Sustainable Valorization of Bauxite Residue (“Red Mud”): Exploring the Potential of H2 Reduction for Multi-metal Recovery

This study presents a process for the simultaneous recoveryRecovery of metals from bauxite residueBauxite residue (BR) at relatively lower temperatures using H2 reduction to achieve zero-waste discharge (minimal waste generation) of BR. The proposed methodMethod involves blending BR with NaOH and subjecting it to H2 reduction (using different process parameters), resulting in an intermediate material enriched in magnetite and water-soluble aluminate. Optimal process parameters were determined (temperature of 600 °C, a reduction time of 120 min, 20 wt.% NaOH addition, and a reduction atmosphereAtmosphere of 5 vol.% H2 + 95 vol.% N2 with a 20 L/h flowrate), resulting in satisfactory recoveriesRecovery of Fe (74.7%, grade = 40%), Al (81.5%), and Na (91.4%). This approach represents a step towards the sustainable valorizationValorization of BR, i.e., the efficient recoveryRecovery of metals (Fe, Al, and Na) along with a non-magnetic fraction (Ca, Si, Ti, Rare earth elements), a precursor for further Sc, Ti recoveryRecovery, and an additive eventually for building materials.