Cs-leaching behaviors from the radioactive Cs-contaminated soils by mechanochemical reaction

Mechanochemical reaction applied to the radioactive Cs-contaminated soils, granitic and basaltic soils in Fukushima prefecture, for revealing the deconstruction of clay minerals in the soils and Cs-leaching behaviors, The reactions were conducted by a planetary-motion ball-milling machine for the desired durations up to 12h at dry condition and wet conditions with ammonium chloride solution in the different solid to solution ratios. The Cs-leaching behaviors were depended on the type of soils, the milling duration and the dry or wet condition for milling. The Cs-leaching rate for the granitic soil was higher than that of the basaltic soil. The deconstruction of the clay minerals in soil was different between granitic and basaltic soil, but the deconstruction rates were dependent on the milling duration, and were consistent with the Cs-leaching rate. With the dry milling and Cs-leaching by ammonium chloride solution, the Cs-leaching rates were 29% and 13% after 1h treatment, and then 48% and 32% after 3h, for the granitic soil and the basaltic soil, respectively. For the wet milling of the granitic soil, the Cs-leaching rates were increased on the solid to solution ratio and the milling duration, 20% for 1h, and up to 60% for 12h (1:10 of solid to solution ratio). For the wet milling of the basaltic soil, the Cs-leaching rates were not clearly dependent on the solid to solution ratio and the milling duration, but up to 29% for 12h (1:10 of solid to solution ratio). The results indicated that the mechanochemical reaction has the powerful potential for the increase of the Cs-leaching from the contaminated soils, and the volume-reduction after the classification. (author)