贵州普安-晴隆矿区晚二叠世煤及煤灰中伴生元素的富集特征

Enrichment characteristics of associated elements of Late Permian coal and coal ash from Pu'an and Qinglong coal mining area in Guizhou Province

  • 摘要: 运用电感耦合等离子体质谱仪(ICP-MS)和电感耦合等离子体发射光谱仪(ICP-AES)分别对普安-晴隆矿区晚二叠世C17、C19、C22和C26号煤层中8个煤样和7个煤灰样进行微量元素含量的测试分析。结果表明,煤及煤灰中明显富集Li、Sc、V、Cr、Co、Ge、As、Nb、Mo、W、U等元素,且各元素在煤灰中更加富集,Nb、Zr、V、Ga和U等伴生金属元素的含量基本达到或超过了对应元素的边界品位或最低工业品位。煤中伴生元素的富集成因研究表明,V、Cr、Co、Nb和Zr等元素的富集主要受物源区峨眉山玄武岩风化碎屑物质供给的控制;U、S、Mo等元素的有限富集与海水作用有关;而受成煤期同沉积火山灰沉降的影响,煤中Li、Nb、Zr、Mo和U等微量元素表现出一致富集的特点;成煤期后的低温热液作用,使得各煤层,尤其是底部煤层(C19、C26)明显富集As、Mo、U和W等元素。综合分析认为,成煤期同沉积的火山灰沉降和成煤期后的低温热液作用是普安-晴隆矿区晚二叠世煤中伴生元素异常富集的主控地质因素。

     

    Abstract: ICP-MS and ICP-AES were applied to study the geochemical characteristics of trace element content of eight representative coal samples and seven coal ash samples from Late Permian coal seams C17, C19, C22 and C26 in Pu'an and Qinglong coal mining areas. The results showed that the elements such as Li, Sc, V, Cr, Co, Ge, As, Nb, Mo, W and U are enriched obviously in coal and coal ash. Compared with the concentrations of elements from coal samples, the elements from coal ash are further enriched, the content of Nb, Zr, V and U reached or exceeded the cutoff grade or the lowest industrial grade. Evidence suggests that enrichment of V, Co,Ni and Cr can be attributed to the weathered detrital materials of Emeishan basalt, at the same time, the sedimentary environment is also one of the factors that could influence the enrichment of some elements. For example, U, S and Mo are inclined to be enriched when the action of sea water became strong. Some elements like Li, Nb, Zr, Mo and U are consistently enriched and affected by the sedimentation of synsedimentary volcanic ash. Furthermore, the low temperature hydrothermal activity after coal-forming peroid made coal seams, especially the bottom coal seams(C19, C26) obviously enriched in specific elements such as As, Mo, U and W. It is concluded that the sed imentation of synsedimentary volcanic ash and the low temperature hydrothermal activity were together the main control factors effecting the enrichment of the associated elements in the Late Permian coal through comprehensive analysis.

     

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