Single cell extraction of zinc and manganese dioxide from zinc sulphide concentrate and manganese ores

Abstract

The hydrometallurgical processing of zinc sulphide concentrates with sulphuric acid in the presence of manganese dioxide (manganese ore has been employed) and subsequent electrolytic co-deposition of cathodic zinc metal and anodic manganese dioxide is described. The influence of various parameters on the reaction ZnS + MnO2 + 2H2SO4 = ZnSO4 + MnSO4 + S0 + 2H2O has been studied. Optimum conditions for rapid and efficient reaction have been determined. The simultaneous electrowinning of zinc at the cathode and γ-MnO2 at the anode from the leach liquor was studied. The effects of variation of current density, temperature, electrolyte composition etc. have been described in detail. During leaching 99% extraction of zinc, 98% of manganese, and 96% liberation of elemental sulphur was achieved. 80–90% anodic and cathodic current efficiencies can be obtained under optimum conditions with impurity levels of only a trace of manganese in the zinc deposit and vice-versa. The anodically deposited manganese dioxide was the γ-battery active variety and was found to be satisfactory. The results indicate the potential for the development of a technique for zinc and manganese dioxide production in a single cell.