Process for producing ammonium sulfate crystals

A continuous process for producing ammonium sulfate crystals, wherein the process comprises:

• i) feeding a solution of ammonium sulfate comprising impurities to a heat-integrated series of crystallization sections;
• ii) crystallizing ammonium sulfate crystals from the solution of ammonium sulfate;
• iii) purging a fraction of the solution of ammonium sulfate from each of the crystallization sections;
• and
• iv) discharging ammonium sulfate crystals from each of the crystallization sections, wherein
• the ammonium sulfate crystals discharged from each of the crystallization sections are not charged to another crystallization section, and wherein
• the process further comprises:
• heat-integrating the crystallization sections by steam, and
• purging a fraction of the solution of ammonium sulfate from each crystallization section in the series to the next crystallization unit in the series, as defined by descending temperature of steam supply, with the exception that the fraction of the solution of ammonium sulfate purged from the final crystallization section in the series is discharged from the series.