Effect of CaF₂ Addition on the Viscosity and Structure of CaO–SiO₂–MnO Slags

摘要

The viscosity of the CaO–SiO_(2)–MnO(–CaF_(2)) slags (CaO/SiO_(2) = 1.0, MnO = 10, 40 mass%) was measured to clarify the effect of CaF_(2) on the viscous flow of molten slags at high temperatures. Furthermore, the Raman spectra of the quenched glass samples were quantitatively analyzed to investigate the structural role of CaF_(2) in a depolymerization of silicate networks. The critical temperature of the slags abruptly increased at 15 mass% CaF_(2), which was confirmed to originate from a crystallization of cuspidine using XRD analysis. The viscosity of the slags continuously decreased by CaF_(2) addition in the 10 mass% MnO system, whereas the viscosity of the 40 mass% MnO system was not significantly affected by CaF_(2) addition. The activation energy for the viscous flow of silicate melts decreased by CaF_(2) addition and its tendency became less significant in the more basic composition, i.e . in the 40 mass% MnO system. The effect of CaF_(2) on the viscosity of the slags was quantitatively analyzed using micro-Raman spectra of quenched glass samples accompanying with a concept of silicate polymerization index, Q~(3)/Q~(2) ratio. A polymerization index continuously decreased with increasing content of CaF_(2) in the 10 mass% MnO system, whereas it was not affected by CaF_(2) in the 40 mass% MnO system. Consequently, the bulk thermophysical property of the CaO–SiO_(2)–MnO–CaF_(2) slags was quantitatively correlated to the structural information.