添加晶种对磷酸二氢钾结晶特性的影响

Effect of seeding on characteristics of potassium dihydrogen phosphate crystallization

采用间歇结晶法研究了磷酸二氢钾的添加晶种结晶,考察了添加晶种时的搅拌速率、温度以及添加的晶种粒度、晶种量对结晶产品粒度分布和平均粒径的影响,并与自发成核结晶进行了比较。实验结果表明:添加晶种结晶能有效改善产品粒度分布、增大平均粒径。添加晶种时适宜的结晶条件为:搅拌速率150r/min,温度70℃,晶种粒度40!60目,晶种量1%。产品粒径大于40目的晶体累计质量分数达84.23%,平均粒径为645.37μm。相比自发成核结晶,粒径大于40目的晶体累计质量分数增加了22.46%,平均粒径增大了约100μm。

Crystallization of potassium dihydrogen phosphate （KDP） with seed added was studied by adopting the batch crys- tallization experiment. In the experiment, the impacts of stirring rate and temperature at the time of adding seed, seed size, seed amount on the crystal size distribution （CSD） and average size were investigated. The experimental results indicate that the product with seed added shows better CSD and larger average size. Under the optimum conditions of stirring rate of 150 r/min, temperature of 70 ℃, seed size of 40~60 mesh, seed amount of 1%, the cumulative mass fraction of the crystal size over 40 mesh can be as high as 84. 23% and the average size is 645. 37μm. Compared with the spontaneous nucleation crystallization, the cumulative mass fraction of the crystal size over 40 mesh in- creased by 22.46%, the average size increased about 100 μm.