为了深度解析典型有毒害微量元素在燃煤产物中从微米到纳米单颗粒的分布特性，选取某燃煤电站产物(炉渣BA、飞灰FA、石膏SG)为研究对象，利用超声分散结合离心对样品分粒径后，借助单颗粒等离子体飞行时间质谱(spICP-TOF-MS)对As、Pb和Cr分布进行了跨尺度解析，并利用机器学习整合提取数据解析了3种元素在燃煤产物全样、1～10 μm和<500 nm颗粒中的分布特性。结果表明，As、Pb和Cr仅在燃煤FA全样中明显富集；FA和SG样品1～10 μm颗粒中，粒径对As和Pb的分布有一定影响， Cr在FA和SG样品1～10 μm颗粒中分布不受粒径影响；在BA、FA及SG样品<500 nm颗粒中分别有3 426、18 386、和3 787个单颗粒被有效识别，FA和SG样品中含Pb和Cr的颗粒占比高于含As颗粒，SG样品中含As(1.1%)、Pb(3.6%)和Cr(7.6%)的纳米颗粒占比明显高于FA；BA、FA和SG样品<500 nm单颗粒中，As、Pb、和Cr均与Fe、Ti、Mg、Al表现出强关联性，As在FA中还与Cr、Rb、Mn和Pb有一定关联性，Pb在FA中还与Ba、Ce、Ga、Zr和Sr存在一定关联；而在SG样品中As、Cr和Pb三者之间存在较强关联性，此外Cr在SG样品中与Sn、Ni和Rb等存在一定相关性。As、Pb和Cr在不同粒径燃煤产物中富集与燃煤多元组分成核与颗粒生长过程密切相关，煤中多元组分对这3种元素的形态转化与分布有不同程度影响，研究结果为深入揭示燃煤重金属在颗粒中跨尺度迁移转化机制奠定了基础。

For obtaining a deep understanding of typical hazardous elements distributions in coal combustion products (CCPs) from micro to nano size, the products of a coal-fired power plant (slag BA, fly ash FA, gypsum SG) were selected as the research objects. After the sample was divided into particle sizes by ultrasonic dispersion and centrifugation, the distribution of As, Pb and Cr was analyzed by single particle plasma time of flight mass spectrometry (spICP-TOF-MS). The data extracted by machine learning integration were used to analyze the three elements in the whole sample of coal-fired products, 1-10 μm and <500 nm particles. The results indicate that the As, Pb, and Cr are obviously enriched in FA. Particle size from 1 μm to 10 μm will affect the distributions of As and Pb in FA and SG samples. Distributions of Cr in particles from all the samples are not affected by the particle size. There are 3 426, 18 386, and 3 787 particles can be measurement (<500 nm). Pb and Cr bearing single nano- size particles are abundant in comparison with As bearing single particles both in FA and SG samples. As, Pb and Cr bearing particles in SG samples are more abundant than that in FA samples, and the proportions of particle numbers are 1.1%, 3.6% and 7.6% respectively. As, Pb and Cr show strong associations with Fe, Ti, Mg and Al in the BA, FA and SG samples. As also shows a high association frequency with Cr, Rb, Mn and Pb in FA. Pb has high associations with Ba, Ce, Ga, Zr and Cr in FA. While in the SG samples, As, Cr and Pb have very strong associations. In addition, Cr is also found to be associated with Sn, Ni and Rb in SG samples. The enrichment of As, Pb and Cr in coal-fired products with different particle sizes is closely related to the process of coal-fired multicomponent nucleation and particle growth. The multicomponent in coal has varying degrees of influence on the morphological transformation and distribution of these three elements. The research results lay a foundation for further revealing the mechanism of large-scale migration and transformation of heavy metals in coal-fired particles.

0 引言

1 试验

   1.1 燃煤电站现场采集与样品分选

   1.2 spICP-TOF-MS测定与数据处理

2 结果与讨论

   2.1 As、Pb、Cr在燃煤产物全样中的分布

   2.2 不同粒径颗粒质量分布

   2.3 spICP-TOF-MS纳米单颗粒实测颗粒数

   2.4 As、Pb和Cr在不同粒径颗粒中分布

   2.5 As在<500 nm单颗粒中的赋存与分布

   2.6 Pb在<500 nm单颗粒中的赋存与分布

   2.7 Cr在<500 nm单颗粒中的赋存与分布

3 结论