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

Abstract

A sample of manganese ore assaying 52.09% Mn, 74.50% MnO2, 5.9% Fe, 2.3% Al2O3 and 2.8% SiO2 was received from M/s. National Carbon Co., Calcutta to investigate the possibility of reducing its iron content by physical methods so that it could be employed in dry cell industry. Petrological examination of the sample revealed that pyrolusite was the principal manganese mineral followed by small amounts of wad, psilomelane and manganite. Hematite, magnetite and goethite constituted the ferruginous gangue and the siliceous gangue consisted mainly of muscovite and quartz. Straight wet magnetic separation of the original sample (mostly 6 mesh) as well as after grinding to -35 mesh size yielded concentrates assaying 53.6% Mn, 4.6% Fe and 53.7% Mn, 4.5% Fe with recoveries of 88.5% and 94.2% Mn respectively. Dry magnetic separation after desling of -35 mesh ground sample produced a concentrate assaying 54.9% Mn and 3.7% Fe with a recovery of only 61.4% Mn. Tabling followed by magnetic separation of the table concentrate as well as slime yielded the best result in a combined non-magnetic manganese concentrate assaying 54.55% Mn and 3.6% Fe with a recovery of 78.2% Mn.