Document Type : Original Research Paper

Authors

• Shadman Mohammadi Bolbanabad ¹
• Masoud Monjezi ¹
• Vahab Sarfarazi ²

¹ Tarbiat modares university

² Hamedan university of technology, mining engineering department

Abstract

The characteristics of fragment size distribution caused by blasting operations in open-pit mines have a direct impact on the economic performance and productivity of mining companies. In this study, dynamic impact loading tests were carried out using the Split Hopkinson Pressure Bar (SHPB) system under a constant pressure of 12.5 MPa to investigate the influence of both the edge notch length and its position relative to the incident bar on the size distribution of fragmented iron ore. By analyzing the fragmentation distribution characteristics of specimens subjected to controlled laboratory impact loading, this study focuses on fundamental rock breakage mechanisms relevant to blasting operations in open-pit iron ore mines, where the fragmented material classified into three particle size categories: large, medium, and fine fragments. Based on this classification, the variation in the mass percentage of fragments with respect to notch length and its position relative to the incident bar was investigated. Ultimately, within the context of laboratory-scale fragmentation analysis, an effective range of notch lengths and positions relative to the incident bar was identified for achieving optimal fragmentation. The results revealed that a notch length between 0.2 and 0.4 and a notch position between L/2 and 2L/3 from the incident bar (where L equals sample length), produced the most favorable fragment size distribution. These findings can help link laboratory-scale fracture behavior to field-scale rock fragmentation considerations and contribute to a broader understanding of breakage processes in mining engineering.

Keywords

• SHPB
• non-persistent edge notch
• fragment size distribution
• fractal dimension
• dynamic compressive strength

Main Subjects

• Rock Mechanics