Process for pulping and cleaning of papermaking raw materials containing impurities

摘要

A cylindrical or conical sieve (3) with classifying slots is used in a method for removing impurities from paper or pulp suspensions, especially from a suspension (S) containing heavy impurities, by passing it directly from an open pulper (1) or a secondary pulper through a closed sieve apparatus (2) to give an "accept stream" (A2) and a "reject stream" (R2) comprising retained impurities which are concentrated on the sieve(s) (3) for removal.