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By Chi Ru?an

Sollutions of ammonium chloride, nitrate and sulfate were studied in extraction of rare earths absorbed on a low-grade, kaolilnitic ore recently discovered in southern China. The results of percolation leaching tests and the recovery of the rare-earth values from these solutions are presented.

Jan 1, 1989

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Gi-Chun Han

This study focused on stabilization of heavy metals and removal of chlorine in MSWI bottom ash by artificial carbonation with washing. Artificial carbonation was carried out by applying CO2(g) injection in washing for fractions above and below 4mesh for reuse as construction materials like aggregate, As a result, carbonation with washing could satisfy Korean environmental regulation and remove chlorine in bottom ash more effectively by resolving residual friedel?s salt(3CaOAl2O3CaCl210H2O).

Jan 1, 2006

By J. Peter, S. E. James, J. L. Watson

A survey of operating zinc smelters and refineries throughout the world has been done in conjunction with the Lead-Zinc 2000 Symposium. This survey follows the examples set by the Japanese Mining Industry Association in 1985 and 1995. Questionnaires were sent to operating zinc plants that covered feed materials, process details, energy consumption and labor requirements. The voluntary responses to the survey were tabulated. Key operating parameters including feed grade, production capacity, quality of the intermediate products and quality of the final products have been compared for both hydrometallurgical and pyrometallurgical processes.

Jan 1, 2000

By M. L. Free

Electrowinning is directly impacted by many parameters that include electrolyte composition, voltage, current density, contact resistance, temperature, electrode spacing, and fluid flow as well as many other interrelated factors. The effects of these parameters are primarily related to thermodynamics, mass transport, and electrochemical kinetics. In this study thermodynamic, mass transport, and electrochemical kinetic equations are simultaneously solved to determine the effects of such parameters on electrowinning current efficiency, power consumption, electrodeposit morphology, and electrodeposit distribution. Modeling predictions will be compared with experimental results.

Jan 1, 2006

By Jong-Shin Chang

The Onsan smelter has tried to do various activities to decrease operation costs. With several expansion projects, the Onsan smelter has aimed at not only a quantitative growth but also qualitative growth through efforts improving operations equipment and processes. Activities to reduce operation costs have been one of those efforts. In particular, the energy cost of operation has been a main target for reduction. The activities to save energy have been carried out in two ways. One is to recover and utilize waste heat as much as possible and another is to replace existing equipment and processes with more energy-efficient ones. This paper reviews recent improvements and future plans for energy saving activities at the Onsan smelter.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By R. J. Wesely

Non-ferrous smelters traditionally have a hot gas handling system. In these systems, the dust is captured as a dry material which is often recycled to the process. Some smelters use wet gas cleaning methods with the recovery of the dust as a wet sludge. Although this sludge can be recycled to the process, in some cases it is preferable to dispose of the sludge. This paper will discuss the disposal methods available and specifically will deal with one type of sludge which has a high arsenic and high lead content. Problems with this sludge were investigated and methods were tested with the aim of stabilizing the sludge so that it passes the EPA TCLP test. Results of the laboratory tests are given.

Jan 1, 2000

By F. J. Tavera

The colloid flotation of lead carbonate precipitates in aqueous media is studied at a pH of 7. The flotation system consisted of five spargered flotation cells in a serial array. The flotation system was operated under controlled conditions of superficial air velocity, superficial liquid velocity, frother concentration, and collector concentration. The measured variables were gas hold-up, bubble size, superficial bubble surface flux, and lead recovery (reported to the concentrate). The experimental data show that it is possible to separate as much as 97% (w/w) lead from the aqueous media when the superficial gas velocity is 1 cm/s and the superficial liquid velocity is 0.19 cm/s.

