Beneficiation of Low Grade Chromite Ores from Sukinda

Abstract

In order to produce directly marketable chrome ore for export and domestic industries, most of the chromite ore beneficiation plants in Sukinda region treat selected rich ores with rejection of huge quantities of low and sub-grade ore (10-38% Cr2O3). Beneficiation is mostly limited to curshing, grinding, desliming and hydrosizing to prod-uce a concentrate of about 50% Cr203 with a yield of about 25-35%. By this also, a huge amount of sub grade fines of about 35-40% Cr203 has been accumulating in the mines. Currently very little efforts are made to treat these low grade ores or recover values from waste dumps. Recently, a study was undertaken at NML. to explore the possibility of developing a flowsheet to produce chromite concentrate preferably with Cr203 content of about 50% with Si02 about 2% from waste dumps analysing between 20 to 23% Cr203, with a view to using these as additional source of feed stock. Detailed physical characterisation, mineralogical analysis, bench and pilot scale studies were undertaken on these samples. The beneficiation process essentially invo- lved removal of ferruginous slime at stages by washing and hydrocycloning and enrichment of different size classified fractions by. simple gravity separation techniques like spiralling and tabling. It was observed that by adoption of the above operations, it was possible to upgrade these low grade ores to obtain concentrate having Cr203 of desired grade with high recovery.