US4073727A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the oxidation of waste liquors arising from the manufacture of paper pulp
Assignee: Groupement Europeen de la Cellulose
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Filing: 1974-03-20
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Granted: 1978-02-14
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Expires: 1994-03-20
Abstract
Abstract A process for the oxidation of waste liquors arising from the manufacture of paper pulp. The process consists of introducing the liquor into a reservoir comprising a series of candles consisting of a sintered material, arranged above the bottom of the reservoir, air being blown through these candles into the liquor which is kept at 70° to 90° C during the oxidation.
Inventors
- 👤 Yves G. Garrigues
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:14
CPC Classifications
D; D21; D21C; D21C11/00; D21C11/0057; Y; Y10; Y10S; Y10S210/00; Y10S210/928
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
78 words
In a process for the oxidation of an aqueous liquor containing caustic soda and sodium sulphide arising from the manufacture of paper pulp, the improvement which comprises: oxidizing the liquor in a reservoir in which are located horizontally disposed candles of a sintered material through which air for oxidation is blown, the air for oxidation being introduced into the candles at about 90° C and oxidation being carried out at a temperature of from 70° to 90° C.
Claim 2
Dependent Claim
78 words
In a process for the oxidation of an aqueous liquor containing caustic soda and sodium sulphide arising from the manufacture of paper pulp, the improvement which comprises: oxidizing the liquor in a reservoir in which are located horizontally disposed candles of a sintered material through which air for oxidation is blown, the air for oxidation being introduced into the candles at about 90° C and oxidation being carried out at a temperature of from 70° to 90° C.
Claim 3
Dependent Claim
22 words
A process according to claim 1, wherein the candles are made of sintered stainless steel and have 3 to 5 micron pores.
Claim 4
Dependent Claim
57 words
A process according to claim 2, wherein the liquor treated is a black liquor containing lignin at a solids content of 48 to 50% by weight and oxidation is effected for about 45 minutes using a volume of air which is at least the volume theoretically required for the oxidation and is less than twice said volume.
Claim 5
Dependent Claim
41 words
A process according to claim 2, wherein the liquor treated is a white liquor and oxidation is effected for about four hours using a volume of air which is about 2.6 times the volume of air theoretically required for the oxidation.
Claim 6
Dependent Claim
58 words
A process according to claim 1, wherein the candles are arranged at about 40 centimeters from the bottom of the reservoir and the liquor level in the reservoir is maintained at about 2 meters from the bottom of the reservoir, the liquor being introduced into the reservoir at the top and being withdrawn laterally just above the bottom.
References Cited (Backward Citations)
US2690425A
Cited
US2774585A
Cited
US3178260A
Cited
US3207572A
Cited
US3545731A
Cited
US3696929A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-13 | 1981-08-15 | 1982-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-13 | 1985-08-15 | 1986-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-13 | 1989-08-15 | 1990-02-14 | $7700.00 | Window Closed / Lapsed |