复分解法氯化铵生产中冷却结晶过程研究

Research on the cooling crystallization process of ammonium chloride by double decomposition reaction

研究了硝酸铵和氯化钾复分解法制取氯化铵的冷却结晶过程,考察了降温速率、搅拌速率、晶种添加量等因素对氯化铵产品的纯度及晶体粒度分布的影响。研究结果表明,采取适宜的降温速率、搅拌速率及适宜的晶种添加能有效地改善氯化铵晶体粒度,提高分离效果;氯化铵冷却结晶适宜操作条件为：降温速率为0.3 K/min、搅拌速率为350 r/min、添加晶种粒度为150-180μm、添加晶种量为1.88%,在此条件下制得的氯化铵产品晶体粒度均一性好,平均粒径更大。

The cooling crystallization process of ammonium chloride by the double decomposition reaction between ammonium nitrate and potassium chloride was studied.The effects of the cooling rate, agitation rate, and adding amount of crystal seed etc.on the purity and the particle size distribution of ammonium chloride product were investigated.Results showed that the particle size of ammonium chloride and separation efficiency could be improved effectively, with proper cooling rate, stirring rate, and crystal seed adding amount.The optimum operation conditions were as follows： cooling rate was 0.3 K/min, agitation rate was 350 r/min ,particle size of crystal seed was 150-180μ m, and quantity of crystal seed was 1.88%.Under these conditions, the ammonium chloride crystals will get bigger and evener particle size.