US3560330A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multistage cellulose pulp bleaching with chlorine and chlorine dioxide
Assignee: Stora Enso Oyj
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Filing: 1967-02-03
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Granted: 1971-02-02
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Expires: 1987-02-03
Abstract
Abstract BLEACHING CELLULOSE PULP IN A MULTISTAGE LPROCESS WHEREIN THE PULP AT LOW CONSISTENCY (2.5-3.5%) IS BLEACHED WITH CHLORINE, THEN TREATED WITH ALKALI TO REMOVE THE MAJOR PORTION OF THE LIGNON CONTENT OF THE PULP, AND THEREAFTER TREATED WITH AN EXCELL OF ELEMENTAL CHLORINE AT A PULP CONCENTRATION OF NOT LESS THAN 5% AND AT A TEMPERATURE OF BELOW 35*C. SMALL AMOUNTS OF CHLORINE DIOXIDE (0.52 GM./KILO OF PULP) MAY OPTIONALLY BE ADDED TO THE ELEMENTAL CHLORINE IN THE SECOND CHLORINE TREATMENT STEP. SUBSEQUENT TREATMENT STAGES MAY FOLLOW WHICH INCLUDE ALKALI WASHES AND CHLORINE DIOXIDE BLEACHINGS.
Inventors
- 👤 Nils Knut Gabriel Ahlborg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:51
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/12; D21C9/14; D21C9/142
Claims Analysis
Total Claims: 0
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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) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |