【摘要】 选用我国三个典型燃煤煤种的电厂飞灰中铁质微珠,进行显微结构与物相组成等方面的研究。揭示出铁质微珠中存在空心微珠、子母珠和实心微珠三种显微颗粒类型,在这些显微颗粒表面可识别出以微粒状和八面体自形晶两种方式存在的赤铁矿和磁铁矿析晶;元素分析表明,燃烧褐煤电厂铁质微珠主要由Fe、Ca、Al、和Si元素组成,燃烧烟煤和无烟煤的电厂铁质微珠主要由Fe、Al和Si元素组成;物相分析发现,Fe在铁质微珠中以四种存在形式:Fe3O4、αFe2O3、γFe2O3和Fe3+玻璃相。这些物相在三个电厂飞灰中呈现出不同的分布特征,反映出不同的燃煤煤种在锅炉中燃烧温度的差异。随着温度的升高,Fe3O4先氧化为γFe2O3,或γFe2O3与Fe3O4的固熔体,然后再转变为αFeO,当温度超过1400℃时,FeO又转化为FeO。更多还原

【Abstract】 The ferruginous sphere is one of the main microscopy particle components in coal fired fly ash. The microstructure and mineral characteristics of the ferruginous spheres in fly ashes from 3 coal fired power plants were studied. The ferruginous spheres in fly ash samples were investigated using scanning electronic microscopy, ICP-AES and Mssbauer spectroscopy, etc. The results are expected to reveal the physicochemical characteristics of the ferruginous sphere and provide the scientific basis for prevention of slag on the boiler heating surface and resource utilization of coal fly ash. Three types of micro-particles, namely cenospheres, plerospheres and solid spheres were identified. Hematite and magnetite occur on the surface of these spheres in the form of dendritic or octahedral euhedral crystals. The element compositions of ferruginous spheres collected from Xiao Longtan power plant include mainly Fe, Si, Al and Ca, etc.; however, those from Jiaozuo and Yaomeng power plants include mainly Fe, Si and Al, etc.. The reason was analyzed in this article. The type of mineral-phase of ferruginous spheres are divided into Fe₃O₄, α-Fe₂O₃, γ-Fe₂O₃ and Fe 3+-silicate, and their contents are quite different among three ash samples, reflecting the difference in combustion temperature of the feed coals in boilers. With increase of the temperature, Fe₃O₄ is generally oxidized to γ-Fe₂O₃ or the co-melted solid including γ-Fe₂O₃ and Fe₃O₄ firstly, then turned to α-Fe₂O₃; but when exceeding 1 400℃, Fe₂O₃ turns to Fe₃O₄ again.更多还原