Patent US3718457A successfully refreshed from Google Patents.
US3718457A
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Process for the recovery of mercury from waste brine from mercury cells
Assignee: Imperial Chemical Industries Ltd
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Filing: 1971-01-29
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Granted: 1973-02-27
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Expires: 1991-01-29
Abstract
Abstract A process for recovering mercury from waste brine from mercury cells comprising adding sulphide or hydrosulphide ions to the brine to precipitate mercury sulphide, trapping the mercury sulphide on a mixed media filter in which the average size of particles in successive super-imposed layers decreases and the specific gravity of the particles increases from the top of the filter downwards, removing the mercury sulphide from the filter by backwashing with an aqueous liquor, separating the mercury sulphide from the backwash liquor and treating the sulphide to produce metallic mercury.
Inventors
- 👤 J Entwisle
- 👤 R Griffiths
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:26
CPC Classifications
C; C01; C01D; C01D3/00; C01D3/14; C01D3/16; C01D1/00; C01D1/04; C01D1/28; C01D1/32; C01G; C01G13/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
21 words
A process according to claim 1 in which the redox potential produced is of a value more negative than 0.25 volts.
Claim 2
Dependent Claim
16 words
A process according to claim 2 in which the bed is also scoured with a gas.
Claim 3
Dependent Claim
15 words
A process according to claim 2 in which the backwashing is carried out using water.
Claim 4
Dependent Claim
15 words
A process according to claim 3 in which the scouring is carried out with air.
Claim 5
Dependent Claim
27 words
A process according to claim 1 in which the brine is treated by air-blowing to reduce the free chlorine content before treatment with the sulphide or hydrosulphide.
Claim 6
Dependent Claim
25 words
A process according to claim 1 in which as a source of sulphide or hydrosulphide ions there is used an alkali metal sulphide or hydrosulphide.
Claim 7
Dependent Claim
21 words
A process according to claim 7 in which the alkali metal sulphide or hydrosulphide is sodium sulfide or is sodium hydrosulphide.
Claim 8
Dependent Claim
28 words
A process according to claim 1 in which the filter comprises granular filtration material selected from coal, activated carbon, graphite, quartz, flint, silica, magnesia, alumina, garnet and sand.
Claim 9
Dependent Claim
24 words
A process according to claim 1 in which the waste brine is treated to remove insoluble mAtter before addition of the sulphide or hydrosulphide.
Claim 10
Dependent Claim
13 words
A process according to claim 10 in which the waste brine is filtered.
References Cited (Backward Citations)
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Cited
US1777546A
Cited
US1981877A
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US2057237A
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US2555970A
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US2860952A
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US2885282A
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US3085859A
Cited
US3382983A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-27 | 1976-08-28 | 1977-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-27 | 1980-08-28 | 1981-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-27 | 1984-08-28 | 1985-02-27 | $7700.00 | Window Closed / Lapsed |