Investigation in CaO–SiO 2 –CaF 2 –C slags during the sintering and melting process

Abstract

The reaction behaviour and mechanism of carbon and mould fluxes during the heating process were deeply considered through TG-FTIR, XRD, DSC, and SEM techniques. The results showed that: there were four main stages of weight loss for slags during heating process. One hundred to 300 °C and 300–500°C were the volatilization of free water and bound water, respectively. Five hundred to 800°C was the decomposition process of carbonate. However, at 800–1400°C, CaO–SiO₂–CaF₂ slag was the reaction of slag component themselves. CaO–SiO₂–CaF₂–C series slags were the reaction behaviour between carbon and slags (C and Ca₂SiO₄, Ca₄Si₂O₇F₂). The DSC and SEM analysis illustrated that the solid phase reaction temperature range of CaO–SiO₂–CaF₂–C being 1320–1370°C was larger than that of CaO–SiO₂–CaF₂ being 1070–1250°C. Additionally, CaO–SiO₂–CaF₂ slag was completely molten at 1400°C, while CaO–SiO₂–CaF₂–C did not, suggesting that the sintering and melting process were suppressed by carbon.