Interfacial Reaction between Refractory Materials and Metallurgical Slags containing Fluoride

Interfacial reaction between refractory materials such as zirconia, magnesia and doloma brick, and the metallurgical slags of the CaO-SiO2-MgO-CaF2 system with varying CaF2 content were investigated at high temperatures using various methodologies with static and dynamic modes. To figure out the corrosion mechanism due to interfacial reaction with the slag, the slag characteristics were examined in terms of flow temperature and viscosity and the corroded interface of zirconia, magnesia and doloma refractories were analyzed by SEM-EDS and EPMA. With an addition of CaF2, three different layers were formed at the interface between slag and zirconia refractory. Furthermore, the corrosion of zirconia refractory was found to be accelerated with an increase of CaF2 which facilitated the dissolution of intermediate compounds. The penetration of slag through the grain boundaries of MgO refractory is enhanced by increasing the content of CaF2 due to an increase in the fluidity of slag in the dynamic mode. On the other hand, in the static condition, a dense Ca2SiO4 layer is formed at the hot face of magnesia-doloma refractory due to a reaction between silica in slag and lime in doloma, resulting in the protection of direct corrosion of refractory brick. However, the thickness of C2S layer decreases with increasing content of CaF2 due to an increase in fluidity of slag.