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:
Mar. 21, 1978
Filed:
Jan. 27, 1977
Hans Peter Kasserra, Brockville, CA;
Du Pont of Canada Ltd., Montreal, CA;
Abstract
A process is provided for preparing ammonium tungstate. In the process, a reduced calcium tungstate is treated in the presence of an oxidizing agent with an aqueous solution having at least ammonium cations and carbonate and/or bicarbonate anions, at a temperature of 10.degree. C to the boiling point of the solution. The reduced calcium tungstate reacts with the ammonium cations to form the ammonium tungstate which is soluble in the solution and with the anions to form a calcium compound which is insoluble in the solution. Oxygen and/or hydrogen peroxide are preferred oxidizing agents. The process is especially useful in separating tungsten values from scheelite ores or concentrates.