Transformation and leaching behavior of Pb in hazardous waste incineration fly ash after thermal treatment with addition of Fe₂O₃

This study investigated the leaching behavior of Pb in hazardous waste incineration fly ash (HWIFA) after adding Fe₂O₃ thermal treatment and revealed the leaching mechanism of Pb from the perspective of phase transformation. The static leaching results showed that at 600 °C-1300 °C, with the addition of Fe₂O₃ increased, the Pb leaching toxicity continued to decrease. The dynamic results indicated that as the thermal treatment temperature was higher than 1100 °C, the addition of Fe₂O₃ can effectively inhibit the dynamic leaching of Pb in HWIFA. Meanwhile, the inhibition effect was not very closely related to the amount of Fe₂O₃. The addition of Fe₂O₃ can react with PbO to form PbFe₁₂O₁₉, which has a better stability. The appearance of PbFe₁₂O₁₉ was the main reason for adding Fe₂O₃ to enhanced the immobilization of Pb. However, the amount of Fe₂O₃ should be carefully controlled to avoid an excessive reducible fraction of Pb in the thermal treated HWIFA, which will affect the long-term stability of Pb.