Liquid–solid equilibria in quinary system Na +,Mg 2+/Cl −,SO 42−,NO 3−–H 2O at 298.15 K

Abstract

In order to develop the nitrate deposits found close to Lop Nur in the Xinjiang region in China, the solubilities of the system Na +,Mg 2+/Cl −,SO 4 2−, NO 3 −–H 2O and its subsystems, the quaternary systems Na +,Mg 2+/SO 4 2−,NO 3 −–H 2O and Mg 2+/Cl −,SO 4 2−,NO 3 −–H 2O, were studied at 298.15 K. The phase diagrams were plotted according to the solubilities achieved. In the equilibrium phase diagram of Mg 2+/Cl −,SO 4 2−,NO 3 −–H 2O, there are two invariant points, five univariant curves and four regions of crystallization: Mg(NO 3) 2⋅6H 2O,MgCl 2⋅6H 2O,MgSO 4⋅7H 2O and MgSO 4⋅(1–6)H 2O. In the equilibrium phase diagram of Na +,Mg 2+/SO 4 2−, NO 3 −–H 2O, there are five invariant points, eleven univariant curves and seven regions of crystallization: Na 2SO 4,Na 2SO 4⋅10H 2O,NaNO 3,MgSO 4⋅Na 2SO 4⋅4H 2O,NaNO 3⋅Na 2SO 4⋅2H 2O,Mg(NO 3) 2⋅6H 2O and MgSO 4⋅7H 2O. In the equilibrium phase diagram of the Na +, Mg 2+/Cl −,SO 4 2−,NO 3 −–H 2O system, there are six invariant points, and ten regions of crystallization: NaCl, NaNO 3,Na 2SO 4,Na 2SO 4⋅10H 2O,MgSO 4⋅Na 2SO 4⋅4H 2O, NaNO 3⋅Na 2SO 4⋅2H 2O,MgCl 2⋅6H 2O,Mg(NO 3) 2⋅6H 2O, MgSO 4⋅(1–6)H 2O and MgSO 4⋅7H 2O.