US2741536A - Available chlorine multi-stage bleaching of sulfite pulp - Google Patents

Available chlorine multi-stage bleaching of sulfite pulp Download PDF

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Publication number
US2741536A
US2741536A US278747A US27874752A US2741536A US 2741536 A US2741536 A US 2741536A US 278747 A US278747 A US 278747A US 27874752 A US27874752 A US 27874752A US 2741536 A US2741536 A US 2741536A
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United States
Prior art keywords
chlorine
pulp
bleaching
stage
per cent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US278747A
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English (en)
Inventor
William A Stone
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Olin Corp
Original Assignee
Olin Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE518419D priority Critical patent/BE518419A/xx
Application filed by Olin Corp filed Critical Olin Corp
Priority to US278747A priority patent/US2741536A/en
Priority to FR1071422D priority patent/FR1071422A/fr
Application granted granted Critical
Publication of US2741536A publication Critical patent/US2741536A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C9/00—After-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
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
    • D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
    • D21C9/144—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites with ClO2/Cl2 and other bleaching agents in a multistage process

Definitions

  • My invention relates to improvements in the multistage bleaching of sulfite cellulose pulps and more particularly to a bleaching operation employing a combination of chlorine dioxide, particularly in the form of a chlorite, and chlorine in the first or preliminary bleaching stage.
  • sulfite pulp has the advantage over sulfate pulp in that it is more readily bleached to a high whiteness and is thus more suitable for many grades of paper and other cellulose products, the high whiteness is frequently obtained at the expense of a considerable loss of strength. For this reason sulfate pulp is sometimes blended with sulfite pulp in spite of the sacrifice in color in order to obtain adequate strength.
  • the minimum operation ordinarily consists of three stages, the first of which is a chlorination stage in which the pulp is treated with chlorine water for a period of about one hour at an acid pH.
  • the lignin is largely chlorinated due to the presence in the acid solution of most of the chlorine as dissolved elemental chlorine. Oxidation is avoided by the acidity of the solution, the pH normally being about 1.8 to 2.0, which restricts the formation of hypochlorous acid, the oxidizing agent in the system.
  • the chlorination reaction is relatively rapid compared to the oxidation reaction, limiting the time of contact also assists in avoiding oxidation.
  • the pulp consistency is about 1.5 to 3 per cent and the preliminary bleach is carried out at the temperature of the available water.
  • the chlorinated pulp is extracted with caustic, for example with 2 per cent caustic, at 120 to 140 F. using a 10 per cent pulp consistency.
  • the bleach is completed by treatment with a hypochlorite under alkaline conditions.
  • the resulting washed pulp has a brightness of about 80 to 82.
  • a sulfite cellulose pulp in aqueous medium is partially bleached in a preliminary stage with sufiicient chlorine dioxide and chlorine to supply about 50 to 60 per cent of the chlorine requirement of the pulp as determined by the permanganate number and then bleached in a subsequent stage with an aqueous solution of a hypochlorite.
  • the amount of the chlorine requirement of the pulp supplied to the preliminary partial bleaching stage by the chlorine dioxide is about 50 to per cent on an equivalent available chlorine basis.
  • the pulp in aqueous medium is partially bleached in the preliminary stage with a chlorite and chlorine at a pH of about 2.5 to 2.7 at approximately room temperature.
  • Example I Instead of the 30 pounds of chlorine conventionally supplied to partially bleach this pulp in the preliminary chlorination stage, 10 pounds of sodium chlorite together with 15 pounds of chlorine, 3 of which were necessary to activate the chlorite, were used. After the treatment had continued for one-half hour the pulp was filtered and washed. The caustic extraction was omitted and the pulp at a consistency of 12 per cent was treated with 28 pounds of available chlorine as calcium hypochlorite at a temperature of F. for two hours. test sheets showed a GE brightness of 80.7. The strength After washing,
  • Example II The same pulp at a consistency of 2.5 per cent was treated with 20 pounds of available chlorine as sodium chlorite and pounds of chlorine per ton, 4 of which were utilized to activate the chlorite. After treatment in the preliminary chlorination stage for one-half hour the pulp was filtered, washed and reslurried to a consistency of 10 per cent with pounds of caustic per ton. The caustic extraction was continued at a temperature of 140 F. for one hour. After washing the pulp and reslurrying to a consistency of 12 per cent, it was treated with 9 pounds of available chlorine as calcium hypochlorite at a temperature of 95 F. for two hours. The finished pulp gave a test sheet having a brightness of 83.9.
  • the strength retention was 92.8 per cent based on per cent Mullen values of 184 for the unbleached stock and 171 for the final pulp. Based on per cent tear values the strength retention was 111.5 per cent.
  • the chlorine requirement in the first stage was reduced by 70 per cent of that when no chlorite was used and the total available chlorine requirement was reduced by per cent.
  • Example 111 to per cent of the chlorine requirement of the pulp as determined by the permanganate number is supplied by chlorine followed by a later stage of bleaching with an aqueous solution of hypochlorite, the improvement which comprises partially bleaching the pulp in the preliminary stage in aqueous medium and under acid conditions with chlorine dioxide and chlorine, the amount of the chlorine requirement supplied to the preliminary partial bleaching stage by the chlorine dioxide being about 50 to per cent on an equivalent available chlorine basis.
  • Sen Gupta Progressive Delignification of Jute Fibre with Chlorine Dioxide. J. Text. Inst. (Trans), September 1951, pgs. T375-384, especially first page.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
US278747A 1952-03-26 1952-03-26 Available chlorine multi-stage bleaching of sulfite pulp Expired - Lifetime US2741536A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE518419D BE518419A (enrdf_load_stackoverflow) 1952-03-26
US278747A US2741536A (en) 1952-03-26 1952-03-26 Available chlorine multi-stage bleaching of sulfite pulp
FR1071422D FR1071422A (fr) 1952-03-26 1953-02-24 Procédé de blanchiment de pâtes de cellulose au sulfite ou au sulfate

