An impact processing system (10) having a central opening (12) enabling material flow into a primary impact zone (14) in which is located an impact mechanism (16) rotatable about a rotation axis (18). An impact structure (20) provided with a plurality of holes (22) surrounds the impact mechanism (16). The rotatable impact mechanism (16) impacts material entering the primary impact zone (14) from the central opening (12) and accelerate the impacted material in a radial outward direction toward the impact structure (20) to effect fragmentation of the impacted material so that when sufficiently fragmented the material is able to pass through the holes (22). An optional outer structure (30) is radially spaced from the impact structure (20) and may comprise one or more segments that cumulatively extend about the axis of rotation (18) for an angle from 30° and 270° inclusive. A rotatable set of impact members (50) may be located between the impact structure and the outer structure. One or more gaps (28) may be provided in the impact structure (20) to allow the passage of large and/or hard objects that cannot otherwise be fragmented. The outer structure (30) is positioned to span across the gaps (28) so that material passing there thought is directed onto the outer structure (30).L'invention concerne un système de traitement par percussion (10) comportant une ouverture centrale (12) permettant un écoulement de matière dans une zone de percussion primaire (14) dans laquelle est situé un mécanisme de percussion (16) pouvant tourner autour d'un axe de rotation (18). Une structure de percussion (20) pourvue d'une pluralité de trous (22) entoure le mécanisme de percussion (16). Le mécanisme de percussion rotatif (16) frappe la matière entrant dans la zone de percussion primaire (14) à partir de l'ouverture centrale (12) et accélère le matériau ainsi frappé dans une direction radiale vers l'extérieur en direction de la structure de percussion (20) pour fragmenter la matière frap
