The dissolution behaviour of alumina, MgO and MgAl_2O_4 particles in a 36 percent CaO-21 percent Al_2O_3-42 percent SiO_2 (mass contents in percent) slag has been studied using a confocal scanning laser microscope in the temperature range of 1470 - 1550 deg C. The double hot thermocouple technique and metallographic examination was also used to characterize the reaction product between the particles and the slag. The total dissolution times for MgO and MgAl_2O_4 particles decreased with increased temperature and were almost identical (approximately 200 s for a 150 #mu#m diameter particle at 1500 deg C.). This phenomenon can be explained by the formation of MgAl_2O_4 layer on the surface of the MgO particle during dissolution. Alumina dissolution times were slightly longer (approximately 250 s for a 150 #mu#m diameter particle at 1500 deg C) than that of MgO and MgAl_2O_4 particles and no reaction layer was observed on the surface of the particles.
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