Stable Phase Equilibrium of the Quinary Water-Salt System Li+, Na+, Rb+, Mg2+ // So42- - H2o At T = 298.2 K

Abstract

Lithium, rubidium, and magnesium are the elements with high development value found in the salt lake in the Qaidam Basin. Isothermal dissolution method was used to study the phase equilibrium of the quinary system Li+, Na+, Rb+, Mg2+ // SO42- - H2O at T = 298.2 K to develop and utilize valuable components in salt lakes and enrich thermodynamic data. Based on the experimental data, a series of diagrams were created. The results indicate that its space diagram consists of 9 crystalline regions, 21 isothermal dissolution curves and 7 four-salt co-saturation invariant points at T= 298.2 K. The quinary system ( Li+, Na+, Rb+, Mg2+ // SO42- - H2O at T = 298.2 K) produced five different double salts (3Na2SO4·Li2SO4·6H2O, Li2SO4·Na2SO4, 3Li2SO4·Rb2SO4·2H2O, Rb2SO4·MgSO4·6H2O), however, no double salt is created when lithium and magnesium or sodium and rubidium interact. The crystal area of the double salt Rb2SO4·MgSO4·6H2O is the greatest in the phase diagram of sodium sulfate saturation, while the crystal area of Li2SO4·H2O is the smallest in the phase diagram of magnesium sulfate saturation. The article concentrates on lithium loss during recovery. The experimental data and research is beneficial for bittern industrial and developing a process for efficient separation and utilization of lithium and rubidium at that stage.

Keywords: lithium sulfate, rubidium sulfate, stable phase diagram, water-salt system.