Fluoride Evaporation and Melting Characteristics of CaF2-CaO-Al2O3-MgO-Li2O-(TiO2) Slag for Electroslag Remelting

This study presents the evaporation mechanism of fluoride from CaF2-CaO-Al2O3-MgO-Li2O-(TiO2) slag and their melting characteristics at different TiO(2)contents by thermogravimetric analysis and melting-temperature-characteristic testing. FactSage is used to identify the major components evaporating from the tested slags. The results show that the slag melting point decreases with an increase in the TiO(2)content. In addition, X-ray diffraction analysis reveal that with an increase in the TiO(2)content, the total CaF(2)and Ca(12)Al(14)F(2)O(32)content increase while the MgAl(2)O(4)content decrease. The gaseous species easily evaporating from slags, including LiF and CaF2, are the primary contributors to fluoride loss. The apparent activation energy for LiF evaporation is calculated to be in the range of 116.75-227.62 kJ mol(-1)and this process can be described as 3D diffusion. In the case of CaF(2)evaporation, the apparent activation energy is calculated to be in the range of 365.98-492.33 kJ mol(-1)and this process followed the mechanism of random nucleation and growth.