Superposition of compression and shear in filtration

E. Höfgen*, A. D. Stickland, P. J. Scales, R. J. Batterham, University of Melbourne, Australia

In times of ever increasing energy costs and environmental consciousness the optimisation of filtration processes for more efficient operation and for reuse of material streams is of high importance. The filtration of suspensions aims to increase the solids concentration. A particulate network forms at a material specific concentration, called the gel point. At concentrations greater than the gel point, suspensions exhibit a strength against deformation. In compression, it is the compressive yield stress Py and, in shear, this resistance is called the shear yield stress τy. For further dewatering of a suspension, an applied force has to be greater than the compressive yield stress Py. In many industrial processes, a superposition of shear and compression is applied to the suspension due to machine design and/or operation. Thereby, the effect of combining shear and compression in filtration is of great interest. However, the interrelated influence of shear and compression is still unclear and needs further investigation.

A novel dewatering device, called High Pressure Dewatering Rolls (HPDR) shown in Figure 1, has been developed at the University of Melbourne that combines shear and compression. With this device, the extent of shear and compression can be adjusted and thus superposition of the two can be investigated. This paper outlines compressional rheology, followed by an overview of the HPDR. ....

Session: L8 - Cake Filtration V - Novel Methods of Consolidation and Deliquoring
Day: 12 October 2016
Time: 10:45 - 12:00 h

Learn more at FILTECH 2018 - Register Now!