Coupling Kinetics Study on Extractive Crystallization of Potassium Sulfate Prepared in Fluidized Bed Crystallizer

Abstract This work presents a novel approach for the growth of potassium sulfate (K 2 SO 4 ) from supersaturated solutions by reaction-extractive crystallization in a fluidized-bed crystallizer (FBC), in which K 2 SO 4 is transformed into potassium chloride and sulfuric acid based on a reactive extraction-crystallization process using triisooctylamine (TOA) in n -octanol as the extraction system. This paper uses the moment transformation method to solve the population balance equations of K 2 SO 4 in the extractive crystallization process, and the crystallization kinetic parameters are obtained by nonlinear regression. The kinetic equations of crystal nucleation, growth, and agglomeration rate in the crystallization process of potassium sulfate are determined, and experiments verify the reliability of the kinetic parameters. The results show that in a specific range, higher supersaturation and fluidization rate are conducive to the nucleation, growth, and aggregation of K 2 SO 4 . Suspension density promotes crystal nucleation and growth but has the opposite effect on accumulation. At the same time, based on the constant calculation equation of particle number and the constant calculation equation of mass, the extraction crystallization coupling mathematical model of the crystal in the fluidization state is established. The effects of suspension density, Reynolds number, extraction rate, feeding rate, and extraction concentration on potassium sulfate’s nucleation, growth, and aggregation rate were studied by combining model calculation with experimental research. A process coupling model of the potassium sulfate extraction crystallization process in a fluidized bed was proposed. The model agrees with the experimental results, which have specific guiding significance for industrial production.