Near-infrared spectrum characteristics and mechanism of coal and rock in mechanized caving face

In order to study the characteristics and absorption mechanism of near-infrared spectra of coal and rock at different occurrence positions in a fully mechanized caving face,the coal and rock drill cores are collected from the fully mechanized caving face of Tashan mine,including gangue in No. 3-5 coal seam,gangue in No. 2 coal seam,rock of immediate roof,rock of main roof,coal in No. 3-5 coal seam,and coal in No. 2 coal seam. According to the difference of occurrence position,the coal and rock drill cores are divided into a total of 6 categories and 27 types of coal and rock samples. In the laboratory,AVANTES near-infrared spectrometer is used to obtain the reflectance spectra curves of 27 kinds of coal and rock samples at long wave near-infrared band (1 100-2 500 nm). Through X-ray diffraction,X-ray fluorescence and industrial analysis,the mineral composition,element content and in-dustrial composition content of coal and rock samples are determined respectively. Meanwhile,in order to study the universality of the characteristic differences between coal and rock spectral curves,22 coal and rock samples from Shanxi,Shandong,Ningxia,Inner Mongolia and other mining areas are collected in turn,and their reflection spectral curves in the long wave near-infrared band (1 100-2 500 nm) are obtained respectively. The study on the spectral characteristics and absorption mechanism of coal and rock samples in the fully mechanized caving face of Tashan mine and the spectral characteristics of coal and rock samples in different mining areas shows that:① Compared with the roof slate,the absolute value of the absorption characteristics and the slope of the curve of the coal seam sandwich are smaller,mainly because the relatively large amount of opaque carbonaceous materials in the coal seam contain the absorption characteristics of inorganic ions at their characteristic wavelengths. Although the groundmass ( mainly the organic compounds composed of C,H and O elements) in coal is 5. 3 times higher than the mineral,there is no obvious absorption characteristic of organic groups in the near-infrared band,and a large number of opaque carbonaceous substances obscure the absorption characteristic of inorganic ions in the near-infrared band,making the spectral curve of the coal relatively smooth and showing an upward trend. ② The difference between coal and rock spectral curves can be described by the sum of the absorption valley depth,slope and roughness. The study on the spectral characteristics and absorption mechanism of coal and rock in a fully mechanized caving face and the spectral characteristics of coal and rock in different mining areas is to provide a reference and basis for coal and rock identification in the coal mining process.