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:
Sep. 26, 1978
Filed:
Aug. 09, 1977
Abstract
Highly pure sodium ammonium hydrogenphosphate and ammonium chloride are prepared from wet process phosphoric acid. A mixture of phosphoric acid, ammonia and/or sodium chloride is added to a circulating mother liquor, to which is additionally added ammonia until the pH of the liquor reaches 5.5 to 9.0. The liquor is then cooled to cause sodium ammonium hydrogenphosphate to crystallize at 30.degree. to 60.degree. C. The resulting filtrate is added with an acidic compound to adjust its pH to 5.6 to 6.4 whereby the solubility of the hydrogenphosphate is increased while that of ammonium chloride is reduced to a minimum. The filtrate is cooled to 5.degree. to 50.degree. C to precipitate ammonium chloride as crystals without involving co-precipitation of the hydrogenphosphate. The filtrate from which the ammonium chloride crystals have been removed is recycled for use as a circulating mother liquor.