加速碳酸化法稳固化工业危险废物焚烧飞灰重金属的研究

Study on Accelerated Carbonation Method to Stabilize the Hazardous Waste Incineration of Fly Ash Heavy Metal

该文对某危险废物处置中心工业危险废物焚烧产生飞灰的加速碳酸化过程进行了研究。测定飞灰中Cr、Ni、Cu、Zn、Cd、Hg、Pb等重金属浸出浓度,其中Pb浸出浓度超过危险废物鉴别标准及填埋场入场控制标准限值,高达288.40mg/L。对飞灰进行碳酸化处理,探讨碳酸化反应时间、反应温度、液固比和CO_2浓度等因素对飞灰中重金属Pb浸出特性的影响。结果表明,在反应时间2~4h,反应温度10~50℃、液固比3∶1~5∶1,CO_2浓度60%~100%范围内碳酸化效果显著。并通过正交实验得到最优反应条件为CO_2浓度100%,反应时间3h,液固比4∶1,反应温度30℃。通过利用X射线衍射(XRD),扫描电镜(SEM)对飞灰碳酸化前后进行表征。结果表明,碳酸化后飞灰中Ca(OH)2、CaClOH消失,CaCO_3增加明显,晶体吸附使得重金属浸出明显下降,飞灰颗粒表面生成了以CaCO_3为主的片状和圆柱状的晶体物质。重金属浸出实验表明,飞灰经碳酸化处理后,重金属Pb浸出浓度由288.40mg/L降至0.02mg/L。碳酸化法处理工业危险焚烧产生飞灰可以有效控制重金属Pb的浸出以及降低体系的pH(由13~14降至7左右),同时实现对温室气体CO_2的固定,具有潜在的应用价值。

This research studies the accelerated carbonation process of fly ash from industrial hazardous waste incin?eration in a hazardous waste treatment center.The concentration of heavy metals such as Cr,Ni,Cu,Zn,Cd,Hg and Pb in fly ash was determined,and the leaching concentration of Pb much exceeded the standard of identification stan?dard of hazardous waste and the standard limit of entrance control of landfill site,as high as 288.40mg/L.To carbonation of the fly ash,discussing the effects to Pb leaching of heavy metal in fly ash of carbonated reaction time,reaction temperature,liquid solid ratio and CO2 concentration.Results show that the reaction time is 2~4 h,the reaction temperature of 10℃to 50℃,the liquid-solid ratio 3∶1~5∶1,CO2 concentration 60%~100%range for real effect is remarkable.And get the optimal reaction conditions through the orthogonal experiment for CO2 concentration 100%,3 h reaction time,liquid-solid ratio 4∶1,reaction temperature 30℃.By using X-ray diffraction(XRD),scanning electron microscopy(SEM)was used to characterize the fly ash carbonation.Results show that the carbonate in the fly ash after the Ca(OH)2,CaClOH disappear,CaCO3 increase obviously,crystal coating makes the leaching of heavy metals decreased obviously,generated on the surface of fly ash particles is given priority to with CaCO3 flake and cylindrical crystal material.Heavy metal leaching experiments showed that the concentration of Pb leaching of heavy metal was decreased from 288.40mg/L to 0.02mg/L after carbonation.Carbonate mineralization process,industrial hazardous incineration fly ash can effectively control the heavy metal leaching of Pb and lower the pH of the system(by 13~14 to 7),at the same time,can fixed the greenhouse gas CO2 and has potential application value.