Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Solubilities, densities and refractive indices of the aqueous quaternary system of lithium sulfate, lithium metaborate and lithium carbonate at 288.15, 298.15, 308.15 K and 0.1MPa were determined with isothermal dissolution method. According to the experimental results, the dry-salt phase diagrams, water-phase diagrams and the diagrams of physicochemical properties including density, pH, refractive index versus composition of lithium sulfate at three temperatures were plotted. In the dry-salt phase diagrams at three temperatures, there are all in four crystallization regions corresponding to lithium metaborate octahydrate (LiBO2*8H2O, LB), lithium carbonate (Li2CO3, LC) and lithium sulfate monohydrate (Li2SO4*H2O, LS), and three univariant-solubility curves corresponding to minerals of LS, LB and LC, and one invariant point of three co-existed minerals (LS + LB + LC). A comparison of the phase diagrams at 288.15, 298.15 and 308.15 K shows that the areas of lithium sulfate monohydrate and lithium metaborate octahydrate are decreased obviously and the area of lithium carbonate region is increased significantly with the increasing of temperature from 288.15 to 308.15 K. Physicochemical properties of density and refractive index in the quaternary system change regularly with the increasing of temperature and the dry-salt composition of Li2SO4 (g/100 g*S) in the solution. With the increasing of Li2SO4 (g/100 g*S) in the solution, density and refractive index are increased firstly to reach the maximum values at the invariant points of three co-existed minerals and then decreased sharply. The calculated values of densities and refractive indices in the quaternary system at three temperatures with the empirical equations are in good agreement with the experimental values.