Separation of Depleted Uranium From Soil

Abstract

Dry and wet physical separation processes were tested at Yuma Proving Ground to remove depleted uranium (DU) from soil. Four sample locations were tested that had varied uranium concentration, weathering, and aging of fired, DU residues. Reduction of soil DU concentration was achieved using simple vibratory or agitated screening techniques. For soils into which the DU had been recently fired, these techniques were successful at removing a large fraction (>70 percent) of the total uranium present (by mass). A heavy liquid separation process based on a water/sodium polytungstate solution was tested. This produced a sinking fraction that contained nearly 100-percent uranium and uranium oxide by mass for the less weathered soils. However, this type of wet separation is not currently practical for field use. A water-based separation process using an angled vibrating table to facilitate gravity transport of separated DU was also tested. This method produced a fraction of concentrated uranium along with fractions of soil particles with reduced densities. However, this process required extensive particle size separation prior to use and produced a contaminated waste stream that required secondary treatment. The extent to which DU and DU residues could be removed from the Yuma soils depended on the extent of soil weathering and corrosion of the DU alloy.

Corrosion and migration of zero-valent depleted uranium products in soil

“…As U migrated away from the source zone, greater concentrations were sequestered in the exchangeable fraction. Larson et al (2009), using the sequential extraction system of Tessier et al (1979), also reported greater concentrations of U in the organic matter fraction, shifting to the carbonate fraction at depths further from the source zone.…”

“…The penetrator rods can vary substantially in the amount of corrosion found, ranging from slight discoloration on the penetrator to extreme corrosion with a large "bloom" of yellow oxidation product. Samples from this DU garden site are included in other studies conducted as part of the ERDC-EL DU program (Larson et al 2009(Larson et al , 2012. Buck et al (2004) also studied U oxidation products in a soil in the southwestern United States that had DU weathering for 22 years.…”

“…Recovered penetrator rods can also be disposed of in LLW facilities. Larson et al (2009Larson et al ( , 2012 evaluated physical separation approaches for removing DU from soil and catchbox sand at both the pilot and field scale. These studies indicated that at least 50% of the DU tends to be in large metallic chunks or in aggregated corrosion product that can be removed by screening methods.…”

Simulated vehicle decontamination and field evaluation of the Decontamination Effluent Treatment System (DETS), 27 June 2017, and associated background studies

“…This is important because CBRN agents may be in the form of particulates. For example, radioactive agents are often in the form of particulates, such as uranium (Larson et al 2012) and finely ground cesium powders. Also, contaminants can adsorb onto particulates.…”

Methods to Reduce Sand Ejecta from Projectile Impact - a Scaled Study with the Goal of Application to Depleted Uranium Penetrator Catch Boxes

“…The study concluded that the humic acid actually competed with the uranium for adsorption sites on the soil, reducing uranium adsorption. Larson et al (2009) studied the removal of DU from contaminated soils and catch box sand. The study indicated that removal of metallic pieces larger than the sand grains (which most are) by screening methods was easily achieved, and that this removal could reliably remove greater than 50% of the DU, most catch box media, and soil.…”