An electrochemical study of the effect of chloride ions on the dissolutionof chalcopyrite in acidic solutions

The electrochemical oxidation of a CuFeS2 (chalcopyrite) concentrate in a m ixed chloride-sulfate electrolyte was studied using carbon paste electrodes . This technique was found to give very reproducible results, and has the a dvantage that actual concentrate particles can be used in place of large cr ystalline mineral samples. It will be demonstrated that during the initial stages of leaching, the oxidation of chalcopyrite at low overpotentials is hindered by the formation of a metal-deficient sulfide surface. When chlori de ions are present, it will be shown by both transient- and steady-state t echniques that the oxidation of the mineral is significantly enhanced. Thes e results have also been found to be in very good agreement with those obta ined by direct leaching of the same concentrate. (C) 2000 Elsevier Science B.V. All rights reserved.