Beneficiation Studies on a Sub Grade Iron Ore Sample From Barbil Region, Orissa

Abstract

A sub grade iron ore fines sample from Barbil region, Orissa state was received for evolving a process, to produce sinter grade concentrates with simple washing and little grind process. The ROM sample consisted of mostly brown coloured fines with little hard – compact chips. It contained mainly hematite with subordinate amounts of ferruginous clay. Quartz, gibbsite and magnetite were found in minor to trace amounts. The sample analysed 60.15% Fe(T), 6.44% SiO2,2.63 %Al2O3 and 4.18% LOI. The recommended process flow sheet comprises of [1] Stage crushing of ROM to -30mm followed by scrubbing and wet screening over10, 6 and 1mm .[2] Jigging of screen over size fractions[10 and 6mm] yielding a primary gravity concentrate.[3] Split Wet high intensity magnetic separation of deslimed sand & slimes at ~14000 gauss to get secondary magnetic concentrate [4] Thickening of Final tails. The process yielded sinter grade concentrate assaying 65.42% Fe(T), 2.24% SiO2, 1.14 % Al2O3, and 0.98% LOI, with 40.1 % Fe recovery yield at 36.9 wt.% yield besides a lumpy concentrate assaying 62.00% Fe(T), 4.12% SiO2, 1.86% Al2O3, and 1.92% LOI with 29.4%Fe recovery at 28.6wt% yield which may be blended with C ore for use in blast furnace as the grade is marginally lower than stipulated grade. In case the lumpy concentrate fails to meet the tumbler index, then it may crushed to sinter size and blended with jig and magnetic concentrates. Thus a sinter concentrate assaying 63.93%Fe, 3.06% SiO2, 1.39 % Al2O3, and 0.98% LOI, with 69.6 % Fe recovery yield at 65.6 wt.% yield could be produced meeting the requirement by simple process without grinding. The tails assayed 53% Fe(T) and may be used in cement industry. Further studies are under progress with grinding circuit for tails followed by gravity, WHIMS and inverse froth flotation process to produce pellet grade concentrates to improve the yield, recovery and to reduce tail losses.