Beneficiation of South African chromite tailings using magnetic separation

Abstract

There are proven and well established widely accepted techniques for concentration of chromite ores such as spiral concentration, jigs and shaking tables. However, these techniques become inefficient and complex when treating fine and ultrafine size particles (less than 75μm) resulting in this size fraction lost to the tailings. As a result, a wet magnetic separation technology for recovery of ultra-fine chromite (Cr2O3) from spirals tailings as a scavenger was investigated. The Middle Group Chromitite layer (MG) spiral tailings was characterized using XRF, XRD, SEM and screen sieves with the aim of determining the viability of using the wet high intensity magnetic separation technology. It was found that the material had a grind size of 39.20% passing 106μm. The size fraction below 106μm showed the chrome content averaging 33%. The grain size of between 1000μm and 106μm showed an average chromite content of 12.7%. The XRD results revealed that the sample is Magnesiochromite along with the different gangue minerals such as Quartz, Enstatite ferroan, F-Iron diiron. The chemical analysis of the head sample showed the presence of calcium, Magnesium, Aluminium, Iron and silica.