US4201667A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for removing arsenic from aqueous mediums
Assignee: FMC Corp
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Filing: 1979-02-09
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Granted: 1980-05-06
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Expires: 1999-02-09
Abstract
Abstract A process for removing arsenic from aqueous mediums by adding, in the presence of phosphorus, sufficient calcium hydroxide to adjust the aqueous medium to a pH of from about 7.0 to 11.5, whereby precipitates of both arsenic and phosphorus are formed and are subsequently separated from the aqueous medium. As a secondary treatment, calcium salts of arsenic and phosphorus in oxidation states lower than +5, and thus dissolved in the aqueous medium are oxidized, as by the addition of chlorine or hypochloride to such medium, and thereby converted to more insoluble forms which are separated from the aqueous medium as precipitates.
Inventors
- 👤 Hsiang P. Liao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:37
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/52; C02F1/5236; C02F1/72; C02F1/76; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/906; Y10S210/911
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
63 words
A process for treating an aqueous, arsenic-containing medium to effect removal of arsenic therefrom which comprises incorporating in said aqueous medium, in the presence of phosphorus, sufficient Ca(OH) 2 to adjust said aqueous medium to a pH of from about 7.0 to 11.5 to thereby precipitate both arsenic and phosphorus from said aqueous medium, and thereafter separating the precipitate from said aqueous medium.
Claim 2
Dependent Claim
63 words
A process for treating an aqueous, arsenic-containing medium to effect removal of arsenic therefrom which comprises incorporating in said aqueous medium, in the presence of phosphorus, sufficient Ca(OH) 2 to adjust said aqueous medium to a pH of from about 7.0 to 11.5 to thereby precipitate both arsenic and phosphorus from said aqueous medium, and thereafter separating the precipitate from said aqueous medium.
Claim 3
Dependent Claim
29 words
A process as defined in claim 1 wherein Ca(OH) 2 is incorporated into said aqueous medium to adjust the same to a pH of from about 9.0 to 11.5.
Claim 4
Dependent Claim
26 words
A process as defined in claim 1 wherein Ca(OH) 2 is incorporated into said aqueous medium to adjust the same to a pH of about 9.0.
Claim 5
Dependent Claim
33 words
A process as defined in claim 1 further including incorporating chlorine into said aqueous medium to oxidize arsenic and phosphorus of compounds thereof soluble in said aqueous medium to enhance the precipitation thereof.
Claim 6
Dependent Claim
20 words
A process as defined in claim 4 wherein chlorine is incorporated into said aqueous medium by the addition of NaOCl.
Claim 7
Dependent Claim
29 words
A process as defined in claim 4 wherein Ca(OH) 2 is incorporated into said aqueous medium to adjust the same to a pH of from about 9.0 to 11.5.
Claim 8
Dependent Claim
26 words
A process as defined in claim 4 wherein Ca(OH) 2 is incorporated into said aqueous medium to adjust the same to a pH of about 9.0.
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) | 1983-05-06 | 1983-11-05 | 1984-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-05-06 | 1987-11-05 | 1988-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-05-06 | 1991-11-05 | 1992-05-06 | $7700.00 | Window Closed / Lapsed |