Carbonation Behavior and Pore-Microstructure Evolution of Press-Formed BOF Slag Leaching Residue Briquettes

To achieve the stabilization and high-value utilization of Basic oxygen furnace (BOF) slag leaching residues, this study proposes a synergistic strategy combining compaction and pressurized carbonation. The effects of moisture content, molding pressure, holding time, and carbonation duration on the carbonation efficiency, mechanical properties, and surface characteristics of the residue briquettes were systematically investigated. Using a combination of orthogonal and single-factor experiments with the carbonation weight gain rate as the primary indicator, this study reveals the intrinsic mechanism by which forming parameters regulate CO2 mass transfer and reaction efficiency through pore structure modification. The results indicate that moisture content is the dominant factor influencing carbonation efficiency, with an optimal moisture range achieving a balance between reaction kinetics and gas diffusion. Furthermore, molding pressure and holding time dictate the effective carbonation depth by altering the pore size distribution. The carbonation process significantly enhances the compressive strength of the specimens, reduces the surface pH from 12.45 to approximately 10.2, and decreases surface roughness, thereby improving environmental compatibility. These findings provide a theoretical foundation for the high-value application of leached steel slag in marine ecological materials and carbon sequestration.