason

Removal of halides (fluoride, chloride) from metallurgical solutions can reduce corrosion rates and improve hygiene from decreased anodic chlorine evolution. This is particularly true for zinc sulphate electrowinning solutions. This paper describes the chemistry of a new process for the removal of halides from such solutions by solvent extraction ? the Teck Cominco Halogon? process, for which patents are pending. In this process, the halides are loaded directly from commercial zinc sulphate solutions and are stripped into a form suitable for disposal. Sulphate extraction efficiency is variable while maintaining halide extraction efficiency. The method of optimizing the solvent composition is demonstrated.

Jan 1, 2003

By Zhi-biao Yin

Copper smelter flue dusts often cannot be directly recycled to the smelting process and accumulate as hazardous wastes requiring environmentally acceptable disposal. Because of the limited amount of flue dust, a separate copper extraction process must be simple and require-a small plant investment. A flue dust process has been developed, consisting of the following steps: (1) roasting a pelletized mixture of hydrated lime and flue dust to fix arsenic and sulfur as insoluble calcium salts, (2) heap leaching the roasted pellets with a buffered ammonia/ammonium salt solution to extract copper as an ammine complex in a lined cell that is the final repository of the leached pellets, and (3) boiling ammonia from the lixiviant to precipitate copper. Condensed ammonia and the filtered solution are returned to leaching. Heap leaching in the final repository cell lowers the capital investment significantly compared with competing extraction processes. Chemistry with respect to arsenic, sulfur and copper is discussed.

Jan 1, 1992

By Bob Drew, Alfred Spanring, Kirschen. Marcus

"Increasing material conversion and energy efficiency, and decreasing carbon dioxide emission levels are crucial for sustainable production processes in the aluminum, cooper, and steel industries. RHI supports these targets by providing a diverse range of solutions including high quality refractory linings, optimum lining maintenance, and process improvements. In this paper examples are provided of process improvements and increased energy efficiency in copper refining, potential energy savings during electric arc furnace and ladle operations in the steel industry, and increased energy efficiency by improved heat transfer in anode baking furnaces in the aluminum industry. In all cases, RHI’s expertise in close collaboration with the customer resulted in an improved performance of the reactor lining and the actual high temperature process with a positive impact on the material conversion and energy efficiency and as a result a decrease in specific carbon dioxide emission levels.IntroductionRefractory linings play an important role in heat transfer during high temperature processes in for example the aluminum, copper, and steel production industries. Due to constantly increasing energy prices worldwide and the increasing demands for environmental and climate protection, improving the energy efficiency and decreasing emission levels of these energy intensive production processes is of significant importance. In this paper, the contribution of modern RHI lining technologies to energy saving measures and the corresponding reduction of specific carbon dioxide emission are described. The type of current refractory solutions for energy intense processes are illustrated with four examples: Optimization and increase of material conversion and energy efficiency in copper refining, energy saving potentials in both electric arc furnace and transport ladle operations in the steel industry, and heat transfer improvements during the carbon anode annealing process in the aluminum industry. These examples focus on particular production processes operating with a high proportion of recycled copper, steel, and carbon anodes. Increased energy efficiency directly decreases the specific energy related carbon emission levels whereas improvements to the metallurgical processes aim to increase material conversion efficiency and, therefore, decrease specific process related carbon emission levels. Significant energy savings can be achieved by maximizing the refractory campaign length through a combination of appropriate refractory material selection, grade zoning, correct installation, careful preheating, and effective maintenance strategies. Besides the efforts to improve the performance and energy efficiency of customer high temperature processes, RHI continuously promotes the development of new low emission carbon-containing refractory bricks and unshaped products."

Jan 1, 2008

By Tang Chaobo

According to the principles of simultaneous chemical equilibrium and electronic charge neutrality, the system of Mg(II)-NH3-CO32--SO42--H2O at 25°C has been thermodynamically analyzed. And the rule of solubility of MgCO3(s) in the system is discovered, the high dissolution field of MgCO3(s) is discovered too. Furthermore, the solubility of MgCO3(s) is increased with the increase of the concentration of SO42-, but it is decreased first then increased with the increase of the concentration of all the CO32- and the total concentration of ammonia and ammonium, and decreased with the value of pH being higher. Those results will has important significance on prepare magnesium chemical products and other salts carbonate that are strict with the content of magnesium with carburization method.

Jan 1, 2006

By David Goodman

The typical operating conditions in Solvent Extraction plants are presented. The various materials of construction used for solvent extraction equipment are reviewed and the history of their use presented. The properties of the materials in common use today, stainless steel, thermoplastics and fiber reinforced plastics, are compared together with cost data. The manufacturing and construction aspects of these materials are discussed.

