Study of the Dissolution of Chalcopyrite in Sulfuric Acid Solutions Containing Alcohols and Organic Acids

Abstract

Chalcopyrite dissolution under environmental conditions has been one of the major challenges facing researchers. The current processes for obtaining copper have pollution issues, which will severely limit their application as environmental controls become stricter. Faced with this problem, a number of eco-friendlier methods, such as GALVANOX and HydroCopper (Outokumpu), have been proposed, although they have not been industrialized, mainly due to their high operating costs. The authors previously proposed an alternative system to leach chalcopyrite, which is based on the use of aqueous polar organic solutions. In the process, copper extraction increases in mixtures of acetone or ethylene glycol with aqueous sulfuric acid solutions. The drawback is the large concentration of oxidizing agents needed to obtain high percentages of chalcopyrite dissolution, which can make the process lose viability. In this investigation, the effect of acetic acid, formic acid, methanol and ethanol, whose chemical characteristics are similar to those previously proposed, were evaluated by cyclic voltammetry. It was found that, in the presence of these organic solvents, higher electrochemical responses were obtained compared with those found with sulfuric acid alone, a similar behavior to that obtained with acetone. Leaching experiments results coincided with the corresponding findings of the electrochemical study and X-ray diffraction results provided evidence to support the proposed reactions.