US3793168A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of recovering silver
Assignee: Individual
•
Filing: 1971-01-18
•
Granted: 1974-02-19
•
Expires: 1991-01-18
Abstract
Abstract A method of recovering metallic silver from scrap photographic film in which the film is first immersed in a solution of hydrochloric or hydrobromic acid and a chromate; thereafter immersed in a hypo bath; the free silver thereafter being removed from the hypo bath by an electrolytic process.
Inventors
- 👤 R Lilly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:07
CPC Classifications
G; G03; G03C; G03C11/00; G03C11/24
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
17 words
A process as defined in claim 1 wherein said silver is removed from said solvent by electroplating.
Claim 2
Dependent Claim
20 words
A process as defined in claim 1 comprising the additional steps of draining the film after immersion in said solution.
Claim 3
Dependent Claim
16 words
A process as defined in claim 1 wherein said solution is agitated during immersion of film.
Claim 4
Dependent Claim
28 words
A process as defined in claim 1 comprising the additional step of washing the film prior to its immersion in said solvent and after immersion in said solution.
Claim 5
Dependent Claim
23 words
A process as defined in claim 5 comprising the additional steps of draining the film after immersion in said solution and after washing.
Claim 6
Dependent Claim
75 words
A process for recovering silver from scrap film which comprises: immersing the film in a solution of potassium dichromate and an acid selected from the group consisting of hydrochloric acid and hydrobromic acid to convert the silver of said film to a silver halide; immersing the film in a solvent selected from the group consisting of sodium thiosulfate, ammonium thiosulfate and ammonium hydroxide to dissolve said silver halide; and removing the silver from said solvent.
Claim 7
Dependent Claim
17 words
A process as defined in claim 7 wherein said silver is removed from said solvent by electroplating.
Claim 8
Dependent Claim
20 words
A process as defined in claim 1 comprising the additional steps of draining the film after immersion in said solution.
Claim 9
Dependent Claim
16 words
A process as defined in claim 7 wherein said solution is agitated during immersion of film.
Claim 10
Dependent Claim
28 words
A process as defined in claim 1 comprising the additional step of washing the film prior to its immersion in said solvent and after immersion in said solution.
Claim 11
Dependent Claim
23 words
A process as defined in claim 11 comprising the additional steps of draining the film after immersion in said solution and after washing.
Claim 12
Dependent Claim
91 words
A process for recovering silver from scrap film which comprises: immersing the film for at least 15 seconds in a solution of 20.64 grams of potassium dichromate per liter of 1.44 normal hydrochloric acid to convert the silver of said film to a silver halide; agitating said solution while the film is immersed therein; draining the film; immersing the film in water; draining the film; immersing the film in sodium thiosulfate for approximately 2 to 3 minutes to dissolve said silver halide; and removing silver from said sodium thiosulfate by electroplating.
Claim 13
Dependent Claim
80 words
A process for recovering silver from exposed film, comprising: a. immersing the film into a first solution of potassium dichromate and an acid selected from the group consisting of hydrochloric acid and hydrobromic acid to cause the silver on said film to be converted to a silver halide, b. thereafter immersing the film into a second hypo soluTion which results in the removal of said silver halide into said second solution, and c. removing the silver from said second solution.
Claim 14
Dependent Claim
18 words
The process as described in claim 14 wherein said removal of the silver is by an electroplating process.
References Cited (Backward Citations)
DE1051117B
Cited
US3510413A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |