Apparatus and method for manufacturing wood pulp by grinding wood block material

In an apparatus for manufacturing ground wood pulp from ligno-cellulose containing block material by separating the fibers therein, including a grinding disc mounted rotatably about a shaft coaxial with both end surfaces of said grinding disc, retaining means to force at least one piece of the block material to be ground against at least one of said end surfaces, means to supply an aqueous liquid to the material, each piece of material being forced against at least the one disc end surface forming a grinding surface with the fibers of the material substantially directed in the plane of the grinding surface, the improvement enabling increased fiber releasing capacity and delivery of pulp of greater uniformity and improved quality comprising, projecting grinding means in the shape of elevations located on at least the one disc end surface, the elevations defining between themselves grooves directed towards the periphery of the end surface, the retaining means being adapted to force each piece of block material along a longitudinal side against at least the one end surface with its fibers directed outwardly from the center of the grinding disc toward the disc periphery while the fibers are separated to orient the fibers in the same direction as the edges of the elevations and carry the fibers radially outward and the elevation edges engage the block fibers under a movement component transverse to the longitudinal direction of the fibers.