studies involved rotating rods 7 , 8 or cylinders 9 -1 1 immersed in various slags and the rate limiting steps have been found The dissolution behaviour of alumina particles in to vary depending on the system (e.g. diVusion in the liquid CaO-Al 2 O 3 -SiO 2 -MgO slags was studied by slag, 9 boundary layer diVusion, 1 1 solid state diVusion across confocal scanning laser microscopy. Three different a reaction layer 7 , 8 ). Lee and Zhang 5 reviewed various methods slag systems were investigated to evaluate the of investigating slag-refractory erosion and summarised effect of changing the MgO content in a high silica the mechanisms for slag-refractory corrosion. tundish slag, and the effect of decreasing the silica To date, relatively few studies have investigated the discontent when dissolving the particles in a ladle slag.solution of oxide inclusion particles in slags, a situation A particle of 80 mm diameter dissolved in 50 s in a characterised by much smaller volumetric ratios between simulated ladle slag but needed 100 s to dissolve in the solid and liquid phases than with solid cylinders and a high silica slag at the same temperature. When rods in slag baths. Recent studies by Zhang et al. 6 reported the silica content was decreased, a decrease in the the dissolution of fused (12 mm diameter) and tubular Al 2 O 3 alumina particle dissolution time was noted. During particles in a synthetic silicate slag. The formation of surface dissolution of alumina particles in a slag containing layers, and their morphology and thickness, was found to MgO, the alumina particle reacts with the slag to in uence the dissolution process. form an MgAlO 4 layer. No reaction layer wasThis present paper presents results on the dissolution observed during the dissolution of alumina particles kinetics of Al 2 O 3 particles in three slags obtained by direct in slags that did not contain MgO. This work observation of the dissolution process in the confocal scanning suggests that the dissolution time of large alumina laser microscope (CSLM). The slags are representative of particles is significant, increasing with particle size ladle and tundish slags. and with decreased temperature. I&S/1629At the time the work was carried out, the authors were in the Center

The dissolution behaviour of alumina, MgO and MgAl2O4 particles in a 36%CaO‐21%Al2O3‐42%SiO2 (mass contents in %) slag has been studied using a confocal scanning laser microscope in the temperature range of 1470 ‐ 1550 °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 MgAl2O4 particles decreased with increased temperature and were almost identical (approximately 200 s for a 150 μm diameter particle at 1500 °C.). This phenomenon can be explained by the formation of MgAl2O4 layer on the surface of the MgO particle during dissolution. Alumina dissolution times were slightly longer (approximately 250 s for a 150 μm diameter particle at 1500 °C) than that of MgO and MgAl2O4 particles and no reaction layer was observed on the surface of the particles.