Investigation on high-value utilization technologies for fly ash from a circulating fluidized bed boiler in large-scale biomass co-combustion

Given the current trend toward large-scale biomass co-combustion in coal-fired power plants, the reutilization of the large amount of biomass-coal co-combustion fly ash (BCCA) generated requires further research. This work focused on the resource utilization of BCCA in the three directions. The effects of temperature and certain additives on the mechanical strength and adsorption properties of the ceramsite made of fly ash (FA) were investigated. Liquid silicon fertilizer was produced by extracting silicon from FA using an alkaline activation method. Under the optimal conditions, the silicon element leaching amount reached 1570.78 mg/L. Toxicity leaching tests showed that the leaching rate of heavy metals from the ceramsite was much lower than the national standard limits. Further acid or alkali pretreatment enhanced the fixation of heavy metals, improved their environmental functionality, and demonstrated the potential for soil remediation applications. Based on these findings, this work proposes an innovative high-value utilization route and provides data and experimental support for the industrial-scale application of high-value FA utilization.