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1. WO1993004231 - PROCESS FOR GAS PHASE DELIGNIFYING WOOD PULP

Publication Number WO/1993/004231
Publication Date 04.03.1993
International Application No. PCT/US1992/006141
International Filing Date 24.07.1992
Chapter 2 Demand Filed 04.02.1993
IPC
C01B 11/02 2006.01
CCHEMISTRY; METALLURGY
01INORGANIC CHEMISTRY
BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF
11Oxides or oxyacids of halogens; Salts thereof
02Oxides of chlorine
D21C 9/14 2006.01
DTEXTILES; PAPER
21PAPER-MAKING; PRODUCTION OF CELLULOSE
CPRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE- CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
9After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters
10Bleaching
12with halogens or halogen-containing compounds
14with ClO2 or chlorites
CPC
C01B 11/025
CCHEMISTRY; METALLURGY
01INORGANIC CHEMISTRY
BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; ; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
11Oxides or oxyacids of halogens; Salts thereof
02Oxides of chlorine
022Chlorine dioxide (ClO2)
023Preparation from chlorites or chlorates
025from chlorates without any other reaction reducing agent than chloride ions
D21C 9/14
DTEXTILES; PAPER
21PAPER-MAKING; PRODUCTION OF CELLULOSE
CPRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
9After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
10Bleaching ; ; Apparatus therefor
12with halogens or halogen-containing compounds
14with ClO2 or chlorites
Applicants
  • OLIN CORPORATION [US]/[US]
Inventors
  • MENDIRATTA, Sudhir, K.
  • CAWLFIELD, David, W.
Agents
  • MEYER, Allen, A., Jr.
  • ISKANDER, F., A.
Priority Data
749,06623.08.1991US
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) PROCESS FOR GAS PHASE DELIGNIFYING WOOD PULP
(FR) PROCEDE DE DELIGNIFICATION DE PATE DE BOIS EN PHASE GAZEUSE
Abstract
(EN)
A process for delignifying wood pulp characterized by admixing an aqueous solution of chloric acid, containing about 30 percent or greater by weight of HClO3, with a non-oxidizable inorganic acid to produce chlorine dioxide gas containing less than 10 percent by volume of chlorine. The wood pulp, having a consistency of 15 percent or greater, is contacted with the chlorine dioxide gas to delignify the wood pulp. The novel process of the present invention reduces the formation of chloroform and significantly reduces the amounts of toxic by-products such as dioxin and other organic chlorides. These undesirable by-products, collectively identified as absorbable organic halides (AOX), require effluents from pulp bleaching processes to undergo expensive treatment methods to eliminate AOX's prior to discharges to sewers. The effluent discharge from the bleaching process of the present invention has less than 2.0 kg adsorbed organic halides (AOX) per ton of wood pulp.
(FR)
Procédé de délignification de pâte de bois consistant à mélanger une solution aqueuse d'acide chlorique, contenant environ 30 % ou plus en poids de HCl03, avec un acide inorganique non oxydable pour produire du gaz de dioxyde de chlore contenant moins de 10% en volume de chlore. La pâte de bois, ayant une consistance de 15 % ou plus, est mise en contact avec le gaz de dioxyde de chlore afin d'être délignifiée. Le procédé de la présente invention réduit la formation de chloroforme et réduit considérablement les quantités de sous-produits toxiques, tels que la dioxine et d'autres chlorures organiques. Ces sous-produits indésirables, identifiés collectivement sous le terme d'halogénures organiques absorbables, exigent que les effluents produits par les processus de blanchiment subissent des traitements onéreux afin d'éliminer lesdits halogénures organiques absorbables avant d'évacuer ces effluents dans les égouts. Les effluents issus du processus de blanchiment de la présente invention contiennent moins de 2 kg d'halogénures organiques absorbables par tonne de pâte de bois.
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