US4021320A
Expired / Lapsed
US
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Electrochemical process utilizing alternating current for recovery of silver from photographic fixer solution and other solutions containing silver ions
Assignee: NOHREN FRANCES W 5170 126TH AVENUE NORTH CLEARWATER FL 33520
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Filing: 1975-09-24
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Granted: 1977-05-03
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Expires: 1995-09-24
Abstract
Abstract The present invention relates to a method of electrochemically removing silver in the form of AgO from a photographic fixer solution containing silver ions without destroying the utility of the solution comprising the steps of applying alternating current having a frequency of between about 0.5 Hz and 800 Hz and a current density of between about 0.1 and 20 amperes per square inch across electrodes immersed in said solution to cause AgO to precipitate at the electrodes. The method can also be practiced above the range of about 20 amperes per square inch at the cost of destroying the utility of the solution. The method can also be used to remove silver in the form of AgO from other solutions.
Inventors
- 👤 Karl Moeglich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:50
CPC Classifications
C; C25; C25B; C25B1/00
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
68 words
A method of electrochemically removing silver in the form of AgO from a photographic fixer solution without destroying the utility of the solution comprising the steps of applying alternating current having a frequency of between about 0.5 Hz and 800 Hz and a density of between about 0.1 and 20 amperes per square inch across electrodes immersed in said solution to cause AgO to precipitate at the electrodes.
Claim 2
Independent Claim
68 words
A method of electrochemically removing silver in the form of AgO from a photographic fixer solution without destroying the utility of the solution comprising the steps of applying alternating current having a frequency of between about 0.5 Hz and 800 Hz and a density of between about 0.1 and 20 amperes per square inch across electrodes immersed in said solution to cause AgO to precipitate at the electrodes.
Claim 3
Dependent Claim
19 words
A method as set forth in claim 1 wherein said frequency is between about 10 Hz and 120 Hz.
Claim 4
Dependent Claim
22 words
A method as set forth in claim 2 wherein said current density is between about 1 and 10 amperes per square inch.
Claim 5
Dependent Claim
22 words
A method as set forth in claim 2 wherein said current density is between about 3 and 7.5 amperes per square inch.
Claim 6
Dependent Claim
15 words
A method as set forth in claim 1 wherein said frequency is about 60 Hz.
Claim 7
Dependent Claim
22 words
A method as set forth in claim 5 wherein said current density is between about 1 and 10 amperes per square inch.
Claim 8
Dependent Claim
22 words
A method as set forth in claim 5 wherein said current density is between about 3 and 7.5 amperes per square inch.
Claim 9
Dependent Claim
29 words
A method as set forth in claim 1 wherein said electrodes are selected from the group of graphite, noble metals, ruthenium oxide coated valve metals, or stainless steel alloys.
Claim 10
Dependent Claim
34 words
A method as set forth in claim 8 wherein said frequency is between about 10 Hz and 120 Hz and wherein said current density is between about 1 and 10 amperes per square inch.
Claim 11
Dependent Claim
30 words
A method as set forth in claim 8 wherein said frequency is about 60 Hz and wherein said current density is between about 3 and 7.5 amperes per square inch.
Claim 12
Dependent Claim
22 words
A method as set forth in claim 1 wherein said current density is between about 1 and 10 amperes per square inch.
Claim 13
Dependent Claim
22 words
A method as set forth in claim 1 wherein said current density is between about 3 and 7.5 amperes per square inch.
Claim 14
Independent Claim
45 words
A method of removing silver in the form of AgO from a photographic fixer solution comprising the steps of placing electrodes into electrical contact with said solution and applying alternating current having a frequency of between about 0.5 Hz and 800 Hz across said electrodes.
Claim 15
Independent Claim
45 words
A method of removing silver in the form of AgO from a photographic fixer solution comprising the steps of placing electrodes into electrical contact with said solution and applying alternating current having a frequency of between about 0.5 Hz and 800 Hz across said electrodes.
Claim 16
Dependent Claim
29 words
A method as set forth in claim 13 wherein said electrodes are selected from the group of graphite, noble metals, ruthenium oxide coated valve metals, or stainless steel alloys.
Claim 17
Dependent Claim
19 words
A method as set forth in claim 13 wherein said frequency is between about 10 Hz and 120 Hz.
Claim 18
Independent Claim
52 words
A method of converting a silver salt to AgO comprising the steps of dissolving the silver salt in a solution of sodium, potassium or ammonium thiosulfate; placing electrodes in electrical contact with the solution; and applying alternating current having a frequency of between about 0.5 Hz and 800 Hz across said electrodes.
Claim 19
Independent Claim
52 words
A method of converting a silver salt to AgO comprising the steps of dissolving the silver salt in a solution of sodium, potassium or ammonium thiosulfate; placing electrodes in electrical contact with the solution; and applying alternating current having a frequency of between about 0.5 Hz and 800 Hz across said electrodes.
