Recovery of precious metals
CA 2021292 C · Owner: Cognis, Inc. · Inventors: Virnig, Michael J.; Mattison, Phillip L.; Lin, Lon-Tang W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An improved process for recovery of precious metals such as gold and silver from aqueous cyanide solutions by contact with certain guanidine reagents. The guanidine reagents not only extract the precious metal but may provide advantages in selectivity of gold over other metals, such as tetra- and pentahydrocarbon substituted non-resin guanidine reagents and tri- and tetra--hydrocarbon substituted resin guanidine reagents.
Read the whole patent
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 July 16, 1990 and granted October 2, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 16, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 16, 2012.
- 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.