冲击载荷下磁铁矿石破坏机制实验研究

    Experimental study on the fracture mechanism of magnetite ore under impact load

    • 摘要: 合理处理大块矿石对于提高矿山生产效率具有重要意义,利用落锤冲击设备对磁铁矿石试件进行不同冲击速度的动载试验。基于波动力学分析了矿石呈不同破坏特征的作用机理,建立了磁铁矿石动载破坏模型,研究了动载下磁铁矿石呈“哑铃状-整体破碎-哑铃状劈裂”的破坏机制。研究表明:因介质波阻抗的不同,动载冲击下的拉伸波与压缩波主导了矿石轴向与环形裂纹的产生;在矿石自由面处,拉伸波的叠加碰撞使矿石不断地发生层裂破坏形成新生断面,且在两自由面相交处的破坏程度较高;不同应力波作用区域形成粗糙度不同的特征断面,破碎大块矿石具有最优动载条件。

       

      Abstract: Treating large lump ore reasonably is of great significance for improving the production efficiency of mine.The impact load test of magnetite ore specimens under different impact velocities are carried out by using the drop hammer impact equipment.The mechanism of different fracture characteristics of ore is analyzed based on wave mechanics.The fracture model of magnetite ore under impact load is established.The fracture mechanism of magnetite ore in the form of dumbbell shapes-integral crush-dumbbell split under impact load is studied.The results show that the stretch wave and the compression wave dominate the generation of axial crack and annular crack of ore under impact load, owing to the wave impedance in different medium; at the free surface of the ore, the superposition collision of stretch wave causes spall fracture and form a new section continuously, and the broken degree is higher at the intersection of the two free surfaces further more; the characteristic sections with different roughness are formed by different stress waves in the shaped region, and there is an optimal impact load condition to crush large lump ore.

       

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