FILTERS FOR SELECTIVE REMOVAL OF LARGE PARTICLES FROM PARTICLE SLURRIES

摘要

A method for removing the high particle size tail of the particle size distribution of a slurry while leaving desirable smaller particles in the slurry. The method involves providing a filter media having a first and second side and being formed of at least one sheet of a fabric that has at least one layer comprising polymeric fibers having a mean number average fiber diameter of less than 1000 nm. A slurry stream is then supplied to one face of the fabric. The stream has a multiplicity of particle sizes comprising a first set of particles of maximum dimension less than 0.1 microns and a second set of particles of maximum individual dimension of greater than 0.45 microns to the first side of said filter media. The slurry stream is passed through said filter media to the second side thereof whereby at least a portion of the larger particles in the slurry are retained on the first side of said media. The filtration efficiency of the fabric towards the first set of particles is less than 0.05 and the filtration efficiency towards the second set of particles is greater than 0.8.