Patent ID: 7380671

Claim:
Process for size classifying ammonium sulfate crystals, said process comprising the steps of: (a) providing a screen having screen openings within a vessel so as to establish first and second volumes within the vessel on respective first and second sides of the screen; (b) feeding to the first side of the screen an ammonium sulfate feed suspension comprised of an ammonium sulfate solution containing ammonium sulfate crystals, the ammonium sulfate crystals comprised of coarse ammonium sulfate crystals having diameters sufficiently large to prevent passage through the openings of the screen and fine ammonium sulfate crystals having diameters sufficiently small to allow passage through the openings of the screen; and (c) while simultaneously maintaining the first and second sides of the screen immersed in contact with the ammonium sulfate solution, size classifying the ammonium sulfate crystals based on crystal diameters by allowing a substantial part of the fine crystals to pass through the openings of the screen to the second volume of ammonium sulfate solution within the vessel on the second side of the screen while the coarse ammonium sulfate crystals are retained in the first volume of ammonium sulfate solution within the vessel on the first side of the screen.