US4417987A
Expired / Lapsed
US
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Process for detoxification
Assignee: Solvay Interox Ltd
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Filing: 1981-12-07
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Granted: 1983-11-29
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Expires: 2001-12-07
Abstract
Abstract When aqueous solutions of a metal cyanide complex are detoxified with hydrogen peroxide, a residue of cyanide remains, which in the case of nickel for example may be present as Ni(CN) 2 . In a process according to the present invention the detoxification of aqueous alkaline solutions of a metal cyanide complex is carried out using a restricted amount of certain complexing agents together with the hydrogen peroxide. A particularly suitable example of such complexing agents is ethylenediaminotetraacetic acid. It is especially preferred to use the complexing agent in a mole ratio to metal of from 0.8:1 to 1.5:1, together with hydrogen peroxide in a mole ratio to cyanide of from 2:1 to 3:1. The process is well suited to the treatment of concentrated solutions of cyanide, in many cases at least 4000 ppm, for example those resulting from the stripping of nickel plating.
Inventors
- 👤 Anthony P. Harrison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:26
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/72; C02F1/722; C02F1/68; C02F1/683; C02F2101/00; C02F2101/10; C02F2101/16; C02F2101/18; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/903; Y10S210/904
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
109 words
In a process for the detoxification of an aqueous alkaline solution of a metal cyanide complex by introduction thereinto of hydrogen peroxide, the improvement wherein detoxification is effected in the presence of a complexing agent in a mole ratio to metal in the metal cyanide of from 0.5:1 to 3:1, said complexing agent being one which can form with nickel cyanide a mixed ligand complex having a stability constant β 12 of not greater than 9.5, said stability constant β 12 being expressed as a logarithm to the base 10 for the dissociation reaction NiL(CN).sub.2.sup.n- ⃡NiL.sup.2-n +2CN.sup.- wherein L represents a molecule of the complexing agent and wherein ##EQU2##
Claim 2
Dependent Claim
109 words
In a process for the detoxification of an aqueous alkaline solution of a metal cyanide complex by introduction thereinto of hydrogen peroxide, the improvement wherein detoxification is effected in the presence of a complexing agent in a mole ratio to metal in the metal cyanide of from 0.5:1 to 3:1, said complexing agent being one which can form with nickel cyanide a mixed ligand complex having a stability constant β 12 of not greater than 9.5, said stability constant β 12 being expressed as a logarithm to the base 10 for the dissociation reaction NiL(CN).sub.2.sup.n- ⃡NiL.sup.2-n +2CN.sup.- wherein L represents a molecule of the complexing agent and wherein ##EQU2##
Claim 3
Dependent Claim
16 words
A process according to claim 1 wherein the metal cyanide complex comprises a nickel cyanide complex.
Claim 4
Dependent Claim
17 words
A process according to claim 2 where the nickel containing cyanide solution is obtained by stripping nickel.
Claim 5
Dependent Claim
23 words
A process according to claim 1 or 2 wherein the detoxification is carried out in the presence of a catalytic amount of copper.
Claim 6
Dependent Claim
16 words
A process according to claim 1 wherein the metal cyanide complex comprises a copper cyanide complex.
Claim 7
Dependent Claim
26 words
A process according to claim 1, 2 or 5 wherein the complexing agent is used in a mole ratio to metal of from 0.8:1 to 1.5:1.
Claim 8
Dependent Claim
31 words
A process according to claim 1, 2 or 5 wherein the complexing agent employed is capable of forming with nickel a complex having a stability constant β 12 of below 8.
Claim 9
Dependent Claim
20 words
A process according to claim 1, 2 or 5 wherein the complexing agent comprises an aminocarboxylic acid or salt thereof.
Claim 10
Dependent Claim
16 words
A process according to claim 8 wherein the complexing agent comprises ethylenediaminetetraacetic acid or salt thereof.
Claim 11
Dependent Claim
27 words
A process according to claim 1, 2 or 5 wherein the hydrogen peroxide is employed in a mole ratio to the cyanide of from 2:1 to 3:1.
Claim 12
Dependent Claim
19 words
A process according to claim 1, 2 or 5 wherein the starting cyanide concentration is at least 4000 ppm.
Claim 13
Dependent Claim
23 words
A process according to claim 1, 2 or 5 wherein the detoxification is maintained at a temperature not in excess of 70° C.
Claim 14
Dependent Claim
18 words
A process according to claim 1, 2 or 5 wherein the detoxification period is at least 30 minutes.
Claim 15
Dependent Claim
46 words
A process according to claim 1, 2 or 5 wherein hydrogen peroxide is employed in a mole ratio to the cyanide of from 2:1 to 3:1 in the presence of at least a catalytic amount of copper and of an aminoacetic acid or salt complexing agent.
Claim 16
Dependent Claim
18 words
A process according to claim 14 wherein the complexing agent comprises ethylenediaminetetraacetic acid or a soluble salt thereof.
Claim 17
Dependent Claim
14 words
A process according to claim 15 wherein mole ratio of complexing agent:cyanide is 1:1±5%.
Claim 18
Dependent Claim
18 words
A process according to claim 1 wherein said metal cyanide complex comprises a group 1B metal cyanide complex.
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) | 1986-11-28 | 1987-05-30 | 1987-11-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-28 | 1991-05-30 | 1991-11-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-28 | 1995-05-30 | 1995-11-29 | $7700.00 | Window Closed / Lapsed |