Decontamination of sandy soils from 137Cs by reagent treatment with agitation leaching

Abstract

The simplest and the most efficient method for decontamination of sandy soils is separation of the finely dispersed fraction (<0.1 mm), with which ∼90% of the contaminating radionuclides are associated, by gravity sedimentation in water. However, for sandy soils from the Russian Research Centre Kurchatov Institute, the decontamination factor in this case is as low as 4–5. The decontamination factor can be further increased by using reagent treatment. The main parameters of the process are reagent composition and concentration, temperature, and liquid to solid ratio. The decontamination factor of 10–14 can be attained by reagent treatment with 2 M H2SO4 + 1 M H3PO4 or 3–4 M H2SO4 solutions for 7 h at 80°C, at the liquid to solid ratio of no less than 2 : 1. Two times higher decontamination factor can be attained by treatment with a 2 M H2SO4 + 0.6 M NH4F solution, but high toxicity of fluorides restricts the possibility of using this reagent.