Yuan Zongshuai, Cai Guangkai, Kong Lingxue, Wu Min, Bai Jin, Bai Zongqing, Li Huaizhu, Li Wen
State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou, 310014, PR China.
J Environ Manage. 2024 Nov;370:122750. doi: 10.1016/j.jenvman.2024.122750. Epub 2024 Oct 2.
Melting treatment has emerged as a promising technology for managing municipal solid waste incineration (MSWI) fly ash owing to its advantageous features of effective detoxification and volume reduction. The melting treatment of MSWI fly ash involves the immobilization of heavy metals by crystals and liquid phase. Herein, the immobilization mechanism of heavy metals (Cu, Pb and Cd) by the crystals and the liquid phase was investigated using melting experiments, thermodynamic calculations and density functional theory (DFT) calculations. Results demonstrate that the immobilization of heavy metals is influenced by a combination of factors: the reaction of heavy metals, physical encapsulation ability of the liquid phase and chemical fixation ability of both the crystals and the liquid phase. An increase in the content of SiO and AlO promotes the conversion of heavy metals oxides into heavy metals chlorides. Furthermore, an increase in the content and polymerization degree of the liquid phase facilitates the physical encapsulation of heavy metals chlorides. The chemical fixation ability of the crystals and the liquid phase differs for Cu and Pb, while Cd cannot be immobilized through chemical fixation. To enhance the immobilization of heavy metals during melting treatment, the chemical composition of MSWI fly ash should be adjusted within the anorthite region of the ternary phase diagram. This study provides valuable insights into the immobilization mechanism of heavy metals by the crystals and the liquid phase during the melting treatment of MSWI fly ash.
熔融处理因其有效解毒和减容的优势特性，已成为一种处理城市固体废弃物焚烧（MSWI）飞灰的颇具前景的技术。MSWI飞灰的熔融处理涉及通过晶体和液相固定重金属。在此，利用熔融实验、热力学计算和密度泛函理论（DFT）计算，研究了晶体和液相固定重金属（铜、铅和镉）的机制。结果表明，重金属的固定受多种因素共同影响：重金属的反应、液相的物理包裹能力以及晶体和液相的化学固定能力。二氧化硅（SiO）和氧化铝（AlO）含量的增加促进了重金属氧化物向重金属氯化物的转化。此外，液相含量和聚合度的增加有利于重金属氯化物的物理包裹。晶体和液相对铜和铅的化学固定能力不同，而镉无法通过化学固定实现固定。为提高熔融处理过程中重金属的固定效果，应在三元相图的钙长石区域内调整MSWI飞灰的化学成分。本研究为MSWI飞灰熔融处理过程中晶体和液相固定重金属的机制提供了有价值的见解。
