| 摘要 |
Guanidine carbonate is isolated from dilute aqueous solutions containing guanidine, urea, pyrolysis products of urea, ammonia and carbon dioxide, by evaporation of the solution at a temperature of 80 DEG to 130 DEG C until a guanidine carbonate content of 20g/l and a pyrolysis products content of not more than 28g/l at 80 DEG C or not more than 128 DEG g/l at 30 DEG C is achieved, without exceeding a heating time of 6 hours at the upper temperature limit, separation of the precipitated pyrolysis products, subsequent cooling to not more than 45 DEG C, addition of ammonia to an ammonia content of 15 to 30 % by weight and separation of the precipitated guanidine carbonate. |
