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Session Chairperson: A. Kasaaian, Elkem Metals Co., P.O. Box 299, Marietta, OH 45750
RECOVERY OF BISMUTH AND ANTIMONY FROM THE ELECTROLYTE IN COPPER ELECTROREFINING TANKHOUSE: Kouji Ando, Naoyuki Tsuchida, Sumitomo Metal Mining Co., Ltd., Niihama Research Laboratories, Hydrometallurgical Research Center, 3-5-3, Nishibara, Niihama, Ehime 792, Japan
An ion-exchange process for recovery of antimony and bismuth from the copper electrorefining process has been studied on both a bench scale test and a pilot test. Recently, the ion exchange technique for the removal of antimony and bismuth from the electrolyte has been in a practice. In the existing technology, the metals recovered are required to process further. The separation of antimony and bismuth is sometime difficult and costly. Sumitomo Metal Mining has developed a noble process to recover antimony and bismuth metals directly from the eluent by an electrowinning. Furthermore, antimony and bismuth were successfully separated. The content of bismuth in antimony metal was less than 0.2%, while the content of antimony in bismuth metal was less than 0.4%.
THE USE OF POLYMER CONCRETE IN ACID CONTAINMENT EQUIPMENT FOR ELECTROMETALLURGICAL PLANT PRACTICE: G.J. Karcas, Corrosion Technology International, Gent, Belgium
Various non-ferrous Metals such as Copper, Nickel, Lead, Zinc and Precious Metals are produced via electrorefining and electrowinning processes. Apart from controlling electro-chemical conditions for the production of these metals, there has always existed the challenge of controlling the severely deleterious effect of the aqueous environment which serves as the medium for the production of these metals. The practice of acid containment in electrometallurgical operations has entered the world of high technology with the advent of advanced acid resistant materials such as Vinyl Ester Resin which is either combined with concrete to form Polymer Concrete or used to coat or line various acid containing vessels and surfaces. The North and South American copper industry has indulged quite heavily in the use of polymer concrete cells, electrolyte storage tanks, and the use of Vinyl Ester Resin for corrosion protective systems. Electrolytic cell and electrolyte storage tank construction has undergone a transformation from a multiple part configuration to a single piece unit. The combination of a wood, steel, or concrete frame with a lining made of lead, asphalt, rubber or plastic has been historically successful in providing protection from chemical and mechanical attack in electrolytic cells and electrolyte storage tanks all over the world. These combinations have now entered the world of obsolescence as materials such as polymer concrete have proven to provide exceptional corrosion and mechanical protection with greatly reduced maintenance requirements. Polymer concrete cells and electrolyte storage tanks fall into the category of modern tankhouse equipment which includes anode preparation machines and stainless steel cathodes, all of which play a vital role in improving quality and productivity while lowering operating costs. Polymer Concrete Cells, and other modern equipment, are succeeding in the difficult, yet important, task of driving electrometallurgical plants into the next millennium.
POSSIBILITIES TO LOWER ENERGY USE IN ELECTROWINNING BY MODIFICATIONS OF LEAD ANODES: O. Forsén , J. Aromaa, Helsinki University of Technology, Laboratory of Corrosion and Material Chemistry, Vuorimiehentie 2, FIN-02150, Espoo, Finland
Lead alloys are most common anodes in metal electrowinning processes from acid solutions, even though their oxygen overpotential is very high. New inventions like mixed metal oxide anodes are not widely used, the main reasons being possibly doubts on the anode operation and large capital investments on the existing lead anodes. The main reaction on lead anodes in sulphate solutions is oxygen evolution, and on the lead dioxide film it has a high overpotential. In this paper we have studied possibilities to decrease the energy consumption in metal electrowinning by lowering the anode overpotential. Samples from currently used anode material were coated with different lead alloys using plasma spraying and detonation coating. Also modifications on the anode microstructure by melting and controlled cooling and additions of certain ions to the electrolyte were studied. Most of the studied procedures were able to lower the anode potential about 100 - 150 mV at the operating current density of 500 A/m2. Rapid cooling during the anode casting was found to be the simplest and thus also the least expensive way to lower the anode potential.
STUDIES RELATING TO THE DEVELOPMENT OF AN ANODE FOR LEAD ELECTROWINNING: D.J. Robinson, Dremco Inc., Point Roberts, WA; T.J. O'Keefe, University of Missouri, Rolla, MO
The pyrometallurgical method of recycling car batteries suffers from a potential for air pollution violations, which prompts the desire for a viable hydrometallurgical alternative. Several Processes have been proposed, including leach-electrowinning routes using HBF4 and/or H2SiF6 based electrolytes, along with anodes of PbO2 on inert substrates. A study has been carried out to evaluate the proposed systems, with the intention of demonstrating a six month life of an electrolyte-anode combination. The work, which focused on the use of H2SiF6, has indicated that there was no acceptable anode, and has lead to the development of a technique to produce smooth, glassy, adherent coatings on graphite, and to the development of an anode composed of a series of copper cored graphite rods. The paper will present results on leaching and electrowinning experiments, as well as the description of a flowsheet for a pilot plant that will be used to produce one tone per day of refined lead from spent battery paste.
APPLICATION OF ELECTROCHEMICAL MEMBRANE METHODS IN HYDROMETALLURGY OF COPPER: A.S. Mustafinova, A.A. Zharmenov, Chemical-Metallurgical Institute, Karaganda, Republic of Kazakstan
Production of electrolytic copper is characterized by large volumes of acidic spent solutions the utilization of which requires considerable expenditures of neutralizing agents. At present, an economically substantiated technology does not exist for treatment of sulfuric acid rinse solutions and spent copper electrolyte which will allow for repeated use of the acid and the metal salts. Therefore, for this aim the most advantageous is the use of electromembrane methods. In the paper there is stated the essence of developed technologies which are distinguished by low waste and provide the extraction from the solutions of metallic copper, nickel and sulphuric acid. There are also considered methods of copper electrolyte processing allowing to regulate its composition by that or another component (H2SO4, Cu, Ni, As). On the base of the detailed study of the behaviour of various types of ion- exchanger membranes in copper-, nickel-, zinc-, arsenic- bearing sulphate solutions there is realized the selection of the most suitable membranes (MK-401, MA-411, MB-2 and MKL-1/MAL-2). Some variants of electromembrane processing of spent solutions of the hydrometallurgy process have passed productions tests on a number of copper-electrolyte enterprises of the countries of CIS (cooperation of Independent States). These tests showed high efficiency of developed methods.
ELECTROMETALLURGY, PAST, PRESENT, AND FUTURE: F. Habashi, Laval University, Department of Mining and Metallurgy, Quebec City, Quebec, G1K 7P4, Canada
While pyrometallurgy is an ancient art and hydrometallurgy can be traced to the Middle Ages, electrometallurgy is the most recent technology since it started only after the discovery of electric current in the ninteenth century. Davy, Faraday, and Bunsen laid the foundation of this technology which had a great impact on other areas of metallurgy, e.g., the liberation of aluminum for the first time from its salts. Once aluminum was available, it was used to liberate other metals from their oxides. Electrometallurgical processes, however, are capital intensive. Improvement of the present technology should be intensely investigated.
FACTORS AFFECTING CO-DEPOSITION OF COBALT AND NICKEL: R. Luo, R.V. Kumar, Department of Mining and Mineral Engineering, University of Leeds, Leeds, LS2 9JT, UK; D.J. Fray, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, UK
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