Effect of Alumina Content and Solid Phase in Molten Flux on Dissolution of Alumina

A dissolution experiment of alumina in mold flux for the continuous casting of steel was conducted using the rotating cylinder method at 1550℃. The weight loss of the rod, the initial dipping area, and the immersion time were measured to determine the dissolution rate of Al2O3. It was concluded that the dissolution rate decreased with increasing Al2O3 content, but increased to a great extent when the solid phase of 2CaO-SiO2 existed together with the liquid in the molten flux. The dissolution rate was found to be linearly proportional to the concentration driving force and the viscosity, [(mass%Al2O3)s-(mass%Al2O3)b]η(-0.988). The physical erosion of the rod surface by the solid 2CaO?SiO2 dispersed in the liquid was attributed to fast alumina dissolution. An intermediate compound of CaO-2Al2O3 was observed on the interface of Al2O3 rods after the dissolution experiment. In addition, the dissolution of alumina in industrial mold fluxes has been examined.