Sichuan Provincial Key Laboratory

Chengdu, China

Sichuan Provincial Key Laboratory

Chengdu, China

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Zeng Y.,Chengdu University of Technology | Zeng Y.,Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions | Cao F.,Chengdu University of Technology | Li L.,Sichuan Provincial Key Laboratory | And 2 more authors.
Journal of Chemical and Engineering Data | Year: 2011

The quaternary system (Li2SO4 + Na2SO 4 + Li2B4O7 + Na2B 4O7 + H2O) is one of the most important and basic subsystems of the brines located in the area of the Qinghai-Xizang (Tibet) Plateau. To make certain the solubility of the lithium, sodium, and borate changes with the temperature, the metastable equilibrium of the quaternary system (Li2SO4 + Na2SO4 + Li 2B4O7 + Na2B4O 7 + H2O) was investigated at 273.15 K using an isothermal evaporation method. The solubilities of the equilibrated solution were measured using chemical analytical methods. The crystalloid forms of the solid phase were determined using an X-ray diffraction method. This system is of a complex type, with a double salt of sodium and lithium sulfate (3Na2SO 4·Li2SO4·12H2O) formed at 273.15 K. The phase diagram of this system consists of three invariant points, seven univariant curves, and five crystallization fields. Comparisons between the phase diagrams of this system at 273.15 K and at 288.15 K show that the crystallization forms and the size of crystallization field of salt have changed. The solubility of salt sodium borate changes with temperature more obviously than that of salt lithium borate. Thus, the crystallization area of Na2B4O7·10H2O becomes bigger obviously, whereas the crystallization area of salt LiBO2· 8H2O becomes smaller at 273.15 K. This difference is beneficial to separate sodium and lithium using an evaporation method, and a rise in temperature is necessary to obtain more lithium borate from the solution. © 2011 American Chemical Society.


Yu X.,Chengdu University of Technology | Zeng Y.,Chengdu University of Technology | Zeng Y.,Institutions of Sichuan Province | Yao H.,Chengdu University of Technology | Yang J.,Sichuan Provincial Key Laboratory
Journal of Chemical and Engineering Data | Year: 2011

The solubilities and physicochemical properties such as density and refractive index of the solution in the ternary systems KCl + MgCl 2 + H 2O and KCl + RbCl + H 2O were investigated at 298.15 K using an isothermal evaporation method. The crystalloid forms of the solid phase were determined using chemical analysis and an X-ray diffraction method. On the basis of experimental data, the metastable equilibrium phase diagrams and the physicochemical properties vs composition in the ternary systems at 298.15 K were constructed. In the metastable phase diagram of the ternary system KCl + MgCl 2 + H 2O at 298.15 K, there are two invariant points, three univariant curves, and three crystallization fields corresponding to potassium chloride (KCl), magnesium chloride hexahydrate (MgCl 2·6H 2O), and a double salt carnallite (KCl·MgCl 2·6H 2O). In the metastable phase diagram of the ternary system KCl + RbCl + H 2O, there are two invariant points and three crystallization fields corresponding to the single salts potassium chloride (KCl), rubidium chloride (RbCl), and a solid solution of potassium and rubidium chloride [(K, Rb)Cl]. Comparisons between the metastable phase diagrams at 298.15 K and at 323.15 K show that the crystallization forms have not changed, while the crystallization zones have slight changes. The calculated densities and refractive indices using an empirical equation have the maximum relative error < 0.016. © 2011 American Chemical Society.

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