Ch2m Hill, Inc.

Maxus Energy Corporation

Thomas E Higgins

In methods for treatment of in ground chromium ore processing residue contamination, ferrous sulfide is provided as a substantially insoluble material in the residue deposit. The ferrous sulfide accordingly may remain substantially in place, in the pores of the soil or residue, even over long periods of time, regardless of underground water movement or diffusion. As a result, the ferrous sulfide may act continuously to chemically reduce and remove contamination. As hexavalent chromium diffuses from the soil or residue, it is reduced by the ferrous sulfide. The ferrous sulfide may be placed into the underground deposit by injecting a ferrous salt solution into the deposit, waiting for a precipitation to elapse, and then injecting a sulfide solution into the deposit.

Treatment of in ground chromium ore processing residue

Provided is a process for the treatment of Cr(VI)-bearing solids or soil by the in situ biological reduction of Cr(VI) to insoluble Cr(III). The pH of the Cr(VI)-bearing solids are adjusted with an acid or base to a pH of about 6.5 to 9.5, and thoroughly mixed in situ mixed with an organic material (such as manure) containing bacteria and nutrients.

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Reston, VA, United States of America

Thomas E Higgins