Abstract:Ionic rare earth acid soluble slag is a kind of low radioactive waste slag, which needs to be disposed safely. Applying ionic rare earth acid soluble slag and fly ash as raw materials, geopolymer was prepared in the presence of alkali exciter. The curing mechanism of radionuclides in geopolymer was analyzed by SEM, XRD and FTIR. The results show that the compressive strength of the geopolymer made by curing at 75 ℃ for 24 h is 45 MPa when Si/Al molar ratio is 2.0, Na/Al molar ratio is 0.9, and curing at 75 ℃ for 1 d. The prepared geopolymer has an amorphous Si/Al gel phase with dense and uniform internal structure and good mechanical properties. The compressive strength of the geopolymer curing body is 12 MPa at 25% addition of acid-soluble slag, and the 7 d leaching rate of thorium in curing body is 3.47×10-5 cm/d at 25% slag addition, and the 7 d cumulative leaching fraction is 4.42×10-5 cm, which is effective for curing radionuclides. Thorium and uranium exist in geopolymers by precipitation and chemically bonded.