摘要
利用高岭土等矿物吸附剂固化半挥发性重金属,是高温处置固体废弃物时降低其环境危害的有效途径。但超过1100℃时,高岭土中的无定形硅铝相转化为莫来石晶体,伴随层状结构坍塌,产生高温失活现象。本文利用硅灰、氢氧化铝和碳酸钙调整高岭土的化学组分,在0~1450℃区间内设置3种煅烧模式,分析矿物吸附剂对重金属Pb的固化效果。结果表明,使用矿物吸附剂可以明显提高PbO的起始挥发温度并降低其挥发率,起到固化重金属Pb的效果。综合考虑吸附剂中重金属Pb的含量和残渣态的比例,适当增加硅和铝的含量均可明显提高吸附剂中重金属Pb的固化率,其中高铝吸附剂在1450℃时对重金属Pb的固化效果更优。这是由于引入的硅和铝可与高岭土中的硅酸盐发生反应,生成非晶硅铝酸盐相。此外,吸附剂对重金属Pb的固化效果与煅烧制度密切相关。研究结果可为水泥窑协同处置废弃物中半挥发性重金属的固化提供理论基础。
Using mineral adsorbents such as kaolin to solidify semi-volatile heavy metals is an effective way to reduce the environmental harm of solid waste during high-temperature disposal.But when the temperature exceeds 1100℃,the amorphous silicon-aluminum phase in kaolin transforms into mullite crystals,accompanied by the collapse of the layered structure,resulting in high-temperature deactivation of the adsorbent.In this article,silica fume,aluminum hydroxide,and calcium carbonate were used to adjust the chemical component of kaolin,and three calcination modes were set up within the range of 0~1450℃to analyze the solidification effect of mineral adsorbents on heavy metal Pb.The results indicated that the use of mineral adsorbents can significantly increase the initial volatilization temperature of PbO and reduce volatilization rate,which achieves the effect of solidifying Pb.Taking into account the content of Pb in the adsorbent and the proportion of residual state,appropriately increasing the content of silicon and aluminum can significantly improve the solidification rate of Pb in the adsorbent.Among them,high aluminum adsorbent has a best solidification effect on Pb at 1450℃.This is because the introduced silicon and aluminum can react with silicates in kaolin to form amorphous aluminosilicate phases.In addition,the solidification effect of adsorbents on Pb is closely related to the calcination system.The research results can provide a theoretical basis for the solidification of semi-volatile heavy metals in the co-processing of waste in cement kilns.
作者
朱绘美
孙晓
李辉
ZHU Huimei(School of Materials Science and Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,Shaanxi,China)
出处
《水泥》
CAS
2024年第2期26-30,共5页
Cement
基金
国家重点研发计划课题(2021YFB3802003)。
关键词
高岭土
化学改性
水泥窑协同处置
重金属PB
kaolin
chemical modification
co-processing in cement kiln
heavy metal Pb
