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

Abstract

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, MgCl2·6H2O, NH4Cl, and MgCl2·NH4Cl·6H2O, respectively. The system can guide the dehydration and deamination of ammonium carnallite to produce anhydrous magnesium chloride.

Solid–Liquid Phase Equilibria in the Ternary MgCl2–NiCl2–H2O System at 303–323 K

“…The solubilities of MgCl 2 and NiCl 2 in water at 303 K were determined to be 35.80 and 40.94%, respectively, which are in good agreement with the previously reported values of 35.90 20 and 41.60%. 21 Therefore, considering the temperature, the analysis method adopted in this experiment appears feasible.…”

Solid–Liquid Phase Equilibria of the Pb2+, Ca2+, Mg2+//Cl––H2O Quaternary System and Its Subsystems at 303.2 K

“…The isothermal dissolution method was used to analyze the equilibrium liquid phase density of the systems of Pb 2+ , Ca 2+ //Cl – –H 2 O, Pb 2+ , Mg 2+ //Cl – –H 2 O, and Mg 2+ , Ca 2+ //Cl – –H 2 O as well as the quaternary system of Pb 2+ , Mg 2+ , Ca 2+ //Cl – –H 2 O at 303.2 K. Initially, a mixed solution was prepared by combining substances which constitute the eutectic. Subsequently, another new salt was introduced and gradually added to the mixed solution covering different mass fractions ranging from 0 to saturation. − All samples were then placed in a constant-temperature bath and stirred for a minimum of 2 weeks. The mixed solution system was considered to reach equilibrium when the adjacent sampling analyses of the same sample were within 0.3%.…”

Investigation of Solid–Liquid Phase Equilibria of Mg2+, NH4+//Cl–, SO42–H2O at T = 303.15 K and P = 88.35 kPa

“…The whole experiment was carried out at the experimental temperature T = 303.15 ± 0.05 K and P = 88.35 kPa. The analysis method of each ion in the supernatant is as follows: , Mg 2+ content was determined by the EDTA method with an uncertainty of 0.005, Cl – content was determined using T860 automatic potentiometric titration apparatus (Hanon Instruments) with an uncertainty of 0.005, NH 4 + content was determined using an automatic Kjeldahl nitrogen determination analyzer (Shanghai Peo Analytical Instrument Co., Ltd.) with an uncertainty of 0.02, and SO 4 2– content was measured by the barium sulfate precipitation method with an uncertainty of 0.05 . At the same time, the density and viscosity (ρ, η) of the equilibrium supernatant obtained after standing were measured.…”