New Insights into the Oxidation Mechanism of Pyrite in Copper-Containing Sulfuric Acid: An Electrochemical, AFM, Raman Spectroscopy and XPS Investigation

Abstract

The oxidation of pyrite in copper-containing sulfuric acid has been the subject of intense research yet has no comprehensive research on electrochemistry and surface species. In this study, pyrite’s electrochemical oxidation mechanism was systematically elucidated in copper-containing sulfuric acid by using electrochemical techniques. Anodic processes occurring in active, passive, and transpassive dissolution regions were studied by linear sweep voltammetry. The corresponding equivalent electrochemical circuits were fitted for these three regions with the potential of ranging from 0.40 V to 0.80 V vs SCE, and the results of fittings were used to clarify the characteristics of electrodes and electrochemical reactions in copper-containing sulfuric acid. With increasing potential, the reactions on the pyrite surface accelerated, and its roughness significantly increased. In addition, the interfacial transfer of electrons is dominated by surface charge transfer. The products of pyrite surface oxidation were identified by Raman spectroscopy and X-ray photoelectron spectroscopy. Based on the results of the electrochemical methods and surface analysis techniques, the mechanism of pyrite oxidation can be clarified and the specific course of the reaction can be described in detail. These results provided further insight into a better understanding of the pyrite oxidation mechanism in the presence of copper ions.