Reduction of Silica content in Limestone Sample No.1 from Purnapani Quarries, of M/s. Hindustan Steel (P) Ltd., Rourkela

Abstract

A Sample of limestone from Purnapani Quarries, Sundergarh District, Orissa, assaying 46.0% CaO,39.6%,CO2, 4.8% MgO, 7.0% SiO2, 9.65% acid insolubles, 1.7 % Al2O3, 0.65% Fe2O3, and 0.3% S was received from M/s. Hindustan Steel (P) Ltd., Rourkela for beneficiation studies to upgrade it to make it suitable for use as flux in Iron and Steel industry. Quartz was the chief gangue mineral. Calcitic and dolomite constituted the carbonate minerals and were fairly liberated from the gangue at 150 mesh size. Optimum conditions for flotation of limestone were determined employed an emulsion of oleic acid as collector for carbonate minerals and sodium silicate as a depressant for the gangue. Flotation employing 1.0 1b/ton of sodium silicate produced a concentrate assaying 49.73% CaO3, 5.15% MgO, 1.18% Al2O3, 0.52% Fe2O3 and 0.2%S able for use as a flux in Iron and Steel industry. Utilisation of flotation concentrate which is in the form of fines either in the open-hearth steel making after agglomeration by briquetting or pelletising or in the iron blast furnace through its introduction into self fluxing sinter or after briquetting to suitable size & strength needs further studies; these studies will be pursued at the National Metallurgical Laboratory and a further Report on the subject will be made in due course.