Pulp refining apparatus

In a high speed pulp refiner having a pair of refiner members having opposed surfaces defining a gap, each member formed with alternating grooves and lands extending continuously between a central port and a peripheral port through which a pulp slurry flows, the edges of the lands defining work edges, the direction of the work edges on one surface being opposite to the direction of work edges on the opposed surface forming intersections therewith, drive means for rotating at least one of the members relative to the other, the grooves and lands defined in the at least one member extending from the one of the central and peripheral ports to the other of said ports in a spiral pattern of at least one revolution having a direction on the member from one port to the other which is opposite to the direction of rotation such that as the at least one member rotates, the intersections will move downstream which will provide a screw pump action to the pulp slurry as it advances from one port to the other, the pitch of the spiral lands forming the work edges on the opposed surfaces of the respective refiner members being such that each of the intersections of the opposed work edges defines an obtuse angle on the downstream side of the lands relative to the direction of rotation and pulp slurry flow such that the pulp fibers suspended in the pulp slurry will be subjected to a pinching action.