SORTIERER

In a paper making process a sorting assembly removes foreign bodies from a fibrous suspension. The assembly has a separation chamber with a suspension inlet, a clean suspension outlet, and a discharge for foreign bodies. The separation chamber is sub-divided into two by a sieve. The sieve is profiled on the suspension inlet and reject material side. The profiled sieve sets up vortices in the incoming suspension. The sieve surface may be flat, cambered or corrugated with peaks and troughs of between 0.3 and 1.5 mm. The sieve is a perforated plate with slits. The incoming suspension impinges on the slots at an angle of between 70 and 110 degrees. The plate may be sheet metal, ceramic or plastic and bears an anti-wear coating. Also claimed is a multi-stage sorting assembly.