A lead-acid battery analogue to in situ anode degradation in copper electrometallurgy

Abstract

When the applied current is interrupted in a copper electrowinning plant, lead anodes tend to corrode once the plant is back in operation. This work aims to show, both from theoretical considerations and experimental evidence, that this phenomenon may arise From the spontaneous coupling of the oxidation of metallic lead to lead (II) sulfate with the reduction of lead (IV) dioxide to lead (II) sulfate on the unenergized anodes. The process is similar to the one that takes place in an idle lead-acid battery. It is shown that, in the above conditions, the protective oxide layer on the anode takes between 5 and IO min to dissolve. Estimates are given for the rate of lead (IV) dioxide dissolution and lead sulfate Formation and conclusions are drawn for plant practice. (C) 1998 Elsevier Science Ltd. All rights reserved.