为探明微观尺度下矿石动态破碎机理及能耗规律，利用分离式霍普金森压杆对磁铁矿石开展冲击破碎试验，分析磁铁矿石的破碎能耗规律，结合扫描电镜技术揭示磁铁矿石的破碎机理。结果表明：在冲击载荷作用下，随入射能增加，磁铁矿石单位体积破碎能耗和平均应变率相应增大。单位体积破碎能耗具有较强的应变率相关性，随平均应变率的增大而增大。随入射幅值增大，磁铁矿石破碎程度由与原试件等高的碎块变为柱状或针状，且碎块粒径在不断减小，最后出现粉末状，阶梯状破碎与波浪状破碎形貌也随之增加，期间出现磁铁矿石出露现象。随入射能增大，磁铁矿石内部沿晶裂隙及穿晶裂隙不断增多，内部裂隙也随之逐渐发生扩展及发育，裂隙长度由短且细转换为长而宽，由裂隙状态转换为宽裂纹状态，最后完全贯通至破裂状态。在入射能为71.44 J时产生穿晶裂隙，沿晶裂隙数量大于穿晶裂隙数量。研究成果有助于矿山在破碎工艺中提高能量的利用率，对于解决目前矿山破碎能耗高的问题有一定的理论意义。

In order to investigate the dynamic crushing mechanism and energy consumption law of the ore at the microscopic scale, impact crushing tests were carried out on magnetite ore using a separated Hopkinson press bar, the crushing energy consumption law of magnetite ore was analyzed, and scanning electron microscope technology was combined to reveal the crushing mechanism of magnetite ore. The results show that under the impact load, with the increase of incident energy, the crushing energy consumption per unit volume and average strain rate of magnetite stone increase accordingly. The energy consumption per unit volume of crushing has a strong strain rate correlation and increases with the increase of average strain rate. With the increase of incident amplitude, the degree of magnetite crushing from the original specimen and the height of the broken pieces to columnar or needle-like, and the particle size of the broken pieces continues to decrease, and finally appearing in the form of powder, and the stepped crushing and wavy crushing morphology also increases, during which the phenomenon of magnetite outcropping occurs. With the increase of incident energy, the magnetite internal along the crystal cracks and perforated cracks continues to increase, the internal cracks are also gradually expanding and developing, the length of the cracks is converted from short and thin to long and wide, and the state of the cracks is converted into a wide crack state, and finally it is completely penetrated to the state of rupture. In the incident energy of 71.44 J, the perforated cracks are generated, and the number of along-crystal cracks is larger than the number of perforated cracks. The research results are helpful for improving the energy utilization efficiency of mines in crushing processes, and have certain theoretical significance for solving the current problem of high energy consumption in mine crushing.