Experimental Determination and Thermodynamic Model of Solid–Liquid Equilibria in the Ternary System (LiCl + SrCl₂ + H₂O) at 273.15 K and Its Application in Industry

Solubilities, densities and refractive indices of the ternary system (LiCl + SrCl₂ + H₂O) at 273.15 K were determined using the isothermal dissolution equilibrium method. The phase diagram of the system consists of two invariant points, three univariant solubility curves and three crystallization areas corresponding to LiCl·2H₂O, SrCl₂·2H₂O and SrCl₂·6H₂O. Applying the Pitzer and Harvie–Weare model, the Pitzer mixing parameters and the solubility product constants (K_sp) of solid phases were fitted to the solubility data; then, the solubilities of this ternary system were predicted. A comparison shows that the calculated solubilities agree well with the experimental results. The phase diagram and Pitzer model for the ternary system at 273.15 and 298.15 K were then used to conduct a computer simulation of brine separation. Lithium chloride and strontium chloride salts can be separated completely by six steps in the brine separation process. This result of the simulation of brine separation can be used as a theoretical reference guideline for salt separation and purification of brine systems.