Abstract: The co-sintering of heavy metal-contaminated soil with fly ash for ceramsite production enables synergistic treatment and resource utilization of both solid wastes. This study investigated different contaminated soil-to-fly ash ratios and sintering parameters, focusing on heavy metal immobilization efficiency. Results showed elevated nickel ( Ni), manganese (Mn),zinc (Zn),chromium (Cr),and copper (Cu) levels in contaminated soil,while fly ash contained higher concentrations of zinc (Zn),lead (Pb),and cadmium (Cd). The optimal mass ratio of contaminated soil,incineration fly ash,sodium silicate and borax is 75 ∶10 ∶5 ∶10 (D1 scheme) and 80 ∶5 ∶5 ∶10 (D2 scheme),with scheme D2 ( preheating at 400 ℃ ,sintering at 1 100 ℃ ) demonstrating superior heavy metal immobilization. Across sintering temperatures,both schemes achieved fixation rates below 15% for volatile heavy metals Cd and Pb,30%-60% for Cu and Zn,and exceeded 80% for non-volatile heavy metals Cr,Ni and Mn. Especially in the D2 scheme,the fixation rates of Cr,Ni and Mn exceed 85%. Ceramsite products from both schemes complied with leaching concentration limits specified in the Technical Guidelines for Pollution Prevention of Solid Waste Recycling (HJ 1091—2020). 

Key words: contaminated soil,incineration fly ash,sintering,heavy metal,thermal conversion characteristics