Jan 1, 2006

By M. I. Kalashnikova

In hydrometallurgical technological flowsheets several methods of target components removal from solution are used. One of these methods is non-ferrous metals removal in the form of rich selective or collective concentrates. In the present work pyrometallugical mattes, thiosulphate containing solutions and pulps, iron powder with elemental sulphur and calcium sulphate were used as the precipitator. It was shown that depending on precipitator compound and process parameters non-ferrous metals precipitate from solution in the different forms with varying content of components including Ni3S2, NiS, Ni3S4, NiS2, (Ni,Co)S2, CuS; Cu1,765S; Cu1,97S.

Jan 1, 2006

By Iris Filzwieser

The secondary copper producer, Montanwerke Brixlegg AG (Austria), produces 73 000 tonnes of cathodic copper per year using ISA tankhouse technology. METTOP GmbH (Austria) evaluated the different anode qualities from the plant with relation to the current efficiency and specific energy consumption. Parameters including the chemical and physical anode quality, current and current density distribution at each cathode, voltage, and distance between each cathode and anode were examined. In addition, the temperature, chemical analysis, and conductivity of the electrolyte was determined for each investigated cell, as well as the anode weight, anode scrap, cathode sheet, and short circuits. Metallographic analysis was also performed on selected dendrites. The investigations resulted in specific improvements in the tankhouse process including the level of anode impurities, and future projects are planned for further tankhouse optimization.

Jan 1, 2006

By M. Olper, M. Maccagni, C. J. N. Buisman, C. E. Schultz

The key point of the CX-EWS process is the conversion of lead compounds, contained in the active mass of spent batteries, into lead sulphide. The obtained lead sulphide is leached with ferric fluoborate electrolyte to dissolve lead and oxidize the sulphur from sulphide to the elemental form. The lead-rich solution is fed into a diaphragm electrolytic cell depositing lead and regenerating ferric fluoborate. The introduction of sulphate reducing bacteria technology in the sulphidization step of the battery paste improves dramatically the economics of the CXEWS process, reducing the costs of chemicals, avoiding gypsum disposal and minimising the unit operations of the process. This paper describes in detail this technology change with reference to the economics of the process.

Jan 1, 2000

By Jesús L. Valenzuela

The solvent extraction for gold from alkaline cyanide solutions has been investigated using LIX 79 guanidine-based extractant. Different variables that could affect the extraction system were evaluated: equilibrium time, aqueous pH and extractant and modifier concentrations. The extraction isotherms of the aurocyanide complex with respect to other cyanoanions were compared and the following order of selectivity Au>Ag>Cu>Zn>>Fe was observed. From the pH isotherms it was found that aurocyanide can be extracted in alkaline media and a better separation with respect to other cyanoaniones was obtained in the range of 10.5 < pH < 11.2. Better selectivity was observed when using LIX 79 and tridecanol at 10% and 5% vol, respectively. Stripping gold from loaded organic was carried out at pH>12, using NaOH and NaCN solutions.

Jan 1, 2003

By J. Miernik, D. Krupka, B. Ochab

The electrolytic zinc plant, with a capacity 75,000 tonnes per year, is part of Zaklady Gorniczo-Hutnicze BOLESLAW. It is the biggest zinc producer in Poland. The electrolytic zinc plant started up in 1955 with a capacity 15,000 tonnes per year, and multiplied its production by 5 till nowadays. At the beginning, the plant processed only calcine from zinc oxides (60% Zn, 3-4% Pb, 0,03 % Cd) which were produced from Waeltz fumes by calcination in a rotary kiln. Participation of calcine from zinc sulfide concentrates in the feed grew during the BOLESLAW plant expansion. Currently, only roasted sulphide concentrates, calcine from fluid-bed roasters, is processed. This paper presents a general description of the ZGH BOLESLAW plant and discusses the processes of roasting, leaching, purification and electrolysis. Also shown are the chemical analyses of the various process materials.

Jan 1, 2000

By M. Dattilo

Research has been conducted over the past three years using the composite anodes versus the lead alloy anodes. The Merrlin composite anodes have shown the improved performance in copper electrowinning versus the lead-calcium-tin anodes. Using the composite anodes a 100-150 mV reduction in anode overpotential has been observed versus the lead alloy anodes in sulfuric acid electrolyte. The composite coating has excellent corrosion inhibiting properties, and reduces or eliminates the formation of manganese oxide scale. Laboratory evidences indicate that, the use of these composite anodes enhances the process of electrowinning by improving the lead alloy corrosion resistance, lowers the electrode potential, reduces the need for cobalt addition, eliminates the anode cleaning, and reduces the generation of acid mist. Field tests are underway.

