超积累植物伴矿景天的焚烧处置及重金属浸出毒性研究

利用流化床焚烧炉与热重分析仪,研究镉(Cd)、锌(Zn)超积累植物——伴矿景天的焚烧失重与飞灰中重金属分布规律。同时,研究不同焚烧温度工况下旋风灰、布袋灰的基本特性和浸出毒性差异,以期为修复植物焚烧产物的进一步处置和资源化利用提供支持。结果表明:伴矿景天焚烧失重可分为水分蒸发、快速裂解和固定碳燃烧3个阶段;旋风灰和布袋灰粒径均呈正态分布规律,且布袋灰粒径更小;2种飞灰的微形貌复杂多样,多为杆状、小球状、不规则的聚合体以及蜂窝状多孔结构;飞灰中Cd、Zn和Pb浓度均随温度升高呈先升高后降低的现象,并在800℃时达到最大值。2种飞灰的TCLP重金属浸出毒性均远超标准限值,存在严重浸出风险。

INCINERATION DISPOSAL OF HYPERACCUMULATOR SEDUM PLUMBIZINCICOLA AND LEACHING TOXICITY OF HEAVY METALS

The weight loss and heavy metal distribution in fly ash from incineration of a cadmium(Cd) and zinc(Zn) hyperaccumulation plant, Sedum plumbizincicola were studied in a fluidized bed incinerator and a thermogravimetric analyzer. Meanwhile, the basic characteristics including particle distribution, microscopic morphology and leaching toxicity of cyclone ash and bag filter ash under different incineration temperatures were compared, to provide data support for the further disposal and resource utilization of incineration products. The results showed that the weight loss of S. plumbizincicola during incineration could be divided into three periods: moisture evaporation, fast decomposition, and fixed carbon combustion. The particle size distribution patterns of cyclone ash and bag filter ash both followed a normal distribution, and the particle size in bag filter ash was smaller. Complex and diverse microscopic morphology of the two fly ashes was found, with mostly rod-shaped, small spherical, irregular polymer and honeycomb porous structure. Metal(Cd, Zn and Pb) concentrations in the fly ashes firstly increased and then decreased with the increasing temperature, and reached maximum values at 800 ℃. In addition, the TCLP leaching toxicity of metals in the two fly ashes far exceeded the standard limit, indicating high leaching risk in environment.