Mineralogical characterisation and leaching characteristics of ilmenite concentrates

摘要

Knowledge of mineral composition and phase distribution within ilmenite concentrates is important in understanding the inter-granular inclusions of impurities, which might have direct effects on the market value and subsequent treatment process. Characterisation of the ilmenite concentrates from Richards Bay, South Africa was investigated along with mineral phase changes associated with the leaching process. A combination of characterisation techniques including the High-resolution Scanning Electron Microscopy and X- Ray diffraction techniques were used. The mineral phase constitution of the ilmenite concentrate were studied prior to the additive leaching process along with the mineral phase changes of the residues. XRD studies showed the presence of alteration phase along with the dominant phases while SEM analyses indicated that the raw concentrates exhibited signature rhombohedral crystal form and crescentic pits, SEM analyses of the leached residue indicated formation of new phases containing pseudo - rutile on the layers of the particles after the leaching process. Although some particles retained the crescentic pit and the sub angular grain structures. The phase constitution changes were predominantly at the grain boundaries and grain edges. The elemental mapping results of the leached residue indicated the presence of pseudo -rutile and unreacted silicate locally enriched in the granular structure with trace alumina on the rims. The XRD could detect the pseudo rutile phase predominantly present in there as compared to the raw ilmenite sample, which occasionally peaked with ilmenite being the dominant phase. Leaching of the trace metals and iron resulted in increased crescentic pits and pseudo-rutile phase present in the residue.