Simultaneous extraction of manganese from low grade manganese dioxide ore and beneficiation of sulphur slag

Abstract

Abstract Pure manganese dioxide was successfully produced from low grade pyrolusite ore (β-MnO 2 ) and sulphur slag. First, the reduction of β-MnO 2 , introduced as pure pyrolusite was studied using different ratios of elemental sulphur at different temperature (300–400 °C), in air or in closed stainless tube. The reduction process was followed by leaching of Mn with H 2 O, 0.1, 0.5 or 1 M H 2 SO 4 . β-MnO 2 was found to undergo a reduction process at obviously low temperature giving Mn 3 O 4 , MnS and MnSO 4 depending on the applied conditions. The efficiency of Mn leaching ranged from 40 to 99%. The optimum conditions of reduction and leaching were applied to low grade pyrolusite from Um Bogma, Sinai and sulphur slag remained from the sulphuric acid industry. MnSO 4 was prepared by concentrating the liquor extract. γ-MnO 2 was produced either by precipitation from the liquor extract using ammonium peroxodisulphate or by electrodeposition on platinum anode. The products were characterised by X-ray diffraction, thermal and chemical analysis.