Continuous classification in a centrifugal fluidized bed apparatus

The optimization of a novel wet centrifugal fluidized bed classifier is discussed in this paper. Experiments in a pilot-scale apparatus and CFD calculations for the pure liquid flow reveal that the Coriolis force induces a strong tangential flow relative to the rotating vessel. Based on this finding a discharge mechanism for the coarse fraction has been developed which consists of a simple nozzle and thus allows a continuous and stable operation of the classifier. The measured pressure drop characteristic of the coarse particle bed reveals the range of fluidizing velocities which are optimal for the performance of classification. With the optimized classifier sharp classifications with a strong reduction of the misclassification of fines were achieved in different experiments with quartz, limestone and glass beads. Down to cut sizes of 5 μm sharp classifications were achieved.