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:
Dec. 10, 1985
Filed:
Apr. 29, 1985
John A Powers, New Albeny, PA (US);
James N Christini, Towanda, PA (US);
GTE Products Corporation, Stamford, CT (US);
Abstract
A method is disclosed for producing ammonium metatungstate from ammonium paratungstate. The method involves first roasting the ammonium paratungstate at from about 275.degree. C. to about 300.degree. C. for from about 10 hours to about 20 hours to remove some ammonia and some water. The roasted ammonium paratungstate is then added to dilute solution of an ammonium metatungstate which is at a pH of from about 3.6 to about 4.2, the rate of addition being such that a slurry is produced having a pH of from about 3.6 to about 4.2. The pH of the resulting slurry is then adjusted to stabilize it at from about 3.6 to about 4.2 followed by evaporation to form a relatively concentrated solution of ammonium metatungstate which is then separated from any insolubles. Ammonium metatungstate is then crystallized from the relatively concentrated ammonium metatungstate solution.