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.