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

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.