Fixation and stabilization of chromium in contaminated materials
CA 2129947 C · Owner: Sevenson Environmental Services, Inc. · Inventors: Pal, Dhiraj; Yost, Karl W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A highly flexible multi-step treatment technology for chemical fixation and stabilization of leachable chromium particularly hexavalent chrome, in contaminated soils solid, wastes, concrete, sludge, sand and gravel and waste waters is disclosed. The process comprises reducing hexavalent chromium to chromous (Cr2+) and chromic (Cr3+) forms in the presence of water under alkaline conditions and fixing the reduced chromium forms with phosphate. The process reduces Toxicity Characteristic Leaching Procedure chromium levels below the regulatory threshold of mg/l as required by the USEPA.
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 11, 1994 and granted October 3, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 11, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 11, 2016.
- 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.