Solubilities, Densities, Refractive Indices, and pH Values of Ternary Systems (LiCl + Li2CO3 + H2O) and (Li2SO4 + Li2CO3 + H2O) at 288.15 K

AbstractSolid-liquid phase equilibria of the ternary systems (LiCl + Li2CO3 + H2O) and (Li2SO4 + Li2CO3 + H2O) are very important for the separation of lithium salts from the salt lake brines. In this paper, the experimental solubilities, densities, refractive indices, and pH values of the ternary systems (LiCl + Li2CO3 + H2O) and (Li2SO4 + Li2CO3 + H2O) at 288.15 K and 0.1 MPa were investigated by means of isothermal solution method. In ternary system (LiCl + Li2CO3 + H2O), there are one eutectic point and two crystallization regions corresponding to Li2CO3 and LiCl·2H2O. Lithium chloride has a strong salting-out effect to lithium carbonate. The crystallization region of Li2CO3 was the largest, indicating Li2CO3 could be easily crystallized and separated from brines. In ternary system (Li2SO4 + Li2CO3 + H2O), there are one eutectic point and two crystallization regions corresponding to the large area of Li2CO3 and the relative small area of Li2SO4·H2O, respectively. The variation trend of solution densities, refractive indices and pH values in the two ternary systems are similar and change regularly with the increasing of the concentration of lithium sulfate or lithium chloride. The calculated values of density and refractive index using empirical equations for the two ternary systems are in good agreement with the experimental values.