Recycling of spent pot linings
CA 2116468 C · Owner: Grolman, Robert J. · Inventors: Turcotte, Gilles Rene; Holywell, George C.; Kimmerle, Frank M.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A process for recycling spent potlining material from aluminum reduction cells contaminated with fluoride and aluminium values. The process comprises first reducing the average particle size of the spent potlining material to smaller than 28 Tyler mesh to form a powder. The powder is then treated with an aqueous sodium hydroxide solution containing about 10 to 60 g/L of sodium hydroxide at a temperature in the range of between 60 and 90°C to form a solution containing fluoride and sodium aluminate and a residual solid. The solution is removed from the residual solid and the content of NaOH is adjusted in the solution to the range of about 10 to 60 g/L of NaOH if the content, differs from …
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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 February 25, 1994 and granted October 27, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 25, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 25, 2016.
- 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.