基于PFC3D的崩落法采场放矿步距优化研究

Optimization of Stope Drawing Step in Caving Method Based on PFC3D

无底柱分段崩落采矿法结构参数是影响放矿损失与贫化的重要因素。以某矿山崩落法采场为工程依托,基于PFC3D软件,建立崩落法采场三维单体数值模型,保持分段高度(21 m)与进路间距(20 m)不变,对放矿步距进行了优化研究。结果表明,放出体的高度随着放矿步距的增加而有所增加,但当达到5.0 m放矿步距后变化不大;随着放矿步距的增加,近椭球体形态的放出体由“短粗”向“瘦长”发育。综合考虑回采率、贫化率与回贫差指标,放矿步距合理范围宜为5.5~7 m。随后建立物理相似模型,取不同的放矿步距进行试验,结合实验室物理放矿结论与三维单体放矿数值模拟结论,得到21 m×20 m采场结构参数下,以矿石回采指标为比较对象,最优放矿步距范围宜为5~6 m。

The structural parameters of pillarless sublevel caving mining method are important factors affecting ore drawing loss and dilution.Takinbg a stope mined by caving method as a background,a three-dimensional monomer numerical model of the caving stope was established by PFC3 D software.In this model,the sublevel height(21 m)and the drift distance(20 m)kept unchanged,and the drawing step was optimized.The results show that the height of the drawing body increases with the increase of the drawing step,but it changes little when the drawing step reaches 5.0 m.With the increase of drawing step,the near ellipsoidal shape of the drawing body develops from“short and thick”to“thin and long”.Comprehensively considering the indicators of recovery rate,dilution rate and dilution difference,the reasonable range of drawing step should be 5.5-7 m.Then,a physical similarity model was established,and different drawing steps were taken for testing.Combined with the conclusions of physical drawing in the laboratory and the conclusions of three-dimensional monomer drawing numerical simulation,it is obtained that the optimal drawing step range should be 5-6 m under the stope structure parameters of 21 m×20 m,taking the ore recovery index as the comparison object.