Solid–Liquid Phase Equilibria of the Ternary System (KBO2 + K2SO4 + H2O) at 288.15, 308.15 K, and 0.1 MPa

Considering the significance of fundamental phase equilibrium data in resource exploitation from salt lake brines, the solid–liquid phase equilibria of the ternary system (KBO2 + K2SO4 + H2O) at 288.15, 308.15 K, and 0.1 MPa were investigated using the isothermal dissolution method. Along this line, the solubilities and physicochemical properties of densities were experimentally determined. Based on the experimental data, phase diagrams and the related physicochemical property diagrams against composition were plotted. It was found that there are one invariant point, two univariate solubility curves, and two crystalline regions corresponding to potassium metaborate hydrate (KBO2·1.33H2O) and arcanite (K2SO4) in the ternary phase diagrams at 288.15 and 308.15 K. In addition, they belong to the hydrate type I and neither double salt nor solid solution was formed. The distributive behaviors of density against the concentration of KBO2 in the equilibrium solution at two temperatures were similar. Moreover, the theoretical values of density were calculated, which were found to be consistent with the experimental values, further demonstrating the accuracy and reliability of this work.