A novel functional lead-based anode for efficient lead dissolution inhibition and slime generation reduction in zinc electrowinning

Lead-based alloy is the most widely used anode material in zinc electrowinning and other metallurgical processes. Lead dissolution during electrowinning not only results in resource loss and pollution generation, but also leads to deteriorations in product quality and adversely effects economic benefits. In this study, we propose a new functional anode preparation process that was precisely and completely fabricated by rapid electrodeposition of an active gamma-MnO2 layer on bare lead-based anode. The prepared anode (MnO2 pre-coated anode [WA]) exhibited an excellent performance in terms of both pollutant reduction and product promotion as compared with the typical bare Pb-1%Ag anode (TPA). Property characterizations and electrochemical analysis indicated that the active gamma-MnO2 layer showed complete and uniform coverage on the lead-based anode, which effectively blocked the contact and reaction of lead with electrolytes. This was beneficial for reducing the amounts of dissolved lead and significantly promoting the purity of zinc. Besides, the needle-like structure and positive electro-catalytical effects of gamma-MnO2 on the oxygen evolution reaction (OER) lowered the anode overpotential, reversely inhibited the Mn2+ oxidation reaction, and reduced 94% of anode slime formation and 94% of lead migration. The MnO2 pre-coating process shows bright prospects for industrial applications in zinc electrowinning and other hydrometallurgy processes. (C) 2020 Elsevier Ltd. All rights reserved.