Filter elements

Claim 1

In a filter thickener comprising: a tank; means for supplying a suspension to be thickened to said tank; at least one filter element in the form of a filter leaf disposed in said tank for submersion in a suspension introduced into said tank; means for establishing a pressure differential between the exterior and the interior of the filter element whereby filtrate passes from the exterior to the interior of the filter element; conduit means for conveying filtrate from the interior of said filter element; means for introducing liquid into the interior of said filter element to discharge thickened suspension adjacent the exterior surface thereof; the improvement wherein said filter element comprises: a horizontal pipe; a flexible flat bag of filter material suspended from said pipe, the flat sides of said bag being secured together to hold said bag in a generally flat configuration, said filter material comprising flexible filter material surrounding said pipe and joined together at its edges to form a closed flexible bag, the flat sides of said flat bag being joined together by stitching extending lengthwise of the bag thus dividing the bag into a plurality of contiguous strips, the flat bag of filter material being suspended from the pipe along substantially the whole length of the top edge of the filter bag, the pipe being disposed substantially horizontally in said tank, a strip along the whole length of the top edge of the filter element being rendered impermeable; said bag being substantially filled with a flexible packing material through which liquid can permeate, said packing material being selected from the group consisting of flexible mesh and flexible mat; and said pipe including aperture means extending substantially the length of the pipe and communicating with the interior of said filter element, said pipe being connected to said conduit means for conveying filtrate from the interior of said filter element through said apertures.