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Expired Canadian patentCanada

Process for treating waste sludge from combustion plant desulfurization units and cementitious product of the process

CA 1108820 A · Owner: Valiga, Richard E. · Inventors: Valiga, Richard E.

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Abstract From the Canadian patent

Aqueous alkaline desulfurization treating units for combustion gases generate as a product an aqueous sludge containing sulfur compounds of calcium. Many such sludge products contain more than 30 percent by weight (of the solids) of calcium sulfite hemihydrate. These waste products are in part calcined at a temperature from 250°C to 650°C to produce a moisture-free, cementitious product which is thereafter recombined with uncalcined aqueous sludge to produce a cementitious product which can be profitably utilized or which may be conveniently discarded as a land fill. If desired, fly ash or bottom ash produced in the combustion process can be combined with the cementitious product.

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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

  • Granted September 15, 1981. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended September 15, 1998.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJuly 26, 1978
GrantedSeptember 15, 1981
Term endedSeptember 15, 1998
Patent numberCA 1108820 A
Classification (IPC)C04B11/00 +2 more

Timeline

Timeline From CIPO dates

1979198119831985198719891991199319951997Application filedJuly 26, 1978Patent grantedSep 15, 1981Term endedSep 15, 1998

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