Beneficiation of iron ore fines from mine rejects

Abstract

Katni area in M.P. is bestowed with some of the sporadic iron ore deposits akin to blue dust. These deposits are invariably associated with highly weathered schist and BHQ (Banded Hematite Quartzite) formations. Both these formation encounter concentrated and thick pockets of iron ore fines assaying in the range of 60 to 63% Fe (T) which are selectively mined and sold to various industries in the country. However, the intervening thinner and leaner mineralized zone having contamination of host rock and assaying in the range of 50 to 55% Fe (T) are dumped/ stacked separately at the mine site on account of lack of market. Lot of iron values are locked up in these reject dumps stacked over the years and is causing huge environmental problem of air and water pollution, thereby resulting in silting of fields in the near vicinity of mine area. Characterization of such mine rejects revealed that extensive weathering makes the deposits very soft and fragile and susceptible to produce extreme fine grained dusty material. The textural disposition of the available minerals i.e., hematite and its associated silicate gangue, are extremely fine grained where 60 to 70% of fines falls below 75 μm (remaining below 20 μm). Recovery of valuables from such fine size materials is evolved at minus 30 mesh (0.5 mm) size using hydro-cyclone and/or stub cyclone followed by WLIMS. The process route produced marketable grade iron concentrates from both the formations (BHQ and Schist) assaying +63% Fe (T) with 75 to 90% Fe recovery (%Wt. yield 75 to 80) and 65% Fe with 80% iron recovery (%Wt. yield 69.0) in Schist formation alone. The evolved flow-sheets are simple and cost effective and paved the way for the recovery of iron values from the dump rejects of both BHQ and Schist formations. One lessee has commercialized the process developed by IBM.