Abstract: In order to avoid producing any secondary waste in the production of a fibrous and a granular material from household, agricultural, forestry waste, organic waste of the manufacturing and/or service industries, the primary waste first undergoes an opening treatment in an opening unit and then, after removal of any metallic components by magnetic separation units, is divided into three fractions. Such division is effected by a fractioning unit into (a) a fine fraction not exceeding the required final product particle size, (b) a coarse fraction easy to process mechanically, and (c) a coarse fraction difficult to process mechanically. The two coarse fractions are then separately reduced to the required final product particle size in reducing unit optimally suited to the particular coarse fraction.