Process for the manufacture of ammonium tungstate from tungstates of alkaline earth metals
CA 1080440 A · Owner: Du Pont Canada Inc. · Inventors: Kelly, Denis B.; Kasserra, Hans P.; Obadia, Isaac
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for the manufacture of a tungstate salt especially ammonium tungstate, is disclosed. The process comprises contacting tri(alkaline earth metal) tungstate with an aqueous solution of a compound having a cation selected from the ammonium ion and alkali metal cations, and mixtures thereof and, at least one anion selected from hydroxide carbonate, bicarbonate, oxalate and phosphate. At least one of the anions is an anion from which an insoluble compound of the alkaline earth metal is derived, the anion being in a concentration such that the insoluble compound is less soluble in the solution than the alkaline earth metal tungstate. In an embodiment the tri- (alkaline earth metal) …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Granted July 1, 1980. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 1, 1997.
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Timeline
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Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.