Mechanism of cobalt removal from zinc sulfate solutions in the presence of cadmium

The effect of cadmium and copper, temperature and reaction time on the removal of cobalt from zinc sulfate solutions using zinc dust was experimentally studied. The results show that the rate and extent of cobalt removal are enhanced when cementation takes place in the presence of less than 400 mg/L of cadmium. Cementation residues were analyzed using electron probe micro-analysis (EPMA) to investigate the distribution of phases in the cementation products and the mechanism of cobalt removal. It was found that formation of Zn–Co and Zn–Cd alloys on the zinc dust particles can enhance cobalt removal whereas the presence of Zn–Cu and Cu–Cd alloys can inhibit cobalt removal.