Beneficiation of low grade Manganese ore from Kumsi, Mysore

A low grade manganese ore from Kumsi in Shimoga district, Mysore, received from the Bureau of Mineral Development, Govt. of Mysore, assayed 34.4% Mn, 4.5% Fe, 30.3% SiO2, and 3.0% Al2O3 and 0.07% Phosphorus. Psilomelane was the principal manganese mineral followed by pyrolusite and manganite. The chief gangue was quartz followed by feldspar, goethite, muscovite, hematite and traces of zircon. Tabling at -65 mesh after classification followed by magnetic separation of table middlings and flotation of slime yielded a combined manganese concentrate assaying 46.1% Mn, with a recovery of 88.5% Mn. High intensity magnetic separation at -100 mesh and flotation of the slime yielded a manganese concentrate assaying 46.5% Mn with a recovery of only 59.9% Mn. Cationic flotation of siliceous minerals using Armeen 12 (Dodecylamine technical) at 10.0 to 10.5 pH yielded the best results. The manganese concentrate obtained assayed 47.0% Mn, 3.92% SiO2 with a recovery of 92.4% Mn. Use of Rosin Amine D Acetate in place of Armeen 12 yielded almost identical results.