Recovery of chromite values from tailings of COB plant using enhanced gravity concentrator

Abstract

In world scenario, India is ranked third largest producer of chromite ore. Odisha Mining Corporation Ltd. is operating a chromite ore beneficiation (COB) plant with a capacity of 0.15 mtpa. The process route basically involves comminution, classification followed by gravity separation. The present plant practice generates tailings with some chromite values associated with it. In the present study, an attempt was made to recover chromite values from the tailings using enhanced gravity separator such as Falcon concentrator, a high g-force generating equipment. The tailing sample is very fine grained in nature and contains significant amount (~68 Wt.%) of particle below 11 μm. The chemical analysis of head sample shows a value of 20.23% Cr2O3. Mineralogical study revealed that chromite is the major chromite bearing mineral and clay, gibbsite and spinel are the major gangue minerals present in the material. The process parameters are optimised with respect to feed particle size, bowl rotation speed and the back water flow rate. It was observed that high rotation of the bowl and high back water flow rate favour generating a clean concentrate with Cr2O3 more than 40% with >68% recovery.