Pilot Plant studies on beneficiation and agglomeration of a low grade Limestone sample from Purnapani Quarries, Orissa, For Hindustan Steel Ltd.

A 500-tons representative sample of limestone from Purnapani Quarries, Orissa, was received from Hindustan Steel Ltd., for beneficiation and agglomeration tests on a Pilot Plant scale along with a request to supply beneficiated pellets. The sample assaying 37.1% CaO, 15.3% SiO2, 4.0% MgO, 6.3% Al2O3, 3.1% Fe2O3, 33.5% CO2, was ground to 90% -200 mesh; the limestone was separated from quartz by froth flotation using 0.68 -0.77 Kg/ton sodium oleate and 0.46-0.23 Kg/ton sodium silicate. The upgrade concentrates, after dewatering and drying, was mixed with 6% molasses and agglomerated on a pellet which could withstand effective handling, storage and use as flux steel-making. The test results indicated that (i) 86.3% of the total insolubles could be rejected in the tailings producing a concentrate, constituting 68.6% by weight of the original sample and assaying 4.10% insolubles, with an overall recovery of 87.3% CaO. (ii) The grade of the concentrate could be improved to 3.53% insolubles with a recovery of 78.4% CaO. Alternatively, the recovery of CaO could be improved to 92.3% CaO, but the concentrate would be slightly of poorer grade.