Calculation of thermodynamic properties of LiF---AlF3, NaF---AlF3 and KF---AlF3

The scheme of dissociation of cryolite in NaF---AlF3 melts is proposed and applied to the LiF---AlF3 and KF---AlF3 systems. The constants and enthalpies of dissociation for alkali-cryolites are evaluated from experimental data. The mole fractions of each proposed species at 1298K in these three melt systems are calculated, and the variation of alumina solubility in alkali-cryolite can be explained on the basis of the ionic structure for the MF- AlF3 (M: Li, Na and K) melts. The thermodynamic properties and liquidus data of MF-AlF3 systems are calculated by using the selected evaluated parameters. Some results are compared with experimental values.