Copper chloride leaching from chalcopyrite and bornite concentrates containing high levels of impurities and minor elements

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. Copper chloride leaching from chalcopyrite and bornite concentrates containing high levels of impurities and minor elements has been studied using a two-stage countercurrent leach circuit at 95 °C to maintain a high copper extraction and a low cupric concentration in the pregnant leach solution for subsequent copper solvent extraction. A high calcium chloride concentration (165 g/L or higher) was used to maintain a high cuprous solubility and enhance copper leaching. With 3 h of leaching time for each stage, at a particle size of P80 of 14 μm, the copper extractions were 99.1 and 98.5 % for chalcopyrite and bornite concentrates respectively while the iron extractions were 73.3 and 99% respectively. The extractions of copper and iron from chalcopyrite concentrate decreased very slightly with increasing particle size to P80 of 30 μm while the extractions of copper and iron from bornite concentrate decreased by ~ 3.6% with increasing particle size to P80 of 40 μm. The concentration of Cu(II) + Fe(III) in the pregnant leach solution was 0.1 to 0.2 M, indicating the pregnant leach solution was suitable for subsequent copper solvent extraction. Sulfur oxidation to sulfate was 1.2–1.7% for chalcopyrite concentrate, and 2.1% for bornite concentrate. The extractions of Bi, Cr, Pb, Ag and Zn were very high. The extractions of Sb, As and Ni were high for chalcopyrite concentrate while they were low for bornite concentrate.