Abstract: The scheme of dissociation of cryolite in NaF-AlF3 melts was proposed. The constants and heats of dissociation for cryolite were evaluated from experimental data. The mole fractions of each kind of ions at 1298K in NaF-AIF3 melts were calculated based upon this scheme. The thermodynamic mixing function for liquid NaF and solid AIF3, and liquidus data of NaF-AlF3 systems were calculated by using the above evaluated parameters. The results obtained are in good agreement with the experimental data.

Key words: cryolite, thermodynamic function, NaF-AIF3 melt