Dissolution behavior of Al2O3 and MgO inclusions in the CaO-Al2O3-SiO2 slags: Formation of ring-like structure of MgAl2O4 and Ca2SiO4 around MgO inclusions

Abstract

The dissolution behavior of Al2O3 and MgO particles in various CaO-Al2O3-SiO2 slags was investigated using a confocal scanning laser microscope at 1550 degrees C. The dissolution paths of AI,03 and MgO particles varied depending on slag compositions. Reaction products such as CaO center dot 6Al(2)O(3), CaO center dot 2Al(2)O(3) and Ca2Al2SiO7 formed on the surface of Al2O3 particle. Surprisingly, however, in the case where reaction products were MgAl2O4 and Ca2SiO4 phases, these reaction products formed ring-like structure around MgO particles. Inside of the ring-like structure, liquid phases of which compositions correspond to the co-saturation compositions with MgO and MgAl2O4 (Ca2SiO4) phases. In addition, this unique dissolution phenomenon retarded the dissolution rate of MgO particle in molten slags. In the present study, the dissolution mechanism of this unique dissolution phenomenon is proposed.