Beneficiation And Dewatering Studies On A Sub-Grade Iron Ore Sample From Orissa, India

A detailed study was undertaken to beneficiate sub-grade iron ore sample from Kenojhar District, Orissa, India containing 57% Fe (T), 7.7% SiO2, 4.8% Al2O3, 4 % L.O.I. 0.4% TiO2,1.3 % Mn and traces of S(T) to make it suitable for the user industry. The mineralogical study indicated that it predominantly consists of haematite with subordinate amounts of goethite and clay. Quartz, Cryptomelane / Psilomelane, Pyrolusite, Gibbsite, Feldspar and Muscovite mica were present in very minor to trace amounts. The Denver grind ability tests indicated, that the sample could be categorized as ?medium soft to medium.? The Bond ball mill work index was determined to be 14.19 kwh per short ton. The beneficiation process involved classification followed by tabling of the classified sand, ground to minus 48 mesh size. The table slimes were subjected to Wet High Intensity Magnetic Separator (WHIMS). The developed process yielded a composite concentrate from tabling and WHIMS operations assaying 65% Fe(T), 2% SiO2, 1.8% Al2O3, 2% Mn and 0.9% LOI with a recovery of 60.1% Fe (T), amounting to 52.5 wt.% yield. To meet the size specifications for pellet making, it was further ground. Dewatering studies were also carried out on the ground combined concentrate and rejects. The thickener area of ground combined concentrate using 0.02 kg/t of Sufloc A 1115 flocculant was 0.02 m2/tonne of dry solids per 24 h. And for the combined rejects using 0.12 kg/t of flocculant, it was 0.035 m2/tonne of dry solids per 24 h. The moisture content, in the pressure filtration cake, in the ground combined concentrate product was 10.0%, and productivity was 506.7 kg/m2h. Thus, by thickening and filtration of process products, 90% of water used in the process could be recovered. The study highlights the development of a simple and cost effective flowsheet with almost complete water recovery for a subgrade iron ore sample. Keywords: tabling, WHIMS, thickener, filtration