Solubilities, Densities, Refractive Indices, and pH Values in the Ternary Systems (Li2SO4 + Li2CO3 + H2O) and (LiCl + Li2CO3 + H2O) at 308.15 K

Solid-liquid phase equilibria of the ternary system (Li2SO4 + Li2CO3 + H2O) and (LiCl + 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 (Li2SO4 + Li2CO3 + H2O) and (LiCl + Li2CO3 + H2O) at 308.15 K and 0.1 MPa were investigated with the method of isothermal dissolution equilibrium. 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 center dot H2O, respectively. In ternary system LiCl + Li2CO3 + H2O, there are also one eutectic point and two crystallization regions corresponding to Li2CO3 and LiCl center dot H2O. 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. 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.

Automated summary

The solid-liquid phase equilibria of the ternary systems (Li2SO4 + Li2CO3 + H2O) and (LiCl + Li2CO3 + H2O) were investigated through experimental methods. The results showed that Li2CO3 has a large crystallization region in both systems, indicating an easy separation from the brines.