This study focuses on optimizing blasting parameters for millisecond blasting of medium-deep holes at the Jinduicheng Open-pit Molybdenum Mine, addressing its complex blasting conditions. Through numerical simulations, the research systematically examines how hole spacing, row spacing, and delay time influence blasting effectiveness. Field rock samples were prepared and tested to acquire actual in-situ rock mechanical parameters. Borehole acoustic data were analyzed using RSM acoustic logging software to determine rock wave impedance. A ten-segment detonation velocity meter measured explosive detonation velocity, enabling rock-explosive matching. Simulation parameters were established based on measured rock mechanical properties and explosive characteristics. LS-DYNA software was employed to construct numerical models with varying hole and row spacing, inter-hole and inter-row delay times.

To address the issues of low explosive energy utilization and suboptimal fragmentation distribution at an open-pit mine in Weinan, this study developed a specialized decoupled spacer for bulk emulsion explosives based on spaced charging theory. Using LS-DYNA software, a numerical model was developed to simulate blasting processes with three distinct charging structures:continuous charging, BJQ-spaced charging, and the novel decoupled charging method. Blasting stress nephograms were generated for each charging structure, enabling comparative analysis of stress distribution characteristics across different charging modes. Field optimization experiments successfully validated the numerical simulation results for the evolution of rock stress distribution. The results demonstrate that the developed decoupled spacing device effectively meets engineering requirements for spaced charging while significantly expanding stress distribution ranges. Field implementation reduces boulder yield by 7.14% and fine ore yield by 10.08%, while increasing the average fragment size by 5 cm. This solution addresses issues of high explosive consumption and uneven fragmentation, lowers subsequent loading and transportation costs, and provides valuable references for charging structure optimization in similar mining operations.