Influences of Na₂O and K₂O Additions on Electrical Conductivity of CaO-MgO-Al₂O₃-SiO₂ Melts

The present study investigated the influences of Na₂O and K₂O additions on electrical conductivity of blast furnace type CaO-MgO-Al₂O₃-SiO₂ melts by the four-electrode method. Both the single addition of Na₂O or K₂O and the double additions of Na₂O and K₂O were studied. It was found that electrical conductivity monotonously increased as the amount of Na₂O addition was gradually increased, whereas, when K₂O was added, there was a continuous decrease of electrical conductivity. With melts containing both Na₂O and K₂O, electrical conductivity first decreased but then increased when Na₂O was gradually substituted for K₂O while keeping the molar fractions of other components constant. In other words, the mixed-alkali effect took place in CaO-Mg-Al₂O₃-SiO₂-ΣR₂O melts.