PRODUCTION OF CATHODE COPPER FROM LEACH LIQUOUR BY SELECTIVE ELECTROWINNING PROCESS
Abstract
This work is aimed to have a direct Cu extraction from leach solution of chalcopyrite concentrate as an alternative to conventional smelting, refining and electrorefining methods. First of all, main aspects of kinetics of chalcopyrite leaching in sulphuric acid solution and transformation reactions of chalcopyrite at high temperatures were reviewed in detail, as well as processing and beneficiation of sulphide (chalcopyrite) copper ores. Consequently, the classic atmospheric acid leaching experiments was applied to oxidative roasted concentrate with a copper grade 21.1 under agitation by stirring. Therefore, the formation of a passive layer of sulphur on the chalcopyrite surface was concluded to be the main reason of the blocked reactions in the leach solution. The supply of elemental sulphur, sulphides in the solution should be removed in order to increase the dissolution rate. Therefore, the sulphides in the chalcopyrite were transformed into sulphates and oxides by heat treatment at 500 °C prior to leaching process. Furthermore, Cu extraction was resulted in very high yields of 99.82%. At the end of the leaching, the electrowinning experiments were carried out for 10 hours at 2.5 V to leach liquor with a high Cu and low Fe content and a 99.999% purity cathode copper (A Grade) was obtained and all iron ions remained in the solution.
Keywords
Cathode copper, atmospheric acid leaching, selective electrowinning.
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