US4196043A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Kraft pulp bleaching and recovery process
Assignee: Kimberly Clark Tissue Co
•
Filing: 1974-10-21
•
Granted: 1980-04-01
•
Expires: 1994-10-21
Abstract
Abstract A Kraft pulp bleaching process comprising from one to about three treatments with ozone and a final treatment with an alkaline peroxide solution, the treatments being separated by an alkaline extraction, wherein effluent from the bleach treatments is utilized in subsequent bleaching operations or in the chemical recovery system of a Kraft pulping process.
Inventors
- 👤 Rudra P. Singh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:38
CPC Classifications
D; D21; D21C; D21C11/00; D21C11/0021; D21C11/0028; D21C9/00; D21C9/10; D21C9/1026; D21C9/1057
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
130 words
In a method of kraft wood pulping including a kraft chemical recovery system and a kraft wood pulp bleaching operation, the improvement which comprises bleaching the kraft wood pulp by a sequence of treatments comprising: from one to about three treatments with ozone; a final treatment with an alkaline peroxide solution; separating the treatments with alkaline extractions; recycling effluent from the alkaline extractions and alkaline peroxide treatment to reduce the fresh water requirements of the bleaching operations; and introducing effluent from the bleaching operation into the kraft pulp chemical recovery system; wherein the method is free of any treatments employing chlorine or chlorine-containing compounds and; whereby the need for treating the effluent being introduced into the kraft pulp chemical recovery system for the removal of chlorine containing salts is eliminated.
Claim 2
Dependent Claim
130 words
In a method of kraft wood pulping including a kraft chemical recovery system and a kraft wood pulp bleaching operation, the improvement which comprises bleaching the kraft wood pulp by a sequence of treatments comprising: from one to about three treatments with ozone; a final treatment with an alkaline peroxide solution; separating the treatments with alkaline extractions; recycling effluent from the alkaline extractions and alkaline peroxide treatment to reduce the fresh water requirements of the bleaching operations; and introducing effluent from the bleaching operation into the kraft pulp chemical recovery system; wherein the method is free of any treatments employing chlorine or chlorine-containing compounds and; whereby the need for treating the effluent being introduced into the kraft pulp chemical recovery system for the removal of chlorine containing salts is eliminated.
Claim 3
Dependent Claim
28 words
A method as recited in claim 1 in which the effluent from the alkaline peroxide treatment is used in an alkaline extraction step in a subsequent bleaching operation.
Claim 4
Dependent Claim
30 words
A method as recited in claim 1 in which the effluent from a second or third alkaline extraction is used in an earlier alkaline extraction in a subsequent bleaching operation.
Claim 5
Dependent Claim
16 words
A method as recited in claim 1 in which the number of ozone treatments is 2.
Claim 6
Dependent Claim
26 words
A method as recited in claim 1 in which the effluent from the bleaching operation is utilized at the brown stock washer in the recovery system.
Claim 7
Dependent Claim
25 words
A method as recited in claim 1 in which the effluent from the bleaching operation is utilized to dissolve the smelt in the recovery system.
Claim 8
Dependent Claim
22 words
A method as recited in claim 1 in which the effluent from the bleaching operation is utilized at the lime mud washer.
Claim 9
Dependent Claim
22 words
A method as recited in claim 1 in which the effluent from the bleaching operation is utilized in the kiln stack scrubber.
References Cited (Backward Citations)
US1683262A
Cited
US1957937A
Cited
US2147618A
Cited
US3366534A
Cited
US3382149A
Cited
US3453174A
Cited
US3451888A
Cited
US3632469A
Cited
US3740308A
Cited
US3867246A
Cited
US3798119A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-01 | 1983-10-01 | 1984-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-01 | 1987-10-01 | 1988-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-01 | 1991-10-01 | 1992-04-01 | $7700.00 | Window Closed / Lapsed |