Experimental study on the leaching performance of U(VI) solidified by uranium tailing cement with different admixtures and ratios

Abstract

Research into radionuclide leaching behavior in the treatment of low-level radioactive waste solidification has been a widespread concern. To study the leaching performance of U(VI) in solidified bodies in simulated groundwater environment, fly ash and slag powder were mixed in different ratios with uranium tailing cement. The U(VI) leaching results from solidified bodies prepared using pure Portland cement, fly ash, slag powder, fly ash, and slag powder were compared and analyzed. The results showed that the leaching performance of solidified U(VI) decreased with increased pH, but the effects were different and had similar inhibitory effects on U(VI) leaching in neutral and alkaline environments. The variation trend of leaching concentrations was also different with admixture changes. When fly ash was added, the U(VI) leaching concentration trend first increased, then decreased, and finally became stable. However, there was no increasing process between pure Portland cement and slag powder, which might have been due to the different admixture chemical compositions. Comparing the leaching rate at 42 d in a neutral environment, it was found that the leaching rate of 15% slag powder was the lowest, at 2.47296 ×10−5 cm/d.