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In situ formation of magnetite reactive barriers in soil for waste stabilization

United States Patent

March 4, 2003
View the Complete Patent at the US Patent & Trademark Office
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Reactive barriers containing magnetite and methods for making magnetite reactive barriers in situ in soil for sequestering soil contaminants including actinides and heavy metals, organic materials, iodine and technetium are disclosed. According to one embodiment, a two-step reagent introduction into soil takes place. In the first step, free oxygen is removed from the soil by separately injecting into the soil aqueous solutions of iron (II) salt, for example FeCl.sub.2, and base, for example NaOH or NH.sub.3 in about a 1:1 volume ratio. Then, in the second step, similar reagents are injected a second time (however, according to about a 1:2 volume ratio, iron to salt) to form magnetite. The magnetite formation is facilitated, in part, due to slow intrusion of oxygen into the soil from the surface. The invention techniques are suited to injection of reagents into soil in proximity to a contamination plume or source allowing in situ formation of the reactive barrier at the location of waste or hazardous material. Mixing of reagents to form. precipitate is mediated and enhanced through movement of reagents in soil as a result of phenomena including capillary action, movement of groundwater, soil washing and reagent injection pressure.
Moore; Robert C. (Edgewood, NM)
Sandia Corporation (Albuquerque, NM)
09/ 542,437
April 4, 2000
This invention was made with support from the United States Government under Contract DE-AC04-96AL85000 awarded by the U.S. Department of Energy. The Government has certain rights in this invention.