THE STUDY OF POWER CONSUMPTION DURING RADIAL AND AXIAL SEGREGATION IN HORIZONTAL ROTATING CYLINDERS

Abstract

When binary granules of different material properties are rotated in a horizontal rotating drum they often segregate. Within the first few seconds, the smaller particles move towards the radial core in what is known as radial segregation. Depending on granular properties, drum speeds, and drum dimensions, the granules can segregate into "bands" known as axial segregation. Prior experiments by Gebrehiwot show that while rotating black beans and rice at a mixed state axial segregation as well as power dissipation were observed. Similar experiments were performed using barley, black beans, lentils, pintos, rice, and safflower. In the experiments that axial segregation occurred there was a substantial decrease in torque and power. Density, particle size by volume, and static angle of repose calculated by the fixed funnel method were measured for each granule. Axial segregation only occurred when the density ratio of the materials was between 1-1.2 (similar density's), and the size ratio was greater than 4 (large size difference). In relation to static angle of repose, axial segregation was observed when the angle ratio of the mixed granules was 0-1 (similar) and 1.1-3 (different). A separate experiment using nylon hose shows that radial segregation does occur in the absence of the avalanche effect where the larger granule concentrates to the core.