Solid-Liquid Phase Equilibria of Ternary System (NH4Cl–MgCl2–H2O) and Quaternary System (NH4Cl–MgCl2–SrCl2–H2O) at 288.15 K

Magnesium and strontium play an important role in many industries, which are widely distributed in Oilfield brines in Nanyishan area of Qaidam Basin. In order to effectively separate magnesium and strontium mixed salts, the solid-liquid phase equilibria of the ternary system (NH4Cl–MgCl2–H2O) and quaternary system (NH4Cl–MgCl2–SrCl2–H2O) at 288.15 K have been determined by the methods of isothermal dissolution equilibrium. The phase diagram of the ternary system (NH4Cl–MgCl2–H2O) at 288.15 K contains two invariant points, three univariant curves, and three crystallization regions corresponding to NH4Cl, MgCl2·6H2O and double salt NH4Cl·MgCl2·6H2O. The phase diagram of the quaternary system (NH4Cl–MgCl2–SrCl2–H2O) has two invariant points, five invariant curves, four crystallization regions corresponding to NH4Cl, MgCl2·6H2O, SrCl2·6H2O, and double salt NH4Cl·MgCl2·6H2O. Due to the different dissolution behaviors of chloride salts in the aqueous systems, the component of MgCl2 has a relatively strong salting-out effect on other salts.