Technical Feasibility of Bauxite-Enhanced Vitrification for Utilizing AOD Slag as a Supplementary Cementitious Material

To recycle unmanageable AOD slag along with reduction of CO2 emissions, the utilization of vitrified argon oxygen decarbonization (AOD) slag with bauxite as a supplementary cementitious material was explored. The results demonstrate that AOD slag can be effectively vitrified by incorporating 15 wt% bauxite as an alumina source, facilitating the formation of a stable glass phase. The resulting vitrified product exhibits excellent properties, including initial and final setting times of 337 and 437 minutes, respectively, soundness (<0.05 mm), and a compressive strength of 88.7 MPa. Notably, the robust cementitious matrix effectively encapsulates and immobilizes Cr ions, reducing the total chromium leaching concentration to 0.09 mg/L—well below the 0.15 mg/L regulatory limit specified by the HJ/T 301-2007 industrial standard. The leached Cr3+ can be easily oxidized in the liquid environment of pH >11 and oxidation-reduction potential >0. The carbonation reaction contributes to reducing the conversion of hexavalent chromium, thereby lowering its concentration. These findings suggest that vitrifying AOD slag with Al2O3-rich solid waste as supplementary cementitious materials is a promising and environmentally sustainable method.