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:
Aug. 09, 1983
Filed:
Jan. 04, 1982
Applicant:
Inventors:
Leo W Beckstead, Arvada, CO (US);
Paul B Queneau, Golden, CO (US);
Assignee:
Amax Inc., , US;
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C22B / ; C01G / ;
U.S. Cl.
CPC ...
423 58 ; 423593 ; 423 61 ;
Abstract
Synthetic scheelite (calcium tungstate) having a low sulfur content is produced in high yield from an aqueous solution of sodium tungstate, that can be contaminated with sulfate ion dissolved therein, by digesting the solution with solid calcium sulfate whereby low-sulfur calcium tungstate precipitates. The solution remaining after filtration of the calcium tungstate product can be treated with calcium sulfate to precipitate additional purified calcium tungstate or to generate a calcium tungstate-calcium sulfate mixture that can be recycled for digestion with additional sulfate-contaminated sodium tungstate solution.