Optimization of Fragmentation Control and Blasting Parameters for Limestone Blasting

This research focuses on addressing fragmentation heterogeneity in the Dengjiashan limestone mining area, which is exacerbated by complex joint development conditions and affects downstream processing productivity and economic performance. Through systematic quantification of the effects of critical blasting parameters on fragmentation consistency, this research establishes a foundation for optimizing precision blasting using orthogonal experimental methodology. The cumulative rates of 8 cm, 3 cm, and 0.5 cm sieving were used as the evaluation indices for fragmentation distribution to examine four key variables, including hole network parameters, delay time, subdrilling, and charge interval, in on-site blasting tests. Test results indicate that establishing an air buffer layer between explosive columns effectively modulates stress-wave propagation and energy-transmission efficiency, substantially reducing the 8 cm sieve undersize accumulation while predominantly regulating boulder yield, with drilling-pattern parameters exerting direct control over explosive energy concentration patterns. Meanwhile, reduced blasthole spacing configurations produce finer fragmentation patterns, whereas expanded spacing configurations result in coarser fragmentation. The delay time affects the stress-wave superposition effect by precisely controlling the blasting timing, effectively lowering the percentage of 8 cm oversize fragments in adjacent rows while primarily determining the medium and fine particle-size distribution characteristics. Optimizing subdrilling depth between 2.5 m and 2.8 m can help reduce the foundation, but the effect weakens when blasthole spacing exceeds the optimal range. Furthermore, range and variance analyses quantitatively assessed parameter influences, revealing charge spacing and blasthole patterns as dominant controls on coarse fragments, while delay timing critically governed the distribution of medium and fine particles. The optimized parameter combination comprised 6.0 m×3.5 m hole spacing, 20 ms interhole delays, 33 ms interrow delays, 2.8 m subdrilling depth, and 2.0 m charge intervals. This study systematically evaluated the effects of critical blasting parameters on fragmentation characteristics in Dengjiashan limestone, successfully addressing fragmentation nonuniformity while enhancing downstream processing efficiency and reducing operational expenses.