Study On Phase Equilibrium Of Na～+,K～+,NH₄～+‖NO₃～- Aqueous Salt System And Mixing Solvent System

The paper mainly considered the phase equilibrium of Na+ K+ NH4+ || NO3 -H2O system and correlative subsystem containing the additives. Firstly, the study is on the primary choose of additives and its influence on K+ || NO3~-H2O, NH4+ || NO3"-H2O, Na+ || NO3~-H2O systems. Secondly, some preliminary phase equilibrium study on the system K+ NH4+ || NO3~-H2O , K". NH4+ || NOr-NH3,H2O , K+ NH4+ || NO3~-CH3OH,H2O and Na+. K+. NH4+ || NO3 -H2O are presented. At last, the phase equilibrium model according to the statistic thermodynamics theory is predicted.By the determination of different additives influence on the crystal rules of the potassium nitrate, the primary selection to methanol, alcohol, acetone and ammonia is carried out. The results show that the methanol and ammonia have the best separation effect. At the same time, additives influence on the binary system expressed that the solubility of potassium nitrate and sodium nitrate all enhanced with the increase of methanol and ammonia concentration, and the solubility of ammonia nitrate decreases with the increase of methanol but rises with the increase of ammonia concentration.The study on the K\ NH4+ II NO3~-H2O showed that the graph contains the five crystal sections , which included the potassium nitrate, the ammonium nitrate, the potassium nitrate and solid solution, the ammonia nitrate and solid solution ,and the solid solution crystal sections. The result revised the past conclusion that this system is complete solid-solution area without the single crystal one, and also filled the blank of the system equilibrium data lacked.Choosing the ammonia and methanol as the additive, equilibrium studies of K\ NH4+ II NO3 -H2O system are conducted at the different additive concentration, which includes methanol concentration from 10%~60% and ammonia from 5%~25% ?The results show that the solid solution of system almost disappeared and the crystal section is mostly of KNO3's when the ammonia to 25% at 25癈, similarly when the ammonia to 20% at 10癈.In addition, the potassium nitrate and the ammonium nitrate separated completely and the solid solutiondisappeared when methanol concentration is greater than or equal to 50% at 10 "C. The calculation of the thermodynamics model on mixing solvent system indicated the predicted data satisfactorily correlates with the experiment ones.The phase equilibrium in the quaternary system of Na\ K+> NH/ II NC^-t^O at 10癈has been achieved by experiment. The phase diagram of this system has been made and it mainly consists of four crystallization regions, the potassium nitrate, the ammonia nitrate, the sodium nitrate and solid solution crystal sections. The experiment results supply the blank of this system.The results can be used in and afford the data and theoretical foundation for development of technology on the separation of KNOs...