Evaluation of high-density cement-based materials (HDCM) for immobilizing spent fluidized catalytic cracking catalysts

Spent fluidized catalytic cracking catalysts (SC) are considered toxic solid waste due to it is contained heavy metal ions, which can be polluting for the environment and harmful to humans. Since conventional disposal methods can be harmful to both the environment and people, therefore, new disposal methods need to be developed. In this study, 80 kg/m3 and 150 kg/m3 of SC are incorporated into the design of high-density cementbased materials (HDCM). The mechanical properties, hydration kinetics, durability, and environmental characteristics of HDCM containing SC are evaluated. The results shown that the HDCM has good mechanical properties, with a 6.62% increase in compressive strength at 28 days for HDCM containing 80 kg/m3 of SC. Furthermore, the HDCM containing SC has better long-term volumetric stability, with a 44.55% reduction in dry shrinkage compared to the reference. Further, the HDCM has a good immobilizing ability for heavy metal ions. The leaching concentrations of Ni and V from C1 are only 0.203 mg/L and 0.282 mg/L, and the immobilizing rate is 99.08% and 98.26%, respectively. For the C2, the leaching concentrations of Ni and V are 0.198 mg/L and 0.402 mg/L, the immobilizing rate is 99.31% and 98.25%.