Abstract: A refiner plate for the face of a refiner disc comprising a plurality of refiner segments arranged side-by-side on the face of the disc to form a substantially annular refining region. Each refiner segment has an inlet zone for receiving the material to be refined, an outer zone for refining and discharging refined material and an intermediate refining zone disposed intermediate the inlet zone and the outer zone. The outer zone has a pattern including a plurality of radially disposed bars defining an upper surface, a plurality of radially disposed grooves disposed intermediate the bars defining a lower surface, and dams traversing each of the grooves for restricting radial flow through the respective grooves. The dams include full height dams extending from the lower surface to the upper surface and partial height dams extending from the lower surface to a height intermediate the lower and upper surfaces. At least one full height dam is disposed in each of the grooves, as the radially outermost dam.

Abstract: An improved pattern of bars and grooves on the plates of a rotating disc refiner, whereby the inherent restriction in the transfer of material into the grooves of the refining zone is reduced relative to conventional designs. The invention can be implemented at one or both of the transition from an innermost, feed zone to an intermediate, refining zone, or the transition from an intermediate, refining zone to an outer, refining zone. The invention can be generally understood as providing an asymmetric or jagged transition line from one zone to another. The asymmetry can be seen in a plate segment, relative to the segment central axis, or it may be seen as a saw tooth shape with respect to laterally adjacent regions of the same zone. Preferably, a line connecting the inlets on laterally successive regions of a particular zone, defines a substantially continuous saw tooth shape or a succession of jagged, "Z" shapes.