Abstract
Metal oxide matrix composite anode containing a coating of lead and cobalt was produced and tested to develop an improved yet low-cost alternative anode for base metal electrowinning. The novel anode consists of a top coating of PbO2-Co3O4 electrodeposited onto Ti substrate with a protective interlayer of SnO2-Sb2O3. The anode was tested under typical copper electrowinning conditions. The results showed that the novel anode possesses considerable advantages compared to the conventional PbCaSn type anodes, including catalytic activity for oxygen evolution, reflected in up to 300 mV lower anode potential resulting in corresponding energy savings, and significantly lower corrosion rates resulting in lower operating costs and higher quality cathode. Continuous anodisation over a one week period showed a corrosion rate of approximately 0.1 g m-2 h -1. Cross section studies showed that the top coating of PbO2-Co3O4 and interlayer of SnO2-Sb2O3 effectively stopped the penetration of acid to the surface of the Ti substrate during anodisation, preventing passivation. Moreover, the lower corrosion rate enabled the production of virtually lead-free cathodes.