Measurements of Solid–Liquid Equilibria in Quaternary System LiBr–MgBr2–KBr–H2O and Its Two Ternary Systems (LiBr–MgBr2–H2O and MgBr2–KBr–H2O) at 288.15 and 308.15 K

The solid–liquid equilibria in the LiBr–MgBr2–KBr–H2O system was measured, along with its two subsystems, LiBr–MgBr2–H2O and MgBr2–KBr–H2O, at 308.15 and 288.15 K using the isothermal dissolution equilibrium method. The stable phase diagrams of the three systems at 308.15 and 288.15 K were plotted. For the ternary LiBr–MgBr2–H2O system, two univariant curves, one ternary invariant point, and two crystallization fields, the fields being MgBr2·6H2O and LiBr·2H2O, were identified. The ternary system MgBr2–KBr–H2O contained three univariant curves, two ternary invariant points, and three crystallization fields corresponding to KBr, KBr·MgBr2·6H2O, and MgBr2·6H2O. From the stable phase diagram of the quaternary system, five univariant curves, four crystallization fields, and two invariant points were observed. The corresponding solids of the four crystallization fields were KBr, LiBr·2H2O, KBr·MgBr2·6H2O, and MgBr2·6H2O. The quaternary phase diagrams at 288.15 and 308.15 K had similar shapes, and the shapes of each crystallization field were identical. The crystallization field of KBr was larger than the other crystallization fields. With an increase in temperature, the crystallization field of KBr became smaller and that of LiBr became larger.