Physicochemical properties of KF-NaF-AlF3 molten electrolytes

Abstract

Conductivity of molten mixtures KF-NaF-AlF3 is measured in the whole concentration range of the [NaF]/([KF] + [NaF]) ratio at the cryolite ratio CR = 1.3 and 1.5 in the temperature range from 800°C to liquidus temperature. Replacement of K+ cations by Na+ ones results in a considerable conductivity increase. Alumina solubility rises with temperature and cryolite ratio ([KF] + [NaF])/[AlF3] in the KF-NaF-AlF3 system, and decreases with sodium fluoride content. Regression equations obtained allow calculating alumina solubility and electrical conductivity in the KF-NaF-AlF3 system in the CR range from 1.3 to 3.0 depending on the concentration of the components and temperature.