Rigid filter plate and process for manufacture of the same

Claim 1

An improved rigid sludge dewatering filter plate comprising at least two layers; the first layer comprising a thin, flat filtering element having an exposed, dense upper surface and a lower surface; said filtering element consisting essentially of jagged, irregular particles of one or more substances selected from the group consisting of aluminum oxide, corundum, emery, garnet, silicon carbide, boron carbide and manufactured crystalline alumina products, bonded together with an adhesive bonding agent, wherein the particles are of at least two sizes within the range consisting essentially of about 8 grid to about 100 grid and are oriented with average particle size increasing from the upper surface to the lower surface of the filtering element; and the second layer being a supporting element comprised of particles larger than the largest particles used in the filtering element, bonded together and to the lower surface of the filtering element with an adhesive bonding agent.

Claim 22

A method of manufacturing an improved rigid sludge dewatering filter plate which comprises: (a) mixing an adhesive bonding agent with inert particles of diameter greater than 8 grid to form a supporting element mixture; (b) introducing the supporting element mixture into a filter plate mold to a predetermined depth; (c) tamping the supporting element mixture in the mold; (d) mixing an adhesive bonding agent with jagged, irregular particles of at least two sizes within the range consisting essentially of 8 grid to 100 grid, wherein the particles are comprised of one or more materials selected from the group consisting of aluminum oxide, corundum, emery, garnet, silicon carbide, boron carbide and manufactured crystalline alumina products, to form a filtering element mixture; (e) introducing the filtering element mixture into the filter plate mold to a predetermined depth of between about 1/8 inch and about 2 inches on top of the tamped supporting element mixture; (f) smoothing the upper surface of the filtering element mixture with smoothing means; (g) tamping the filtering element mixture in the mold; and (h) curing the resulting filter plate.

Claim 23

A method of manufacturing an improved rigid sludge dewatering filter plate which comprises: (a) mixing an adhesive bonding agent with inert particles of diameter greater than 8 grid to form a supporting element mixture; (b) introducing the supporting element mixture into a filter plate mold to a predetermined depth; (c) tamping the supporting element mixture in the mold; (d) mixing an adhesive bonding agent with jagged, irregular particles of at least two sizes within the range consisting essentially of 8 grid to 100 grid, wherein the particles are comprised of one or more materials selected from the group consisting of aluminum oxide, corundum, emery, garnet, silicon carbide, boron carbide and manufactured crystalline alumina products, to form a filtering element mixture; (e) introducing the filtering element mixture into the filter plate mold to a predetermined depth of between about 1/8 inch and about 2 inches on top of the tamped supporting element mixture; (f) smoothing the upper surface of the filtering element mixture with smoothing means; (g) tamping the filtering element mixture in the mold; and (h) curing the resulting filter plate.