Solid-Liquid Phase Equilibria of NaCl-NH4Cl-MgCl2-H2O and Its Subsystems NaCl-NH4Cl-H2O and NaCl-MgCl2-H2O at T=303.15 K

摘要

In this work, the phase equilibrium solubility data of a quaternary system NaCl-NH4Cl-MgCl2-H2O and its two ternary subsystems (NaCl-NH4Cl-H2O and NaCl-MgCl2-H2O) were measured by an isothermal solubility equilibrium method and a wet slag method. For the two ternary subsystems (NaCl-NH4Cl-H2O and NaCl-MgCl2-H2O), the solubility of the equilibrium liquid phase and physical properties (density and viscosity) are determined: this system is simple, contains a cosaturated point and three crystalline regions, and the solubility experiment data is compared with the literature values, fitting the invariant point under different temperatures. It can provide basic data for a brine system containing ammonium chloride, sodium chloride, magnesium chloride, and so on. The solubility of the quaternary system NaCl-MgCl2-NH4Cl-H2O was measured by an isothermal method, and the corresponding phase diagrams were drawn. From the phase diagrams, it is found that there are two cosaturated points and four solid-phase crystalline zones; the solid-phase crystallization region corresponds to NaCl, MgCl2 center dot 6H(2)O, NH4Cl, and MgCl2 center dot NH4Cl center dot 6H(2)O, respectively. The system can guide the dehydration and deamination of ammonium carnallite to produce anhydrous magnesium chloride.