Patent ID: 8444807

Claim:
A method for preparing paper pulp from recycled papers containing contaminants, comprising the following successive stages: a) a first stage of mashing the paper in the presence of water in order to obtain a mixture of fibres and contaminants in suspension; b) a second stage of coarse screening of said mixture, in order to separate said mixture into a pulper rejects stream comprising coarse contaminants and a pulper accepts stream, the first and second stages being carried out by means of a pulper with a helical agitator, in which at least one grid pierced with holes is positioned under the helical agitator; c) a third stage of fine screening for separating the pulper accepts stream into a secondary rejects stream comprising fine contaminants from the pulper accepts stream obtained in stage b) and a secondary accepts stream; d) a fourth stage of washing said pulper rejects stream comprising said coarse contaminants and said secondary rejects stream comprising said fine contaminants in order to separate recoverable fibrous materials therefrom, said fourth stage being carried out by means of a washing drum having at least two successive zones, each zone being provided with holes over at least part of its respective surface; wherein the fiber content of water coming from the first zone is greater than that coming from the second and washing water coming from the first zone of said drum washer is sent to an intermediate mixing chest in which the accepts from said pulper is collected before being finely screened, and wherein the washing water from the second zone is sent to the pulper.