Beneficiation of Iron ore Fines from Large Deposits of Waste Dumps

Abstract

About 20 million tonnes of low grade iron ore fines have been accumulated and stacked over the years as 'Dump Rejects' in the Gua iron ore mine of Bihar and about 8 million tonnes of generated fines are stacked in the Dalli Iron Ore Mine, M.P., under operation by Steel Authority of India Ltd., (SAIL). In order to conserve and utilise these valuable iron ore fines, the authorities of the RDCIS, SAIL, Ranchi have sponsored two samples for pilot plant scale beneficiation studies in order to evaluate the possibility of upgrading these fines to be used as sinter feed. The ore dressing division of the Indian Bureau of Mines (IBM), Nagpur has carried out mineral charac-terisation of these fines and evolved suitable process flowsheets based on continuous scale testing to yield iron ore concentrates in the size range of all minus 6 mm and assaying over 63% Fe which would suit as sinter feed. The process of beneficiation, comprised scrubbing, trommel washing, classification, jigging and hydrocycloning/ spiralling. The iron ore fines of Dalli Mine assayed 57.97% Fe, 5.23%A120, 7.52% SiO 2 and 3.73% LOI. The composite concentrate obtained in the pilot plant studies assayed 63.75% Fe, 2.1 % A1203, 2.65% SiO 2 with weight percent yield of 66.7 and iron recovery of 73.2%.The iron ore fines from the reject dumps of Gua iron ore mine assayed 61.5% Fe(T), 0.54% FeO, 3% SiO 2'3.26% A1203 and 6.5% LO1. The composite concentrate obtained assayed 63.44% Fe„ 2.17% SiO,, 2.76% A120. and 5.47% L01 with weight percent yield of 79.2 and iron recovery of 81.3%. The occurrence of higher percentage of goethite and limonite as well as the complex textural association of hematite with goethite/limonite and silicates precluded the production of high grade (+65% Fe) iron concentrate with high recovery. However the above concentrates produced fully meet the size and chemical specification stipulated for sinter feed and allow commercial utili-sation of these waste rejects.