Patent US4512879A successfully refreshed from Google Patents.
US4512879A
Expired / Lapsed
US
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Process for producing a metalliferous concentrate from a particulate feed material
Assignee: Battelle Memorial Institute Inc
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Filing: 1983-07-20
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Granted: 1985-04-23
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Expires: 2003-07-20
Abstract
Abstract A concentrate containing precious metals is produced from a particulate feed material containing particles of various sizes by a size fractionation step, a gravity separation step performed on each size fraction separately, a magnetic separation step and a second gravity separation step. The process is especially intended for separating gold and other metals from so-called "black sand" placer deposits.
Inventors
- 👤 Yosry A. Attia
- 👤 Ted L. Tewksbury
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:05
CPC Classifications
B; B03; B03B; B03B9/00; B07; B07B; B07B9/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
156 words
A process for producing a metalliferous concentrate from particles of varying sizes, said process comprising: subjecting said particles to a preliminary separation step in which only particles smaller than about 10 mesh are retained; dividing said retained particles into a first fraction containing large particles and a second fraction containing smaller particles; subjecting said first and second fractions separately to a first gravity separation step, thereby producing from each of said first and second fractions a denser fraction and a lighter fraction; subjecting said denser fractions to a low-intensity magnetic separation step producing at least one low-intensity non-magnetic fraction and at least one strongly magnetic fraction; subjecting said at least one low-intensity non-magnetic fraction to a high-intensity magnetic separation step, thereby producing at least one non-magnetic fraction and a weakly magnetic fraction; and subjecting said at least one non-magnetic fraction to a second gravity separation step, thereby separating a denser fraction to form said metalliferous concentrate.
Claim 2
Dependent Claim
156 words
A process for producing a metalliferous concentrate from particles of varying sizes, said process comprising: subjecting said particles to a preliminary separation step in which only particles smaller than about 10 mesh are retained; dividing said retained particles into a first fraction containing large particles and a second fraction containing smaller particles; subjecting said first and second fractions separately to a first gravity separation step, thereby producing from each of said first and second fractions a denser fraction and a lighter fraction; subjecting said denser fractions to a low-intensity magnetic separation step producing at least one low-intensity non-magnetic fraction and at least one strongly magnetic fraction; subjecting said at least one low-intensity non-magnetic fraction to a high-intensity magnetic separation step, thereby producing at least one non-magnetic fraction and a weakly magnetic fraction; and subjecting said at least one non-magnetic fraction to a second gravity separation step, thereby separating a denser fraction to form said metalliferous concentrate.
Claim 3
Dependent Claim
15 words
A process according to claim 1 wherein said feed material comprises black sand containing gold.
Claim 4
Dependent Claim
41 words
A process according to claim 1 wherein said denser fraction formed in said second gravity separation step is thereafter subjected to electrostatic separation and is thereby separated into a conductive fraction, which forms said metalliferous concentrate, and a relatively non-conductive fraction.
Claim 5
Dependent Claim
15 words
A process according to claim 3 wherein said feed material comprises black sand containing gold.
Claim 6
Dependent Claim
34 words
A process according to claim 3 wherein said process is conducted with the fractions to be processed slurried in water and wherein said denser fraction is dewatered before being subjected to said electrostatic separation.
Claim 7
Dependent Claim
15 words
A process according to claim 5 wherein said feed material comprises black sand containing gold.
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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) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |