Trial on the Application of Capillary Phenomenon of Solid CaO to Desulfurization of Liquid Fe

Abstract

In order to carry out the de-sulfurization of liquid Fe, solid CaO is usually used as a flux, but some of solid CaO particles are not melted into molten slag, and all CaO are not always used for the refining. We have investigated how to use the solid CaO directly and efficiently for the above refining processes. Solid CaO particles have small capillary tubes from their surface to inside. When a molten slag is wetted with solid CaO, the molten slag containing some impurities such as CaS and P₂O₅ is expected to penetrate into those capillary tubes. Although chemical reactions in solid phase are generally believed to be very slow due to slow diffusion in solid phase, those impurities are absorbed in solid CaO rapidly by capillary force and they are removed from molten steels. We named this refining process as Capillary Refining. In the present paper, we have tried to apply capillary refining to de-sulfurization of liquid Fe and carbon-saturated liquid Fe by using molten CaO–Al₂O₃ and CaO–SiO₂–MgO–Al₂O₃ slags.