Jan 1, 2003

By Laurence G. Dyer, David G. Dixon, John Rumball, Maziar Eghbalnia, Edouard Asselin

"Linear scan voltarnmetry was used to determine the reactions that occur during the cyanidation of petzite (Ag3AuTe2). Gold oxidation in petzite requires more oxidising conditions than are required for pure gold, it also does not achieve the same current (related to reaction rate). Tellurium oxidation occurs at a similar potential in water and cyanide, but as a component of petzite is impeded somewhat in water, likely due to the stability of the precious metals. Pre-treatment of petzite to oxidise tellurium in the absence of cyanide prior to gold recovery appears to be at least moderately successful.IntroductionWhile gold occurs most prevalently in its native form, many other gold bearing phases appear throughout natural systems [I]. Tellurides are a common group of such minerals, many of which also contain silver, often existing in association with native gold deposits. The six major gold-bearing tellurides are calaverite (AuTe2), sylvanite [(Au, Ag)2Te4], montbrayite [(AuSb)zTe3], krennerite [(Au1-x, Ag,)Te2], petzite (Ag3AuTe2) and muthmannite (AuAgTe2) [2]. While several other phases exist they are much more complex (i .e. buckhornite), which dilutes and confuses the influence of each specific component. Studies of gold tellurides have predominantly focussed on calaverite as it is the simplest and most common phase, however petzite, commonly found in Australia and North America, is the focus of this investigation.Gold processing via cyanidation has been operated for more than a century and is a highly effective hydrometallurgical treatment of native gold deposits. However, some gold alloys such as tellurides have proven to be somewhat less responsive under the same conditions. Several groups have shown that gold/silver tellurides are amenable to cyanidation, but are significantly more refractory than native gold [3]. Pre-oxidation steps have been tested to remove constituents that would consume cyanide such as sulfides. Such species are also linked to the precipitation of oxidised telluriwn, forming a passive layer, further inhibiting gold recovery [2]. It is uncertain to the definite reasons underpinning the refractory nature of precious metal tellurides in conventional cyanidation."

Jan 1, 2012

By J. Sjöblom

New copper and nickel processes, flash converting and DON, direct high-grade nickel matte smelting, have been developed in order to replace the conventional and not so environmentally friendly PS-converting process. With a laboratory scale laminar-flow furnace the combustion reactions of sulfidic feed particles can be investigated under simulated flash smelting conditions. In the present study, finely ground and screened feed fractions of a copper matte and a nickel matte were flash oxidized in a laminar-flow furnace. The experiments were carried out using 20, 21 vol% and 75 vol% O2 in nitrogen, at temperatures 1100 and 1300 °C and reaction zone length of 7.5-16 cm. The samples were quenched in a water film after a specified reaction time. The matte particle reactions were stopped after short residence time intervals in order to obtain a better understanding of the reaction mechanisms. Chemical analysis was used to determine oxidation degree, and optical and scanning electron microscope combined with energy dispersive analysis was used for characterization of the reacted particles. On the basis of the experimental results the reactivity of the mattes is discussed and possible reaction and dust formation mechanisms are considered.

Jan 1, 1999

By P. A. Botha

The coal seams in the Waterberg basin occur in correlates of the Vryheid and Volksrust Formations as developed in the main Karoo basin. In the Vryheid Formation, five thick seams of predominantly dull coal are present, whereas a multitude of thin, lenticular seams (a few millimetres to 2 metres}, predominantly of bright coal, are developed in the overlying Grootegeluk Formation. During exploration, the coal seams were divided into 11 zones. Analytical data on float and middlings fractions (RD less than 1.40 and between 140 and 1.80, respectively} were used mainly for stratigraphic correlation of the zones in the Grootegeluk Formation. The affinities of the major and trace elements for different mineral phases and/or organic material are discussed on the basis of correlation matrices and vertical variation diagrams. Titanium and vanadium clearly show some degree of organic affinity. P 205' AI203 and alkaline-earth elements are also positively correlated by the presence of goyazite in the coal. This type of investigation gives an indication of the degree to which undesirable elements like P and S can be removed during coal beneficiation, of which coal zones are unsuitable for the production of metallurgical coal on account of a high content of these elements, and to what extent the blending of different coal zones is required to keep the concentration of these elements within acceptable limits.

