Research

The solubility of cesium (Cs) in incineration bottom ash is low due to strong trapping of Cs in the amorphous phase on the surface of microcline, which is a kind of alkali feldspar. When Cs salts such as Cs carbonate and Cs chloride are added to pure microcline and heated, Cs is trapped at an extremely high rate and becomes insoluble (Fig. 1). Since the Cs trapped by this process is fixed very tightly, it cannot be extracted unless hydrofluoric acid is used. Similar Cs trapping occurs when using a reagent to synthesize microcline (Fig. 2). In this study, we are applying this phenomenon of Cs capture by microcline (aluminosilicate) to Cs-enriched materials (e.g., fly ash with high Cs concentration) generated during volume reduction thermal treatment of removed soil and decontamination waste, aiming to establish a technology to reduce the mobility of Cs in the waste to be finally disposed of to the extent possible (Fig. 3).