Preparation of High-strength ceramsite from municipal solid waste incineration fly ash and clay based on CaO-SiO2-Al2O3 system

With the increasing production of incineration fly ash (FA), its disposal has attracted more and more attention. Based on the transformation behavior of the FA/clay system during the sintering process, the feasibility of preparing high-strength ceramics from FA/clay was evaluated from the theoretical analysis and experimental verification perspective. The theoretical analysis showed that mixing FA and clay can reduce the liquid formation temperature, promoting the sintering process. Meanwhile, according to the CaO-SiO2-Al2O3 phase diagram, by controlling the addition of FA of 40 wt%, the potential balanced phases of the FA/clay system can be transformed into anorthite (CaAl2Si2O8), which is a typical ceramsite forming phase. The X-ray diffraction analysis confirmed that anorthite was the dominant phase in the sintered FA/clay sample. The experimental verification results presented that under the addition of 40 wt% FA, the sintering temperature of 1200 degrees C, and the holding time of 20 min, the obtained ceramsite with extremely excellent strength performance and heavy metal stability can meet the quality requirements of lightweight aggregates. This study can provide a reference for the resource utilization of FA and related hazardous wastes.