Quantitative X-ray diffraction study into bauxite residue mineralogical phases

Over 100 million tonnes of bauxite residue is produced annually as a by-product of the Bayer process. Bauxite residue utilisation represents both a challenge and an opportunity for the alumina industry. Bauxite residue is a fine-grained, complex mixture of numerous mineral phases, which varies based on refinery operating conditions and bauxite ore. Quantitative X-ray diffraction by Rietveld refinement was used to characterise several industrially sourced residues and better understand the potential value and risk in this material. Particular emphasis was placed on characterisation of aluminium bearing phases to identify opportunities for process optimisation and residue utilisation. Analysis revealed that a significant proportion, up to 66%, of the total aluminium in some residues can be hosted within iron oxides via solid solution.