The Crystallization Behavior Of Potassium Dihydrogen Phosphate And Its Application In The Post-polyester Purification Process

Adopt recrystallization method to study the crystallization behavior of potassium dihydrogen phosphate in water solution studied the different factors of agitation rate,cooling rate,pH value and metal ion doping on the metastable zone width,the crystallion rate,crystal morphology and crystal particle size.The crystallization process of potassium dihydrogen phosphate in aqueous solution crystallization process were studied.Under the optimum process condition,making the paiticle size large and distribution uniform,the crystallization process of optimization application to the polyether polyols post-processing refining process can obviously shorten the polyether post-processing refining period,improve the efficiency of polyether production.The experiment shows that with the increase of agitation rate,the metastable zone width and the induction period were decrease;when the agitation rate was 3 00r/min,the crystallization rate of the minimum was 0.43 g/min with the cooling rate and the pH value of solution constant.With the increase of cooling rate,the metastable zone width increased,the induction period and average particle decreased;when the cooling rate was 0.3?/min,the average particle size of crystal biggest was 530.21?m;When the pH was 3.0,the metastable zone width and induction rate were minimize,the crystallization rate of maximum was 1.3g/min.In the process of KDP crystallization,control the agitation rate was 200 r/min,the cooling rate was 0.3 ?/min,the pH value of the solution were 3.0,making the KDP crystal particles large and the particle size was 530.21?m,it also effectively prevent the vug.This paper studies the process of potassium dihydrogen phosphate crystallization in the actual production of the polyether post-processing technique,The crystallization technology of filtration alkali catalyst from different molecular weight of polyether emulsion was optimized by neutralization,crystallization of potassium dihydrogen phosphate,vacuum filtering,and so on.when the Na +/K + was 1:1,control the agitation speed on 90?110 r/min and the pH in 3?4,can get dihydrogen phosphate salt crystals with uniform particle size distribution and particle larger particle;the average content of potassium and sodium of the refined polyether were 2.6 ppm and 2.2 ppm,the sum of sodium and potassium ion content less than 5 ppm of now industry requirements;The crystallization products particles of Potassium dihydrogen phosphate and sodium dihydrogen phosphate were larger,and has formed a good bridging effect,the crystallization solution with low viscosity and filtration speed,it can significantly shorten the filter time of polyether post-processing,and increased the productivity of the polyether after refining process.The optimization of the Polyether post-processing crystallization process has positive significance to the actual production process.