Beneficiation of low-grade, hard Chrome ore from Kittaburu, Singhbhum District, Bihar

Abstract

A low grade hard chrome ore received for beneficiation tests assayed 34.97% percent Cr2O3, 17.75 percent FeO, and 14.99 percent SiO2.Jigging the -10+28 mesh fraction, followed by classification and tabling of the -28 mesh portion (including the jig middling) gave a combined concentrate assaying 51.23 percent Cr2O3, 22.50 percent FeO, and 3.44 percent SiO2 with an overall recovery of 82.8 percent Cr2O3. A middling product obtained during the tabling test, when mixed increased the recovery of chromite to 88.2 percent. Straight tabling, after grinding to -28 mesh and classification gave a combined concentrate assaying 50.72 percent Cr2O3 with a recovery of 85.5 percent. Treating the -28 mesh ore in a spiral concentrator followed by tabling of the spiral middling, crushed to -65 mesh, gave a combined spiral-table concentrate assaying 50.17 percent Cr2O3 with a recovery of 84.4 percent. Mixing a low grade concentrate gave a product assaying 49.72% percent Cr2O3 with an overall recovery of 88 percent. Magnetic separation of the gravity concentrate was found to reduce the FeO content from 22.38 percent to only 21.66 percent inspite of a loss of 14.5 percent of the chromite in the magnetic product. Flotation tests were performed under varying conditions using fatty acids and cationic reagents. The best test gave a concentrate assaying 49.25 percent Cr2O3 with a recovery of only 59.1 percent of chromite.