PROCESS FOR BLEACHING LIGNOCELLULOSE, CELLULOSE, AND SYNTHETIC FIBROUS MATERIALS USING ALKALI PEROXIDES Russian patent published in 2000 - IPC

FIELD: paper-and-pulp industry. SUBSTANCE: process includes following operations: preparation of aqueous suspension of fibrous materials, addition of alkali to increase pH of suspension above 7.5, addition of peroxide-containing solution, heating of fibrous materials, interaction of peroxide-containing solution with fibrous materials, and discharge of fibrous materials for further processing. According to invention, aqueous suspension contains approximately 0.25 to 50 wt % of fibrous materials, amount of peroxide- containing solution added is 0.15 to 50% based on the weight of kiln- dried fibrous materials, and the latter are heated to at least 90 C. At least one of operations is conducted in at least one vessel whose contact surface is made from one or more metals such as niobium, hafnium, tantalum, or their alloys allowing peroxide decomposition rate to be restricted below 2 g/min/sq. cm •10^-4. EFFECT: enhanced bleaching efficiency. 10 cl, 17 dwg, 5 tbl