Phase Equilibria Of The Quinary System And Its Subsystems Containing Lithium,Sodium,Potassium,Chloride And Borate Ions

As the economy develops faster and faster,person's demand for resources become higher and higher.With the depletion of solid mineral deposits,people begin to turn their attention to the development and utilization of liquid mineral deposits.That is,the development and utilization of salt lake resources.The phase diagram of water and salt system plays an important role in salt deposition,transformation,separation and extraction.In this paper,the isothermal solution equilibrium method was used to study the phase equilibrium of the quinary system(Li+,Na+K+Cl-,BO2--H2O),two quaternary systems and two ternary systems at 298.15K.The solubility data and physicochemical property data were obtained.Based on the obtained data,the corresponding phase diagram,water diagram and physicochemical property versus composition diagram were drawn and the solid phase was identified:The ternary system(Li+,K+//BO2--H2O)is a simple co-saturated type at 288.15 K and 298.15 K,there is no double salt and solid solution format.At both temperatures,there was one co-saturation point(LiBO2·8H2O+KBO2·1.33H2O)and two single salt crystallization zones.The equilibrium solid phase was LiBO2·8H2O and KBO2·1.33H2O,respectively.With the increase of temperature,the solubility of the two salts increases and the crystalline phase area decreases.At both temperatures,the physicochemical properties of the liquid phase changed regularly with the increase of KBO2·1.33H2O content.The refractive index and density values of the liquid phase were fitted by empirical formulas,and the experimental values were in good agreement with the calculated values.At 298.15K,the quaternary system(Li+,K+//Cl-,BO2--H2O)was composed by three co-saturation points(LiCl+KCl+LiBO2·2H2O5 LiBO2·8H2O+KCl+KBO2·1.33 H2O,KCl+LiBO2·2H2O+LiBO2·8H2O),seven univariate solubility curves,and five single salt crystallization zones.The five single salt crystallization zones were divided into KCl,KBO2·1.33H2O,LiBO2·8H2O,LiBO2·2H2O,and LiCl·H2O.The crystallization region of LiBO2·8H2O is the largest,indicating that the salt is most easy to crystallize.The density and refractive index of J(H2O)in the equilibrium liquid phase changed regularly with the increase of the content of J(K+).At 298.15K,the quaternary system(Na+,K+//Cl-,BO2--H2O)was composed of three co-saturation points(KBO2·1.33H2O+NaBO2·4H2O+KCl,NaCl·NaBO2·2H2O+NaCl+KCl,NaBO2·4H2O+NaCl·NaBO2·2H2O+KCl),seven univariate solubility curves and five single-salt crystal-lization zones.Corresponding into KCl,KBO2·1.33H2O,NaBO2·4H2O,NaCl·NaBO2·2H2O and NaCl.The density and refractive index of J(H2O)in the equilibrium liquid phase changed regularly with the increasing of the content J(Cl-).For the quinary system(Li+,Na+,K+//Cl-,BO2--H2O)at 298.15 K,there are five co-saturation points,corresponding to LiCl·H2O+NaCl+LiBO2·2H2O+KCl,NaCl+KCl+LiBO2·2H2O+NaCl-NaBO2-2H2O,LiBO2·8H2O+NaCl·NaBO2·2H2O+KCl+LiBO2·2H2O,NaBO2·4H2O+LiBO2·8H2O+KCl+NaCl·NaBO2·2H2O,KBO2·1.33H2O+NaBO2·4H2O+KCl+LiBO2·8H2O,respectively.It was composed of eleven univariate curves and seven single salt crystallization zones,corresponding to KBO2·1.33H2O,NaBO2·4H2O,NaCl,NaCl-NaBO2·2H2O,LiCl·H2O,LiBO2·8H2O,and LiBO2·2H2O.The J(H2O)in the equilibrium liquid phase changed regularly with the increase of the content of J(Cl-).