Study on the release regularity of heavy metals from coal gangue with differentlithology in Xinjiang

In order to understand the release law of heavy metals in coal gangue with different lithology in Xinjiang and prevent and resolve the environmental risks caused by heavy metals. In this paper, the roof and floor coal gangue of Piliqing mining area and Wucaiwan mining area were used to study the release law of V, Cr, Ni, Cu, Zn, Ba, Pb, Th and U heavy metals in the leaching process by X-ray diffraction, X-ray fluorescence spectroscopy and inductively coupled plasma mass spectrometry. The results show that: ① The mineral composition of coal gangue is mainly kaolinite and quartz. ② The contents of heavy metals Ni, Cu, Zn and Ba in sandstone and clay rock gangue in Xinjiang are high. The content of Ba in sandstone gangue is 416.05 μg/g, and the content of V in clay rock gangue is up to 247.02 μg/g. The content of most elements in coal gangue is high and the release of elements is large after leaching. ③ The adsorption of clay minerals is an important reason for the decrease of element release concentration of clay rock gangue in the later stage of leaching. ④ The ‘shrinking core model’ shows that the release of heavy metals from coal gangue with different lithology is the result of multi-factor coupling. The environmental effect evaluation of element leaching results shows that clay rock gangue is more harmful than sandstone gangue, and the cumulative effect of heavy metals caused by long-term and multi-period leaching is worthy of attention.