Thermal beneficiation of low grade ferruginous Manganese ores

The low-grade high phosphorus ferruginous ores in which iron is either chemically combined with manganese or very finely distributed, cannot generally be upgraded by conventional ore-dressing techniques. The paper examines theoretical considerations involved in the thermal beneficiation of ferruginous ores whereby iron and phosphorus are preferentially reduced to the metallic state in gas or oil-fired furnaces. Two low grade manganese ores have been studied by thermal beneficiation. It has been observed that at 1300-1400°C it is possible to enrich the manganese: iron ratio in slag to 15-20:1 from the initial value of 4:1. The slag, however, contains considerable quantities of silica and can be suitably treated for making low carbon ferro-manganese. The paper records the results of effect of different variables such as temperature, quantity of reducing agent and time in the thermal beneficiation of low grade Indian manganese ores. (Messrs C. Sankaran, Junior Scientific Assistant, M.C. Sen, Senior Scientific Officer and P.P. Bhatnagar, Assistant Director, National Metallurgical Laboratory