US4072587A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Separate recovery of silver and gold from cyanide solutions
Assignee: United States Department of the Interior
•
Filing: 1977-04-21
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Granted: 1978-02-07
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Expires: 1997-04-21
Abstract
Abstract Silver and gold are selectively recovered from cyanide solutions by addition of lime, and precipitation of the silver as sulfide by means of sodium sulfide, followed by electrowinning of gold from the filtrate.
Inventors
- 👤 Harold J. Heinen
- 👤 David G. Peterson
- 👤 Roald E. Lindstrom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 16:11
CPC Classifications
C; C01; C01G; C01G5/00
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
79 words
A process for selective recovery of silver and gold from cyanide solutions containing both metals comprising (1) adding to the solution about 0.1 to 2.2 pound CaO per ton of solution, (2) treating the resulting solution with sodium sulfide in an amount of about 110 to 150 percent of the stoichiometric amount to precipitate the silver as silver sulfide, (3) filtering to remove the precipitated silver sulfide, and (4) electrolyzing the filtrate to deposit the gold at the cathode.
Claim 2
Dependent Claim
79 words
A process for selective recovery of silver and gold from cyanide solutions containing both metals comprising (1) adding to the solution about 0.1 to 2.2 pound CaO per ton of solution, (2) treating the resulting solution with sodium sulfide in an amount of about 110 to 150 percent of the stoichiometric amount to precipitate the silver as silver sulfide, (3) filtering to remove the precipitated silver sulfide, and (4) electrolyzing the filtrate to deposit the gold at the cathode.
Claim 3
Dependent Claim
26 words
The process of claim 1 in which the silver and gold-containing cyanide solution is obtained by stripping activated carbon loaded with cyanide complexes of the metals.
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) | 1981-02-06 | 1981-08-08 | 1982-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-06 | 1985-08-08 | 1986-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-06 | 1989-08-08 | 1990-02-07 | $7700.00 | Window Closed / Lapsed |