Abstract: A pulper has a circular rotor that carries a set of peripheral blades that rotate within a stator having a set of peripheral lobes that interact with the peripheral blades as they rotate to reduce and defiber materials, e.g., to produce pulp slurries for paper-making. A cone assembly is mounted over the center of the rotor on a base plate. The cone assembly includes a blade that extends across the common axis of rotation of the base plate and the rotor and projects into a tank beyond the height of the peripheral blades and the stator lobes. A support structure, preferably in the form of a “cone”, supports the blade. The cone preferably has a pyramidal structure and in one form extends sufficiently far up the blade so that, typically, no more than 2 to 3 inches of the blade project above the outer surface of the cone. The blade has a triangular structure terminating in a central apex for use in reducing slabs of large sheet materials such as reel broke.

Abstract: To defiber a wide variety of materials, rotor and stator constructions are varied 1) to increase the agitation of stock in a tank or 2) to increase defibering effectiveness and increase flow rate through a recirculation line or to downstream equipment. To increase agitation, lobes of the stator are configured and sized to reduce the stator-rotor interface below 50% of its maximum possible value. To increase defibering effectiveness and increase the recirculation flow rate, the stator lobes are configured and sized so the stator area at the interface exceeds 50% of its maximum possible value. These lobe area changes are made in a way that also preserves a desired acquisition angle on cutting edges on rotor for the given material so that the lobes reliably "acquire" and reduce the stock. To increase homogeneity of treatment, deflectors on the stator and/or rotor require that all the stock traverses the defibering interface between peripheral teeth on the rotor and opposed stator bars.