基于PFC~(3D)数值模拟的金山店铁矿东区合理覆盖层厚度研究

覆盖层在无底柱分段崩落采矿法开采中起着重要作用,既要为挤压爆破和端部放矿创造必要条件,还需保证崩落法生产的安全性,选择合适的覆盖层厚度对矿山开采具有重要意义。首先,根据金山店铁矿东区采场结构参数,利用椭球体放矿理论计算出合理覆盖层厚度为20 m,并以覆盖层充当缓冲层时覆盖层厚度计算公式验证了该厚度能满足安全要求;其次,利用PFC~(3D)数值模拟软件进行三轴压缩试验找到与金山店铁矿东区岩体力学强度参数相匹配的矿岩颗粒微观参数;最后,根据矿岩微观参数建立放矿数值分析模型,通过选取的不同覆盖层厚度进行模拟放矿,依据放矿后矿石的回收率和贫化率大小来分析覆盖层厚度对开采指标的影响,认为20 m厚度覆盖层条件下的矿石回收率和贫化率达到最优值。理论计算和数值分析表明,金山店铁矿东区崩落法开采时覆盖层厚度取20 m,可取得较好的技术经济效果并保证采场安全。

Research on the Reasonable Covering Layer Thickness in the East Area of Jinshandian Iron Mine Based on PFC3D

Covering layer plays important roles in the mining activities of pillarless sublevel caving method,it not only confirms the condition of extrusion blasting and side ore drawing,but also the safety of sublevel caving,so determination of the covering layer thickness is of great significance for ore mining. Firstly,the reasonable covering layer thickness is calculated as 20 m by using the ore-drawing ellipsoidal theory based on the stope structure parameters in the east area of Jinshandian Iron Mine,then using covering layer thickness calculation formula to verify its safety when covering layer serves as buffer layer,the verification results show that the thickness can meet safety requirement;besides that, the triaxial compression test by using PFC3D numerical simulation software is conducted to get the ore and rock particles microscopic parameters corresponding with the strength of rock mass mechanics parameters of the east area of Jinshandian Iron Mine;finally,the ore drawing numerical a-nalysis model based on the ore and rock particles microscopic parameters is established,the ore drawing simulation test is done by selecting the different covering layer thickness,the influence of covering layer thickness to mining indicators is judged based on the recovery rate and depletion rate after ore drawing,the results show that the optimal recovery rate and depletion rate can be obtained under the condition of 20 m covering layer thickness. The above theoretical calculation and numerical analysis re-sults indicate that the better technical and economical effects can be obtained and the stope safety production can be guaranteed under the condition of 20 m covering layer thickness in the esat area of Jinshandian Iron Mine.