Dissolution kinetics of alumina into mold fluxes for continuous steel casting

Abstract

Dissolution kinetics of alumina into mold fluxes for the continuous steel casting was investigated by employing the rotating cylinder method. The dissolution rate of Al2O3 was determined by measuring weight loss of Al2O3 rod, initial dipping area and immersion time. It is concluded that the alumina dissolution is controlled not only by the mass transfer in the molten flux but also by the formation of intermediate compounds such as CaO(.)6Al(2)O(3), CaO(.)2Al(2)O(3), and 2CaO(.)Al(2)O(3) SiO2 on the rod/flux interface. Concentration driving force, rod rotation speed, temperature of molten flux and chemical composition are also important factors which affect the alumina dissolution. The dissolution rate increased with addition of MgO or CaF2, or up to 5%mass of Na2O, and then decreased with further increase in the amount of Na2O content. The physical erosion of the rod surface by the solid 2CaO(.)SiO(2) dispersed in the liquid was attributed to fast alumina dissolution.