Coal Fly Ash as Raw Material for Immobilization of Sr-Contaminated Soil by Microwave Heating: Mechanism and Performance

Abstract

In this work, coal fly ash, hereinafter CFA is proposed to work as raw material for immobilization of Sr-contaminated soil by microwave sintering in the path towards resource utilization of solid waste. The immobilization mechanism and performance was systemically investigated through phase evolution, microstructure, elemental distribution, and physical properties. The results shown that the Sr could be incorporated into feldspar strontian (SrAl2Si2O8) at 1300 °C for 30 min. Moreover, the maximum solid solubility of SrSO4 was more than 30 wt.%. The Sr was homogeneously distributed in the sintered matrices without substantial enrichment. The sintered matrix exhibited high density (2.53 g/cm3). Thus, microwave heating coupled with CFA could provide a new method for immobilization of Sr-contaminated soil in case of the spent nuclear reprocessing cycle in nuclear power plants or a nuclear accident emergency.