Influencing of unloading height on impact ramming effect in the process of orepass unloading

During the unloading process in orepass, the impact and compaction of ore rock will cause orepass blockage, shaft wall damage and other problems, which will affect the safe and efficient production of mine.The unloading height is one of the main factors that affects the impact ramming effect of orepass unloading.To explore the effects characteristics of the process, take porosity variation and peak impact force on shaft wall as the standard, respectively represents the tamping effect of ore unloading on the storage material and the impact effect on the shaft wall.A numerical model of orepass unloading is established by PFC^2D to simulate the process of impact compaction under six unloading heights.On the basis of this, the influence characteristics of unloading height on the variation of porosity and the peak stress of shaft wall are analyzed.The conclusions are as follows.The change of storage porosity and the peak value of sidewall impact force are positively correlated with the unloading height and negatively correlated with the distance from the measured range to the storage surface.Reducing the height of ore unloading can reduce the tamping range and effect in the process of ore unloading.Under the conditions of the diameter of the storage section 6 m and the storage height 24 m, within the range of 5 m from the material storage surface, with the reduction of the unloading height, the tamping effect on the material storage is also significantly weakened, and the tamping effect in the remaining range is less affected.Lowering the height of ore unloading can reduce the impact of ore unloading on the shaft wall.Under the current structural parameters of the orepass, the peak value of the impact force of the shaft wall in the range of 9 m below the storage surface is significantly affected by the unloading height, while the influence degree is small in the other ranges.The mine can reduce the height drop between the unloading station and the ore storage surface of the ore storage section of the orepass, reduce single ore discharge, supporting the shaft wall and other measures to reduce or prevent the negative impact of impact compaction on the orepass system.