Value-added recycling of iron and titanium from bauxite residue (Red Mud) via a flux-free smelting separation process

With enriched iron and titanium elements, red mud produced by the lime-free Bayer process showing high recycling value. This work proposed a pre-reduction and flux-free smelting process to recycle Fe/Ti resources from this red mud. Considering the extraction of titanium from smelting slag, classical calcareous flux was abandoned to avoid the formation of refractory perovskite. Instead, the FeO generated by pre-reduction of red mud itself was creatively applied to regulate the subsequent smelting separation. The full melting temperature of slag can be reduced from > 1700℃ to 1450℃-1550℃, as the FeO content in slag reached 10-20 wt%. The transition from rutile to ferrouspseudobrookite contributed to this change. Since the pre-reduced sample was smelted at 1600℃ for 60 min, 93.60 wt% of the iron element in red mud can be recycled in the form of iron nugget with grade of 99.6 wt%. Titanium in red mud can be recycled as Ti-rich slag, with TiO2 content of 55.91 wt%, for titanium dioxide production. The FeO in slag also suppressed the side reactions (i.e., carbonization of titanium and iron, reduction of silicon) in smelting process, which improved slag fluidity and iron nugget purity. This technique also provides a new approach for the utilization of V-bearing titanomagnetite, ilmenite, and other similar resources.