Carbothermal reduction of residues of bauxite (red mud) and ilmenite (tionite): A sustainable approach to resource recovery

Red mud, a by-product of alumina production from bauxite, and tionite, a residue from titanium dioxide manufacturing from ilmenite, represent two large-scale industrial wastes with significant environmental impact and underutilized resource potential. Both residues contain high concentrations of iron and titanium-bearing phases, yet their stability and complex mineralogy hinder direct valorization. In this work, a carbothermal reduction strategy was applied to simultaneously address the removal of iron and the structural modification of titanium phase. Calcium oxide was introduced as a fluxing agent, not only to enhance reduction kinetics but also to promote the formation of calcium titanate, thereby destabilizing the rutile-rich tionite structure. The primary objective was the selective reduction and separation of iron, while preparing a CaO-modified titanium-bearing slag suitable for subsequent leaching. This approach highlights a dual benefit: mitigating the environmental burden of industrial residues and providing a pathway toward resource recovery of iron and titanium.