三水磷酸氢二钾结晶工艺研究

Crystallization Process of Dipotassium Hydrogen Phosphate Trihydrate

绘制了磷酸氢二钾溶解度和饱和溶液质量分数与温度的关系曲线及70℃下磷酸氢二钾溶液质量分数与密度的关系曲线。采用间歇实验法研究了搅拌速率、pH值、降温方式、磷酸氢二钾溶液质量分数和结晶终点温度对三水磷酸氢二钾结晶过程的影响。结果表明:随着搅拌速率、降温速率、结晶终点温度的降低和磷酸氢二钾溶液质量分数的增大,晶体平均粒径逐渐增大;自然冷却所得晶体的平均粒径较大;pH值为8.7左右时的结晶得率最高。

The relationship curves between the solubility or mass fraction of dipotassium hydrogen phosphate saturated solution and the temperature were plotted.The relationship curve between the mass fraction of dipotassium hydrogen phosphate solution and the density at 70 ℃ was plotted.Effects of stirring rate,pH value,cooling methods,mass fraction of dipotassium hydrogen phosphate and the end point crystallization temperature on crystallization process of dipotassium hydrogen phosphate trihydrate were studied by a batch experiment.Results showed that,with the decrease of stirring rate,cooling rate,and the end point crystallization temperature,the increase of mass fraction of dipotassium hydrogen phosphate solution,the average particle size of the crystals gradually increased.The average particle size of the crystals obtained by natural cooling was larger than that by other methods.When the pH value was 8.7,the crystal yield was the highest.