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. 16, 1986
Filed:
Feb. 25, 1985
Tai K Kim, Towanda, PA (US);
Carl W Boyer, Wyalusing, PA (US);
Martin B MacInnis, Towanda, PA (US);
Donald H Ennis, Towanda, PA (US);
GTE Products Corporation, Stamford, CT (US);
Abstract
A method is disclosed for producing crystalline ammonium metatungstate from ammonium paratungstate. The method involves heating ammonium paratungstate in a multiple hearth furnace at from about 200.degree. C. to about 400.degree. C. to form a relatively uniformly heated ammonium paratungstate. A slurry of the heated ammonium paratungstate in water is then digested at from about 70.degree. C. to about 100.degree. C. for less than about 6 hours at relatively constant volume while maintaining the pH of the slurry at from about 4.2 to about 3.0 by the addition of ammonia as necessary to form a solution of ammonium metatungstate. The resulting ammonium metatungstate solution is then evaporated to a fraction of its original volume to concentrate it and any insolubles are removed. The ammonium metatungstate is then crystallized from the concentrated solution.