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Abstract

A method of washing cellulosic pulp to remove dissolved solids as well as dirt, inorganic fillers and fiber debris. A mat of cellulosic pulp having a weight of 3 to 100 lbs. of dry fiber per 1000 sq.ft. is positioned between a pair of porous endless belts to provide a composite structure. The composite structure is moved in a generally vertical path of travel through a vessel containing a plurality of superimposed rolls and the composite structure is passed over the rolls in a manner in which a first of the belts is in direct contact with one roll and the second of the belts is in direct contact with the next adjacent roll. A stream of water is directed against the composite structure as it travels in the upper portion of the vessel, and the water is cascaded downwardly through the vessel and directed into contact with opposite sides of the structure to thereby remove dissolved solids, as well as inorganic fillers. The tension of the belts as they pass over the rolls creates a dewatering action. After passing through the vessel, the washed pulp mat is removed from the belts, and the washing water is discharged through an outlet in the vessel and can be used in other portions of the papermaking process.

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First Claim