Abstract
Open-pit coal mining often employs loosening blasting, with perforation blasting accounting for a significant portion of the coal seam mining costs. For coal of the same quality, the price of lump coal is much higher than that of crushed coal. Therefore, reducing the percentage of crushed coal in the blasting process is an important means to improve quality and efficiency in open-pit coal mining. How to develop a reasonable blasting scheme based on actual geological conditions has been a hot topic among scholars. In response to this issue, this study combines numerical simulation and field tests. Using the LS-DYNA software's fluid-solid coupling algorithm, the effects of charge structure, explosive type, intermediate medium, and hole spacing parameters on blasting results are analyzed. An optimized blasting scheme is determined, with specific parameters including a charge spacing of 7 m, hole spacing of 11 m, charge structure with a 5 m blocking length, 4 m upper charge length, 2 m intermediate coal powder spacing, and 5 m lower charge length, using low-density explosives. This optimized scheme is applied in field tests, and a comparison with the control group shows that the fines rate decreased from 30.10 to 24.17%, a reduction of 5.93%; the lump coal proportion increased from 59.33 to 68.41%, an increase of 9.08%; and the proportion of large coal lumps decreased from 10.57 to 7.42%, a decrease of 3.15%. The fines rate and large lump rate decreased in the experimental group compared to the control group, improving blasting efficiency and effectively reducing the downtime of the surface production system due to blockages. This study not only provides theoretical guidance for blasting in soft coal seams of open-pit coal mines but also offers scientific support for practical engineering applications, demonstrating significant engineering value and broad application prospects.