Liquid–solid equilibria in quinary system Na+,Mg2+/Cl−,SO42−,NO3−–H2O at 298.15 K

In order to develop the nitrate deposits found close to Lop Nur in the Xinjiang region in China, the solubilities of the system Na+,Mg2+/Cl−,SO42−, NO3−–H2O and its subsystems, the quaternary systems Na+,Mg2+/SO42−,NO3−–H2O and Mg2+/Cl−,SO42−,NO3−–H2O, were studied at 298.15 K. The phase diagrams were plotted according to the solubilities achieved. In the equilibrium phase diagram of Mg2+/Cl−,SO42−,NO3−–H2O, there are two invariant points, five univariant curves and four regions of crystallization: Mg(NO3)2⋅6H2O,MgCl2⋅6H2O,MgSO4⋅7H2O and MgSO4⋅(1–6)H2O. In the equilibrium phase diagram of Na+,Mg2+/SO42−, NO3−–H2O, there are five invariant points, eleven univariant curves and seven regions of crystallization: Na2SO4,Na2SO4⋅10H2O,NaNO3,MgSO4⋅Na2SO4⋅4H2O,NaNO3⋅Na2SO4⋅2H2O,Mg(NO3)2⋅6H2O and MgSO4⋅7H2O. In the equilibrium phase diagram of the Na+, Mg2+/Cl−,SO42−,NO3−–H2O system, there are six invariant points, and ten regions of crystallization: NaCl, NaNO3,Na2SO4,Na2SO4⋅10H2O,MgSO4⋅Na2SO4⋅4H2O, NaNO3⋅Na2SO4⋅2H2O,MgCl2⋅6H2O,Mg(NO3)2⋅6H2O, MgSO4⋅(1–6)H2O and MgSO4⋅7H2O.