Claim 20
Dependent Claim
24 words
A method as set forth in claim 16 wherein said silver salt is selected from the group of silver chloride, sulphate, phosphate, and nitrate.
Claim 21
Dependent Claim
19 words
A method as set forth in claim 17 wherein said frequency is between about 10 Hz and 120 Hz.
Claim 22
Dependent Claim
24 words
A method as set forth in claim 18 wherein said current has a density of between about 0.1 and 20 amperes per square inch.
Claim 23
Dependent Claim
18 words
A method as set forth in claim 16 wherein said frequency is between 10 Hz and 120 Hz.
Claim 24
Dependent Claim
15 words
A method as set forth in claim 20 wherein said frequency is about 60 Hz.
Claim 25
Independent Claim
110 words
A method for continuously processing photographic fixer solution to remove silver therefrom comprising the steps of: providing a cell having mutually spaced electrodes therein and a source of alternating current coupled to said electrodes; continuously supplying said solution to said cell to submerge a predetermined portion of said electrodes; applying alternating current having a frequency of between 0.5 Hz and 800 Hz and a current density of at least 0.1 amperes per square inch across said electrodes; continuously removing said processed solution from said cell whereby the solution in said cell to be processed will be maintained at a predetermined level, and collecting a precipitate of AgO from said cell.
Claim 26
Independent Claim
110 words
A method for continuously processing photographic fixer solution to remove silver therefrom comprising the steps of: providing a cell having mutually spaced electrodes therein and a source of alternating current coupled to said electrodes; continuously supplying said solution to said cell to submerge a predetermined portion of said electrodes; applying alternating current having a frequency of between 0.5 Hz and 800 Hz and a current density of at least 0.1 amperes per square inch across said electrodes; continuously removing said processed solution from said cell whereby the solution in said cell to be processed will be maintained at a predetermined level, and collecting a precipitate of AgO from said cell.
Claim 27
Dependent Claim
18 words
The method of claim 22 wherein the current density is between 0.1 and 20 amperes per square inch.
Claim 28
Dependent Claim
16 words
The method of claim 23 wherein said frequency is between about 10 Hz and 120 Hz.
Claim 29
Dependent Claim
12 words
The method of claim 22 wherein said frequency is about 60 Hz.
Claim 30
Dependent Claim
19 words
The method of claim 22 wherein said current density is between about 1 and 10 amperes per square inch.
Claim 31
Dependent Claim
19 words
The method of claim 22 wherein said current density is between about 3 and 7.5 amperes per square inch.
Claim 32
Dependent Claim
116 words
A continuous method for converting a silver salt to AgO comprising the steps of dissolving the silver salt in a solution of sodium, potassium or ammonium thiosulfate; providing a cell having mutually spaced electrodes and a source of alternating current coupled to said electrodes; continuously supplying said solution to said cell to submerge a predetermined portion of said electrodes; applying alternating current having a frequency of between 0.5 Hz and 800 Hz and a current density of at least 0.1 ampere per square inch across said electrodes; continuously removing said solution from said cell whereby the solution in said cell will be maintained at a predetermined level, and collecting a precipitate of AgO from said cell.
Claim 33
Dependent Claim
116 words
A continuous method for converting a silver salt to AgO comprising the steps of dissolving the silver salt in a solution of sodium, potassium or ammonium thiosulfate; providing a cell having mutually spaced electrodes and a source of alternating current coupled to said electrodes; continuously supplying said solution to said cell to submerge a predetermined portion of said electrodes; applying alternating current having a frequency of between 0.5 Hz and 800 Hz and a current density of at least 0.1 ampere per square inch across said electrodes; continuously removing said solution from said cell whereby the solution in said cell will be maintained at a predetermined level, and collecting a precipitate of AgO from said cell.
Claim 34
Dependent Claim
18 words
The method of claim 28 wherein said current density is between 0.1 and 20 amperes per square inch.
Claim 35
Dependent Claim
17 words
The method of claim 28 wherein said frequency is maintained at between 10 Hz and 120 Hz.
Claim 36
Dependent Claim
14 words
The method of claim 28 wherein said frequency is maintained at about 60 Hz.
Claim 37
Dependent Claim
21 words
The method of claim 28 wherein the current density is maintained at between about 1 and 10 amperes per square inch.
Claim 38
Dependent Claim
21 words
The method of claim 28 wherein the current density is maintained at between about 3 and 7.5 amperes per square inch.
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) | 1980-05-02 | 1980-11-01 | 1981-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-02 | 1984-11-01 | 1985-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-02 | 1988-11-01 | 1989-05-03 | $7700.00 | Window Closed / Lapsed |