Effect of TiO₂ addition on the dissolution of MgO·Al₂O₃ inclusions in TiO₂‐bearing ladle slags

In order to clarify the removal behaviors of inclusions, the dissolution of MgO·Al 2 O 3 inclusions in CaO–SiO 2 –MgO–Al 2 O 3 –(0–10%)TiO 2 slags was observed in situ at 1450°C–1500°C by confocal scanning laser microscopy (CSLM), and the slag‐inclusion interfacial reaction was investigated by the scanning electron microscope (SEM). It was found that the addition of TiO 2 in the slags may change the dissolution mechanism of MgO·Al 2 O 3 inclusions, and the dissolution was controlled by diffusion in the boundary layer or in slag with a diffusion coefficient ranging from 2.38 × 10 −9 to 7.35 × 10 −9 m 2 ·s −1 . Besides, the addition of TiO 2 slightly changed the solubility of MgO·Al 2 O 3 in the slags, but its impact on slag properties played a more profound role in the dissolution of the inclusions. An appropriate addition of TiO 2 (e.g., 5%) helped the dissolution due to the lower viscosity and melting point of the slag, while an excessive TiO 2 content (e.g., 10%) showed an opposite effect. The dissolution rates of MgO·Al 2 O 3 inclusions were smaller than that of Al 2 O 3 inclusions. The lower chemical driving force of MgO·Al 2 O 3 and the precipitated MgO particles near the inclusion‐slag boundary were the main reasons to result in the lower mass transfer rates.