Abstract: Apparatus is disclosed for the manufacture of fiber pulp from lignocellulose-containing materials including radially extending grinding segments for use with a pair of opposed counter-rotating grinding discs in which the grinding segments include an inner radial zone with alternating raised bars and grooves projecting radially thereon parallel to the radius of the grinding segment, and an outer radial zone including a first group of alternating raised bars and grooves projecting outwardly thereon in a first direction and a second plurality of alternating raised bars and grooves projecting outwardly thereon in a second direction, both sets of these raised bars and grooves extending outwardly at angles of between about 5.degree. and 30.degree. with the first and second directions being opposite to each other with respect to the grinding segment itself. Methods for manufacturing fiber pulp from lignocellulose-containing material employing such grinding segments are also disclosed.