US4003833A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Detoxification of aqueous waste streams containing cyanide
Assignee: Monsanto Co
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Filing: 1976-05-24
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Granted: 1977-01-18
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Expires: 1996-05-24
Abstract
Abstract A method is provided for treating aqueous streams containing minor amounts of cyanide i.e., up to about 1000 ppm, to reduce cyanide content to less than 1 ppm by contacting said stream with formaldehyde and a compound capable of generating the HSO3<-> ion at specified conditions of pH, temperature and reactant-cyanide ratios.
Inventors
- 👤 James V. Cavender, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:49
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/52; C02F1/54; C02F1/5236; C02F2101/00; C02F2101/10; C02F2101/16; C02F2101/18
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
105 words
The method of treating an aqueous stream containing cyanide wastes in a concentration of up to about 1000 ppm of said contaminant which comprises contacting said stream with formaldehyde and a compound which will generate HSO 3 - at a temperature from about 80° to about 135° C while maintaining the pH of the reaction mixture in the range from about 8 to about 12 for a period of time sufficient to reduce the cyanide content to less than 1 ppm using a HCHO/CN - molar ratio of at least one and an HSO 3 -/CN - molar ratio from about 1.0 to about 1.5.
Claim 2
Independent Claim
105 words
The method of treating an aqueous stream containing cyanide wastes in a concentration of up to about 1000 ppm of said contaminant which comprises contacting said stream with formaldehyde and a compound which will generate HSO 3 - at a temperature from about 80° to about 135° C while maintaining the pH of the reaction mixture in the range from about 8 to about 12 for a period of time sufficient to reduce the cyanide content to less than 1 ppm using a HCHO/CN - molar ratio of at least one and an HSO 3 -/CN - molar ratio from about 1.0 to about 1.5.
Claim 3
Dependent Claim
30 words
The process of claim 1 wherein said compound generating HSO 3 - is chosen from the group consisting of sulfur dioxide, alkali metal metabisulfites, alkali metal bisulfites and ammonium bisulfite.
Claim 4
Dependent Claim
16 words
The method according to claim 1 wherein said compound generating HSO 3 - is sulfur dioxide.
Claim 5
Dependent Claim
15 words
The process of claim 3 wherein said compound generating HSO 3 - is sodium metabisulfite.
Claim 6
Dependent Claim
16 words
The process of claim 3 wherein said temperature is from about 100° to about 120° C.
Claim 7
Dependent Claim
16 words
The process of claim 4 wherein said temperature is from about 100° to about 120° C.
Claim 8
Dependent Claim
17 words
The process of claim 5 wherein said pH is maintained in the range from 9 to 10.
Claim 9
Dependent Claim
17 words
The process of claim 6 wherein the pH is maintained within the range of 9 to 10.
Claim 10
Dependent Claim
22 words
The process of claim 7 wherein said HCHO/CN - molar ratio is 1.5 and said HSO 3 -/CN - ratio is 1.2.
Claim 11
Dependent Claim
23 words
The process of claim 8 wherein said HCHO/CN - molar ratio is about 1.5 and said HSO 3 -/CN - ratio is 1.2.
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) | 1980-01-18 | 1980-07-19 | 1981-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-18 | 1984-07-19 | 1985-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-18 | 1988-07-19 | 1989-01-18 | $7700.00 | Window Closed / Lapsed |