Alumina Dissolution into Silicate Slag

Dissolution of commercial white fused and tabular Al 2 O 3 grains into a model silicate slag was investigated after 1 h at 1450° and 1600°C. Formation of CA 6 and hercynitic spinel layers was observed at all Al 2 O 3 /slag interfaces. The spinel layer was not always continuous, and so, compared with the CA 6 layer, it had a less‐significant effect on the dissolution process. The CA 6 layer that formed adjacent to the tabular Al 2 O 3 was incomplete at both temperatures, so that its dissolution was not a totally indirect process. These incomplete CA 6 and spinel layers meant that slag penetrated into the tabular Al 2 O 3 grains, which, thus, were corroded and disintegrated by the penetrating slag. There was evidence of liquid in the CA 6 layer adjacent to the fused Al 2 O 3 after 1 h at 1450°C, which also enabled direct dissolution. After 1 h at 1600°C, fused Al 2 O 3 revealed a thick (∼60 μm), continuous and unpene‐trated CA 6 layer, indicating fully indirect dissolution at this temperature.