Performance of catalytically activated anodes in the electrowinning of metals

The performance of titanium anodes coated with oxides of Ir–Co or Ir–Ta has been compared using long term polarization techniques under simulated electrowinning conditions. Possible reasons for anode failure are explained from SEM and XRD. Potentiodynamic studies in 2m H2SO4 indicate that approximately 450mV reduction in anode potential can be achieved with Ti/(Ir–Co) as against lead. This anode is also suitable in chloride contaminated sulfate electrolyte. The anode potential measurements in different electrowinning electrolytes indicate that a potential saving up to 370– 420mV can be achieved. It is interesting to note that mixed electrolyte containing sulfate and chloride behaves similarly to pure chloride electrolyte with respect to anode potential.