Thermal Conductivity of the Molten CaO-SiO₂-FeO _x System

Thermal conductivity measurements were carried out on synthetic steelmaking slag using the hot-wire method. Furthermore, local structure analysis in the melts was carried out in order to investigate the relationship with the composition dependence. The thermal conductivity of the CaO-SiO₂-FeO _x melts significantly decreased as the content of FeO _x increases, particularly at lower basicity. Both chemical analysis and the observation show that the amount of Fe²⁺ increases when CaO/SiO₂ is smaller, implying more basic behavior of FeO than FeO_1.5. According to further analyses by Mössbauer spectroscopy, the degree of basicity of FeO_1.5 remains virtually unchanged in the composition range of interest. From the experimental results, it could be concluded that the thermal conductivity of the silicate melt containing iron oxide is highly dependent on the valence of the Fe ion and comparatively independent of the amphoteric behavior of FeO_1.5.