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 2 M H2SO4 indicate that approximately 450 mV 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 370-420 mV 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.