Use of wash press for pulp alkali addition process
CA 2075875 A1 · Owner: Griggs, Bruce F. · Inventors: Joseph, James C.; Terrett, Stuart T.; Eachus, Spencer W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Unbleached pulp is combined with an aqueous alkaline solution while in a state of low consistency to distribute a first amount of alkaline material substantially uniformly throughout the pulp. The consistency of the pulp is then increased to above about 18% and the, high consistency alkali containing pulp is then treated with oxygen to effect delignification. Additional alkali may be applied onto the high consistency pulp prior to oxygen delignification to provide a total amount of between 0.8 and 7% by weight of oven dry pulp. The invention contemplates the use of one or more wash presses for reducing the overall amounts of alkaline material utilized in the process. High strength low …
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 August 12, 1992. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended August 12, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 12, 2014.
- 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.