Solubility of Na2O·xAl2O3 in NaF-KF-AlF3-based low-temperature electrolyte

Abstract

AbstractThe solubility of Na2O·xAl2O3 in a NaF-KF-AlF3-based low-temperature electrolyte was investigated, and the influence of electrolyte temperature at 750 ℃, CR = 1.3–1.4, CaF2, and LiF on the alumina solubility was studied. The dissolution rate of alumina in the electrolyte was determined by measuring the alumina concentration in the electrolyte at different times with an oxygen analyzer. The results showed that in the NaF-KF-AlF3-based low-temperature electrolyte, the dissolution rate of alumina in Na2O·xAl2O3 was faster than that of Al2O3. As the Na2O content in alumina increased, the dissolution rate increased. Similarly, a higher CR of NaF-KF-AlF3 and a higher temperature of the molten salt (750–850 °C) increased the dissolution rate of alumina in the electrolyte. The dissolution rate of alumina in NaF-KF-AlF3 decreased after adding CaF2 and LiF. According to the kinetics analysis, the dissolution rate of alumina followed the zero-order reaction rate law from 0–5 min, which showed that it depended on the amount of alumina absorbed in the electrolyte in the first five minutes.