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US278747A US2741536A (en) 1952-03-26 1952-03-26 Available chlorine multi-stage bleaching of sulfite pulp

Publications (1)

Publication Number Publication Date
US2741536A true US2741536A (en) 1956-04-10

Family

ID=23066179

Family Applications (1)

Application Number Title Priority Date Filing Date
US278747A Expired - Lifetime US2741536A (en) 1952-03-26 1952-03-26 Available chlorine multi-stage bleaching of sulfite pulp

Country Status (3)

Country Link
US (1) US2741536A (enrdf_load_stackoverflow)
BE (1) BE518419A (enrdf_load_stackoverflow)
FR (1) FR1071422A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3433702A (en) * 1965-06-28 1969-03-18 Hooker Chemical Corp Woodpulp bleaching process
US3501374A (en) * 1968-12-26 1970-03-17 Hooker Chemical Corp Sequential bleaching of kraft pulp with chlorine dioxide and chlorine
US3536577A (en) * 1963-07-12 1970-10-27 Hooker Chemical Corp Bleaching of cellulosic materials with chlorine dioxide
USRE28887E (en) * 1968-12-26 1976-06-29 Hooker Chemicals & Plastics Corporation Sequential bleaching of kraft pulp with chlorine dioxide followed by chlorine
USRE28884E (en) * 1965-06-28 1976-06-29 Hooker Chemicals & Plastics Corporation Woodpulp bleaching process
US4325783A (en) * 1978-03-30 1982-04-20 Erco Industries Limited Bleaching procedure using chlorine dioxide and chlorine solutions

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE446444A (enrdf_load_stackoverflow) * 1941-08-06
GB191357A (en) * 1922-01-04 1923-03-22 Schmidt Erich Process for obtaining and cleaning cellulose from wood and similar substances containing cellulose
US2129719A (en) * 1937-09-13 1938-09-13 Mathieson Alkali Works Inc Bleaching method
US2166330A (en) * 1938-09-12 1939-07-18 Mathieson Alkali Works Inc Method of bleaching
US2235837A (en) * 1937-09-01 1941-03-25 Mathieson Alkali Works Inc Bleaching cellulose

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB191357A (en) * 1922-01-04 1923-03-22 Schmidt Erich Process for obtaining and cleaning cellulose from wood and similar substances containing cellulose
US2235837A (en) * 1937-09-01 1941-03-25 Mathieson Alkali Works Inc Bleaching cellulose
US2129719A (en) * 1937-09-13 1938-09-13 Mathieson Alkali Works Inc Bleaching method
US2166330A (en) * 1938-09-12 1939-07-18 Mathieson Alkali Works Inc Method of bleaching
BE446444A (enrdf_load_stackoverflow) * 1941-08-06

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3536577A (en) * 1963-07-12 1970-10-27 Hooker Chemical Corp Bleaching of cellulosic materials with chlorine dioxide
US3433702A (en) * 1965-06-28 1969-03-18 Hooker Chemical Corp Woodpulp bleaching process
USRE28884E (en) * 1965-06-28 1976-06-29 Hooker Chemicals & Plastics Corporation Woodpulp bleaching process
US3501374A (en) * 1968-12-26 1970-03-17 Hooker Chemical Corp Sequential bleaching of kraft pulp with chlorine dioxide and chlorine
USRE28887E (en) * 1968-12-26 1976-06-29 Hooker Chemicals & Plastics Corporation Sequential bleaching of kraft pulp with chlorine dioxide followed by chlorine
US4325783A (en) * 1978-03-30 1982-04-20 Erco Industries Limited Bleaching procedure using chlorine dioxide and chlorine solutions

Also Published As

Publication number Publication date
FR1071422A (fr) 1954-08-31
BE518419A (enrdf_load_stackoverflow)

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