Dissolution Kinetics of Al₂O₃, CaAl₄O₇, and MgAl₂O₄ Inclusions Into CaO–Al₂O₃–SiO₂ Slags with Varying MgO Content

The dissolution phenomenon of Al₂O₃, CaAl₄O₇, and MgAl₂O₄ inclusions in CaO–Al₂O₃–SiO₂ slags with 0, 3, and 6 wt pct MgO content at 1773 K was investigated using confocal scanning laser microscopy. It was observed that the complete dissolution time of Al₂O₃ and CaAl₄O₇ decreased as the MgO content increased, while the impact of the MgO content on MgAl₂O₄ was minimal. The dissolution kinetic of inclusions was primarily governed by diffusion in the molten slag. The diffusion coefficients (D) were similar for different inclusions and the value ranged from 1.54 × 10⁻⁹ to 5.66 × 10⁻⁹ m²/s. The Zh number was employed to determine the inclusion capacity of slags, and Ry number was utilized to calculate the inclusion dissolution rate. The addition of MgO into the slag led to the opacification, causing difficulty in in-situ observation. Furthermore, effect of MgO with content of 0, 3, 6 wt pct on the dissolution of Al₂O₃, CaAl₄O₇, and MgAl₂O₄ inclusions was elucidate. Correlations between Zh number and Ry number of Al₂O₃, CaAl₄O₇, and MgAl₂O₄ inclusions dissolving in CaO–Al₂O₃–SiO₂ slags with 0, 3, and 6 wt pct MgO were obtained. Predictions for dissolution times were generated for inclusions with diameters ranging from 1 to 1000 μm across the 0 to 6 wt pct MgO slag composition range.