Experimental study on optimizing explosive energy distribution for a cost-effective solution to minimize blasting hazard and improve rock fragmentation

Flyrock (FYR) poses significant safety and environmental hazards during blasting, presenting substantial risks to nearby populations, infrastructure, and natural resources. The top-charge plays a key role in fragmenting the inert-stemming portion of the blasthole; however, its concentrated energy and high velocity-of-detonation (VoD) produce strong upward forces, resulting in energy escape that contributes to FYR and poor rock-fragmentation (RFG). Therefore, an optimized blasting pattern is essential to manage top charge for effective FYR control and improved RFG. Five parameters contributing to FYR were identified through a literature review and ranked based on the opinions of twenty domain experts using the Borda Ranking Method, with explosive energy identified as the most influential parameter. Despite extensive research on blasting parameters affecting FYR and rock RFG, the impact of explosive-energy-distribution (EED) remains underexplored. Therefore, this study examines top-charge EED through eleven experimental blasts in a limestone quarry, using different explosive sizes and distribution patterns, while keeping other drilling and blasting parameters constant. FYR distances were measured using a total-station survey instrument, while RFG was evaluated using digital-image-analysis with Split-Desktop^®. Results revealed that EED significantly affects the FYR and RFG. Optimal results were obtained with 100 mm thick slices of high explosive evenly distributed with ammonium-nitrate-fuel-oil (ANFO), resulting in a 19.6% reduction in FYR and 13.1% improvement in RFG compared with conventional blasting results. This study offers a practical and cost-effective solution for the blasting industry to reduce FYR, enhance RFG, lower operational costs, minimize resource waste, and foster safer and more sustainable mining practices.