Particulate foam flotation process for remediation of Fukushima contaminated soils - 000209

In a radioactively contaminated soil, cesium 137 is known to be fixed on fine particles, preferentially the micrometric phyllosilicate particles. Cesium is almost irreversibly adsorbed on the planar and frayed edge sites of the phyllosilicates. Particulate foam flotation technology assisted by cationic surfactant and operating in continuous mode was first tested in 2017 to separate these fine phyllosilicates from others particles in non-contaminated french soils. The objectives were to define the range of surfactant concentration needed to float fine phyllosilicate particles and to understand the influence of soil textural and physico-chemical properties on the separation of phyllosilicates particles. Than flotation tests on real Japanese contaminated soils in Okuma (Fukushima prefecture) were successfully conducted by the CEA, AREVA and VEOLIA teams in collaboration with ANADEC/ATOX. For 2 big bags, results reached the targets with a reduction of the volume of contaminated soil by a factor between 3 to 7 containing 45% of the radioactive Cs initially present in the soil. To further improve the cesium extraction efficiency, optimizations of the preparation of the soil (drying, crumbling, pre-sieving and dispersion in water) have been proposed. (authors)