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 x 10-9 to 5.66 x 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 mu m across the 0 to 6 wt pct MgO slag composition range.