Solid–liquid equilibrium in the aqueous system containing the chlorides of lithium, rubidium and magnesium at 323 K

The densities, refractive indices and compositions of solutions of electrolyte mixtures in quaternary system LiCl + RbCl + MgCl2 + H2O at 323 K were determined by isothermal evaporation method. The stereo phase diagram, the metastable phase diagram, the water content diagram, and the diagrams of the physicochemical properties depending on the composition were obtained using the measured data. The metastable phase diagram of this quaternary system contains three invariant points (H1, H2, and H3), seven univariant curves, and five crystallization fields corresponding to single salts lithium chloride monohydrate (LiCl·H2O), rubidium chloride (RbCl), magnesium chloride hexahydrate (MgCl2·6H2O), and two double salts: lithium carnallite (LiCl·MgCl2·7H2O) and rubidium carnallite (RbCl·MgCl2·6H2O). The scope of areas of crystallization of salts is such that RbCl·MgCl2·6H2O > RbCl > LiCl·H2O > MgCl2·6H2O > LiCl·MgCl2·7H2O. The physicochemical properties of the solutions, at equilibrium, change regularly with the change of the concentration of MgCl2.