Method for preparing iron oxides
CA 2421363 C · Owner: Rubini, Carlo · Inventors: Conca, Esterino; Petrini, Guido; Rubini, Carlo
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Highly pure iron oxides are prepared by reaction of metallic iron in the form of microspheroidal particles or of scraps or cuttings with an agitated aqueous solution of a mono- or polycarboxylic acid with a pKa of 0.5 to 6 relative to the first carboxyl and capable of decomposing by heating in air at 200 to 350 °C, to carbon dioxide and water using 0.03 to 1.5 moles of acid per g-atoms of iron a water/iron weight ration of 1 to 20, and by oxidation of the ferrous carboxilate to ferric salt with an agent selected from oxygen, mixtures containing oxygen hydrogen peroxide, organic peroxides and hydroperoxides.
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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
- Filed March 7, 2003 and granted August 28, 2012. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 7, 2023.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 7, 2025.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.