Beneficiation of a low grade limestone sample from M/s Rohtas Industries Ltd, Dalmia Nagar, Bihar

A low grade limestone assaying 38,68% CaO, 30,48% CO2, 3.13% MgO, 17.92% SiO2, 4.03%Al2O3, 1,54% Fe2O3 and 21.24% in- soluble was received from M/s, Rohtas Industries, Ltd, Dalmia Nagar for the production of a concentrate suitable for cement manufacture. The chief gangue mineral in the sample was quartz which was fairly liberated from calcite below 200 mesh. Fatty acid flotation followed by two cleanings of the rougher float yielded a concentrate suitable for cement manufacture assaying 47.43% CaO, 7.7% SiO2, and 9.55% in-soluble with a recovery of 85.2% CaO. Three cleanings of the rougher float further improved the grade to 49,2% CaO, 6,31% SiO2 and 8.05% insoluble with a recovery of 82.3% CaO. Results of grindability tests with the ore and settling studies with the concentrate and tailing are also presented.