黔西南煤燃烧产物微量元素分布特征及富集规律研究

Distribution and Enrichment of Trace Elements in Coal Combustion Products from Southwestern Guizhou

通过对黔西南高砷煤及燃烧产物(底灰、粗飞灰、细飞灰和烟气)中微量元素含量、水溶性及赋存状态的测定,分析了微量元素在燃煤产物中的分布特征及富集规律,探讨了燃煤过程中微量元素迁移转化机制.结果表明,As和Sb是黔西南高砷煤的主要危害元素,含量分别为(256±195)μg.g-1和(26±21)μg.g-1.根据元素在燃煤产物中富集程度的差异,将其分为4类:Ⅰ底灰富集型(Cr和W);Ⅱ均匀富集型(Cu和Ba);Ⅲ飞灰富集型(Mn和Mo);Ⅳ细飞灰超富集型(As、Cd、Sb和Pb).As的挥发性强于Sb和Pb.As在细飞灰上表现出强烈的富集;而Sb和Pb在原煤和燃烧产物中的分配具有明显的正相关关系(R2=0.990 1,P<0.05).亲石元素容易在底灰沉积或组成飞灰颗粒基质,亲硫元素燃烧后易于吸附在飞灰颗粒表面.而飞灰颗粒粒径越小,比表面积越大,所吸附的微量元素含量越高.

The main aim of this study was to research the distribution and enrichment of trace elements in the high arsenic coal and the combustion products（bottom ash,coarse fly ash,fine fly ash and flue gas） from southwestern Guizhou.The characteristics of enrichment behavior,elements transformation mechanism during combustion were analyzed.The results indicated that arsenic and antimony were the main toxic elements,their concentrations were（256±195）μg·g-1 and（26±21）μg·g-1,respectively.The elements were classified into four groups based on their enrichment behavior in combustion products： ClassⅠ,Enriched in the bottom ash（Cr,W）;Class Ⅱ,Equally distributed between bottom ash and fly ash（Cu,Ba）;Class Ⅲ,Enriched in the fly ash（Mn,Mo）;Class Ⅳ,Enriched in the fine fly ash（As,Cd,Sb,Pb） strongly.The volatile of arsenic is stronger than that of antimony and lead.Arsenic shows a strong enrichment in fine fly ash,while the distribution of antimony and lead shows a positive correlativity in combustion products（R2=0.990 1,P0.05）.The lithophile elements are easy to accumulate in the bottom ash or become the matrix of fly ash.On the other hand,the chalcophile elements adsorb in the surface of fine particles during combustion.Fine particles can adsorb more gaseous elements because of high specific surface area.