As the key link of coal gangue slurry filling, slurry pipeline transportation is an important guarantee to realize the slurry mixing and safe transportation of gangue from solid powder. To realize the underground excavation gangue of the Huangling No. 2 coal mine without raising the ground, the slurry filling technology is proposed to transport the slurry made by gangue through the pipeline and fill it into the goaf. The phase composition and microstructure characteristics of underground excavation gangue in the Huangling No. 2 coal mine were analyzed by X-ray diffraction and an electron microscope scanning test, the slurry-forming properties of gangue powder with different particle sizes and gradations were studied, and the influence of gangue slurry concentration on its rheological properties was analyzed. The experimental results show that the gangue powder crushed using a cage crusher can be made into stable slurry when the particle grading size is the natural crushing gradation with the upper limit of particle size less than 3 mm. The viscosity of the slurry is positively correlated with the concentration. When the concentration is below 70%, the increase in viscosity is small, and when the concentration is above 70%, the increase in viscosity is significant. It is determined that the concentration of the Huangling No. 2 coal mine slurry is 70%. Based on the determination of slurry preparation parameters, the simulation analysis of slurry pipeline transportation was carried out, the influence of design velocity on the velocity distribution of the pipeline section and the variation law of slurry concentration was explored, and the design velocity of the project is determined to be 1.5 m/s. The engineering practice shows that the slurry preparation parameters are reasonable. The crushing and pulping of gangue under the ground and the safe transportation of a 6 km pipeline are realized, which provides a reference for similar engineering projects.

This study examines the particle size and distribution of the main chemical components of gangue during the crushing process. Coal mine gangue was chosen as the research object, and its particle size and chemical components at various crusher discharge settings were examined through screening, grinding, chemical composition testing, and other methods. The findings demonstrate that the characteristic particle size in the gangue particle size distribution model has a logarithmic upward trend as the width of the discharge port increases. In contrast, the uniformity index has shown an exponential downward trend. The analysis of the distribution rate and enrichment ratio of the main chemical components of the gangue at different widths of the discharge port shows that the gangue exhibits obvious selective crushing during the crushing process. The distribution rate of each component is affected by the size of the screen aperture to various extents. As the discharge port width increases, the elements of CaO and MgO are enriched in the coarse-grained products, while those containing Fe2O3 are enriched from fine-grained to coarse-grained. Gangue particles containing Al2O3, SiO2, and C are enriched in the fine-grained product. In addition, by analyzing the alterations in the main chemical components of gangue at different particle size intervals, it was found that the amount of each component first rises and then falls, and the trend of enrichment ratio to particle size follows an exponential pattern. The research results have significance for guiding the selection of resource utilization methods of gangue with different particle sizes after crushing.

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