COPPER EXTRACTION BY ELECTROLEACHING OF METALLIC SULPHIDES FLOTATION CONCENTRATES

Copper occurs in the crust of the earth, predominantly, as sulphides. Among the copper sulphide minerals, the chalcopyrite is the most abundant and the most refractory to the conventional oxidative processes. This work aims at developing an electrolytic process for treating a copper sulphides flotation concentrate, more precisely chalcopyrite (CuFeS2) and bornite (Cu5FeS4) in the percentages of 70 and 30%, respectively. The electro-leaching tests of the flotation concentrate were accomplished in a suitable reaction system, where the sulphides particles were suspended by magnetic stirring and the current supplied by a power Source MCE 8257 0 -18 V / 0 -20 A. The pH of the reaction system was monitored every 30 minutes and controlled by adding concentrate hydrochloric acid, and so was the redox potential. The success of the electro-leaching of sulphide concentrates depends, to some extent, on the effective generation of hypochlorite ions and hypo-chlorous acid, due to the electrochemical chlorine evolution and hydroxyl ions in the surface of the polarized electrodes. Through the electro-leaching tests nearly the total dissolution of sulphides could be observed and the recovery of copper was approximately 83%. It was, also, evident, considering the activation energy values for chalcopyrite dissolution, the major component in the concentrate under study, which was around 30 kJ/mol, that the dissolution process of that m.