The use of carbon paste electrodes with non-conducting binder for the study of minerals: Chalcopyrite

A pulverized chalcopyrite mixture with graphite and silicon was subjected to electrochemical studies and found to have similar behaviour to that of chalcopyrite massive electrodes, with the advantage of excellent reproducibility, since the problems of polishing deficiency, fracture and lack of homogeneity that solid electrodes present, are avoided. From voltammetric studies of these carbon paste-chalcopyrite electrodes in H₂SO₄, HNO₃ and HCl media, it has been established that the reduction process is limited by the diffusion of protons to the interface. This study also shows that the increase of chloride ion concentration energetically favours the chalcopyrite reduction process, allowing for the separation of the processes of formation of chalcocite and bornite. On the other hand, this study also shows a reversible oxidation of the bornite and chalcocite obtained in the previous chalcopyrite reduction.