Chemistry and Engineering Aspects of the Application of Soluble Phosphates for Uranium Treatment in Groundwater - 17255
Treatment of uranium in groundwater is challenging because of the equilibrium partitioning of uranium between sorbed and aqueous phase complexes in mobile and immobile pore space. In situ groundwater treatment strategies for uranium hold promise because of their reliance on fundamentally altering uranium chemical speciation as well as aquifer geochemical conditions. For the last 30 years uranium in situ reductive precipitation has been the leading technology; however, there have been only a handful of large-scale applications. Recently, within the last 10 years, the application of soluble phosphates has been identified as a viable means of treating soluble uranium, while at the same time changing the balance in terms of the availability of sorbed/immobile uranium to re-mobilize. Uranium reacts with soluble phosphate to form a range of low-solubility uranium minerals; surface passivation can also result, limiting the availability of uranium for dissolution. Here we discuss the application of dissolved phosphate in a small-scale pilot test in a tailings pile. (authors)