Breaking up filter cake residues on filter cloth - using jets of liq. followed by compressed air to break up released material

摘要

In the intervals of filtering slurries with filter cloths held on rotary circular supports and during which the majority of the cake, esp. its upper layers, is removed radially over the edge of the filter, while the residue of the cake is then broken up by compressed air applied from below the cloth, this residue is subjected to initial breaking up by pressurised liq. jets directed vertically down from above the cake. The filtrate may be used for these jets, which are spaced along a radius of the cloth, e.g. at intervals of 30-400 nm. The jets form circular cuts as the filter revolves, and the pipe feeding the jets may be reciprocated lengthwise to produce a more extensive network of cuts. The system is esp. for fine slurries which tend to form a compact layer which might be temporarily lifted by the cleaning compressed air rather than broken up, and is more effective than known liq. washing methods. The broken-up cake residues mix with the new slurry applied in the next filtering cycle.