Determination of dissolution time of Al2O3 and MgO inclusions in synthetic Al2O3-CaO-MgO slags

The dissolution of Al2O3 and MgO inclusions in synthetic CaO-Al2O3-MgO slags have been investigated in situ with a confocal scanning laser microscope (CSLM). The dissolution mechanisms were elucidated by using analytical-rate expressions. A set of parameters is introduced to distinguish between reaction control and diffusion control of the dissolution process. It was found that whereas Al2O3 inclusion dissolution rates are limited by diffusion, MgO dissolution appears to be limited by surface reaction. For both Al2O3 and MgO, the dissolution rate and the apparent activation energy increased when the slag composition was slightly shifted away from the saturation limit of the dissolving species in the phase diagrams.