烧结机共处置危险废物过程中重金属Pb、Zn的挥发特性

Volatile characteristics of lead and zinc during co-processing hazardous waste in sintering machines

利用化学试剂PbCl2、ZnCl2来模拟危险废物,研究了烧结机共处置危险废物过程中Pb、Zn的挥发特性.首先选取PbCl2、ZnCl2两种化合物的纯化学试剂分别进行了热重分析实验,然后对掺有一定比例PbCl2、ZnCl2的烧结矿原料进行煅烧,采集分析煅烧烟气和煅烧所得烧结矿中Pb和Zn的总量.实验结果表明,在刚开始煅烧的一段时间内,Pb、Zn两种重金属挥发特性相似,均是随着时间的增加以及温度的升高而挥发率逐渐上升,而当煅烧超过一定时间后,其挥发和固化反应会达到平衡,当煅烧的温度为1200℃时,Pb和Zn的挥发率分别为97.13%和65.04%.运用化学反应动力学理论对Pb、Zn两种重金属在烧结机共处置过程中的挥发规律进行动力学模拟,模拟结果表明,PbCl2中Pb挥发的动力学方程可表示为α=f(T,t)=1-exp[-7.90exp(-5595/T)t];而ZnCl2中的Zn为α=f(T,t)=1-exp[-0.534exp(-3210/T)t].

This study used PbCl2 and ZnCl2 to simulate hazardous waste and investigated the volatile characteristics of Pb and Zn during co-processing in sintering machines. Thermal gravity analysis（ TGA） experiments of pure chemical reagents of PbCl2 and ZnCl2 were carried out,and then raw materials of sinter ore mixed with a certain proportion of PbCl2,ZnCl2 were calcined. The total contents of Pb and Zn in the flue gas and sinter ores after calcining were analyzed. The results show that the volatile characteristics of Pb and Zn are similar at the beginning of the calcining experiment,and Pb and Zn proportions increase with the increase of time and temperature until the balance of volatilization and solidification reactions are reached when the calcining exceeds certain time. When the temperature is 1200 ℃,the volatilization of Pb is 97.13%,while Zn is 65.04%. The volatilization laws of these two heavy metals were modeled using chemical reaction kinetics. The kinetic equation of Pb in the form PbCl2 can be represented as α = f（ T,t） = 1-exp [-7.90exp（-5595 / T） t],while Zn in ZnCl2 as α = f（ T,t） = 1-exp [-0.534exp（-3210 / T） t].