Research on coal gangue recognition of GF-5 hyperspectral image

Coal gangue is one of the main pollution sources in coal mining area, which can cause air, water, land and vegetation pollution. Therefore, in order to protect the ecological environment, coal gangue is usually buried underground. However, with the influence of soil erosion and other human factors, coal gangue from historical landfills gradually exposed to the surface, mixed with sand, and became the source of pollution again. In this study, through the analysis of X-ray powder diffraction and spectrum of coal gangue samples in Ordos coal mining area, it is found that the coal gangue in this area contains kaolinite. Kaolinite has unique spectral characteristics in the short wave infrared spectrum, which can be recognized by hyperspectral remote sensing. China launched the GF-5 satellite on May 9, 2018, equipped with a hyperspectral imager called the Advanced Hyperspectral Imager (AHSI). It has a spectral range of 400-2500 nm, with spectral resolutions of higher than 5 nm in the VNIR and 10 nm in the SWIR, respectively. On the basis of data processing, kaolinite information is extracted from hyperspectral reflectance data. Based on the field sample validation and image spectral analysis, it is concluded that hyperspectral data of GF-5 can effectively identify kaolinite information. At the same time, it is found that the spectrum of kaolinite in coal gangue is obviously different from that of kaolinite in clay mining, and they can be distinguished. Therefore, the distribution of coal gangue in mining area can be indicated by the identified kaolinite information.