Synergistic Approach for Reducing Iron Content in Partially Laterised Khondalite Rock through Physical and Chemical Beneficiation

Abstract

Partially laterised Khondalite (PLK) refers to the waste material produced during the mining of bauxite ore. The PLK sample contains 39.6% Al2O3, 21.30% Fe2O3, 27.45% SiO2, and 1.1% TiO2. This study presents a novel method for reducing the iron (Fe) content to less than 2%, suitable for refractory industrial applications through various physical and chemical beneficiation techniques. The characterisation of the PLK feed sample was carried out using X-ray diffraction (XRD), and it shows that kaolinite and gibbsite are the major phases and hematite, ilmenite, and quartz are the minor phases. Since the physical beneficiation process (composite non-magnetic product) only achieved limited iron removal (5.24%), the hydrochloric acid (HCl) leaching process was adopted. The optimal leaching conditions for reducing iron to below 2% were found to be 80˚C, 6 molar concentration, 15% pulp density, and 3 hrs of leaching. Kinetic analysis, based on the initial rate method, indicated a first-order reaction mechanism, with the leaching process being reaction-controlled and an activation energy (Ea) of 42.76 kJ/mol.