Phase equilibria in the quaternary KBr–MgBr2–K2SO4–MgSO4–H2O system at (323.15 and 348.15) K

Abstract

Aiming to utilize the bromine resource in bittern comprehensively, the phase equilibria in the quaternary KBr–MgBr2–K2SO4–MgSO4–H2O system at (323.15 and 348.15) K were researched by the isothermal dissolution equilibrium method. The solubilities and equilibrium solid phases were determined, and the corresponding phase diagrams were plotted. The phase diagram at 323.15 K comprises six invariant points, thirteen univariant curves, and eight crystallization areas corresponding to KBr, K2SO4, MgSO4·H2O (Kie), MgSO4·4H2O (Tet), MgSO4·6H2O (Hex), MgBr2·6H2O (Mb), K2SO4·MgSO4·4H2O (Leo) and KBr·MgBr2·6H2O (Car-Br), respectively. The phase diagram at 348.15 K consists of five invariant points, eleven univariant curves, and seven crystallization areas corresponding to KBr, K2SO4, Kie, Mb, Leo, K2SO4·2MgSO4 (Lan) and Car-Br, respectively. With the Pitzer and HW models, the solubilities of the quaternary KBr–MgBr2–K2SO4–MgSO4–H2O system at (323.15 and 348.15) K were calculated, and the results are essentially consistent with the experimental data.