Process for antipollution treatment of a spent refining catalyst and recovery of metals

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 October 30, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended October 30, 2011.
• A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 30, 2013.
• We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.