Influences of Na2O, K2O and Li2O Additions on Electrical Conductivity of CaO–SiO2–(Al2O3) Melts

Abstract

The electrical conductivity of molten slag is an important thermophysical property and plays a prominent role in the modeling and operation of electric smelting furnaces.1) Heat consumption is the biggest energy consumption in the smelting process of the electric furnace. The appropriate resistance value of melt is the most important factor affecting electric energy efficiency during heating.2) Therefore, in order to improve the heat efficiency, it is crucial to have a comprehensive understanding of the electrical conductivities of the melts. Furthermore, electrical conductivity is very sensitive to the structure of the slag,3,4) and the structure information could be deduced from the variation behavior of electrical conductivity. Alkali metal oxides are important components in oxide melts, such as glass melts, mould flux, etc. However, the investigations about the influence of alkali metal oxides on the electrical conductivity of oxide melts are very scarce. Isard found that if one alkali oxide was gradually replaced by another in a series of glasses, the electrical resistivity showed pronounced maxima while the viscosity showed a deep minimum.5) Zhang’ et al.6) investigated the influences of Na2O and K2O additions on the electrical conductivity of CaO–SiO2–(Al2O3) melts, and found that as gradually substituting Na2O for K2O, there was a minimum value of electrical conductivity. This phenomenon was called the mixed alkali effect. Terai put forward an explanation that the substitution of the alkali ions in the glass by different alkali ions caused the mobility of each alkali ion to decrease pronouncedly and the activation energy for migration to increase rapidly.7) Similarly, Influences of Na2O, K2O and Li2O Additions on Electrical Conductivity of CaO–SiO2–(Al2O3) Melts