Disc-type pulp refining apparatus

In an apparatus for refining lignocellulosic pulp stock, such as wood chips, sawdust, bagasse and the like, in which the pulp stock is ground in a grinding zone extending axially at an angle to the axis of rotation of a pair of opposed disc members, which rotate relative to one another within a housing in the environment of a fluid medium, said grinding zone being defined between a rotating grinding element carried by an outer peripheral portion of at least one of said opposed disc members, said grinding zone extending at an angle from an inner portion of at least one of said opposed disc members, said inner portion extending radially outwards from the axis of rotation, and a facing correspondingly inclined stationary grinding element mounted in said housing, the pulp stock being advanced by conveyor means into a central opening in said inner portion and discharged from said housing by valve means after completion of the grinding operation, the improvement comprising:

• a plurality of sector-shaped channels in said inner portion for receiving the pulp stock from said central opening and accelerating it toward said grinding zone under the influence of the centrifugal force generated by the relative rotational movement of said opposed disc members, the axial width of said sector-shaped channels being defined by two spaced annular wall members in said inner portion and the sector area of said channels being defined by a plurality of rotatable blades disposed between said walls.