Beneficiation of low grade Chrome-ore from Boula Chromite Mine, Nausahi, Keonjhar, Orissa

Abstract

A low grade Chrome-ore from Boula Chromite Mine, Nausahi, Keonjhar District, Orissa assayed 44.70% Cr2O3, 17.18% FeO, 15.33%MgO, 13.43% SiO2, 7.90% Al2O3, 0.55% CaO and 0.04% P. The chief ore mineral was chromite. Talc was the main gangue with considerable amounts of serpentine and anthophyllite. Tabling was done with ore crushed to -35 and -43 mesh sizes in roll crusher as well as in rod mill and the results are compared. In general, the ore ground in rod mill gave better results. Humphrey’s Spiral, magnetic separation and flotation methods also yielded good grades of concentrates, but with lower recoveries. Tabling of the ore wet ground to -35 mesh in rod mill after classification was found to be the best method of concentration for this ore. A concentrate assaying 53.11% Cr2O3, 19.89 % FeO with a recovery of 94.4% Cr2O3 could be obtained, but the Cr/Fe ratio in the concentrates was too low for metallurgical purposes, as the iron was in chemical combination in chromite and could not be lowered by any ore-dressing methods.