Reduction of Silica content in Limestone Sample No.2 from Purnapani, Sundergarh Dt., Orissa

A Sample of limestone (Sample No.2) from Purnapani Limestone Quarries, of the Hindustan Steel Ltd., Rourkela, assaying 43.8% CaO,36.9% CO2, 4.2%MgO, 11.4% SiO2, 2.8% Al2O3, 0.99% Fe2O3 and 0.25% total S, was studied for its amenability to beneficiation to make it suitable for use as a flux in the Iron & Steel Industry.
Quartz which was the chief gangue was fairly liberated at about 150 mesh. Flotation tests employing 1.0 1b/ton of oleic acid emulsion and 1.0 1b/ton of sodium silicate produced a concentrate assaying 49.67% CaO with recovery of 97.3% CaO, 4.5% MgO, 1.44% SiO2, 0.8% Al2O3, 0.9% Fe2O3 and 0.18% S with a recovery of 94.4% CaO. This beneficiated product is chemically suitable as a metallurgical flux. However, it is in the form of fines and its utilisation in the open hearth steel furnaces after briquetting or pelletising and in the iron blast furnaces through self fluxing sinter or alternatively after briquetting to optimum size and strength will be investigated in the National Metallurgical Laboratory and reported upon in due course.