Novel reduction roasting and leaching method for manganese dioxide ore using Fe[sbnd]P slag as the reductant

Abstract

Manganese dioxide (MnO2) ore is the principal resource used in the manganese (Mn) metallurgy industry. However, the traditional Mn metallurgy industry consumes a large amount of coal, which contributes to environmental pollution and has a large carbon footprint. In recent years, efforts have focused on developing a low-cost reduction method using on a non-coal reductant. In this study, FeP slag, a byproduct of the yellow phosphorus industry, was used as the reductant for MnO2 ore and sulphuric acid (H2SO4) was used as a leaching agent. The chemical analyses of the roasted products and thermodynamic simulations were conducted to elucidate the chemical principles in the roasting process. It was found that FeP and Fe2P in FeP slag can react with MnO2; correspondingly, the proposed reactions are FeP + 4MnO2 = FePO4 + 4MnO and Fe2P + 5MnO2 = 5MnO + FeO + FePO4, respectively. In addition, the thermodynamic analysis showed that these reactions are spontaneous at the test temperature. Furthermore, the effects of the reduction roasting conditions and the leaching conditions on the recovery of Mn were investigated. The experimental validation for reduction roasting and H2SO4 leaching revealed that 98.2% of the extracted Mn was obtained when the mixture (Fe–P: MnO2 ore = 5:100, m/m) was roasted at 500 °C for 5 h and the leaching process was performed using 2-mol/L H2SO4 at 70 °C for 30 min with a liquid-to-solid ratio of 10 and a stirring rate of 200 rpm. The proposed method can be used to reduce costs and coal consumption and comprehensively benefit the Mn metallurgy industry.