The New Lead-based Anodes In Zinc Electrowinning Study

Pb-Ag alloys have been widely used as anodes in the process of zincelectrowinning. Although the anodes can meet requirements of the process, theoverpotential of oxygen evolution on the surface of anodes is quite high, and theexhausting of precious metal is too high. In search of a better anode, a large numberof studies have been carried out. However, researchers have not found a suitablealternative to Pb-Ag alloys now. On this problem, the author improve theelectrochemical properties of lead anodes by a kind of simple and effective method-surface treatment; and obtained two kinds of new type anodes-Pb/MnO₂ andPb/β-PbO₂/MnO₂. The results of electrochemical examination on the new typeanodes showed that : the oxygen evolution overpotential of the anodes- Pb/MnO₂ andPb/β -PbO₂/MnO₂ are lower than the oxygen evolution overpotential of Pb-Ag alloys,and the value of η is less than 650mV at industry current densities. At the same time,the lifetime of the new type anodes is more than one year under the condition of lowsilver content in lead. It is attributed to the protective action of MnO₂ on the surfaceof anodes.