Jan 1, 1999

By C. Camurri

Results from the Metallurgical Department of Universidad de Conception showed that fire-refined copper could be rolled without previous remelting for deoxidation. The goal of this work is to determine the rheology of fire-refined copper from tensile tests at different temperatures and strain rates, and Ford plane compression tests. All that in order to simulate and calculate rolling process variables. For rheology hardness coefficients, n variables between 0.28 at 600°C and 0.46 at ambient temperature are obtained. The sensibility coefficient for strain rate m varies between 0.056 at 600°C and 0.006 at ambient temperature. The activation energy for plastic flow Q in the considered temperature range is 1436 cal/mol.

Jan 1, 1999

By Linda C. White

The use of red mud, a waste product of the ?Bayer? process for bauxite refining, was investigated for its arsenic removal effectiveness from aqueous solutions under various conditions. Red mud efficiently removed As(III) between a pH range of 7.6 and 9; and As(V) in the pH range between 5.5 and 6. Pre-washing of the red mud with salt water considerably improved its arsenic adsorption capabilities. With appropriate red mud dosage, the residual arsenic in solution was decreased below the regulated acceptable arsenic limit (0.1 mg/L) from aqueous industrial wastes. The arsenic adsorption followed first-order rate kinetics and fitted the Langmuir isotherm model. Results suggest that red mud is potentially a useful adsorbent for removal of arsenic from contaminated water or industrial waste solutions.

Jan 1, 2003

By Doug Halbe

?Many are called, but few are chosen.? The biblical adage applies not only to life, but also to hydrometallurgical processes. There have been, in the past, many outstanding successes with new processes ? and also some dismal failures. What are the odds of success for a new process? When there have been problems, why? What can you do to make sure these problems don?t occur with your process? What effect will a slow startup have on project economics? How do financial institutions ? the people who loan your company money for the project ? feel about new processes and why? Is it possible to predict or estimate the time required to reach design parameters?and if so, how do you sell this estimate to management ? and financial institutions? Probably most important ? when do you start thinking about the answers to these questions?

Jan 1, 2003

By I. Van de Voorde

In this paper, results are presented concerning the search to implement Supported Liquid Membranes (SLM) Technology for the recovery of copper, nickel and zinc from electroplating and other effluents to prevent metal waste. A study of the influence of the individual parameters and of their combined effect on mass transfer in small-scale laboratory equipment has been performed, enabling to set forward the appropiate operating conditions for a pilot plant installation. The SLM pilot plant has been tested extensively, including short and long term runs, with real process solutions. It was demonstrated that the SLM technolgy is applicable for solutions containing 800 mg/L of metal ions, but also to the treatment of solutions with low metal content of origin other than plating shops. It was demonstrated by system analysis that the recycled salts are usable to produce metal electrolytes (for example Watt&apos;s nickel bath).

Jan 1, 2003

By Edgar Blanco

A thermodynamic and experimental investigation to develop a new process for converting molybdenite concentrate to molybdenum dioxide by a water-vapor oxidation process was carried out. In addition, the behavior of rhenium and selenium in molybdenum concentrate during the process was investigated. The kinetics of the reaction were determined by measuring the weight change of a sample with time in water vapor at temperatures between 700-1000°C. The results were analyzed by a Shrinking Unreacted Core model under chemical reaction control, which showed an activation energy value of 102 kJ/mol. To determine the behavior of rhenium and selenium, their concentrations in the molybdenum sulfide and the product molybdenum dioxide were measured by the use of ICP. While most rhenium remained with the molybdenum dioxide after the water vapor oxidation, almost all selenium volatilized. These results agree with thermodynamic analysis.

Jan 1, 2006