煤炭洗选过程中砷的迁移与富集规律

在煤炭资源的加工利用过程中，部分重金属元素会在环境中富集，对环境和人体均有一定危害。选用内蒙古低灰高硫煤样和高灰低硫煤样进行浮沉和浮选试验，通过电感耦合等离子质谱仪(ICP-MS)、X射线衍射分析、X射线荧光分析、扫描电镜能谱分析、红外光谱分析等测试方法，研究重金属砷元素在煤中的赋存形式及洗选过程中的迁移富集规律。试验结果表明，在两种煤的矿物组成中，硅铝酸盐结合态存在的砷占比为最高，均达到50 % 以上，但是硅铝酸盐矿物种类并不相同，砷的赋存具有明显的差异性；浮沉结果显示低灰高硫煤中的砷主要与矿物质伴生集中在密度较大的部分，而高灰低硫煤主要富集在密度较低、有机质含量较高的部分；浮选中砷迁移规律也存在差异，低灰高硫煤中的砷在浮选过程中向尾煤中迁移，高灰低硫煤中的砷则相反，浮选过程中向精煤中迁移。以上规律表明，低灰高硫煤通过浮沉和浮选脱除砷是可行的，但是对于高灰低硫煤效果不好。

Migration and enrichment of arsenic during coal washing

During the processing and utilization of coal resources, some heavy metal elements will be enriched in the environment, which is harmful to the environment and the human body.In this study, low-ash, high-sulfur coal samples and high-ash, low-sulfur coal samples from Inner Mongolia were selected for float-and-sink test and flotation, and were analyzed by inductively coupled plasma mass spectrometer (ICP-MS), X-ray diffraction analysis, X-ray fluorescence analysis, and scanning electron microscopy energy spectrum analysis.Infrared spectroscopy and other test methods were used to study the occurrence form of heavy metal arsenic in coal and its migration and enrichment law during the processing.The experimental results show that the two coal samples demonstrates the highest proportion of arsenic present in the aluminosilicate bound state, reaching more than 50 %, but the types of aluminosilicate minerals are not the same, and the occurrence of arsenic has obvious differences.Flotation results show that arsenic in low-ash and high-sulfur coal sample is mainly associated with minerals and concentrated in the denser part, while high-ash and low-sulfur coal is mainly concentrated in the part with lower density and higher organic content; there are also differences in the migration law of arsenic in flotation.During the flotation, the arsenic in low-ash and high-sulfur coal migrates to the tailings, while the arsenic in the high-ash and low-sulfur coal migrates to the clean coal.The above findings show that it is feasible to remove arsenic from low-ash and high-sulfur coal sample by flotation but the effect is not so good for high-ash and low-sulfur coal sample, indicating that the removal of arsenic must consider the impact of coal type.