Volatilization Characteristics of Zn and Pb in the Process of Sintering Ceramsite from Electroplating Sludge with Different Si/Al Ratios
In order to study the transfer and transformation of Zn and Pb under different working conditions and solid matrix components during the firing of electroplating sludge ceramsite,the firing experiments of ceramsite with different Si/Al ratios were carried out using electroplating sludge and shale as raw materials.The sintering temperatures was selected as 700,800,900,1 000 and 1 150℃.The residence time was 8,16,24,32,40 minutes.The results showed that the volatilization rates of Zn and Pb increased gradually with the increased of temperature and reaction time.When the sintering temperature was 1 150℃and the residence time was 40 minutes,the volatilization rate of Zn and Pb reached the maximum,and the volatilization rate of Pb was higher than that of Zn.The volatilization rate of heavy metals decreased with the increased of Si/Al ratio in ceramsite.The kinetic analysis results showed that the reaction order and activation energy of Zn decreased and that of Pb increased with the increased of Si/Al ratio.The results of XRD analysis showed that the distribution of Pb in the ceramide at 1 150℃was small,which may be related to the low melting boiling point of Pb oxides.While Zn mainly existed in the ceramsite in the structure of ZnCr2O4 and ZnGa2O4 with relatively stable properties,and the distribution of Zn in the ceramsite was large.The SEM analysis further showed that the increased of Si/Al ratio in ceramsite raw materials leaded to the increase of glass-phase substances produced by ceramic melting at high temperature,and the inhibition of heavy metal volatilization was enhanced.
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