US3630828A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bleaching of a low-density, substantially uncompacted, porous fluffed cellulosic pulp
Assignee: FPInnovations
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Filing: 1968-05-13
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Granted: 1971-12-28
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Expires: 1988-05-13
Abstract
Abstract The bleaching of chemical wood pulp at high consistencies with gaseous bleaching agents is performed by repeatedly contacting the pulp, at a consistency above 15 percent and while unsupported, with radial spaced breaker arms extending from a rotating shaft thereby producing a comminuted pulp of low density and a substantially uncompacted porous fluffed structure and thereafter bleaching the comminuted fluffed pulp at a consistency above 15 percent with a gaseous bleaching agent such as chlorine dioxide gas.
Inventors
- 👤 Norman Liebergott
- 👤 Frederic H Yorston
- 👤 Raimbault M A T De Montigny
- 👤 John E Tasman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:09
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1026
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
24 words
A process as claimed in claim 1 in which the pulp is dewatered to a consistency between 15 and 60 percent before comminution thereof.
Claim 2
Dependent Claim
14 words
A process as claimed in claim 1 in which the pulp is wood pulp.
Claim 3
Dependent Claim
17 words
A process as claimed in claim 3 in which the wood pulp is unbleached before being comminuted.
Claim 4
Dependent Claim
26 words
A process as claimed in claim 1 which comprises removing unreacted chlorine in said second zone from the pulp by means of passage of air therethrough.
Claim 5
Dependent Claim
22 words
A process as claimed in claim 1 in which the fluffed pulp in said first zone has a consistency of 15-60 percent.
Claim 6
Dependent Claim
42 words
A process as claimed in claim 1 in which the residence time in the first zone is from 20 seconds to 5 minutes, during which time from 50 85 percent of the potential amount of chlorine is acquired by the fluffed pulp.
Claim 7
Dependent Claim
27 words
A process as claimed in claim 1 in which the breaker arms have a linear peripheral speed in the range of 1,500 to 6,000 feet per minute.
Claim 8
Dependent Claim
58 words
A process as claimed in claim 1 in which the comminuted fluffed pulp, following treatment in the second zone, is heated to a temperature of about 60* to 100* C. and the preheated pulp is contacted with the gaseous ammonia reagent for a reaction time of about 1 to 30 minutes at a temperature of about 60*-100* C.
Claim 9
Dependent Claim
22 words
A process as claimed in claim 1 in which the gaseous ammonia reagent includes steam or a nonreactive gas as a diluent.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-27 | 1975-06-28 | 1975-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-27 | 1979-06-28 | 1979-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-27 | 1983-06-28 | 1983-12-28 | $7700.00 | Window Closed / Lapsed |