Deeply understanding the physicochemical properties of LCDSP slag from atomic structure to macroscopic properties: A blueprint for the green and low-carbon steelmaking process

Low-Carbon Double Slag converter steelmaking Process (LCDSP) demonstrates significant potential for green-sustainable steelmaking. This study integrates mineralogy, coexistence thermodynamics, and molecular dynamics to investigate the physicochemical properties of dephosphorization (De-P) and decarbonization (De-C) slags generated by LCDSP, explore the short- and medium-range structure of disordered networks in amorphous LCDSP slags and their relationship with thermophysical properties. Results reveal De-P slag's superior phosphorus enrichment capability compared to De-C slag, evidenced by P-rich phase distribution and concentration. De-C slag exhibits higher temperatures and increased network modifier/former ratios, leading to elevated free oxygen proportion and reduced oxygen network polymerization. The viscosity and surface tension of the De-C slag are lower than those of the De-P slag, which is reflected in the decrease in the proportion of high-order rings and the increase in the proportion of low-order rings in the De-C slag. Increasing the proportion of Non-Bridging Oxygen (NBO) in De-C slag enhances the anharmonicity of tetrahedral structural units and phonon scattering, resulting in a decrease in the phonon mean free path, thereby making the thermal conductivity of De-C slag lower than that of De-P slag. Compared to the conventional steelmaking process, the LCDSP achieves 79.55 % increase in P2O5 content within De-P slag and reduces average lime consumption by 28.48 % per ton of steel. The LCDSP with low lime consumption and low waste residue emissions depicts a promising blueprint for clean steel production and low-carbon metallurgy.