Process for producing feed-grade urea

Patent metadata

Field	Value
Publication number	US-12116335-B2
Application number	US-202118035030-A
Country	US
Kind code	B2
Filing date	Sep 10, 2021
Priority date	Nov 6, 2020
Publication date	Oct 15, 2024
Grant date	Oct 15, 2024

Abstract

A process for the production of feed grade urea starting from a liquid urea melt, the process comprising processing the urea melt (6) to promote the formation of biuret until a concentration of at least 3% biuret, and subjecting the so obtained biuret-containing urea melt (8) to a shaping process to obtain a granular urea product.

First claim

What is claimed is:

1. A process for the production of feed grade urea starting from a liquid urea melt, the process comprising:
processing the urea melt to form biuret from urea, until a target concentration of biuret in the melt is reached, said target concentration being 3% by weight or higher;
subjecting the so obtained biuret-containing urea melt to a shaping process to obtain a granular urea product.

2. The process according to claim 1 , wherein the target concentration of biuret in the melt is 5% by weight or greater.

3. The process according to claim 1 , wherein the step of processing the urea melt to form biuret includes maintaining the urea melt in a reaction space under biuret-forming conditions for a predetermined residence time until said target concentration of biuret is reached.

4. The process according to claim 3 , wherein the biuret-forming conditions includes a temperature of 160° C. to 180° C.

5. The process according to claim 3 , wherein the residence time is 5 min to 60 min.

6. The process according to claim 3 , wherein said reaction space is maintained under a continuously stirred condition during the processing of the urea melt to form biuret.

7. The process according to claim 3 , wherein said reaction space is maintained at atmospheric pressure.

8. The process according to claim 1 , wherein the urea melt contains at least 96% urea by weight.

9. The process according to claim 1 , wherein no formaldehyde is added to the urea melt before the shaping process.

10. The process according to claim 1 , wherein the shaping process includes granulation or prilling.

11. The process according to claim 1 , further comprising:
reacting ammonia and carbon dioxide at a synthesis pressure in a urea synthesis plant to obtain a reaction effluent containing urea, water and unconverted ammonium carbamate;
processing said reaction effluent in one or more recovery steps at a lower pressure to recover unconverted reagents, obtaining a purified aqueous solution of urea; and
processing said aqueous solution in an evaporation step to remove water and obtain the urea melt.

12. The process according to claim 11 , further comprising:
removing gaseous ammonia from a reaction space during the formation of biuret; and
recycling the gaseous ammonia to the urea synthesis plant as a source material for the synthesis of urea.

13. The process according to claim 12 , further comprising:
condensing the gaseous ammonia with water; and
recycling said condensed gaseous ammonia and water as aqueous solution of ammonia.

14. The process according to claim 2 , wherein the target concentration of biuret in the melt is in a range of 5% to 15% by weight.

15. The process according to claim 3 , wherein the biuret-forming conditions includes a temperature of 160° C. to 170° C.

16. The process according to claim 3 , wherein the biuret-forming conditions includes a temperature of 165° C.

17. The process according to claim 3 , wherein the residence time is 20 min.

18. The process according to claim 1 , wherein the urea melt contains at least 99% urea by weight.

Assignees

• Casale Sa

Inventors

• Marrone Leonardo

Classifications

• C05C9/005

  Post-treatment · CPC title

• Y02P20/50

  Improvements relating to the production of bulk chemicals · CPC title

• C07C273/14

  Separation; Purification; Stabilisation; Use of additives · CPC title

• C07C273/02

  of urea, its salts, complexes or addition compounds · CPC title

• C07C273/16 Primary

  Separation; Purification · CPC title