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贵州中北部存在着高砷煤并引起环境和健康问题,对这些地区的煤进行了中子活化分析(INAA)、电子探针(EMPA)、能谱扫描电子显微镜(SEM-EDX)、低温灰化(LTA)、X射线衍射(XRD)、X光吸收精细结构(XAFS)和连续淋滤实验分析,综合研究了这些煤中砷的赋存状态。结果表明不同煤中砷具有不同的赋存状态。在部分样品中砷主要以无机砷的形式存在,而在其它样品中砷主要以有机砷的形式存在。除了黄铁矿和毒砂外,SEM-EDX结合LTA和XRD发现硫酸盐、粘土也不同程度含有砷。XAFS显示煤中的砷主要以As5+的形式存在。连续淋滤实验表明在样品ZJ-1中超过50%的砷不能被淋滤出来,而在另外两个样品(ZJ-8和RH-5B)中绝大部分的砷被淋滤出来。综合分析表明一些煤中以+5价存在的砷主要与有机质结合。煤中如此高的砷及其主要与有机质结合的现象是很罕见。
High-arsenic coal is present in central and northern Guizhou and causes environmental and health problems. Coal in these areas has been subjected to neutron activation analysis (INAA), electron microprobe (EMPA), energy dispersive spectroscopy (SEM-EDX) (LTA), X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) and continuous leaching experiments were conducted to study the occurrence of arsenic in these coals. The results show that different coal arsenic has a different state of occurrence. In some samples, arsenic is mainly present in the form of inorganic arsenic, while in other samples, arsenic is present mainly in the form of organic arsenic. In addition to pyrite and arsenopyrite, SEM-EDX combined with LTA and XRD found sulfate, clay also contains varying degrees of arsenic. XAFS shows that arsenic in coal is mainly present in the form of As5 +. Continuous leaching experiments showed that more than 50% of the arsenic in sample ZJ-1 could not be leached out, while most of the arsenic in the other two samples (ZJ-8 and RH-5B) was leached out. A comprehensive analysis shows that arsenic present at +5 in some coal is mainly bound to organic matter. Such a high level of arsenic in coal and its combination with organic matter are rare.