FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT

Description

D21B covers the preparation and mechanical processing of fibrous raw materials destined for papermaking, including pulping processes, fiber separation, and treatment operations prior to paper formation. This subclass encompasses both wood and non-wood fiber sources (such as plant stalks, recycled paper, and textile waste) and their conversion into usable pulp through chemical, mechanical, or combination methods. The classification includes fiber washing, screening, cleaning, and other mechanical treatments that condition raw fibers for subsequent papermaking stages. D21B excludes the actual papermaking process itself (covered by D21D-D21H) and fiber-to-pulp chemical conversion that is part of integrated pulping systems.