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Abstract To improve ore recovery ratio and the quality of medium-length hole blasting in non-pillar sublevel caving method, this study first investigated the effects of brow line failure on rock movement and ore recovery indexes based on rock blasting fragmentation mechanisms, the granular dynamics theory and ore drawing theory. Subsequently, control strategies to enhance blasting quality and reduce brow line failure were explored through energy impact crushing experiments, experiments on the radial rock-breaking effects of blast holes with different detonation velocities, and underground physical simulation experiments using full blast hole length detonating cord blasting. The experimental results indicate that as the degree of brow line failure increases, the ore recovery ratio gradually decreases, while the waste ratio gradually increases. Bottom initiation and the use of the full blast hole length detonating cord were identified as the optimal initiation method and charging structure for medium-length hole blasting in non-pillar sublevel caving method, effectively improving blasting quality and reducing damage to the brow line.
Ming et al. (Fri,) studied this question.