Methods of treatment of chromite ore processing residue
AssigneeRedox Solutions, LLC
InventorsSteven A. Chisick, Timothy Clark Heffernan, Thomas P. McCullough, Gary Joel Meyer
Life of this patent
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Abstract
Methods to reduce hexavalent chromium (Cr(VI)) in chromite processing wastes include one or more of the following steps: contacting the chromite processing wastes with an oxygen scavenger or chemical reducer; permitting the chromite processing wastes to react with the oxygen scavenger or chemical reducer; contacting the chromite processing wastes with ferrous ion; contacting the chromite processing wastes with sulfide ion; and, contacting the chromite processing wastes with ferrous sulfide.
Claims16
A method to reduce hexavalent chromium (Cr(VI)) in chromite ore processing residue, the method including crushing or grinding the chromite ore processing residue, then contacting the chromite ore processing residue with an oxygen scavenger or chemical reducer, permitting the chromite ore processing residue to react with the oxygen scavenger or chemical reducer, and then contacting the chromite ore processing residue with sulfide ion and ferrous ion to reduce Cr(VI) in the chromite ore processing residue.
A method to reduce hexavalent chromium (Cr(VI)) in chromite ore processing residue including placing the chromite ore processing residue in a treatment vessel, adding an oxygen scavenger or chemical reducer to the treatment vessel, contacting the chromite ore processing residue with the oxygen scavenger or chemical reducer, mixing the oxygen scavenger or chemical reducer with the chromite ore processing residue in the treatment vessel, permitting the chromite ore processing residue to react with the oxygen scavenger or chemical reducer, and then contacting the chromite ore processing residue with sulfide ion and ferrous ion to reduce Cr(VI) in the chromite ore processing residue.
A method to reduce hexavalent chromium (Cr(VI)) in chromite ore processing residue including contacting the chromite ore processing residue with sulfide ion and ferrous ion to reduce Cr(VI) in the chromite ore processing residue, obtaining toxic characteristic leaching procedures (TCLP) extraction fluid from the thus-treated chromite ore processing residue, determining the pH of the TCLP extraction fluid from the thus-treated chromite ore processing residue, and, if the pH of the TCLP extraction fluid from the thus-treated chromite ore processing residue is below 7, adding a base to the thus-treated chromite ore processing residue to increase the pH of TCLP extraction fluid from the thus-treated chromite ore processing residue to above 7.
A method to reduce hexavalent chromium (Cr(VI)) in chromite ore processing residue including contacting the chromite ore processing residue with a polysulfide to reduce Cr(VI) in the chromite ore processing residue.
Dependencies are inferred from the claim text.