Process for the recovery of sulphate
CA 2041914 C · Owner: Alford, Raymond E. · Inventors: Mok, Felix M.; Alford, Raymond E.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Process for separating sulphate from a contaminating chromium component contained in an aqueous liquor by the crystallization of a sulphate compound. The sulphate may be separated substantially free of chromium component by adjustment of the pH to the range of from about 2.0 to about 6.5, followed by cooling of the liquor to precipitate the sulphate compound from solution which sulphate is subsequently removed. The process provides an effective method for the separation of sulphate from dichromate and is, particularly useful in the production of chlorate.
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 May 7, 1991 and granted December 30, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 7, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 7, 2013.
- 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.