Crystallization dynamics of the post-cooling molten slag against temperature rise

Turning molten slag into a solid state involves a complex cooling history that significantly influences the quality of the final product. It is crucial to unveil the crystallization dynamics of molten slag during practical cooling, particularly in the post-cooling course with temperature rise. In this work, we employed the single hot thermocouple technique to visually investigate the crystallization behavior of blast furnace slag. A series of control experiments were conducted to quantify the effects of temperature rise features and chemical composition on incubation time (τo-τl), crystallization temperature region (To ∼ Te), and the average crystal growth rate (Vα). The results proved that the governing factor of Vα changed from nucleation growth rate to nucleation rate, resulting in a significant difference in crystallization phenomena between the continuous cooling condition and temperature rebounding condition. Considering the post-peak temperature, temperature rise rate, and corrected optical basicity exerted remarkable effects on the crystallization behaviors, we established correlations for predicting τo-τl, To, Te, and Vα by fitting experimental data. These correlations offer valuable insights for optimizing cooling parameters in dry slag treatment, contributing to a comprehensive understanding of crystallization dynamics in high-temperature slag subjected to intricate cooling histories.