超积累植物与煤在混烧过程中重金属的迁移特性

Transfer characteristics of heavy metals during co-incineration of hyperaccumulator and coal

通过在管式炉中进行了煤与超积累植物——伴矿景天的混烧实验,主要研究了不同燃烧温度、不同氮氧比气氛以及煤与伴矿景天的不同混合质量比对混烧过程中重金属(Cd、Zn与Pb)迁移情况的影响,并应用XRD技术分析灰渣中重金属的存在形式。实验分析表明:升高温度能在不同程度上增强Cd、Zn与Pb的挥发,提高其在飞灰中的含量;与单独燃烧伴矿景天相比,煤与伴矿景天混烧更有利于Cd和Zn保留在底渣中,但不利于Pb保留在底渣中;对于不同氮氧比气氛而言,Zn和Cd在底渣中的含量随着气氛中氧气含量的提高而升高,而气氛对Pb的影响是随着氧气含量的增加,Pb在底渣的含量是先增加后减少;当煤在混烧中的比例较高时,Cd更多向飞灰迁移,Pb和Zn则更多地残留于底渣。

Co-incineration of coal and hyperaccumulator-Sedum plumbizincicola was carried out in a laboratory-scaled tube furnace. In this study,the distribution and migration of cadmium（ Cd）,zinc（ Zn）,and lead（ Pb）were studied under different conditions（ including Sedum plumbizincicola and coal blending ratio,temperature,and redox atmosphere） during co-incineration of Sedum plumbizincicola and coal,and X-ray diffraction was implemented to elucidate heavy metals species. The results revealed that an increasing temperature could enhance the volatility of Cd,Zn,and Pb and increase their contents in fly ash. In compared to incineration of Sedum plumbizincicola,it was better to retain Zn and Cd in the bottom ash,but it was not good for to retain Pb in the bottom ash for the co-incineration of coal and hyperaccumulator-Sedum plumbizincicola. As the redox atmosphere,when the amount of oxygen（ O_2） in the atmosphere had gone decreased down,Zn and Cd content in the bottom ash increased.However,the impact of the atmosphere on Pb was that with increasing O_2 concentrations,Pb content in the bottom ash increased firstly and then decreased. When the coal fraction was higher in the mixture of Sedum plumbiznciola and coal,Cd content in the fly ash was promoted,but Pb and Zn content in the bottom ash were increased.