Effect of basicity on the structure and viscosity properties of HIsmelt slag: A molecular dynamics simulation

HIsmelt is an emerging and potentially promising non-blast furnace ironmaking process, and the characteristics of its slag are crucial to the smelting process. Currently, there is no atomic-scale research on the slag of the HIsmelt process. In this work, molecular dynamics simulations were employed to investigate the effect of basicity on the structure and viscosity properties of the HIsmelt CaO-SiO₂-Al₂O₃-FeO slag system at 1773 K. The slag structure was characterised by calculating structural parameters, including radial distribution function, coordination number, oxygen type, and bond angle distribution. Furthermore, the viscosity of the slag system was estimated by using the self-diffusion coefficient and compared with mathematical models. The results indicate that basicity has a negligible impact on the short-range ordering of aluminosilicates in the HIsmelt slag system. As slag basicity increases from 0.4 to 1.8, the concentration of bridging oxygen decreases, non-bridging oxygen increases, and the [SiO₄]⁴⁺ and [AlO₄]⁵⁺ network structures undergo depolymerisation in the system. Additionally, the self-diffusion coefficient of atoms increases, and the slag viscosity exhibits a declining trend with increasing basicity. In the basicity range of 0.8 −1.8, the current MD simulations align with the results of the previous models.