Method for recycling sulfur dioxide from sulfite pulping liquors
CA 2021240 A1 · Owner: Norman, Jack C. · Inventors: Norman, Jack C.; Sell, Nancy J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Combined acidification and evaporative concentration of sulfite based chemical and sulfite based semichemical spent liquors expel massive amounts of gaseous sulfur dioxide and water vapor from the spent liquor. The concentration of the expelled sulfur dioxide is sufficiently high so that the sulfur dioxide and water vapor can be recycled directly, without further separation to produce fresh, sulfite pulping liquor.
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 20, 1990. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended July 20, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 20, 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.