Improvement of harmlessness and resource utilization of incineration fly ash by high temperature sintering

Incineration fly ash is a hazardous solid waste that needs to be disposed of in an environment-friendly way. High-temperature sintering is a feasible solution to meet above requirement. Therefore, the impact of high-temperature sintering on the physicochemical properties and toxicity of incineration fly ash, and the selection of the optimal preparation of admixture to study the impact on the performance of the prepared cement were studied. The results indicated that high-temperature sintering reduces the content of chlorine and dioxins in Incineration fly ash, while producing new phases such as Larnite and Gehlenite. Sintering increased the pozzolanic activity of incineration fly ash from 47.52 % to 63.01 %, which was still below the requirement of Chinese standards GB/T 2847-2005 for admixture with an activity higher than 65 %. Sintering solidified most heavy metals, except for Cr. Although the compressive strength of sintered incineration fly ash was higher than that of unsintered incineration fly ash, it still fell short of meeting the requirements of P·O42.5 in Chinese standards GB 175–2007 when the dosage exceeded 10 %. According to the maximum Cl− limit (Chinese standards GB 175–2007), the maximum dosage of un-sintered and sintered incineration fly ash should not exceed 6.25 % and 10.52 %, respectively.