Investigation on Solid-State Carbothermic Reduction Behaviors of Pyrolusite Ore

Manganese is essential to iron and steel production because of its sulfur-fixing, deoxidising, and alloying properties. Also, manganese has no satisfactory substitute in producing aluminium alloys and battery cells. It was estimated that manganese ore consumption reached about 200 million metric tons in the last decade. The most important manganese ore is pyrolusite (MnO2), which is composed of higher manganese oxide and needs more energy to obtain manganese metal. Previous studies suggest that pre-reduced ore pellets in FeMn production lead to a significant drop from ~3000 to ~1600 kWh t−1in energy consumption. Hence, the prereduction of manganese ores is essential to increasing ferromanganese production efficiency and cost-effectiveness. This study analysed the kinetics and mechanism of roasting of pyrolusite manganese ore for use in ferromanganese production. Mixtures of ore-coke in a ratio of 1:0.15 were prepared for carbothermic reduction. The effect of ore sizes (5–20 mm), reduction temperatures (900–1100 °C) and holding time (60–180 min) on the reduction behaviour were examined. Optimum conditions were obtained for a higher reduction of ore. The decomposition of higher oxide states of manganese was confirmed from XRD analysis of raw and reduced ores. Our study indicated that the reduction of the ore was inversely dependent on its size, whereas a higher temperature and the holding time improved the reduction of the ore.