Claims
- 1. A process for removing copper from a copper-containing oxamide, which comprises:
- a) contacting the oxamide with an effective amount of an aqueous solution of a complexing agent which is capable of forming copper-containing water-soluble complexes and which imparts to the aqueous solution a pH in the range of 2 to 8, and
- b) removing purified oxamide from the solution of the copper-containing complex, and wherein the complexing agent comprises a secondary or tertiary nitrogen-containing organic compound having two or more carboxy groups, which are either free or partially salified.
- 2. The process as claimed in claim 1, wherein the complexing agent is selected from the group consisting of N,N'-1,2-ethandiylbis(N-(carboxymethyl)-glycine), N,N-bis(carboxymethyl)glycine, N,N-bis(2-(bis(carboxymethyl)amino)ethyl)glycine, N,N'-cyclohexandiylbis(N-(carboxymethyl)glycine), N,N'-(oxydi-2,1-ethandiyl)bis(N-(carboxymethyl)-glycine), N,N'-(thiodi-2,1-ethandiyl)bis(N-(carboxymethyl)glycine) and the corresponding derivatives partially salified with alkali or alkaline-earth metals.
- 3. The process as claimed in claim 1, wherein the concentration, by weight, of the complexing agent in the aqueous solution is between 0.01 and 10%.
- 4. The process as claimed in claim 3, wherein said concentration is between 0.2 and 6.0%.
- 5. The process as claimed in claim 1, wherein oxamide is contacted with the aqueous solution of the complexing agent at a temperature between 60.degree. and 150.degree. C.
- 6. The process as claimed in claim 5, wherein the temperature is between 100.degree. and 125.degree. C.
- 7. The process as claimed in claim 1, wherein the contacting time between the oxamide and the aqueous solution of the complexing agent is between 1 and 6 hours.
- 8. The process as claimed in claim 1, wherein the step of contacting oxamide with the aqueous solution of the complexing agent is repeated one or more times.
- 9. The process as claimed in claim 1, wherein the starting oxamide has a particle size between 300 and 3,000 mesh.
- 10. The process as claimed in claim 9, wherein said purified oxamide contains less than 25 ppm of copper.
- 11. The process as claimed in claim 1, wherein said copper-containing oxamide is contacted with said complexing agent by using a multiple-contact system in which oxamide is subjected to multiple contacts with aqueous solutions of the complexing agent having different extraction efficiencies.
Priority Claims (1)
Number |
Date |
Country |
Kind |
20122 A86 |
Apr 1986 |
ITX |
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Parent Case Info
This application is a continuation of application Ser. No. 032,552, filed on Apr. 1, 1987, now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
3776957 |
Newkirk |
Dec 1973 |
|
3989753 |
Riemenschneider et al. |
Nov 1976 |
|
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2427269 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
32552 |
Apr 1987 |
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