Dissolution Kinetics of SiO₂ into CaO-Fe₂O₃-SiO₂ Slag

High-basicity sinter is the predominant Fe-bearing material used in blast furnace process in East Asia. The dissolution of SiO₂ into molten calcium ferrite influences the assimilation process. In this study, a rotating cylinder method was used to explore the dissolution kinetics of SiO₂ into CaO-Fe₂O₃-SiO₂ slag. The influencing factors, including temperature, rotating time and speed, and initial composition of the slag, were considered. Results showed that the dissolution rate increased with increasing rotation speed and temperature, whereas the increase in ω(SiO₂) or ω(Fe₂O₃)/ω(CaO) ratio in the initial slag composition decreased the dissolution rate. The diffusion coefficient and activation energy of SiO₂ during the dissolution process ranged from 2.09 × 10⁻⁶ to 6.40 × 10⁻⁶ cm² s⁻¹ and 106.62 to 248.20 kJ mol⁻¹, respectively. Concentration difference between the boundary layer and bulk phase was the primary driving force of the dissolution process; however, this process was also influenced by the slag viscosity and ion diffusivity.