COTTON CELLULOSE MANUFACTURE PROCESS Russian patent published in 2003 - IPC

FIELD: paper-and-pulp industry. SUBSTANCE: crude cotton cellulose is subjected to hoeing, cleared, and moistened with hot sodium hydroxide solution at 60-80 C. Digestion is carried out in sodium hydroxide solution with sulfanol additive (emulsifier) at modulus 1:13 to 1:8 and temperature 125-160 C during 3-6 h. Cellulose is then bleached for 1.0-2.5 h in sodium hypochlorite at concentration of active chlorine in bleaching solution 0.7-2.0 g/l at temperature 20-40 C. Bleached pulp undergoes sulfuric acid souring involving rinsing with softened water (water hardness no higher than 0.1 equ/l with weight proportion of iron no higher than 0.03 mg/l) followed by pressing, and drying. The latter operation is conducted in two-stage aerofountain drier consisting of several sections with first-section air temperature 160-175 C and 2nd, 3rd, and 4th-section temperatures, 90-100, and 75-80 C, respectively. Drying lowers moisture to 2-10%. Hydrodynamic pulp bleaching process should satisfy following conditions: 19500 </= Re </= 2060 at ratios d_m/D ~0.46, H/D ~1.8 and D/d~2.1, where Re is Reynolds number, d_m agitator diameter, D bleaching tub diameter, and H height of pulp layer in tub. Product can be used for production of nitrocellulose, acetylcellulose, carboxymethylcellulose, microcrystalline cellulose, copper-ammonia fiber, cardboard, and in gun powder production. EFFECT: improved quality of product utilizing environmentally safe process. 1 dwg, 2 tbl