Patent US4256557A successfully refreshed from Google Patents.
US4256557A
Expired / Lapsed
US
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Copper electrowinning and Cr+6 reduction in spent etchants using porous fixed bed coke electrodes
Assignee: United States Department of the Interior
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Filing: 1979-10-16
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Granted: 1981-03-17
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Expires: 1999-10-16
Abstract
Abstract Exhausted Cr+6 oxidizing solutions containing Cu+2 values are electrolyzed by placing an exhausted Cr+6 etching or oxidizing solution containing copper ion and Cr+3 ions in an electrolytic cell containing at least one pair of carbon particle electrodes, and forcefully flowing the exhausted solution through the electrodes and simultaneously impressing a direct current across the electrodes such that at the cathode divalent copper is reduced to copper metal and Cr+6 values are reduced to trivalent chromium and at the anode water is oxidized to oxygen.
Inventors
- 👤 David M. Soboroff
- 👤 Hector O. McDonald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:45
CPC Classifications
C; C25; C25C; C25C7/00; C25C7/02; C02; C02F; C02F1/00; C02F1/46; C02F1/461; C02F1/46104; C02F1/46109; C02F1/46114; C02F1/467; C02F1/4676; C25C1/00; C25C1/12; C02F1/4678; C02F2001/46133; C02F2101/00; C02F2101/10; C02F2101/20; C02F2101/22
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
102 words
A method of reducing Cr +6 to Cr +3 and recovering copper values from spent chromium oxidizing solutions, comprising: placing an exhausted Cr +6 etching or oxidizing solution containing copper ions and Cr +3 ions in an electrolytic cell containing at least one pair of carbon particle electrodes as the cathode and anode respectively; and forcefully flowing said exhausted solution through the electrodes and simultaneously impressing a direct current across said electrodes such that at the cathode divalent copper is reduced to copper metal and Cr +6 values are reduced to trivalent chromium and at the anode water is oxidized to oxygen.
Claim 2
Independent Claim
102 words
A method of reducing Cr +6 to Cr +3 and recovering copper values from spent chromium oxidizing solutions, comprising: placing an exhausted Cr +6 etching or oxidizing solution containing copper ions and Cr +3 ions in an electrolytic cell containing at least one pair of carbon particle electrodes as the cathode and anode respectively; and forcefully flowing said exhausted solution through the electrodes and simultaneously impressing a direct current across said electrodes such that at the cathode divalent copper is reduced to copper metal and Cr +6 values are reduced to trivalent chromium and at the anode water is oxidized to oxygen.
Claim 3
Dependent Claim
17 words
The method of claim 1, which further comprises, after said electrolysis, recovering plate copper from said cathode.
Claim 4
Dependent Claim
30 words
The method of claim 1, wherein the current impressed across said electrodes has a density of 1 to 5 amp/dm 2 at a potential ranging from 3 to 10 volts.
Claim 5
Dependent Claim
21 words
The method of claim 1, wherein the surface area of the cathode relative to the anode ranges from 2:1 to 1:1.
Claim 6
Dependent Claim
21 words
The method of claim 1, wherein said exhausted solution has a divalent copper ion concentration of 100 g/l to 1 g/l.
Claim 7
Dependent Claim
22 words
The method of claim 1, wherein the carbon particles in said electrodes range in size from minus 4 to plus 20 mesh.
Claim 8
Dependent Claim
23 words
The method of claim 1, wherein said carbon particles are metallurgical coke particles, petroleum coke particles, foundry coke particles or coke breeze particles.
Claim 9
Dependent Claim
32 words
The method of claim 1, wherein said exhausted Cr +6 etching solution is derived from the etching of brass, printed circuit boards and plastic substrates by aqueous hexavalent chromium sulfuric acid solutions.
Claim 10
Dependent Claim
19 words
The method of claim 1, wherein said electrolysis is conducted for a time ranging from 4 to 96 hours.
References Cited (Backward Citations)
US883170A
Cited
US1851603A
Cited
US3682796A
Cited
US3679557A
Cited
US3804733A
Cited
US3896013A
Cited
US3966571A
Cited
US3919062A
Cited
US3915822A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-16 | 1984-09-15 | 1985-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-16 | 1988-09-15 | 1989-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-16 | 1992-09-15 | 1993-03-17 | $7700.00 | Window Closed / Lapsed |