Technology for removing radioactive Cs from incineration fly ash

Radioactive cesium contained in incineration fly ash is highly soluble in water. We took advantage of this fact to develop a method for first using water cleaning to transfer cesium to water and then using adsorbent to recover this cesium in high concentrations. Since the adsorbent becomes radioactive waste, inorganic minerals such as zeolite are desirable from the point of view of long-term storage stability; however, zeolite is not suitable for cleaning water containing materials that inhibit cesium adsorption such as K+ and Na+. The feature of the new technology is that it provides a method for effective recovery of cesium from contaminated cleaning water using insoluble ferro-cyanide which is synthesized in situ, and for heat treatment of this cesium adsorbed from the ferro-cyanide to zeolite, thereby achieving reduction of radioactive waste and improvement of stability for long-term storage. (author)