US4014764A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for desilvering used bleach fix baths
Assignee: Agfa Gevaert AG
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Filing: 1972-04-17
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Granted: 1977-03-29
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Expires: 1992-04-17
Abstract
Abstract Photographic bleach fix baths are desilvered by electrolysis in a cell in which the cathode and anode chambers are separated by a diaphragm, with the exclusion of air, and the bleach fix bath is removed from the cell before the potential is switched off. For increasing the current yield the bleaching agent can be reduced prior to electrolysis for example by the addition of sodium dithionite.
Inventors
- 👤 Adolf Seiler
- 👤 Heinz Meckl
- 👤 Helmut Haseler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:45
CPC Classifications
C; C25; C25C; C25C1/00; C25C1/20; G; G03; G03C; G03C5/00; G03C5/26; G03C5/395; G03C5/3954
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
105 words
A method for electrolytically recovering silver from spent aqueous bleach-fix photographic processing solution containing ions of both silver and iron III comprising introducing into said processing solution a chemical compound characterized by the ability to reduce iron III to iron II, impressing a direct electrical current between a cathode which is immersed in a first pool of such processing solution and an anode which is immersed in a second pool of anolyte solution, thereby plating silver onto said cathode, said first and second pools being separated from one another by a non-porous cation permeable barrier or a porous barrier, and excluding air from said pools.
Claim 2
Independent Claim
105 words
A method for electrolytically recovering silver from spent aqueous bleach-fix photographic processing solution containing ions of both silver and iron III comprising introducing into said processing solution a chemical compound characterized by the ability to reduce iron III to iron II, impressing a direct electrical current between a cathode which is immersed in a first pool of such processing solution and an anode which is immersed in a second pool of anolyte solution, thereby plating silver onto said cathode, said first and second pools being separated from one another by a non-porous cation permeable barrier or a porous barrier, and excluding air from said pools.
Claim 3
Dependent Claim
14 words
A method in accordance with claim 1 wherein said chemical compound is sodium dithionite.
Claim 4
Dependent Claim
34 words
A method in accordance with claim 1 wherein said processing solution is a bleach-fix solution which comprises a ferric salt of an amino polycarboxylic acid as bleaching agent and a thiosulfate as fixing agent.
Claim 5
Dependent Claim
33 words
A method in accordance with claim 1 wherein said processing solution is a bleach-fix solution which comprises a ferric salt of ethylene diaminetetraacetic acid as bleaching agent and a thiosulfate as fixing agent.
Claim 6
Independent Claim
118 words
A method for electrolytically recovering silver from spent aqueous bleach-fix photographic processing solution containing ions of both silver and iron III comprising introducing into said processing solution a chemical compound characterized by the ability to reduce iron III to iron II, impressing a direct electrical current between a cathode which is immersed in a first pool of such processing solution and an anode which is immersed in a second pool of anolyte solution, thereby plating silver onto said cathode, said first and second pools being separated from one another by a non-porous cation permeable barrier or a porous barrier, excluding air from said pools, and regenerating said processing solution by introducing oxygen therein after removal of silver therefrom.
Claim 7
Independent Claim
118 words
A method for electrolytically recovering silver from spent aqueous bleach-fix photographic processing solution containing ions of both silver and iron III comprising introducing into said processing solution a chemical compound characterized by the ability to reduce iron III to iron II, impressing a direct electrical current between a cathode which is immersed in a first pool of such processing solution and an anode which is immersed in a second pool of anolyte solution, thereby plating silver onto said cathode, said first and second pools being separated from one another by a non-porous cation permeable barrier or a porous barrier, excluding air from said pools, and regenerating said processing solution by introducing oxygen therein after removal of silver therefrom.
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) | 1980-03-28 | 1980-09-27 | 1981-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-28 | 1984-09-27 | 1985-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-28 | 1988-09-27 | 1989-03-29 | $7700.00 | Window Closed / Lapsed |