Simulation studies on metastable phase equilibria in the aqueous ternary systems (NaCl-MgCl2-H2O) and (KCl-MgCl2-H2O) at 308.15 K

The solubilities and densities of the aqueous metastable ternary systems (NaCl-MgCl2-H2O) and (KCl-MgCl2- H2O) at 308.15 K were determined by the isothermal evaporation method. On the basis of the experimental results, the phase diagrams for those systems were plotted. It was found that the former system belongs to the hydrate-I type with one invariant point of (NaCl + MgCl2·6H2O), two univariant curves, and two crystallization regions corresponding to halite (NaCl) and bischo.te (MgCl26H2O); and the latter system belongs to the type of incongruent-double salts with two invariant points of (KCl + KCl·MgCl26H2O) and (MgCl2 ·6H2O + KCl·MgCl2 ·6H2O), three univariant curves, and three crystallization regions corresponding to potassium chloride (KCl), carnallite (KCl·MgCl2·6H2O) and bischofite (MgCl2·6H2O). No solid solutions were found in both systems. © Higher Education Press and Springer-Verlag GmbH 2009.