Jan 1, 1991

By M. R. Dahm

The demand for low sulfur steel by steel manufacturers and their customers has been steadily increasing for 25 years. Historically sulfur has been controlled by various means and with various additives but lime-magnesium external desulfurization of hot metal has become established as the dominant method in North America today. Magnesium powder produced from primary magnesium ingot has been the major source or raw material. However, periodic increases in the price of this commodity have encouraged producers to look to secondary magnesium for an alternate source of magnesium. Secondary magnesium from post-consumer scrap can be cleaned, sized, and prepared to produce a high quality magnesium reagent for use in hot metal desulfurization at a lower cost than material processed from primary ingot.

Jan 1, 2000

By Yiming Rong, Gang Wang

"Water quenching is one of common heat treatment processes but with complex physical phenomenon, in which vaporizing, bubbling and convection are involved. The general simulation of liquid quenching processes is conducted by using temperature dependent value of heat transfer coefficient (HTC) obtained from experimental measurement under a strong assumption. A preliminary multiphase flow model developed by using Ansys-CFX for water quenching has been presented in this paper, which shows a distributed HTC with a time dependent feature. The conjugate heat transfer is used to describe thermal conduction in the simplified workpiece, and generation, growth and flow of bubbles are modeled by using Eulerian-Eulerian method for the gas-liquid multiphase flow. The simulation result shows the intense variation of heat exchange through the interface between workpiece and liquid, and the unsteady distribution around the solid surface.IntroductionQuenching is a rapid cooling process which makes the desired solid phase transformations happen for the certain material properties. For aluminum alloy, rapid quenching will prevent all phase transformation and generate a supersaturated single phase."

Jan 1, 2012

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from the University of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

By D. Maurice, W. D. Riley, J. A. Hawk

"The increased penetration of wrought aluminum into the automotive market is stimulating a need to separate wrought aluminum from cast aluminum because of: a) the additional value of scrap wrought alloys and b) the increase in the total amount of aluminum automotive scrap will outstrip the demands of secondary aluminum foundry industry. The availability of clean fractions of wrought and cast aluminum and incidentally, a clean cast magnesium fraction will allow increased recycling of aluminum used in the automotive industry.Hot crushing has been tested previously and proposed as a means to separate cast from wrought alunrinum product. The underlying concept is that when a mixture of cast and wrought aluminum is thermally processed and then subjected to crushing action, differences in toughness between wrought and cast aluminum alloys will become more pronounced. Hence, it should be possible for conditions can be established such that the cast material fragments, while the wrought material, having lost much less of its toughness, merely deforms. The two types of product could then be separated by simple sizing methods.In this paper we report on the testing of this concept. We were unable to replicate the results which originally demonstrated proof of concept. Possible reasons for this are discussed, as well as the possibility that the original results may not be as desirable as the current results for subsequent sorting."

Jan 1, 2000

By Claudia Gasparrini

Uranium occurs in a variety of minerals, the more common primary ones of which are uraninite-pitchblende, coffinite and a group known as the complex multiple oxides. Identification and description of the uranium-bearing and associated minerals in ore samples may give a preliminary indication of the potential economic importance of the deposit and may also suggest initial approaches to metal extraction. The present paper reviews the common uranium minerals, describes their manner of occurrence and compares the types of deposits with which they are associated. Methods and techniques for their identification are described and their leaching characteristics discussed.

Jan 1, 1981

By E. Allaine

Carbochlorination kinetics of pure MoO3, Nb2O5, Ta2O5 and V2O5, by Cl2+CO+N2 gas mixtures was investigated between 380 and 1000 °C. Standard free energy of carhochlorination reactions and phase stability diagrams of these refractory metal compounds were calculated. The influence of total gas flow rate, temperature, reactants partial pressures on the reactivity of these oxides were investigated. The apparent activation energies were found to be about 83, 75, 110 and 100 kJ/mole below 650°C for MoO3, Nb2O5, Ta2O5 and V2O5, respectively. Above this temperature, the Arrhenius plots exhibit a rate anomaly attributed to thermal decomposition of COCl2 and/or structural changes of these refractory metal oxides. The apparent reaction order of carbochlorination of these oxides with respect to Cl2+CO was determined. For these refractory metal oxides, the reaction rate was maximum for a Cl2/CO ratio of about 1 in the chlorinating gas mixture. Results of carbochlorination of these oxides are compared and discussed.

