Beneficiation of iron ore slimes from Karnataka through dispersion and selective flocculation

Abstract

During the wet processing of iron ores, substantial amount of fine particles/slimes is generated in downstream which need to be recovered effectively for their usage and beneficiation. The present paper describes the beneficiation studies of Iron ore slime from Karnataka, India through dispersion and selective flocculation in presence of surfactants and polymers with a view to produce pellet grade fines. The slime sample had a feed grade of 63.84% total Fe, 2.64% Silica and 3.98% alumina. Detailed characterization data indicated that 76 Wt% of the sample was below 49 micron size. XRD analysis indicates that the sample constituted hematite and goethite as in major phase whereas magnetite, kalonite and silica in minor phase. The zeta-potential data indicates that the iep is about 5.1. The dispersion studies of the fine iron ore particles were carried out with sodium hexa meta phosphate (SHMP), tetra sodium pyrophosphate (STPP) and Dispersant N6, a low molecular weight anionic poly-acrylamide polymer. The effect of process parameters pulp density, types of reagents and their dosage on the separation index following dispersion was studied. The selective flocculation studies were carried out on fully dispersed slime sample using modified starch and polyethylene oxide as selective flocculant. The results show that about 95% recovery could be achieved through the separation following dispersion with the enhancement of Fe grade from 1.5 wt. % to 2 wt. %.