US4481040A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the chemical dissolution of oxide deposits
Assignee: NUCLEAR ELECTRIC PLC
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Filing: 1982-06-10
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Granted: 1984-11-06
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Expires: 2002-06-10
Abstract
Abstract Oxide deposits containing chromium are dissolved by contacting the deposits sequentially with (i) a permanganate salt in acid solution to remove chromium therefrom as hexavalent chromium; (ii) a reducing agent in acid solution to destroy excess permanganate ions and manganese dioxide formed by reduction of the permanganate; and (iii) a mixture of a reducing agent and complexing acid to dissolve the residual chromium depleted oxide.
Inventors
- 👤 Ian R. Brookes
- 👤 Malcolm E. Pick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:00
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/02; G; G21; G21F; G21F9/00; G21F9/001; G21F9/002; G21F9/004
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
94 words
In a process for the chemical dissolution of oxide deposits containing a proportion of chromium and in particular for the chemical decontamination of oxide deposits contaminated with activated species the improvement which consists essentially of contacting the oxide deposits sequentially with (i) a permanganate salt in acid solution to remove chromium therefrom as hexavalent chromium; (ii) a reducing agent in acid solution to destroy excess permanganate ions and manganese dioxide formed by reduction of the permanganate; and (iii) a mixture of a reducing agent and complexing acid to dissolve the residual chromium depleted oxide.
Claim 2
Dependent Claim
94 words
In a process for the chemical dissolution of oxide deposits containing a proportion of chromium and in particular for the chemical decontamination of oxide deposits contaminated with activated species the improvement which consists essentially of contacting the oxide deposits sequentially with (i) a permanganate salt in acid solution to remove chromium therefrom as hexavalent chromium; (ii) a reducing agent in acid solution to destroy excess permanganate ions and manganese dioxide formed by reduction of the permanganate; and (iii) a mixture of a reducing agent and complexing acid to dissolve the residual chromium depleted oxide.
Claim 3
Dependent Claim
24 words
A process according to claim 1 wherein the contacting with the phase (iii) chemicals is commenced before the reaction of phase (ii) is complete.
Claim 4
Dependent Claim
13 words
A process according to claim 1 wherein the permanganate salt is potassium permanganate.
Claim 5
Dependent Claim
23 words
A process according to claim 1 wherein treatment (i) is carried out for a period of time of from 5 to 24 hours.
Claim 6
Dependent Claim
22 words
A process according to claim 1 wherein treatment (ii) is carried out for a period of time from 0.5 to 1 hour.
Claim 7
Dependent Claim
21 words
A process according to claim 1 wherein treatment (ii) is carried out using a mixture of oxalic acid and nitric acid.
Claim 8
Dependent Claim
23 words
A process according to claim 1 wherein treatment (iii) is carried out for a period of time of from 2 to 7 hours.
Claim 9
Dependent Claim
21 words
A process according to claim 1 wherein treatment (iii) is carried out using a mixture of oxalic acid and citric acid.
Claim 10
Dependent Claim
16 words
A process according to claim 1 which is carried out at a temperature of 95° C.
Claim 11
Dependent Claim
19 words
A process according to claim 1 wherein waste solution therefrom is treated with at least one ion exchange resin.
References Cited (Backward Citations)
US3080262A
Cited
US3013909A
Cited
US3496017A
Cited
US3615817A
Cited
US3664870A
Cited
US3873362A
Cited
US4226640A
Cited
GB2064852A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-11-06 | 1988-05-07 | 1988-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-06 | 1992-05-07 | 1992-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-06 | 1996-05-07 | 1996-11-06 | $7700.00 | Window Closed / Lapsed |