Drain Height Measurement for Fine Particles in Centrifugal Force Field

Abstract

Water content of a packed bed of particles dewatered by a centrifuge and filter is significantly influenced by the drain height of the packed bed. Drain height is used to be measured by Haines apparatus in a gravitational field. However, the measurement of drain height for fine particles less than 50μm diameter is difficult because their drain heights are generally more than a few meters. Therefore, measurement of the drain height of fine particles in a centrifugal force field was investigated.
Experimental work on glass spheres and calcium carbonate powder was carried out using a vertical-axis centrifuge and acrylic dewatering tube. The residual equilibrium saturation of the packed bed from 1 to 4cm high was measured under the centrifugal force ranging from 100 to 4, 500 G. The drain height in a centrifugal force field was obtained from analysis of the curve of saturation of the packed bed plotted against the centrifugal force. The values of drain constant obtained by this method agreed with those calculated from the data based on the Haines apparatus in a gravitational field. It is suggested that this method can be applied to measure the drain height of fine particles less than 50μm diameter with a small amount of sample and in a few hours.