D - Textiles – Paper – 21 – C
Patent
D - Textiles, Paper
21
C
D21C 3/02 (2006.01) D21C 3/00 (2006.01) D21C 3/22 (2006.01) D21C 11/00 (2006.01) D21C 11/14 (2006.01)
Patent
CA 2112802
A process is proposed for the production of cellulose out of wood and annual plants, in which the digesting liquor contains free caustic soda, eventually sodium salts of alkyl benzenesulfonic acids, of aromatic or aliphatic carboxylic acids. By addition of anthraquinone or its derivatives to the digesting liquor, the delignification is improved. The limitation of quantities for price reasons is eliminated, because anthraquinone is resistant to wet oxidation and can be reintroduced into the digesting process. The solubility and therefore the effectiveness of anthraquinone is improved by the use of sulfonic acid salts. For the recovery of the digesting chemicals contained in the black liquor, it is proposed that the solubilized lignin is precipitated with mineral acid or carbon dioxide, that eventually the hemicelluloses are separated by ultrafiltration and the resins by extraction and that the residual organic compounds, except the sulfonates and the carboxylates, are burned in an aqueous phase with air and/or oxygen. The solution of chemicals, containing no more wood decomposition products, can by caustification of the carbonates be re-transformed into caustic soda and after partial crystallization of the aliphatic carboxylates be used for the cycle of pulp production. The sodium acetate isolated by crystallization can by means of membrane electrolysis be split in acetic acid and sodium hydroxide. The caustic soda is reintroduced to the digesting process, the acetic acid is treated separately.
Doppenberg Frank
Gordon Otto
Plattner Eric
Granit S.a.
Ridout & Maybee Llp
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