Extraction of copper from copper and cadmium residues of zinc hydrometallurgy by oxidation acid leaching and cyclone electrowinning

Copper and cadmium residue (CCR) is a hazardous solid waste generated in the process of zinc hydrometallurgy, and contains large amounts of Cu, Zn, Cd and Pb. Recovery of Cu from this material was investigated in the present study. CCR containing 30-40 wt.% Cu was leached in an oxidizing atmosphere with H2SO4 and the optimum leaching conditions were determined as follows: H2SO4 concentration of 180 g/L, L:S ratio of 3:1 (mL/g), H2O2 excess coefficient of 7.0, leaching temperature of 80 degrees C, and leaching time of 3 h. The leach solution was then subjected to cyclone electrowinning without purification or concentration, for recovery of Cu. The leaching step showed over 95% extraction of Cu under the optimized conditions. The cyclone electrowinning yielded Cu of > 99.5% purity with current efficiencies exceeding 97%.