Evaluation of manganese dioxide deposition on lead-based electrowinning anodes
By Mohammadi, Maysam; Alfantazi, Akram
Published in Hydrometallurgy
2016
Abstract
Abstract In this study, the initial stages of the MnO2 electrodeposition on different lead-based electrowinning anodes (Pb-MnO2 and PbAg) in sulfuric acid electrolyte solutions were investigated. The MnO2 deposition and its preliminary effects on the oxidation of the anodes were studied using electrochemical techniques including potentiostatic polarization and linear potential sweep voltammetry. The potentiostatic polarizations were accompanied by chemical analysis of the electrolyte to investigate the manganese oxidation rates on the anodes. Scanning electron microscopy (SEM) was employed to characterize the deposited MnO2 layers. The presence of MnO2 particles on the Pb-MnO2 composite anode contributed to the deposition of a very uniform, dense, and stable MnO2 layer. The effects of the MnO2 composite particles in the composite anode on the current distribution, Mn3 + disproportionation rate and Mn2+ oxidation rate, were proposed as the possible causes of the observed properties of the MnO2 layer on this anode. The MnO2 layer on the Pb-MnO2 anode grew quickly during the initial stages. This layer became smoother over the course of polarization. Although the oxidation of the anodes was hindered by the deposited MnO2 layer, this effect was more significant on the composite anode than the conventional PbAg anode. This was attributed to different properties of the MnO2 layers deposited on these anodes.