Phase Equilibria for the Aqueous Quinary System Li+, Na+, K+, Mg2+//Cl--H2O Saturated with NaCl•2H2O at 258.15 K

The phase diagram can guide the comprehensive utilizationof saltlake brine, particularly lithium extraction. In this paper, the studyon phase equilibria of the quinary system Li+, Na+, K+, Mg2+//Cl--H2O saturated with NaCl center dot 2H(2)O and its subsystemLi(+), Na+, Mg2+//Cl--H2O at 258.15 K were carried out using the isothermaldissolution equilibrium method. Based on the experimental data, equilibriumdiagrams for stable phases were plotted. For the equilibrium diagramof the quaternary system Li+, Na+, Mg2+//Cl--H2O at 258.15 K, thereare two invariant points, five univariant curves, and four crystallizationfields. The quinary system Li+, Na+, K+, Mg2+//Cl--H2O saturatedwith NaCl center dot 2H(2)O at 258.15 K contains three invariantpoints, seven univariant curves, and five crystallization fields.Comparing the phase diagram of the system at 258.15 K to that at 298.15K reveals that, except KCl, all crystallization zones have decreased,and LiCl center dot MgCl2 center dot 7H(2)O has the smallestcrystallization zone compared to the other salts in the systems. Thisfundamental research could be valuable for promoting comprehensiveutilization of the lithium-containing salt lake brine.