Reduction of Iron content in a Manganese ore from M/s. National Carbon Co., Ltd., Calcutta

Abstract

10 tonnes of a manganese ore sample assaying 50.6% Mn, 75.2% MnO2, 5.32% and 4.72% SiO2 was received from M/s. National Carbon Co. Ltd., Calcutta for carrying out pilot plant tests to lower the iron content in order to make it suitable for manufacture of dry batteries. Pyrolusite and cryptomelane were the chief manganese minerals with some jacobsite and braunite. Magnetite, hematite and goethite were the iron-bearing minerals. Wet magnetic separation of the ore after grinding to -35 mesh produced a concentrate assaying 52.7% Mn and 3.7%Fe with a recovery of 94.0% Mn. High intensity dry magnetic separation of this concentrate could not be carried out successfully to reduce the iron content further .Wet magnetic separation of the ore after grinding to 200 mesh yielded a manganese concentrate assaying 53.5% Mn and 3.89 % FE with a recovery of 90.8% Mn. The results of setting and filtration studies have been presented. Based on the results obtained, a flowsheet and a list of equipment have been drawn out for setting up of a commercial plant to produce 7500 tons of concentrate per year.