US 12,110,264 B2
Process for producing urea and biuret
Leonardo Marrone, Mercallo (IT); and Alberto Benedetti, Como (IT)
Assigned to Casale SA, Lugano (CH)
Appl. No. 18/267,826
Filed by Casale SA, Lugano (CH)
PCT Filed Nov. 19, 2021, PCT No. PCT/EP2021/082271
§ 371(c)(1), (2) Date Jun. 16, 2023,
PCT Pub. No. WO2022/128328, PCT Pub. Date Jun. 23, 2022.
Claims priority of application No. 20214560 (EP), filed on Dec. 16, 2020.
Prior Publication US 2024/0043375 A1, Feb. 8, 2024
Int. Cl. C07C 273/16 (2006.01)
CPC C07C 273/16 (2013.01) 13 Claims
OG exemplary drawing
 
1. A process for the production of urea, the process comprising:
concentrating an aqueous urea solution by crystallization in a crystallization section to produce solid crystals of urea and a urea crystallization purge aqueous phase comprising urea, water and biuret;
purging the urea crystallization purge aqueous phase from the crystallization process; and
further processing at least a portion of said urea crystallization purge aqueous phase in a high-biuret urea processing section to produce a high-biuret urea in a solid form, wherein the high-biuret urea comprises at least 55% by weight of biuret;
wherein urea is produced at a high pressure of synthesis in a urea synthesis section, obtaining a synthesis effluent;
said effluent is processed in a recovery section at one or more pressure levels lower than the synthesis pressure to recover unconverted reagents which are recycled to the synthesis section, and said aqueous urea solution is obtained in the recovery section.