Battery Active Manganese Dioxide from Low Grade Manganese ores by Chemical Process

Low-grade manganese ore containing 39.5% MnO2, 3.52% MnO, 24.2% Fe, 7.53% SiO2 and & 43% Al2O3 was reduced by coke oven gas at temperature range of 350°C to 550°C. The reduced ore was leached with dilute nitric acid to obtain a liquor containing about 210 gm of manganese per litre. This manganese nitrate solution was decomposed at about 190°C, to give battery active manganese dioxide and nitrogen tetroxide, the latter on passing through water in presence of air was recovered as nitric acid. More than 95% of manganese dioxide suitable for dry-cell, chemical and other industries. About 95% of nitric acid used in leaching is recovered in suitable strength for recycling. (S.R. Srinivasan, Senior Scientific Assistant, Mr. Gurdial Singh, Senior Scientific Assistant and Dr. B.C. Kar, Assistant Director, National Metallurgical Laboratory, Jamshedpur)