The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 11, 2002
Filed:
Jan. 18, 2000
Hiroyuki Kuwahara, Kitakyushu, JP;
Kazuyoshi Horibe, Kitakyushu, JP;
Nobumasa Noma, Fukuoka-ken, JP;
Masakazu Takeuchi, Yukihashi, JP;
Yukio Akimaru, Fukuoka-ken, JP;
Nippon Steel Chemical Co., Ltd., Tokyo, JP;
Abstract
This invention relates to a process for purifying crystalline substances by charging the feed crystals containing impurities in a solid state to the top of a tower-type continuous crystallizer equipped with an agitating device, 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, taking out the purified crystals as melt from the lower section, and taking out the mother liquor containing the concentrated impurities from the upper section and comprises 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 mm or more. This procedure makes it possible to form good crystals and a slurry layer in the crystallization tower and yield a crystalline product of high purity in high yield even when applied to feed crystals of reportedly inferior properties.