PROPERTIES OF SOME ALKALI FLUORIDE-CHLORIDE SALT MIXTURES .1. PRIMARYCRYSTALLIZATION AND DENSITY-MEASUREMENTS

The primary crystallization and density of the fluoride-chloride salt systems (i) NaF-LiCl and (ii) NaF-(LiCl + KCl) eutectic were determine d experimentally using thermal analysis and the Archimedean technique, respectively. The corresponding liquidus curves for the two systems w ere constructed and compared. Molar volume and excess volume functions were computed from density data at different compositions and tempera tures. The positive values of the excess volumes correspond to volume expansion that increases with temperature for both systems. The result s suggest that as far as the primary crystallization and density behav iours are concerned, it is possible to replace the component, pure LiC l, in the fluoride-chloride salt system by the eutectic mixture of (Li Cl + KCl) for the system's use as a potential electrolyte for aluminiu m electrolysis.