Study On Crystallization Process Of Ammonium Chloride In System Of K⁺、NH₄⁺//Cl^-、NO₃^-—H₂O

In many areas,such as industry、agriculture、food industry、pharmaceutical industry, etc. Ammonium chloride as an important inorganic has a wide range of use. There are several ways of producting ammonium chloride, such as Union soda、legitimate、 metathesis method, etc. More than 90% of Ammonium chloride is producted from Union soda. In recent years, the way of metathesis method potassium chloride and ammonium nitrate through which product potassium nitrate and Ammonium chloride is becoming the mainstream technology because of cheap and readily available raw materials, low investment and pollution, but the extraction of byproduct ammonium chloride has a greater impact on the yield and quality of nitrate. There are problems of low nitrogen content, high potassium content in the product ammonium chloride, small particle size, uneven distribution, the low yield, difficult to separate in the actual production process. In this thesis, combining the relationship of the ratio of the actual solution from metathesis method for the production of ammonium chloride, we studies crystallization of ammonium chloride to provide a reference for process optimization of the production process.Firstly, this paper by studying the process of evaporation and crystallization of ammonium chloride solution explore the relationship between the temperature of and chloride yield and purity.The results show that with the increase of the rate of evaporation, Ammonium chloride and potassium content yields were all increased. Determination of the suitability of the evaporation rate of about is 56% -60%, and the cooling temperature is 60℃, which is the basis for subsequent experiments. Secondly we study the effect of impurities substance as potassium nitrate, ammonium nitrate, Sodium nitrate on the solubility of ammonium chloride in aqueous solution and use the empirical equations for the fitting. Beside we used intermittent dynamic method to measure crystallization kinetics data of ammonium chloride cooling crystallization process in an aqueous solution. The experimental results show that Ammonium chloride in water cooling crystallization process is in line with the growth of linearly independent, using least squares regression,we obtained nucleation and growth kinetics equation of chloride cooling crystallization process, and analyzes the impact of various factors on the crystallization process Ammonium chloride.Through the study of Ammonium chloride crystallization kinetics evaporation rate equation, we determine the optimal conditions of production and provide theoretical guidance for the production of ammonium chloride by metathesis method process parameters.