US4051026A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recovery of silver from silver-containing solutions
Assignee: KU Leuven
•
Filing: 1975-10-28
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Granted: 1977-09-27
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Expires: 1995-10-28
Abstract
Abstract Silver is recovered from silver-containing solutions such as waste waters from the photographic and electroplating industries, by treating such solutions with a cation exchanger in the presence of thiourea or thiourea derivatives. The cation exchanger may be selected from tectosilicates, phyllosilicates and organic cation exchangers.
Inventors
- 👤 Adrien Edgard Henri Julien Cremers
- 👤 Andre Petrus Adolf Maes
- 👤 Jozef Leonia Pleysier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:28
CPC Classifications
C; C01; C01G; C01G5/00; C01G5/003; C22; C22B; C22B3/00; C22B3/20; C22B3/26; C22B3/34; C22B3/42; Y; Y02; Y02P; Y02P10/00; Y02P10/20
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
24 words
A process of recovering silver from silver-containing solutions, which comprises treating such solution with a cation exchanger in the presence of a thiourea material.
Claim 2
Dependent Claim
24 words
A process of recovering silver from silver-containing solutions, which comprises treating such solution with a cation exchanger in the presence of a thiourea material.
Claim 3
Dependent Claim
28 words
The process as claimed in claim 1, wherein said thiourea material is selected from the group consisting of thiourea, phenylthiourea, alkyl and aryl derivatives of thiourea and thiosemicarbazide.
Claim 4
Dependent Claim
35 words
The process as claimed in claim 1, wherein said thiourea material is used in a proportion such as to arrive at a molar ratio of at least 3:1 for thiourea material to silver in solution.
Claim 5
Dependent Claim
24 words
The process as claimed in claim 1, wherein said thiourea material is added to said silver-containing solution shortly before contact with said cation exchanger.
Claim 6
Dependent Claim
27 words
The process as claimed in claim 1, wherein said cation exchanger is selected from the group consisting of synthetic and natural tectosilicates and synthetic and natural phyllosilicates.
Claim 7
Dependent Claim
16 words
The process as claimed in claim 1, wherein said cation exchanger is an organic cation exchanger.
Claim 8
Dependent Claim
29 words
The process as claimed in claim 1, wherein said cation exchanger is used in a proportion of 3 to 20 grams per gram of silver as present in solution.
Claim 9
Dependent Claim
28 words
The process as claimed in claim 1, wherein said cation exchanger is contacted with a combination of said silver-containing solution and said thiourea material in a discontinuous way.
Claim 10
Dependent Claim
31 words
The process as claimed in claim 1 wherein after the aforesaid treatment, silver is recovered from said cation exchanger by treatment with substances capable of forming anionic or neutral silver complexes.
Claim 11
Dependent Claim
35 words
The process of recovering silver from silver-containing solutions, which comprises the steps of: a. forming silver-thiourea complexes in said solution by adding thiourea material thereto; and b. adsorbing said silver-thiourea complexes on a cation exchanger.
Claim 12
Dependent Claim
35 words
The process of recovering silver from silver-containing solutions, which comprises the steps of: a. forming silver-thiourea complexes in said solution by adding thiourea material thereto; and b. adsorbing said silver-thiourea complexes on a cation exchanger.
Claim 13
Dependent Claim
55 words
In a process for recovering silver from a silver-containing solution which comprises the steps of adsorbing the silver on a cationic exchange material and then recovering the silver from the cationic exchange material, the improvement which comprises: adding thiourea material to the silver-containing solution in amount sufficient synergistically to increase the amount of silver recovered.
Claim 14
Dependent Claim
55 words
In a process for recovering silver from a silver-containing solution which comprises the steps of adsorbing the silver on a cationic exchange material and then recovering the silver from the cationic exchange material, the improvement which comprises: adding thiourea material to the silver-containing solution in amount sufficient synergistically to increase the amount of silver recovered.
Claim 15
Dependent Claim
27 words
In a process as defined in claim 11 wherein the thiourea material is added in amount of at least 3:1 molar ratio of thiourea material to silver.
Claim 16
Dependent Claim
42 words
In a process as defined in claim 12 which includes the step of rendering complexing agents such as cyanides and thiosulfates in said solution ineffective whereby said silver forms silver-thiourea complexes in said solution which are adsorbed by said cationic exchange material.
References Cited (Backward Citations)
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US2726141A
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US3725259A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-26 | 1981-03-28 | 1981-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-26 | 1985-03-28 | 1985-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-26 | 1989-03-28 | 1989-09-27 | $7700.00 | Window Closed / Lapsed |