The Effect Of Mineral Adsorbent On The Migration Characteristics Of Heavy Metals And The Thermodynamic Simulation In The Process Of Waste Incineration

In this paper,the SK2-4-12 tube furnace is used as the combustion reactor,and the actual waste is used as the raw material to study the effect of mineral adsorbent kaolin and diatomite at different temperatures(600 ℃,700℃,800℃ and 900 ℃)and different addition amount(1%,2%,3%,4%)on the migration characteristics of heavy metals Pb,Cd,Cu and Zn during the waste incineration process.At the same time,using the simulation software HSC Chemistry 6.0 to calculate the morphological distribution of heavy metals,and to explore the effect of silicon-aluminum ratio on the migration characteristics of heavy metals.The Research indicates:Kaolin has a certain adsorption effect on Pb,Cd,Cu and Zn.As the amount of kaolin added increases,the adsorption of kaolin to heavy metals gradually increases.Based on the adsorption efficiency when the added amount is 4%:at 600℃ and 700℃,the adsorption efficiency of kaolin for heavy metals is Cd>Zn>Pb>Cu,at 800℃ and 900℃,the adsorption efficiency is Cd>Pb>Zn>Cu.Among them,the temperature for the best adsorption efficiency of Pb is 900℃,and 700℃ for Cd,Cu and Zn.Combined with SEM and XRD analysis,it was found that kaolin coexists with Pb and Cd physical adsorption and chemical adsorption,and can generate corresponding aluminosilicates with Pb and Cd oxides and chlorides,while Cu and Zn are mainly physical adsorption.Diatomite can make heavy metals more distributed in the bottom ash.The adsorption of Pb,Cd and Zn is more obvious.With the increase of the amount of diatomite,the adsorption of diatomite to heavy metals gradually increases.Based on the adsorption efficiency at 4%addition level:at 600～800℃,the adsorption efficiency of diatomite to heavy metals in order is Cd>Zn>Pb>Cu,at 900℃,it’s Cd>Pb>Zn>Cu.Among them,the temperature for the best adsorption efficiency of Pb is 900℃,800℃ for Zn,700℃ for Cd and Cu.Thermodynamic simulation results indicate that without the addition of adsorbent,as the temperature rises,the heavy metals Pb,Cd,Cu,and Zn will exist more in gaseous form and the presence of chlorine makes it easier for heavy metals to gaseous oxides and chlorine compounds at high temperatures,thereby promoting the volatilization of heavy metals.In the case of adding diatomite,diatomite can react with Pb,Cd,Zn to form corresponding silicate,which has no effect on the morphological change of Cu,indicating that the adsorption of diatomite on Pb,Cd,Zn coexisting with physical adsorption and chemical adsorption,and it is mainly adsorption on Cu is physical adsorption.When the ratio of silicon to aluminum is changed,the migration distribution of heavy metals Pb and Cu has not changed.The curing rate of Cd increases with the rise of Si ratio.At 900℃,when the ratio of silicon to aluminum is 5:1,the curing rate of Cd reaches the highest,when the ratio of silicon to aluminum is 1:1,the curing rate of Zn is the highest.