Potentiodynamic and electronmicroscopy investigations of lead-cobalt alloy coated lead composite anodes for zinc electrowinning

AbstractBy means of potentiodynamic investigations, the mechanism of the anodic processes taking place on the surface of lead–cobalt alloy coated lead plate composite anodes during zinc electrowinning from model sulphate electrolytes have been established. The influence of the pretreatment of the lead substrate and of the organic additives in the electrolyte for deposition of lead–cobalt coatings on this process has been studied. On the basis of the cyclic voltammograms obtained, information about the corrosion rate of the composite anodes in the lead dioxide region has been deduced. Scanning electron microscopy (SEM) observations showed a nucleation and growth of 'ear-like' structures on the lead–cobalt composite coatings. The presence of such structures provides a larger surface area and leads to depolarisation of the oxygen evolution reaction respectively.