Solubilities, Densities and Refractive Indices for the Two Ternary Systems (Li2SO4 + LiB5O8 + H2O) and (LiCl + LiB5O8 + H2O) at 298.15 K and 101.325 kPa

Abstract

In this paper, in order to guide the lithium salt production from solar ponds in salt lakes, the two ternary systems (Li2SO4 + LiB5O8 + H2O) and (LiCl + LiB5O8 + H2O) at 298.15 K and 101.325 kPa were studied using the isothermal dissolution experimental method. The solubilities, densities and refractive indices were measured experimentally. From the experimental data, the phase diagrams and the diagrams of physicochemical properties, including density and refractive index, against composition Li2SO4 and LiCl in each ternary system were established. The phase diagrams for the two ternary systems at 298.15 K all have one invariant point, two univariate solubility curves and two crystalline regions corresponding to lithium pentaborate pentahydrate (LiB5O8·5H2O), lithium sulfate monohydrate (Li2SO4·H2O, in the former system) and lithium chloride monohydrate (LiCl·H2O, in the later system). In addition, both ternary systems are of the hydrate type I, neither double salt nor solid solution were found. The variations of density and refractive index against the concentrations of lithium sulfate in the former system and lithium chloride in the later system are similar. On the basis of empirical formulae for density and refractive index, the calculated data agree well with the experimental values, which indicate that all data obtained are reliable.