Bauxite Residue / Red Mud

Bauxite residue (commonly known as red mud) is the highly alkaline waste slurry generated when aluminium oxide (alumina) is extracted from bauxite ore via the Bayer process. Between 1 and 1.5 tonnes of red mud is produced per tonne of alumina. The global aluminium industry generates over 150 million tonnes of red mud per year, creating an enormous potential secondary REE resource. Red mud contains elevated concentrations of scandium (typically 70-130 ppm Sc), along with lanthanum, cerium, and vanadium that were present in the original bauxite. The economic recovery of scandium from red mud has been demonstrated at commercial scale by Sumitomo Metal Mining (Japan) using HPAL circuits, and is being investigated by Rio Tinto (Yarwun, Australia), UC RUSAL (Russia), and others. The circular economy concept of recovering critical minerals from industrial waste streams rather than dedicated mines is a key driver behind the growing interest in red mud REE recovery.