Process for wet screening fibrous suspensions

摘要

In a waste paper or carton recovery process pre-used material is chopped and soaked in water to form a fibrous suspension (S) from which foreign bodies are removed by sieve (1) filtration. The sieve apertures (3) are esp. elongated holes between 1 and 8 mm wide, pref. 1-3 mm. The fibres are driven through the apertures by the action of a wiper blade (4). The sieve is a cylindrical drum with an interior feed of suspended fibres used in association with a print pre-sorting assembly. The hole (3) ratio of length to width is pref. between 2 and 10. The holes are approx. separated by intervals of 1-6 mm. The blade sweeps the holes at an angle of approx. 75degrees to the direction of travel.