Solid-Liquid Phase Equilibria in the Quinary System Containing Lithium, Sodium, Calcium, Chlorine, and Boric Acid with Sodium Chlorine Saturated at 323.15 K

Abstract

The solid-liquid equilibria of the quinary system LiCl–NaCl–CaCl₂–H₃BO₃–H₂O with sodium chlorine saturated at 323.15 K were studied by the isothermal dissolution equilibrium method. Based on the measured experimental solubility data, the dry-salt phase diagram, water content diagram, and sodium chloride content phase diagrams were plotted. The dry-salt phase diagram in this system consists of one invariant point saturated with LiCl·H₂O, CaCl₂·2H₂O, and H₃BO₃, three univariant curves, and three crystallization regions saturated with NaCl corresponding to CaCl₂·2H₂O, LiCl·H₂O, and H₃BO₃. No solid solution was found in the system. The areas of crystallization zones increase according to the above order. The Jänecke index of H₂O and NaCl and the refractive index change regularly with the Jänecke index of LiCl. The calculated refractive indices agree well with the experimental data using the semiempirical equation. These results on phase diagrams of the quinary system can supply theoretical references for lithium salts and boric acid separation from calcium chloride-type brine.