Blast Design Optimization in a Fractured Marble Quarry Using Kuz-Ram Modeling and SHOTPlus Simulation: A Case Study from Cameroon (Northern Region)

Abstract

Rock fragmentation efficiency directly influences productivity and operating costs in surface mining. This study presents an integrated approach for optimizing blast design at the Bidzar marble quarry in northern Cameroon, where complex metamorphic geology with dense fracture networks challenges fragmentation control. The methodology combines geological structural mapping, the Kuz-Ram fragmentation model, Langefors-Kihlstr?m empirical design, SHOTPlus Professional simulations, and WipFrag digital image analysis. Four experimental blasts were analyzed, and an optimized design was developed through iterative parameter adjustment in Matlab. Results show that incorporating structural geology parameters, particularly dominant ENE-WSW fracture orientation and discontinuity spacing, significantly improves fragmentation prediction accuracy. The optimized blast configuration (89 mm hole diameter, 3.2 m burden, 3.6 m spacing, 157.3 g/t powder factor) is predicted to reduce oversize fragments (>800 mm) to 3.80%, compared to measured values ranging from 5.40% to 13.24% in the four experimental blasts. The optimized design would achieve a powder factor of 157.3 g/t, which is 27.2% lower than the average of initial blasts (216.1 g/t). SHOTPlus simulations predicted a 95.3% success rate with 4.7% oversize, closely matching Kuz-Ram predictions (3.8% oversize). However, these performance indicators are based on model predictions; field validation is required to confirm these projected improvements. This study demonstrates that explicitly integrating structural geological data into blast design is essential for fractured rock masses, a factor often overlooked in conventional approaches. The proposed methodological framework offers quarry engineers a practical tool for improving fragmentation efficiency, reducing explosive consumption, and supporting more sustainable mining practices in structurally controlled environments. The approach is applicable to other quarry operations with similar geological conditions.