Effect of MgO/Al2O3 ratio on the structure and properties of blast furnace slags: A molecular dynamics simulation

SiO2-Al2O3-CaO-MgO is the most significant slag system in the blast furnace ironmaking process and it is very important to investigate the microstructure and viscosity of the system. In this paper, molecular dynamics simulations were carried out to explore the effects of MgO/Al2O3 ratio on structure and properties of the system. Based on the self-diffusion coefficients, the viscosities were calculated by Einstein-Stokes equation and compared with the experimental value and the Factsage value. The results showed that with the increase of MgO/Al2O3 ratio, the stability of [SiO4](4-) and [AlO4](5-) tetrahedron became weaken and the relative proportions of bridge and non -bridge oxygen showed a decrease. And due to the increase of MgO, more Mg2+ ions are used as network modifiers to reduce the degree of polymerization of the system, resulting in a decrease in the viscosity, which is consistent with experimental results. Finally, based on the present study, in the case of increasing Al2O3 content of blast furnace slag, the fluidity of slag could be adjusted by controlling MgO/Al2O3 ratio, thereby providing a basis for stable operation of blast furnace ironmaking.