Uranium (U) was successfully removed from contaminated soils from the Fernald Environmental Management Project (FEMP) site near Fernald, Ohio. The laboratory column leach process, referred to as the simulated heap leach process, using 0.5 M sodium bicarbonate as the dominant reagent, was able to achieve uranium removals of 75-90%, corresponding approximately to the percentage of uranium in the oxidized state. Parametric optimization studies are reported. The dissolution of uranium took place in two stages: a rapid desorption associated with soil surfaces and a slow step associated with diffusion of uranium toward solid surfaces. In addition, use of the oxidizing agent, sodium peroxide, improved uranium removal due to oxidation of U(IV), enhancing the solubility of the uranium. The results suggest that the process will be effective for field scale remediation of uranium-contaminated soils because of the efficiency, mild complexing agent employed, lack of prescreening of the soil and the simple equipment necessary. Two relevant companion studies have recently been completed. The first, a scale-up demonstration [Turney, W.

Over the last few years, using soils contaminated with uranium from Fernald, Ohio, we have shown that an unsaturated leach scheme is an effective way for removing uranium . We have extended this work to contaminated soils from other sources (Kitten et al., 1995) and here we extend this study to a significantly larger volume in addition to a different soil type.A uranium-contaminated site, consisting of 218 cubic yards of soil contaminated with uranium from projectile testing, was subject to three processes for volume reduction:1 . a physical separation based on levels of radioactive contamination, followed by 2. a chemical separation using a leach scheme employing sodium bicarbonate (0.5 M) as the leaching agent in an unsaturated flow scheme, and 3. an ion exchange process for removing soluble uranium from solution.The objective of this research was to show that processes proven in the laboratory are applicable to larger volumes of soil.

NATIONAL LABORATORY Los AlamosNationalLaboratory,an affirmativeaction/equalopportunity employer, is operated by the Universityof Californiaforthe U.S. Department of Energy under contractW-7405-ENG-36. By acceptanceof this a_cle, the publisherrecognizesthat the U.S. Governmentretains a nonexclusive,royalty-frse licenseto publishor reproducethe publishedformof thiscontribution, or toallow othersto do so, for U.S. Governmentpurposes. The Los Alamos National Laboratory requests thatthe publisheridentifythisarticleas work performedunderthe auspicesof the U.S. Departmentof Energy. FormNo.836 R5 ST262910/91 LA-UR-94-1361 HEAP LEACH STUDIES ON THE REMOVAL OF URANIUM FROM SOIL REPORT OF LABORATORY-SCALE TEST RESULTS Technical Task Plan AL121121 Soil Decontamination Task Group Uranium in Soils Integrated Demonstration