Investigation on the optimization of blasting parameters for medium-length hole mining in a copper mine based on blasting crater test

In the medium-length hole drilling, blasting, and mining processes of underground metal mines, issues such as low blasting efficiency and uneven block size distribution are particularly pronounced. These challenges have become a critical bottleneck restricting the achievement of safe and efficient mining operations in the mining industry. A representative skarn-type copper mine is selected as the research subject. Based on the classical blasting crater theory, a systematic testing system for blasting craters is established, progressing from single-hole, multi-hole and inclined-step configurations. The objective is to comprehensively investigate the variation patterns of blasting crater characteristics under various parameter conditions. By employing theoretical analysis methods, an optimization approach for the blasting parameters of medium-length holes based on characteristic parameters is developed. This provides a robust theoretical foundation for achieving precise blasting control under complex geological conditions. Based on the existing test results, the blasting parameters for medium-length holes have been determined in accordance with the engineering geological characteristics of the mine. These parameters are expected to significantly enhance the blasting efficiency and improve the control over the size of blasted fragments. The results indicate that the optimal central depth of charge is 0.975 m, the optimal volume of blasting crater is 1.035 m³, the optimal radius of blasting crater is 0.994 m, the optimal spacing of the blasting holes is 1.82 m, and the minimum resistance is 1.58 m. Comprehensively considering the influence of the actual production conditions of the mine, the parameter value range of the blasting crater has been further optimized. It is recommended that the minimum resistance is 1.1-1.6 m, the optimal bottom spacing of the blasting holes is 1.20-1.85 m, and the unit explosive consumption is 0.35-0.45 kg/t. These parameters ensure the rational utilization of blasting energy in rock masses with varying degrees of integrity. In response to the challenge of controlling the blasting effects of medium-length holes in metal mines, a set of precise blasting parameters and processes is developed, which significantly enhances the blasting effect of medium-length holes in mines. These research findings have significant guiding implications for the safe and efficient mining of mines.