2022 Volume 55 Issue 4 Pages 171-180
The reaction extraction is prospective in potassium dihydrogen phosphate (KDP) crystallization with the advantages of easy scale-up and low energy consumption. Hence, crystallization by reactive extraction is also regarded as a promising approach for the production of KDP, which is generally acknowledged in academic circles. As a result of high stirring rate, the crystals impact the wall surface and cause erosion of the wall and attrition of crystals. It is noteworthy that the particle attrition is an unneglected link in the reactive extraction crystallization. It could lead to the degradation of industrial product quality, and result in a series of environmental problems. However, the influence of the crystal attrition in the reactive extraction crystallization has long been ignored by scholars. In this study, KDP is prepared by reactive extraction from phosphoric acid and potassium chloride with trioctylamine-isoamyl alcohol (TOA) as extracting agent. The effects of the reactive extraction-crystallization process (extraction system temperature, stirring rate, and phase ratio) on the grain size of the products are quantified by single-factor experiments in order to determine the optimal conditions for the coupled process. In order to investigate the attrition degree of the extracted crystals, the attrition characteristics of KDP are investigated in a laboratory-scale stirring type crystallizer (STC). An exponential decay attrition model is proposed to describe the time-dependent attrition behavior of crystals under different conditions. This work could be helpful for the design and optimization of KDP preparation using the extraction method.
