Stabilization And Solidification Of Heavy Metals In MSWI Fly Ash Based On Accelerated Carbonation Technology

With the advantage of weight and volume reduction, detoxification and energy recovery, incineration has become a promising municipal solid waste management method. However, hazardous municipal solid waste incineration fly ash (MSWIFA) will be generated after incineration, where soluble heavy metals are accumulated. Therefore, the residues have to be properly managed before transportation and landfill. Coal-fired fluidized bed boiler fly ash (CFAFA) was utilized as additive and accelerated carbonation technology (ACT) was employed to investigate the effects of additive proportion and parameters of ACT had on leaching of heavy metals and carbon dioxides (CO2) sequstration. After that, ACT on mixed fly ash were compared with solidificating heavy metals in MSWIFA by adding cement and lime (CaO). The weights of parameters of ACT on leaching of heavy metals and CO2 sequstration was also analyzed.The mian results are showed as follows:Adding CFAFA to MSWIFA and ACT on mixed fly ash are all conducive to stabilizating and solidificating heavy mental. But ACT will weakened the stabilization and solidification of adding CFAFA to MSWIFA on heavy mental. Comparing with solidification of cement adding and lime adding, ACT on mixed ash (CFBFA:MSWIFA=1:1) has the advantage of stabilizing and solidificating Pb. The unconfined compressive strength of solidified body with CFBFA adding is exceeded the lower limit for transportation and landfill. Especially the unconfined compressive strength of MSWIFA is higher after mixed with CFBFA, while the unconfined compressive strength of ash samples will be lower with carbonation treatment.GA-BP network was established on MATLAB to evaluate the weights of parameters of ACT on leaching of heavy metals and CO2 sequstration. The results show that water-to-solids ratio, carbonated temperature, carbonated time are the mianly influencing factors on leaching of heavy metals. Except for water-to-solids ratio, carbonated temperature and carbonated time, the concentration of CO2 is also an important parameter for CO2 sequstration.