The Size Segregation of Polydispersed Particles During Feeding into a Vessel

Abstract

The size segregation of polydispersed particles being fed from a hopper at various heights into a container has been studied. Experiments were conducted in a small (14cm) and large (28cm) container. The outlet diameter of the hopper was also changed. Tested particles ranged from 150 to 650μm in size. The bias that arises when removing samples from inside the container, and the effect of sample size, were incorporated into the assessment of the degree of segregation.
The particle heap was classified into upper and lower layers; the lower layer consisted of particles accumulated through repulsion against the container bottom, and the upper layer formed a slope having a constant angle of repose. It was found that, in the lower layer, larger particles were concentrated in the central region while smaller particles were distributed in the vicinity of the container wall. This layer became thicker with increasing feed outlet height and outlet diameter. The lower layer was thicker in the small container than in the large one. The opposite trend was observed in the upper layer, where smaller particles were concentrated in the central region while larger particles were distributed in the vicinity of the container wall. The above tendency was enhanced with decreasing outlet diameter.