Process Conditions of Pb and Zn Removal from Washing Solution of Municipal Solid Waste Incinerator Fly Ash by CO_2

In order to investigate the removal efficiencies of Pb and Zn from the washing solution of fly ash by CO2,the effect of CO2 concentration,feeding time,flow rate,system reaction temperature and heavy metal initial concentrations on Pb and Zn sedimentation in the washing solution were studied.The results showed that decreasing initial concentrations of Pb and Zn in the washing solution resulted in decreasing residue rates of Pb and Zn after feeding CO2.Increasing CO2 concentration,feeding time,or flow rate,or reducing system reaction temperature,all effectively decreased the residue rates of Pb and Zn.The residue rates of Pb and Zn reached less than 3% and 0.1% respectively when the optimal process conditions of CO2 precipitation treatment were CO2 concentration 10%,feeding time 80 s,flow rate 2 mL/min and system reaction temperature 40-50 ℃.