The Dissolution Kinetics of MgO into CaO-MgO-Fe₂O₃ Slag

Calcium ferrite is the main binding phase for high-basicity sinter. The production and structure of calcium ferrite greatly influence the quality of the sinter. With the change in gangue composition, MgO becomes an important factor in the generation of calcium ferrite. In this study, the rotating cylinder method was used to study the dissolution kinetics of MgO into CaO-MgO-Fe₂O₃ melt. The experimental variables included the temperature, the initial composition of the melt, the Fe₂O₃/CaO mass ratio, the rotation time, and the rotation speed. The results indicate that the dissolution rate increases with increasing dissolution time, temperature, and rotation speed but decreases with increasing MgO content and Fe₂O₃/CaO mass ratio in the initial slag. The dissolution rate was observed to increase and then decrease with the addition of SiO₂ in the initial slag. The activation energy and diffusion coefficient for MgO dissolution were found to range from 117.31 to 234.24 kJ mol⁻¹ and from 1.03 × 10⁻⁶ to 1.18 × 10⁻⁵ cm² s⁻¹, respectively. The concentration difference between the solid and liquid phases is the main driving force for dissolution, but the viscosity and magnesium ion diffusivity of the melt also affect the process.