Investigation of Cu–S intermediate species during electrochemical dissolution and bioleaching of chalcopyrite concentrate

The electrochemistry behaviour of chalcopyrite electrodes was investigated by cyclic voltammetry. The results showed that the Cu–S intermediate species during electrochemical dissolution of chalcopyrite was mainly as Cu2S, CuxS (1 < x < 2) and CuS. The formation process of these species was analysed. It was shown that the oxidation of chalcopyrite can only produce CuS, but CuxS and Cu2S were mainly formed due to the reduction reaction of copper ion and sulphur. Furthermore, it was found that the addition of copper ion could greatly affect the formation of Cu–S intermediate species. Therefore, during bioleaching of chalcopyrite, the effect of different concentrations of copper ion on the bioleaching process was investigated. The results revealed that when the copper concentration was low, it was hard to form Cu–S species in the ore residue. However, as copper concentration increased, the formation of Cu–S intermediate species also increased and could be detected by X-ray diffraction.