Ferric ion and pyrite effect on the oxidation-reduction reaction of chalcopyrite surface using electrochemical techniques and thermodynamic calculations

Acidic dissolution of chalcopyrite in the presence of ferric ion is a scientific challenge that is the subject of research by many researchers. The role of pyrite has also been studied as catalyst and enhancer of chalcopyrite leaching. Previous studies have shown the chalcopyrite electrochemical leaching in the presence of oxidants, and oxidation-reduction reactions depend on reaction environmental conditions. In this paper, in addition to electrochemical techniques (cyclic voltammetry and chronoamprometry), mathematical calculations and thermodynamic equations have been used to investigate the effect of ferric ion and pyrite on oxidation-reduction reactions of chalcopyrite. First, the oxidation-reduction reactions of chalcopyrite surface by cyclic voltammetry in acidic medium and then the effect of ferric ion addition on these reactions have been investigated. Then effect of pyrite presence along with the ferric ion (pyrite / ferric ion) is studied by the above method. The results of cyclic voltammetry method showed that ferric ion and pyrite increased the anodic and cathodic peak intensities and had a positive effect on chalcopyrite surface reactions. Also results of chronoamprometry and thermodynamic studies showed increase of free energy of chalcopyrite oxidation reaction in the presence of pyrite which was -22.45 kJ/mol.