Characterisation of South African chromite middle group seams

Abstract

In this paper, detailed physical and chemical characterisation of the South African chromite Middle group seams (MG 1, 2, 3 and 4) was conducted to determine the effect it has in choosing the type of milling equipment and establish how the mineralogical characteristics vary in order to decide whether they should be processed separately or blended together. The chemical composition was analysed using XRF, mineralogical phases determined using XRD and elemental analysis as well as grain particle sizes were obtained from SEM and EDS. XRF results showed that the Cr2O3 content in all seams was between 30 and 35% by weight and mostly associated with Fe, Si, Mg, and Al elements. Most dominant phases are that of chromite and magnetite in all the samples. The amount of chromium element by % weight in all seams ranged between 20% to 28% as obtained from the EDS. The particle size of the grains in the ore ranged between 20 to 420μm, with majority being between 150 and 200μm. SEM showed that minerals were well distributed within the ore, with very few that were clustered together. From above mentioned mineralogical analysis that has been conducted thus far it was observed that all Middle group seams showed very similar characteristics, and blending them for processing would be most recommended, however they can also be processed separately depending on the availability of the ore.