| 摘要 |
An integrated process for urea/melamine production. In the process, urea is synthesized from ammonia and carbon dioxide, obtaining molten urea and a gaseous mixture comprising steam and ammonia. The gaseous mixture is condensed, obtaining a cold aqueous ammoniacal solution. Melamine is synthesized from urea with formation of off-gases, comprising ammonia and carbon dioxide. The off-gases are absorbed in at least one fraction of the cold aqueous ammonical solution, with formation of a carbamate aqueous solution. The carbamate aqueous solution is decomposed, obtaining ammonia, carbon dioxide and steam, and a residual aqueous ammoniacal solution. The ammonia and the carbon dioxide are recycled for the urea synthesis. The residual aqueous ammoniacal solution obtained is treated to recover ammonia and carbon dioxide for the urea synthesis.
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