Patent ID: 6607474
Filing Date: 2003-08-19
Classification: A62D,B09C,C02F

Abstract:
A method for reducing mobile hexavalent chromium to non-leachable trivalent chromium in alkaline chromium-contaminated particulate matter, the method comprising the steps of:contacting a source of hexavalent chromium with ferrous ions to produce ferric ions; oxidizing iron pyrite to produce ferrous sulfate and sulfuric acid; contacting the alkaline chromium-contaminated particulate matter with the ferrous sulfate and the sulfuric acid for a time sufficient to convert ferrous sulfate into ferric sulfate and to reduce mobile hexavalent chromium to trivalent chromium in the particulate matter, wherein ferrous sulfate produced by oxidizing iron pyrite is a source of ferrous ions in the first contacting step.