Study On The Analysis Of The Carbonate And The Metastable Properties Of Borate In Boron-containing Carbonate Brine

It is of great significance to study the basic physical and chemical properties of carbonate type brine for comprehensive utilization of resources.Due to the analysis interference from borates and carbonates in brine,there is no suitable method to determine the concentration of CO₃^2-and HCO₃^-accurately in boron containing systems.The related fundamental researches stay in brine without boron,and the results were unsuitable for the boron-containing brine.Besides,the studies on the crystallization kinetics of borates were also focused on the sulfate and chloride brine,and the studies on carbonate brine were in its infancy,which brings lots of inconvenience to subsequent research and development.Based on the existing research,we build a new method by combination classical titration?double indicators method?with spectrophotometry and infrared absorption spectroscopy methods to build a new method.The method can satisfy the concentration of CO₃^2-and HCO₃^-accurately determined.Besides,we measured the metastable zone width of borax in carbonate type simulated brine.Our studies provided the basic data and theoretical basis for the further research and development.Specifically,the results of dissertation are:?1?We combined spectrophotometry and titration to determine the accurate concentration of CO₃^2-and HCO₃^-,respectively.The conditions of spectrophotometry for the determination of total inorganic carbon concentration were carefully studied.The results showed that relative standard deviations were within±5%,and the recoveries were within 100%±7%.The method can determine the concentrations of CO₃^2-and HCO₃^-in boron containing systems.But it also has some shortcomings such as narrow linear range and low sensitivity.?2?Chemical titration and infrared spectroscopy were combined.The linear range was 0?0.5 mol/L,the relative standard deviations were within±4%and recoveries were about 100%±10%.Compared with the titration-spectrophotometry,the method has advantages of wide linear range,strong anti-interference ability,high accuracy and precision.In conclusion,the method can satisfy the determination of CO₃^2-and HCO₃^-in boron containing carbonate type brine.?3?The solubility data of borax in Na⁺//Cl^-,SO₄^2-,B₄O₇^2--H₂O systems were measured by dynamic equilibrium method.The results showed that the order of influence of coexisting salts on the solubility of borax was Na₂CO₃>Na₂SO₄>Na Cl,and Na Cl+Na₂CO₃>Na₂SO₄+Na₂CO₃.The changes of the solubilities were explained according to the related thermodynamic parameters.?4?The metastable zone width of borax in Na⁺//Cl^-,SO₄^2-,B₄O₇^2--H₂O systems were measured.The results showed that the metastable zone width widens with the increase of cooling rate;and narrows with increasing concentration and temperature.The order of the influence was Na₂CO₃>Na₂SO₄>Na Cl in single salt,and Na₂CO₃+Na₂SO₄>Na₂CO₃+Na Cl in double mixed system.The width of the zone is analyzed by the self-consistent equation and the classical nucleation equation,and the variation law of the width of the zone is explained by the related nucleation parameters.