Studies On The Metastable Phase Equilibria Of The Quinary System K⁺,Rb⁺,Cs⁺,Mg²⁺//Cl^--H₂O At 298K And Its Partial Subsystems At Multi-temperature

The metastable phase equilibria of the quinary system K⁺,Rb⁺,Cs⁺,Mg²⁺//Cl^--H₂O at 298 K,quateranary subsystems K⁺,Cs⁺,Mg²⁺//Cl^--H₂O at 298 K,323 K and348 K and quateranary subsystem Rb⁺,Cs⁺,Mg²⁺//Cl^--H₂O at 298 K,323 K were studied using an isothermal evaporation method.The solubility,density and refractive index of the equilibrium solution were measured,and through the experimental data to draw the quinary system of the spatial three-dimensional map,plane projection,water content and physical and chemical properties–composition;Phase diagrams,magnified graphs,water content maps,and physicochemical properties–composition of two quaternary subsystems.The system K⁺,Cs⁺,Mg²⁺//Cl^--H₂O at 298 K,323 K and 348 K is of a complex quaternary system,with complex salt potassium carnallite?KCl.MCl Cl₂.6H₂O?,cesium carnallite?Cs Cl.Mg Cl₂.6H₂O?and solid solution?K,Cs?Cl.The complex system at 298 K,323 K and 348 K is the metastable phase diagram by 4 covariance,9univariate curves and 6 crystal regions.Comparing the metastable phase diagram at298 K,323 K and 348 K,the crystal form of single salt,double salt and solid solution are not changed at all temperature conditions,however,the size of crystal region is changed.With the increase of temperature,the solid solution?K,Cs?Cl is decreased,and the contents of single salt KCl,Cs Cl,Mg Cl₂.6H₂O and carnallite KCl.Mg Cl₂.6H₂O and Cs Cl.MCl Cl₂.6H₂O were increased.The results show that the temperature of the solution is favorable for the seperating of KCl salt during the constant temperature evaporation process.The system Rb⁺,Cs⁺,Mg²⁺//Cl^--H₂O at 298 K and 323 K is of a complex quaternary system,with complex salt potassium carnallite?Rb Cl.MCl Cl₂.6H₂O?,cesium carnallite?Cs Cl.Mg Cl₂.6H₂O?and solid solution?Rb,Cs?Cl.The complex system at 298 K and 323 K is the metastable phase diagram by 4 covariance,9univariate curves and 6 crystal regions.Comparing the metastable phase diagram at298 K and 323 K,the crystal form of single salt,double salt and solid solution are not changed at all temperature conditions,but the size of crystal region is changed.With the increase of temperature,the solid solution?Rb,Cs?Cl is decreased,and the contents of single salt Rb Cl,Cs Cl,Mg Cl₂.6H₂O and carnallite Rb Cl.Mg Cl₂.6H₂O and Cs Cl.MCl Cl₂.6H₂O were increased.The results show that the temperature of the solution is favorable for the seperating of Rb Cl salt during the constant temperature evaporation process.The quinary system K⁺,Rb⁺,Cs⁺,Mg²⁺//Cl^--H₂O at 298 K is of complex type,with three carnallite type double salts are K-carnallite?KCl.Mg Cl₂.6H₂O?,Cs-carnallite?Cs Cl.Mg Cl₂.6H₂O?,and three solid solution?K,Cs?Cl,?K,Rb?Cl and?Rb,Cs?Cl formed.The spatial stereogram of the system at 298 K contains 11 single salt,carnallite and solid solution of the crystalline phase region;24 univariate curves and10 invariant point.11 crystalline forms of salts correspond to four single salts bischofite?Mg Cl₂.6 H₂O?,rubidium chloride?Rb Cl?,cesium chloride?Cs Cl?and potassium chloride?KCl?,three carnallite type double salts KCl.Mg Cl₂.6H₂O,Cs Cl.Mg Cl₂.6H₂O and Rb Cl.Mg Cl₂.6H₂O,and three solid solutions?K,Cs?Cl,?K,Rb?Cl and?Rb,Cs?Cl.