STUDIES ON INITIAL DISSOLUTION KINETICS FROM POLARIZATION DATA .4. CHALCOPYRITE IN FERRIC-CHLORIDE

Abstract

Electrochemical aspects of chalcopyrite dissolution in acidic ferric chloride have been investigated through concurrent polarization studies of individual half cell reactions. Mixed potential, E(m), and mixed current, i(m), obtained from intersections of such curves at different solution conditions have been analyzed to interprete the initial dissolution kinetics. Similar to pyrite, chalcopyrite oxidation also shows a passivating region and E(m) invariably lies in this region, However, the overall process is controlled by the cathodic process at lower ferric ion concentrations up to 0.04 M, where the cathodic process is under activation control. At higher ferric ion concentrations, the overall process control shifts gradually to mixed control and then anodic control. These results are explained by the electrochemical model.