#### Filter cake compaction by oscillatory shear

S. Illies*, H. Anlauf, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany

We investigate the influence of oscillatory shear on the compaction of filter cakes for different model materials. The model systems investigated vary in particle size and shape and therefore show different compaction characteristics. Parameters varied are frequency, displacement and normal pressure as well as the number of cycles. The effect of oscillatory shear is compared to the compaction obtained by applying solely mechanical pressure. Results show that by applying oscillatory shear, a significant reduction of compaction pressure needed to obtain a certain degree of compaction can be obtained. However the advantage over conventional pressing is different for each particle system. We further evaluate the effect of compaction on the degree of cracking that occurs during filter cake desaturation. The compaction achieved by oscillatory shear leads to a significant reduction in filter cake cracking...

It was found that the compaction with number of cycles in general follows an exponential decay law. The variation of shear length implies that shear length and oscillation frequency are not independent parameters but that the resulting mean shear rate determines the degree of compaction that can be reached. The compaction behavior with frequency or shear rate respectively was strongly influenced by the superimposed normal pressure. The effect of oscillatory shear on the compaction of the filter cake was compared to the compaction obtained by applying solely mechanical pressure. By applying oscillatory shear, a significant reduction of compaction pressure needed to obtain a certain degree of compaction could be obtained. Compaction by oscillatory shear also proved to be a promising method to avoid filter cake cracking in a subsequent desaturation step...

**Session: **L8 - Cake Filtration V - Novel Methods of Consolidation and Deliquoring

**Day:** 12 October 2016

**Time: ** 10:45 - 12:00 h

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