The Volatile Properties Of Cu And Cr During Ceramsite Firing From Electroplating Sludge

Firing ceramsite is an effective way to recycle electroplating sludge.In the process of firing ceramsite from electroplating sludge,the volatilization behavior and volatilization kinetics of heavy metals are still unclear,which restricts the control of heavy metal volatilization.Study on Cu and Cr at different temperatures（700℃,800℃,900℃,1000℃,1150℃）during the firing of ceramsite under the conditions of electroplating sludge and additives（NaCl,Na₂S,CaO）with different Si/Al ratios.In order to provide the scientific basis for the control of heavy metals in the process of calcining ceramsite from electroplating sludge.（1）The ratio of silicon to aluminum affects the volatilization rate of heavy metals.High silicon aluminum is not conducive to the volatilization of heavy metals.The maximum volatilization rates of Cu and Cr are 37.1%and 15.8%in the ceramsite with a low Si/Al ratio,respectively;in the ceramsite with a high Si/Al ratio,the maximum volatilization rates of Cu and Cr are 34.1%and8.71%,respectively.The adsorption effect of Si O₂content on Cu is not very obvious.Compared with the behavior change of heavy metal Cu,the solidification effect of ceramsite with high silicon-aluminum ratio content on Cr is relatively high.（2）The influence of NaCl,Na₂S,and CaO on the volatilization of Cu is greater than that of Cr.Adding NaCl will increase the volatilization rate of Cu and Cr during ceramsite firing.Under the conditions of 1150℃and 40 min,the maximum volatilization rate of Cu is increased by 9.2%,and the maximum volatilization rate of Cr is increased by 3%.The addition of Na₂S and CaO inhibits the volatilization of heavy metals Cu and Cr.After adding Na₂S at1150℃and 40min,the maximum volatilization rate of Cu decreased by11.1%,and the maximum volatilization rate of Cr decreased by 2%.Compared with the additive Na₂S,CaO has a stronger inhibitory effect on the volatilization of heavy metals,the maximum volatilization rate of Cu decreases by 14.4%,and the maximum volatilization rate of Cr decreases by5.4%.（3）According to the volatilization law in the process of ceramsite production from electroplating sludge,the corresponding volatilization kinetic equation was fitted.Different working conditions and material conditions affect the parameter changes of the volatilization kinetics of heavy metals,which lead to the change of the volatilization kinetic equation,and achieve the purpose of predicting the volatilization of heavy metals in the process of calcining ceramsite from electroplating sludge.