Abstract: Apparatus for refining pulp stock which is ground in an inclined grinding zone extending from a peripherally outer portion of a pair of opposed disc members which rotate relative to one another within a housing. The pulp stock is advanced by a conveyor into a central opening between the opposed disc members, from which opening it is accelerated radially towards the grinding zone under the influence of the centrifugal force generated by the rotational movement of the disc members by means of a plurality of sector-shaped channels defined between the opposed disc members.

Abstract: The invention relates to the production of a wholly mechanical pulp of improved strength properties. The lignocellulosic material is fed into a substantially closed chamber where it is mechanically abraded under a power input of fifteen or more horsepower days per ton. During the abrading step, the material is maintained in an inert gaseous atmosphere of a pressure of ten to eighty psig, preferably twenty to forty psig.