RE-MINING RED MUD WASTE FOR CRITICAL MINERAL RECOVERY

Red mud, a mine tailing waste of the Bayer process used in aluminum production, is a slurry formed during the caustic digestion of bauxite, an aluminum ore. This process has dominated global alumina production for over a century, generating approximately 1 to 1.5 tons of red mud per ton of alumina. Red mud is notable for its composition, containing valuable constituents such as aluminum (Al, 1-9%), iron (Fe, 5-14%), titanium (Ti, 1-12%), and trace amounts of rare earth elements (REEs) (~0.1% in total), which includes elements like scandium (Sc), valued significantly at $4-5K/kg as Sc2O3 despite its low concentration (typically around 120 ppm or 0.012%). Research efforts have been focused on developing secure and efficient processes to selectively enrich these rare elements from red mud. Beyond its elemental composition, red mud's high alkalinity (pH >11) presents significant environmental challenges, necessitating the development of technologies for its reclamation to reclaim resources and mitigate environmental pollution. Herein, we aim to provide a comprehensive mineralogical and elemental analysis of red mud, identifying minerals hosting REEs, and highlighting advancements in recovering titanium, gallium, rare earth elements (especially scandium), and iron from this industrial waste residue.