The electrical conductivity of CaO-SiO₂-Fe_tO slag in contact with iron was measured at 1300°C using AC bridge (1000 H_z). A drastic increase of the electrical conductivity was observed with increase of Fe_tO content. The Arrhenius relation between the conductivity and the temperature were satisfied in both high and low Fe_tO slag (33.6 mol% and 67.5 mol% respectively).
Experiments were also carried out on the effect of additives on the electrical conductivity of the slag. From the results obtained for the fayalite composition, of which SiO₂ was substituted for additives, CaO and MgO were found to contribute to the conductivity by almost the same degree as equivalent Fe_tO. TiO₂ changed the conductivity only a little, which means that TiO₂ can be substituted for equivalent SiO₂. The conductivity of the slag, where SiO₂ was substituted for Al₂O₃, was equal to that of the slag, where Al₂O₃ was assumed to fix equivalent Fe_tO. CaF₂showed a minor increase of the conductivity.
The electrical conductivities were also measured varying the basicity (CaO/SiO₂) of the slag with constant Fe_tO and additives such as MgO, CaF₂, B₂O₃, Al₂O₃ and TiO₂.