Studies On Equilibria And Uncertainty Of The Quinary System Na⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O And Its Subsystems At 323 K

The underground brine of Northeast Sichuan,Eastern Sichuan,central Sichuan and Western Sichuan in Sichuan basin is rich in strontium and is important liquid strontium resources.In order to develop and utilize the strontium resources,it is necessary to study on phase equilibria and uncertainty of the quinary system Na⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O and its subsystems at 323 K.The first,it is to provide the basic phase equilibrium data for the exploitation and utilization of the brine resources;the second,it can be used to predict the equilibrium law of the geochemical phase of the brine.Studies on earth scientific research,the phase diagrams are mainly used to determine the migration and enrichment of elements,the stable existence of mineral rocks in the crust and mantle and the temperature,pressure,composition range,physical and chemical conditions of mineralization,physical and chemical conditions of metamorphism and so on.The phase diagrams can not only infer the equilibrium state of a stationary system,but also reflect the balance of a system in the above changes.Therefore,the research results of the multi temperature phase equilibrium and phase diagram can reveal the dynamic solid-liquid equilibrium process of the underground brine,design and calculate the process according to the phase diagram,make the optimal technical route,and guide the exploitation and utilization of the underground brine resources.With the development of phase equilibrium research,the reliability of experimental data has become a problem that can not be ignored.The measurement result is an estimate of the true value of the measurement.Although it is sometimes the best estimate,it is not the true value.Therefore,the evaluation of uncertainty of measurement results is becoming more and more important.Based on this,the uncertainty of solubility data and density of some strontium subsystems in the quinary system Na⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O at 323 K were done.The experimental studies on phase equilibria in the quinary system Na⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O at 323 K were done by the method of isothermal solution saturation.It includes three ternary systems:K⁺,Sr²⁺//Cl^--H₂O;Na⁺,Sr²⁺//Cl^--H₂O;Ca²⁺,Sr²⁺//Cl^--H₂O.It includes three quaternary systems:Na⁺,Ca²⁺,Sr²⁺//Cl^--H₂O;Na⁺,K⁺,Sr²⁺//Cl^--H₂O;K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O.In the studies of the quinary system Na⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O,it will be discussed with potassium chloride saturation and sodium chloride saturation.The phase diagrams,density-composition diagrams and water contents of saturated solutions diagrams were plotted based on the experimental data.The discussion of the experimental results is described.The ternary system K⁺,Sr²⁺//Cl^--H₂O belongs to a simple co-saturated type at323K,and without complex salt and solid solution.It can be seen from the phase diagram that there are two univariate curvesand,one invariant point,and two single salt crystallization zones?SrCl2·6H2O,KCl?.The invariant point corresponds to the solution saturated with the salts SrCl2·6H2O and KCl with mass fraction?100w?:w?KCl?=6.52%,w?SrCl₂?=40.70%.The ternary system Na⁺,Sr²⁺//Cl^--H₂O belongs to a simple co-saturated type at323 K,and without complex salt and solid solution.It can be seen from the phase diagram that there are two univariate curvesand,one invariant point,and two single salt crystallization zones?SrCl₂·6H₂O,NaCl?.The invariant point corresponds to the solution saturated with the salts SrCl₂·6H₂O and NaCl with mass fraction?100w?:w?NaCl?=3.73%,w?SrCl₂?=39.31%.The ternary system Ca²⁺,Sr²⁺//Cl^--H₂O belongs to a complex saturation with solid solution at 323 K,and no chemical compound salt is formed.In the experiment,the solid phase was determined by XRD.It can be seen from the phase diagram that there are three invariant points.The three invariant points correspond to the solution saturated with the salts solid solution based on calcium salt+CaCl2·2H2O,solid solution based on strontium salt+solid solution based on calcium salt,solid solution based on strontium salt+SrCl₂·6H₂O.The quaternary system Na⁺,K⁺,Sr²⁺//Cl^--H₂O belongs to a simple co-saturated type at 323 K,and without complex salt and solid solution.It can be seen from the phase diagram that there are three univariate curves and one invariant point,and three single salt crystallization zones?NaCl,KCl,SrCl2·6H2O?.The invariant point corresponds to the solution saturated with the salts NaCl,KCl and SrCl2·6H2O with mass fraction?100w?:w?NaCl?=3.05%,w?KCl?=6.32%,w?SrCl₂?=37.84%.The quaternary system Na⁺,Ca²⁺,Sr²⁺//Cl^--H₂O belongs to a complex saturation with solid solution at 323 K,and no chemical compound salt is formed.It can be seen from the phase diagram that there are seven univariate curves and,three invariant point,and five single salt crystallization zones?NaCl,CaCl2·2H2O,solid solution based on calcium salt,solid solution based on strontium salt,SrCl₂·6H₂O?.The three invariant points correspond to the solution saturated with the salts solid solution based on calcium salt+CaCl2·2H2O+NaCl,solid solution based on strontium salt+solid solution based on calcium salt+NaCl,solid solution based on strontium salt+SrCl₂·6H₂O+NaCl.The quaternary system K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O belongs to a complex saturation with solid solution at 323 K,and no chemical compound salt is formed.It can be seen from the phase diagram that there are seven univariate curves and,three invariant point,and five single salt crystallization zones?KCl,CaCl2·2H2O,solid solution based on calcium salt,solid solution based on strontium salt,SrCl₂·6H₂O?.The three invariant points correspond to the solution saturated with the salts solid solution based on calcium salt+CaCl2·2H2O+KCl,solid solution based on strontium salt+solid solution based on calcium salt+KCl,solid solution based on strontium salt+CaCl₂·2H₂O+KCl.The quinary systemNa⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O?saturated with KCl?at 323 K is studied.It can be seen from the phase diagram that there are seven univariate curves and,three invariant point,and five single salt crystallization zones?CaCl2·2H2O,SrCl2·6H2O,NaCl,solid solution based on calcium salt,solid solution based on strontium salt?.The three invariant points correspond to the solution saturated with the salts CaCl2·2H2O+NaCl+KCl+solid solution based on calcium salt,solid solution based on strontium salt+NaCl+KCl+solid solution based on calcium salt,SrCl2·6H2O+NaCl+KCl+solid solution based on strontium salt.The quinary system Na⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O?saturated with NaCl?at 323 K is studied.It can be seen from the phase diagram that there are seven univariate curves,three invariant point,and five single salt crystallization zones?CaCl2·2H2O,SrCl2·6H2O,NaCl,solid solution based on calcium salt,solid solution based on strontium salt?.The three invariant points correspond to the solution saturated with the salts CaCl2·2H2O+NaCl+KCl+solid solution based on calcium salt,solid solution based on strontium salt+NaCl+KCl+solid solution based on calcium salt,SrCl2·6H2O+NaCl+KCl+solid solution based on strontium salt.Based on the studies on phase equilibria in the quinary system Na⁺,K⁺,Ca²⁺,Sr²⁺//Cl^--H₂O at 323 K,uncertainties of experimental data were done by the method of GUM.Studies on the uncertainty of density in the phase equilibrium,the calculation method of uncertainty of solution density is established.The calculation method of the uncertainty of SrCl₂ and KCl in the system KCl-SrCl₂-H₂O is established.The phase diagram and density-composition diagram with uncertainty were plotted.The calculation method of the uncertainty of SrCl₂ and NaCl in the system NaCl-SrCl2-H2O is established.The phase diagram and density-composition diagram with uncertainty were plotted.The calculation method of the uncertainty of SrCl₂,KCl and NaCl in the system NaCl-KCl-SrCl2-H2O is established.The phase diagram and density-composition diagram with uncertainty were plotted.