In Situ Observation of the Dissolution of Al2O3 Particles in CaO-Al2O3-SiO2 Slags

The dissolution of Al2O3 particles in CaO-Al2O3-SiO2 slags was investigated by confocal scanning laser microscope at the temperature range from 1723 K to 1853 K. It was found that the rate-limiting step was the diffusion in the liquid slag. The dissolution of Al2O3 particles in CaO-Al2O3-SiO2 slags with various temperatures, CaO/Al2O3, and CaO/SiO2 in slag was in situ observed. Increasing the C/A and C/S of slag promoted the absorption of Al2O3 inclusions by the CaO-Al2O3-SiO2 slag, but only if the slag was pure liquid at the refining temperature. A model related to dissolution driving force and slag viscosity was shown to be v = 18.716 x Delta C/eta to predict the dissolution rate of Al2O3. Effective binary diffusion coefficients for various CaO-Al2O3-rich slags were obtained using the developed model. The dissolution rate of Al2O3 in CaO-Al2O3-SiO2 slags with low SiO2 content at the steelmaking temperature was predicted.