Abstract: The high temperature melting technology was used to solidify the waste FCC catalyst. Three different fluxes, CaO, SiO₂ and CaF₂, were selected to investigate the effects of the fluxing agent type, addition ratio, reaction temperature and reaction time on the solidification of the waste catalyst. The results showed that three kinds of fluxing agents could cure the heavy metals Ni and V on the waste FCC catalysts, and the acid fluxing agent SiO₂ had the best effect. The surface microstructure showed that the catalyst with SiO₂ was smoother, more compact, and had no surface porosity, which was similar to the structure of vitreous body. The leached concentration of the heavy metals Ni and V in the cooling slag were 1.0 mg/L and 0.5 mg/L respectively when the addition of SiO₂ was 20%, the reaction temperature was 1 000 ℃ and the reaction time was 2 h. Increasing the reaction temperature and prolonging the reaction time could strengthen the immobilization of heavy metals Ni and V.

Key words: catalytic cracking, waste catalyst, high-temperature melting, heavy metal, leaching