Jan 1, 1995

By S. A. Platias

Large amounts of dunile tailings can be recycled for olivine produdion from the existing beneficiation adivity of chromite ore in northern Greece. This olivine production aims at the preparation of a material suitable for the substitution of the environmental hazardous quartz sand in the foundries of Europe In smelting of chromite ore the losses that occur ore usually of the order of 6-8% Cr that report in the slag. Most of this is in the form of oxides that cannot be recovered, but usually 30-35% is in the form of FeCr alloy that can be recovered by gravity methods. About 90% of the produced slag is sold for road construdion after crushing to a desired grain size. Finally, recycling of chromites sludges from the ferrochrome produdion plant, through the preparation of pellets, improved the total chromite yield by 2%.

Jan 1, 1996

By T. H. Eyde

Several hundred natural zeolite deposits occur in Tertiary and Cretaceous age formations of the western United States. Most of the large deposits are altered vitroclastic tuffs. Many of these deposits consist of a matrix of a high purity zeolite mineral or minerals in which fragments of unaltered rock are imbedded. These deposits represent an extensive resource of zeolite minerals which can be beneficiated to a consistently uniform, high quality product. The beneficiated natural zeolite products will possess many advantages over the selectively mined, unbeneficiated natural products currently being produced. These advantages will include: uniform particle size, high purity, consistent quality, high brightness, low iron content, high attrition resistence, uniform cation exchange and adsorption capacities, and low price.

Jan 1, 1981

By Nico Steenekamp

At Lonrho Platinum in South Africa, ores from both the Merensky and UG2 reefs of the Bushveld Igneous complex are treated by flotation and smelting to produce a nickel-copper matte which serves as a collector for the platinum group metals (PGM' s). The nickel-copper matte was originally shipped to Norway for treatment and recovery of the contained base metals, with the return of the PGM rich concentrate to South Africa. The Lonrho Platinum Base Metal Refinery was commissioned in 1985. The original process employed a Shenitt Gordon design. The converter matte is treated in a refinery which utilises both atmospheric and pressure leaches for the dissolution of base metals to produce nickel sulphate crystals, copper cathode and a PGM concentrate. This paper refers to flowsheet and operating changes as well as improvements within the Base Metal Refinery.

Jan 1, 1999

By R. Dekkers

Non-metallic inclusions in liquid steel are mainly formed during killing. As far as these particles are not captured by the slag, they are found in the cast steel where they can deteriorate the mechanical properties. Inclusions may also disrupt the continuous casting process, affecting thus directly the quality of the steel and the production capacity. Steel pin samples from the Sidmar plant (Belgium) were taken in different steps of several ladle treatments and in the tundish. Also slab samples were studied. All samples concern the same type of low alloyed aluminium killed steel. The non-metallic inclusions were isolated from the steel matrix and investigated with scanning electron microscopy and energy dispersive spectrometry. The evolution of the non-metallic inclusions is described by their number, size, shape and elemental composition. The main non-metallic inclusions present are aluminium oxides and spinel type compounds.

Jan 1, 1999

By Milan Lj. Stamatovic

The hydrometallurgical recovery of zinc from recycled blast furnace dust from a steel plant (Smederevo Metallurgical Company, Yugoslavia) was investigated. The dust contained 22% Fe, 17% Zn and 0.2% Pb. X-Ray diffractometry showed that the main components were hematite and magnetite, in combination with zinc oxide. Individual particles were generally spherical and ranged in size from 10 to 150 microns; 63% were less than 33 microns in diameter. An effective hydrometallurgical approach proved to be by caustic leaching and electrowinning. Recovery of zinc in the form of zinc powder was over 90%; this material can be used for the cementation of impurities in the conventional hydrometallurgical process for zinc production.

Jan 1, 1994

By V. A. Bryukvin

It has been found that by superimposing symmetric alternating current over the process, the rate of nickel and cobalt leaching from metallized products with copper sulfate solutions increases by a factor of 1.5 to 2.0 and the apparent activation energy of the process investigated is reduced from 12 down to 6.6 kcal/mole. It appears especially attractive to use alternating current for anodic dissolution (oxidation) of metallic scrap of refractory metals and their alloys in ammonia electrolytes permits production of high-grade commercial products in the form of respective ammonium salts using a short and virtually reagent-free process flowsheet. Similar approaches can be applied also for electrochemical processing of nickel and copper scrap in sulfuric acid media with subsequent recovery of pure sulfate salts or electrolytic processing. Electrochemical technology for recycling of tungsten-cobalt (WC 15) and tungsten-rhenium (WR 20) alloys has been also investigated. In the former case, anodic oxidation of carbide alloy was carried out in nitric acid electrolyte with production of pure tungstic acid. The research conducted has indicated that the physicochemical effect of alternating current results in a lower activation energy of electrode reactions due to changes in the mechanisms of the electrode reactions themselves.

Jan 1, 2006