Claims
- 1. A process for purifying crude cyanuric acid, which comprises:
- mixing sufficient amounts of crude cyanuric acid with an aqueous phosphoric acid solution containing about 10% to about 85% phosphoric acid to form a 10% to 45% crude cyanuric acid slurry;
- heating the slurry to a temperature of about 180.degree. C to about 220.degree. C under at least the autogenously developed pressure to digest the crude cyanuric acid;
- cooling the digested cyanuric acid to precipitate the cyanuric acid crystals; and
- recovering the cyanuric acid crystals.
- 2. The process of claim 1, wherein the phosphoric acid is orthophosphoric acid.
- 3. The process of claim 1, wherein the phosphoric acid is pyrophosphoric acid.
- 4. The process of claim 1, wherein the recovered cyanuric acid product contains at least 90% cyanuric acid crystals having particle sizes between 60 and 650 microns.
- 5. The process of claim 1, wherein the aqueous phosphoric acid solution contains about 10% to about 30% phosphoric acid.
- 6. The process of claim 5, wherein the recovered cyanuric acid product contains at least 90% cyanuric acid crystals having particle sizes between 400 and 650 microns.
- 7. The process of claim 1, wherein the aqueous phosphoric acid solution contains about 30% to about 85% phosphoric acid.
- 8. The process of claim 7, wherein the recovered cyanuric acid product contains at least 90% cyanuric acid crystals having particle sizes between 60 and 100 microns.
- 9. The process of claim 1, wherein the crude cyanuric acid is mixed with the aqueous phosphoric acid solution to form a 15% to 25% crude cyanuric acid slurry.
- 10. The process of claim 1, wherein the crude cyanuric acid is digested for up to 60 seconds.
- 11. The process of claim 1, wherein the slurry is heated to a temperature of about 195.degree. C to about 217.degree. C.
- 12. The process of claim 1, wherein mixing the cyanuric acid with the aqueous phosphoric acid solution and heating the mixture is carried out in a single stage.
- 13. The process of claim 1, wherein the recovered cyanuric acid is dried at a temperature of at least 120.degree. C.
- 14. A process for purifying crude cyanuric acid, which comprises:
- mixing sufficient amounts of crude cyanuric acid with an aqueous phosphoric acid solution containing about 10% to about 30% phosphoric acid to form a 10% to 45% crude cyanuric acid slurry;
- heating the slurry to a temperature of about 180.degree. C to about 220.degree. C under at least the autogenously developed pressure to digest the crude cyanuric acid;
- cooling the digested cyanuric acid to precipitate the cyanuric acid crystals; and
- recovering cyanuric acid crystals wherein at least 90% of the cyanuric acid crystals have particle sizes between 400 and 650 microns.
- 15. The process of claim 14, wherein mixing the cyanuric acid with the aqueous phosphoric acid solution and heating the mixture is carried out in a single stage.
- 16. A process for purifying crude cyanuric acid, which comprises:
- mixing sufficient amounts of crude cyanuric acid with an aqueous phosphoric acid solution containing about 30% to about 85% phosphoric acid to form a 10% to 45% crude cyanuric acid slurry;
- heating the slurry to a temperature of about 180.degree. C to about 220.degree. C under at least the autogenously developed pressure to digest the crude cyanuric acid;
- cooling the digested cyanuric acid to precipitate the cyanuric acid crystals; and
- recovering cyanuric acid crystals wherein at least 90% of the cyanuric acid crystals have particle sizes between 60 and 100 microns.
- 17. The process of claim 16, wherein mixing the cyanuric acid with the aqueous phosphoric acid solution and heating the mixture is carried out in a single stage.
Parent Case Info
This application is a Continuation-in-Part of application Ser. No. 447,844, filed Mar. 4, 1974, now abandoned.
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
3357979 |
Sobocinski et al. |
Dec 1967 |
|
3644359 |
Meshiah et al. |
Feb 1972 |
|
3700667 |
Kitano et al. |
Oct 1972 |
|
3761474 |
Meshiah |
Sep 1973 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
345,103 |
Aug 1972 |
SU |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
447824 |
Mar 1974 |
|