In Situ Observation of the Dissolution of Al 2 O 3 Particles in CaO-Al 2 O 3 -SiO 2 Slags

The dissolution of Al 2 O 3 particles in CaO-Al 2 O 3 -SiO 2 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 Al 2 O 3 particles in CaO-Al 2 O 3 -SiO 2 slags with various temperatures, CaO/Al 2 O 3 , and CaO/SiO 2 in slag was in situ observed. Increasing the C/A and C/S of slag promoted the absorption of Al 2 O 3 inclusions by the CaO-Al 2 O 3 -SiO 2 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 × Δ C / η to predict the dissolution rate of Al 2 O 3 . Effective binary diffusion coefficients for various CaO-Al 2 O 3 -rich slags were obtained using the developed model. The dissolution rate of Al 2 O 3 in CaO-Al 2 O 3 -SiO 2 slags with low SiO 2 content at the steelmaking temperature was predicted.