Abstract
Study was made on the desulfurization of hot metal by CaO and Al2O3 powder mixture fluxes. The optimum Al2O3 content to gain maximum rate of desulfurization was observed. These phenomena could be qualitatively considered by equilibrium between solid slag and hot metal. Difference in the desulfurization rate among different Al2O3 content could not explained by a simple diffusion model in solid phase. There was a difference in pore distribution of CaO immersed into different hot metal composition. Thick reacted region was formed and large pore was found in it when aluminum content of hot metal was high and it suggest that desulfurization was promoted by increment of specific reaction surface area with hot metal. In contrast, when silicon content of hot metal was high, a silicon rich film was observed at the surface of CaO, and this was identified as gehlenite. Formation of gehlenite film may reduce the rate of desulfurization and this was consistent with previous study.
