Rate of Dissolution of Sintered Alumina into Molten Slags

Abstract

The dissolution rate of alumina was calculated from the decreasing rate of radius of a cylindrical specimen dipped into CaO-SiO₂-Al₂O₃ (BF-type) or Na₂O-SiO₂ slags. The effects of revolution speed, temperature and slag composition on the dissolution rate were examined. The results are summarized as follows;
(1) The dissolution rate increased with increasing revolution speed. From this result, the dissolution rate was concluded to be limitted by mass transport in slag.
(2) The apparent activation energies of mass transport in BF-type and soda-silicate slags were calculated to be 186 and 113 kJ·mol^-1, respectively.
(3) From the EPMA analysis of specimen after experiment, it was observed that some slag penetrated into grain boundary of alumina specimen and a CaO·6Al₂O₃ compound was produced for CaO-SiO₂·Al₂O₃ slag, but that neither penetration layer nor compound are formed for soda-silicate slags.