Molecular dynamics simulation, spectroscopy characterization and properties testing of high-titanium CaO-SiO2-10 wt%MgO-13 wt%Al2O3-4 wt%FeO-40 wt%TiO2 slag melts

In this study, the effect of the CaO/SiO ₂ mass ratio on the viscosity, free running temperature, electrical conductivity and structure of high-titanium CaO-SiO ₂-10 wt%MgO-13 wt%Al ₂O ₃-4 wt%FeO-40 wt%TiO ₂ slag was investigated. The results revealed that viscosity and free running temperature monotonically decreased with an increasing CaO/SiO ₂ ratio from 0.1 to 0.8, whereas the electrical conductivity followed a trend of first increasing, then decreasing, and ultimately increasing again. XRD analysis revealed only a small amount of Ti-related phases in the quenched slag. This ensured that the high-temperature state structure of the slag was largely preserved. Molecular dynamics simulations, FTIR, and Raman results indicated that Ti-based structural units predominated in the slag. With an increasing CaO/SiO ₂ ratio, the [SiO ₄] tetrahedral and Ti-based structures progressively simplified, while the [AlO ₄ ] tetrahedral and Si-O-Al structures showed a tendency of complexity followed by simplicity. However, the overall degree of polymerization of the slag decreased, leading to the viscosity reduction. The degree of polymerization and the migration capacity of ions and electrons together contributed to complex changes in electrical conductivity. A comprehensive analysis indicated that the slag composition with a CaO/SiO ₂ mass ratio of 0.4 is more favorable for the smelting of vanadium-titanium magnetite in the pre-reduction electric furnace process.