Patent ID: 6403828
Filing Date: 2002-06-11
Classification: B01D

Abstract:
A process for purifying crystalline substances comprising:A) charging the feed crystals containing impurities in a solid state to a vertical tower continuous crystallizer equipped with an agitating device from the top of said crystallizer, B) bringing said solid feed crystals into countercurrent contact with the melt formed by melting the descending crystals by a heating device provided in the lower section; C) taking out the purified crystals as melt from the lower section; and D) taking out the mother liquor containing the concentrated impurities from the upper section, said process for purifying crystalline substances further comprising maintaining the temperature of the mother liquor existing in the upper section in a specified range by either heating the feed crystals or the upper section of the continuous crystallizer or making the average particle diameter of the feed crystals 2.5 mm or more.