Effects of additives and temperature on the dissolution rate and diffusivity of MgO in CaO-Al2O3 slags under forced convection

Abstract

The dissolution rate of dense magnesia specimen in calcium aluminate based melts was measured in air over the temperature range of 1 450-1 600°C, using a rotating disk/cylinder technique. The measured dissolution rates were strongly dependent on the rotation speed with the results indicating mass transfer in the slag phase to be the rate-limiting step. At a given rotation speed, the dissolution rate was strongly dependent on the slag chemistry and temperature. The diffusivity of MgO in the slag was calculated from the dissolution rate and solubility data, using known mass transfer correlations. Addition of FeOx, and CaF2 and increasing the temperature, resulted in substantial increase in the dissolution rate and deduced diffusivity of MgO in the slag. © 2006 ISIJ.