An investigation of the electrowinning of copper with dimensionally stable titanium anodes and conventional lead alloy anodes

摘要

The traditional anodes of choice in the electrowinning industry have been lead basedudanodes. However, these anodes display high energy consumption and low corrosionudresistance during operation. These problems led to the investigation of other anodeudmaterials such as dimensionally stable anodes (DSAs), consisting of mixed metal oxideudcoatings on titanium or nickel substrates. In this study, electrochemical tests, physicaludcharacterisation techniques and electrowinning of copper from synthetic and industrialudelectrolytes were carried out on DSAs and lead anodes. These tests focused on stability,udenergy consumption and copper deposit quality. Potentiodynamic polarisation showedudthat the DSA plate anode exhibited the highest corrosion resistance while, lead and DSAudmesh anodes showed spontaneous passivation in a synthetic solution. These anodes areudtherefore likely to succumb to failure earlier than the DSA plate anode. Lead anodeuddissolution was observed in galvanostatic chronopotentiometry tests. It was also observedudthat the failure mechanism of DSA anodes involves coating loss.udIn electrowinning tests, copper deposits from the lead anode cell showed the presence ofudlead oxide. Furthermore, it was observed that, despite both mesh anodes (DSA 1 andudDSA 2) exhibiting the lowest total energy consumption, they had the highest energyudconsumption per kilogramme of copper produced. The DSA 1 plate anode had theudgreatest current efficiency and therefore had the least energy consumption perudkilogramme of copper. It was also noted that DSA anodes of the same composition mayudexhibit different behaviours as this depends on the method of preparation of the anodeuditself. The presence of iron or manganese in the electrolyte affected cathode quality,udcurrent efficiency, led to voltage fluctuations and an increase in anode potentials.