溶剂萃取法制备钾盐结晶过程研究

发布时间：2018-03-02 12:38

  本文选题：KH_2PO_4　切入点：KCl　出处：《宁夏大学》2017年硕士论文　论文类型：学位论文

【摘要】：KH_2PO_4和K_2SO_4是钾盐工业的重要产品,广泛应用于工业、农业、食品、制药等行业。目前国内外KH_2PO_4多采用中和法生产,K_2SO_4多采用曼海姆法生产。溶剂萃取法是近些年新开发的钾盐生产工艺,具有能耗小,反应条件温和,产品纯度高等特点,具有广阔的发展前景。但溶剂萃取法生产KH_2PO_4和K_2SO_4的工艺不稳定、结晶产品品质不高。鉴于以上现状,本文在测定相平衡数据的基础上,优化结晶工艺,为工业优化该工艺奠定基础。首先,本文采用等温溶解平衡法测定了298.15K、313.15K,K_2SO_4-KCl-H_2SO_4-H_2O和KCl-KH_2PO_4-H_3PO_4-H_2O四元体系及其三元子体系的固-液相平衡及物性参数(密度、黏度),KCl-KH_2PO_4-H_2O三元体系在不同浓度(10%,30%,50%)下的乙醇溶液中的固-液相平衡及物性参数,绘制了相图,溶解度图,物性参数-组成图。采用经验公式对两个四元体系及其三元子体系298.15K、313.15K平衡液相的溶解度、密度和黏度进行了模拟计算。结晶工段作为重要的除杂步骤,优化冷却结晶工艺条件,探究杂质和溶析剂乙醇对KH_2PO_4结晶的影响至关重要。本文围绕制备高品质KH_2PO_4展开研究,考察了各工艺参数对KH_2PO_4结晶工艺的影响。获得最佳工艺条件为:搅拌速率300r/min,降温速率0.25℃/min,陈化时间30min,晶种质量1.01%,晶种目数100目。由于原料湿法磷酸中含有多种微量杂质离子,且杂质离子对KH_2PO_4晶核的生成及生长影响较大,因此,本文研究了掺杂两种含量不同的金属离子对KH_2PO_4结晶的影响。本文的研究成果为溶剂萃取法生产KH_2PO_4和K_2SO_4提供了基础数据,并为生产高品质KH_2PO_4等钾盐奠定了基础。
[Abstract]:KH_2PO_4 and K2SO4 are important products in the potash industry and are widely used in industry, agriculture, food, At present, KH_2PO_4 mostly uses neutralization method to produce K _ 2SO _ 4 by Mannheim method. Solvent extraction is a newly developed potassium salt production process in recent years, which has the characteristics of low energy consumption, mild reaction conditions and high purity of the product. The process of producing KH_2PO_4 and K _ 2SO _ s _ 4 by solvent extraction method is unstable and the quality of crystallization product is not high. In view of the above situation, the crystallization process is optimized on the basis of the determination of phase equilibrium data. First of all, the isothermal dissolution equilibrium method was used to determine the solid-liquid equilibrium and physical properties (densities) of the four component systems and their ternary subsystems of KCl-KH_2PO_4-H_3PO_4-H_2O and the KCl-KH_2PO_4-H_3PO_4-H_2O quaternary systems, which were determined by isothermal dissolution equilibrium method, and the isothermal dissolution equilibrium method was used to determine the solid-liquid equilibrium and the physical properties (densities) of the four component systems and their ternary subsystems. The solid-liquid equilibrium and physical parameters of the KCl-KH2PO4-H _ 2O ternary system in ethanol solution with different concentrations of 10 and 30 and 50. The phase diagram and solubility diagram are drawn. The solubility, density and viscosity of two quaternary systems and their ternary system 298.15K ~ 313.15K equilibrium liquid phase were simulated and calculated by means of empirical formula. As an important impurity removal step, the crystallization section was used to optimize the cooling crystallization process conditions. It is very important to explore the effect of impurities and ethanol on the crystallization of KH_2PO_4. This paper focuses on the preparation of high quality KH_2PO_4. The effects of various technological parameters on the crystallization of KH_2PO_4 were investigated. The optimum conditions were obtained as follows: stirring rate 300r / min, cooling rate 0.25 鈩，

本文编号：1556555