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Expired Canadian patentCanada

Process for removing sulfur dioxide from flue gases

CA 2032425 C · Owner: Stowe, Donald H. Jr. · Inventors: Benson, Lewis B.; Stowe, Donald H. Jr.

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

A process for removing sulfur dioxide from a flue gas in a wet scrubber with an aqueous slurry formed from calcium hydroxide and magnesium hydroxide with magnesium hydroxide or magnesium oxide recovered therefrom. A thickened sludge from a thickener containing calcium sulfite solids is separated and an aqueous sulfite solution removed with a, first portion of the solution returned to the thickener while a second portion thereof is oxidized to form a sulfate solution. Lime is added to the sulfate solution to precipitate calcium sulfate and form an aqueous magnesium hydroxide suspension, with the precipitated calcium sulfate separated from the magnesium hydroxide suspension which may be …

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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 December 17, 1990 and granted February 10, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 17, 2010.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 17, 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.
FiledDecember 17, 1990
GrantedFebruary 10, 1998
Term endedDecember 17, 2010
Patent numberCA 2032425 C
Classification (IPC)B01D53/50 +2 more

Timeline

Timeline From CIPO dates

1991199319951997199920012003200520072009Application filedDec 17, 1990Patent grantedFeb 10, 1998Term endedDec 17, 2010

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.