烧结机共处置过程中重金属Cd、As的挥发特性研究

Research on the volatilizing characteristic of cadmium and arsenic during co-processing with sintering machine

选取优级纯化学试剂Cd Cl2和As2S3来模拟危险废物中的重金属,按一定比例将其与烧结矿原料均匀混合后进行共处置煅烧。主要研究了在煅烧过程中Cd和As的挥发规律,同时对煅烧所得烧结矿进行消解实验求得固化的重金属量。实验结果表明,Cd的挥发率随着温度的升高和时间的增加而不断增大,直到达到一个平衡而不再继续增大,对Cd的挥发进行动力学模拟得到挥发率α与煅烧温度T和煅烧时间t的关系式为α=1-exp(-0.669exp(-3567.6/T)t)。而As则呈现出温度越高挥发率越低的规律,当温度为1 200℃时,煅烧75 min后As的挥发率仅为9.8%,即共处置过程中As与烧结矿原料发生化学反应而固化下来,挥发较少,可认为对人体健康和环境造成的危害较小。

The superior grade pure Cd Cl2 and As2S3were select to substitute for heavy metals in hazardous waste,and then mixed a certain proportion of these compounds(Cd Cl2 and As2S3) with the sinter raw material.The mixture were calcined in a sintering machine.The main research focused on analysis of the volatile characteristics of Cd and As during co-processing with sintering machine,and calculating amount of curing by the sinter digestion experiments.The results show that the volatilization rate of Cd increases with the temperature and time rising,until it reaches a balance.The volatilization of Cd is simulated by dynamics simulation on the basis of experimental data.The relationships among volatilization rate,temperature and time can be described as α = 1-exp(-0.669exp(-3567.6/T) t).While As is opposite,the higher temperature,the lower volatilization rate.When temperature is 1 200℃,the volatilization rate of As is only 9.8% after 75 min.This means most of As react with the sinter raw material and produce stable substances.So it can be considered that As does less harm to human health and the environment.