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US3843473A Expired / Lapsed US ⏱️ 0.0 years remaining

Impregnation of cellulosic pulp under superatmospheric pressure with waste alkaline oxygan gas bleaching liquor followed by oxygen-alkali bleaching

Assignee: Mo och Domsjo AB
•
Filing: 1973-03-23
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Granted: 1974-10-22
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Expires: 1993-03-23
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Abstract

Abstract 1. IN THE BLEACHING OF CELLULOSE PULP BY THE ALKALINE OXYGEN GAS PROCESS, IN WHICH A GAS CONTAINING OXYGEN IS INTRODUCED INTO THE PULP IN THE PRESENCE OF ALKALI, WHICH CAN BE SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE AND SODIUM CARBONATE AND WHICH OPTIONALLY MAY CONTAIN SODIUM SULFIDE, THE IMPROVEMENT WHICH COMPRISES FIRST IMPREGNATED UNDER SUPERATMOSPHERE PRESSURE CELLULOSE PULP OBTAINED FROM A CONTINUOUS PULPING OR DIGESTION PROCESS AND CONTAINING SPENT PULPING LIQUOR WITH WASTE ALKALINE OXYGEN GAS BLEACHING LIQUOR IN ORDER TO DISPLACE A MAJOR PORPORTION OF THE PULPING CHEMICALS FROM THE CELLULOSE PULP BUT RETAIN A MINOR PROPORTION OF SUCH CHEMICALS, AND THEN IMPREGNATING UNDER SUPERATMOSSPHERIC PRESSURE THE RESULTING PULP WITH ALKALI TO BE EMPLOYED IN THE ALKALINE OXYGEN GAS BLEACHING.

Inventors

  • 👤 H Samuelson
  • 👤 I Croon

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 04:45
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1026

Claims Analysis

Total Claims: 2
Claim 1
Independent Claim 123 words
IN THE BLEACHING OF CELLULOSE PULP BY THE ALKALINE OXYGEN GAS PROCESS, IN WHICH A GAS CONTAINING OXYGEN IS INTRODUCED INTO THE PULP IN THE PRESENCE OF ALKALI, WHICH CAN BE SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE AND SODIUM CARBONATE AND WHICH OPTIONALLY MAY CONTAIN SODIUM SULFIDE, THE IMPROVEMENT WHICH COMPRISES FIRST IMPREGNATED UNDER SUPERATMOSPHERE PRESSURE CELLULOSE PULP OBTAINED FROM A CONTINUOUS PULPING OR DIGESTION PROCESS AND CONTAINING SPENT PULPING LIQUOR WITH WASTE ALKALINE OXYGEN GAS BLEACHING LIQUOR IN ORDER TO DISPLACE A MAJOR PORPORTION OF THE PULPING CHEMICALS FROM THE CELLULOSE PULP BUT RETAIN A MINOR PROPORTION OF SUCH CHEMICALS, AND THEN IMPREGNATING UNDER SUPERATMOSSPHERIC PRESSURE THE RESULTING PULP WITH ALKALI TO BE EMPLOYED IN THE ALKALINE OXYGEN GAS BLEACHING.
Claim 2
Dependent Claim 123 words
IN THE BLEACHING OF CELLULOSE PULP BY THE ALKALINE OXYGEN GAS PROCESS, IN WHICH A GAS CONTAINING OXYGEN IS INTRODUCED INTO THE PULP IN THE PRESENCE OF ALKALI, WHICH CAN BE SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE AND SODIUM CARBONATE AND WHICH OPTIONALLY MAY CONTAIN SODIUM SULFIDE, THE IMPROVEMENT WHICH COMPRISES FIRST IMPREGNATED UNDER SUPERATMOSPHERE PRESSURE CELLULOSE PULP OBTAINED FROM A CONTINUOUS PULPING OR DIGESTION PROCESS AND CONTAINING SPENT PULPING LIQUOR WITH WASTE ALKALINE OXYGEN GAS BLEACHING LIQUOR IN ORDER TO DISPLACE A MAJOR PORPORTION OF THE PULPING CHEMICALS FROM THE CELLULOSE PULP BUT RETAIN A MINOR PROPORTION OF SUCH CHEMICALS, AND THEN IMPREGNATING UNDER SUPERATMOSSPHERIC PRESSURE THE RESULTING PULP WITH ALKALI TO BE EMPLOYED IN THE ALKALINE OXYGEN GAS BLEACHING.

References Cited (Backward Citations)

No citation records indexed.

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1977-10-21 1978-04-22 1978-10-22 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1981-10-21 1982-04-22 1982-10-22 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1985-10-21 1986-04-22 1986-10-22 $7700.00 Window Closed / Lapsed

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