Simulation and experimental investigation on one-step process for recovery of valuable metals and preparation of clean mineral wool from red mud

Red mud (RM) is a hazardous alumina industrial solid waste and its utilization faces three major challenges, namely, efficient recovery of valuable metals, favorable control of hazardous substances, and complete utilization of residues. We simultaneously achieved the three goals in a short one-step process, which was inspired by green chemistry principles and focused on multi-objective coupled control. Iron-based metal elements were recovered in reduction smelting process to produce pig iron. Molten slags after smelting were rapidly cooled and fiberized to produce mineral wool and hazardous alkaline substances were immobilized in vitreous fibers. The smelting-reduction process, fibration capacity of RM-based molten slags, and performance and environmental impact of prepared mineral wool were investigated using thermodynamic, molecular dynamics simulations, and experimental methods. The results indicated the recovery rate of Fe could reach above 87%. The obtained mineral wool showed satisfactory properties with the fibrosis rate of around 73%–92%, the mean fiber diameter of 1.57–5.62 μm, and the mean fiber tensile strength of 1520–6700 MPa. The highest Na + leaching concentration was under 1.42 mg/L and the solidification rate of Na + in different samples was above 99.8%. This paper provided a fresh approach to achieve clean and high value-added utilization of RM.