Effects of B2O3 and CaF2 on Melting Temperatures of CaO-SiO2-Fe2O3 System Fluxes

Fluorite is widely employed as fluxing agent in metallurgy flux, which inevitably leads to serious fluorine pollution. B2O3 is employed as fluxing agent of CaO-SiO2-Fe2 O3 steelmaking fluxes to substitute for CaF2. The effects of B2O3 and CaF2 on the melting properties of this system were investigated. The melting temperatures of fluxes including softening temperature (Ts), hemispherical temperature (Th), and flow temperature (Tf) were measured using the hemisphere method. The results indicate that the fluxing effect of B2O3 is more significant than that of CaF2. When the addition amount of B2O3 (mass percent) exceeds 6%, the melting temperatures of fluxes including Ts, Th and Tf are decreased lower than 1300 °C. The basicity of fluxes has a significant effect on the melting temperature, and the melting temperatures of the fluxes increase with the increase of fluxes basicity. However, when B2O3 is used as fluxing agent, the melting temperature changes little with the basicity increasing from 2.5 to 5.0. These characteristics are suitable for steelmaking process. Moreover, Fe2O3 has an important fluxing effect on this CaO-based steelmaking fluxes. This indicates that the fluxes system is suitable for steelmaking process.