Solvent extraction of copper from chloride solution II: Cuprous oxidation by oxygen coupled with simultaneous cupric solvent extraction

Abstract

This study was conducted as part of the development of a novel process for copper recovery from copper sulfide concentrates by chloride leaching, simultaneous cuprous oxidation and cupric solvent extraction to transfer copper to a conventional sulfate electrowinning circuit, and hematite precipitation to reject iron. The kinetics of cuprous and ferrous oxidation by oxygen and cupric solvent extraction were studied as a function of reaction time, stirring rate, oxygen pressure and extractants. The concentration of Cu(I)+Fe(II) decreased linearly with reaction time while the copper extraction increased with reaction time. The rate of cuprous and ferrous oxidation increased with increasing stirring rate and it was proportional to the partial pressure of oxygen. The cuprous and ferrous oxidation by oxygen was enhanced with the addition of organic solution. During the simultaneous cuprous oxidation and cupric solvent extraction, the aqueous solution pH first decreased sharply with time, then remained constant and finally increased, which was determined by the generation of H+ ions (cupric and ferric solvent extraction) and consumption of H+ ions (cuprous and ferrous oxidation by oxygen). The iron extraction increased as the oxidation reaction generated more ferric ions and raised the pH to a higher value. Simultaneous cuprous oxidation and cupric solvent extraction is feasible to transfer copper to the conventional sulfate electrowinning circuit from a chloride leaching system. The optimum copper solvent extraction conditions in chloride solution were proposed.