矿岩交界台阶坡面处抛掷效果模拟研究

Simulation Study on Throwing Effect Step at the Interface of Ore-rock Step Slope

基于露天金属矿山开采常面临矿体和岩体混合的爆破条件,爆区中常有规模不等的矿岩混合爆区,爆破过程中不可避免地造成破碎矿石和岩石相互混合,导致矿石贫化。对某矿14 m台阶ϕ310 mm大直径深孔逐孔、排间梯段起爆、跨越矿岩交界顺序和有序长延时对孔起爆等工况条件下,台阶深孔在爆炸荷载对矿岩交界处抛掷效果的影响进行数值模拟研究分析。模拟得出:①跨矿岩分界线处的正向抛掷速度及位移较大,侧向因应力叠加抵消导致抛掷运动速度及位移较小,因此边界线处主要为正向移动,同时有效避免矿岩混合现象;跨交界炮孔周围因先行起爆,为孔组创造了瞬时自由面条件,导致破碎岩块颗粒整体既向前方正向抛掷,同时也向侧向抛掷分离,利于矿岩体的抛掷分离;从各监测点特性可以看出,台阶整体垂直高度上,在最小抵抗线处位移及速度最大,依次向两侧递减。②在跨越矿岩交界的同排炮孔有序对孔起爆方式下,对孔组在110~150 ms不同延期时间下的模拟结果表明,随着延期时间的增加,有利于为跨交界炮孔提供充足的抛掷空间,减少矿岩体抛掷过程中的碰撞,使得分离沟槽宽度增加,同时矿岩体爆堆高度相对有所提升。③在混合爆区跨越矿岩交界有序长延时起爆,进行爆破分离技术方案基础上,以爆区内矿(岩)区域中心为起爆点,采用各自区域V型起爆方案,可以实现矿岩石的各自中心堆积,同时也强化了跨矿岩交界处抛掷瞬时自由面效应,更有利于深凹沟槽的产生,充分降低混合爆堆矿石的贫化率。该研究为露天金属矿矿岩分离爆破提供理论依据和实际爆破创造有利条件。

Based on the metal open-pit mine is often faced with the blasting condition of mixed ore body and rock mass,there are often mixed blasting areas of ore and rock with different scale in the blasting area,which inevitably results in the mixing of broken ore and rock in the blasting process,resulting in ore dilution.The effect of blast load on the throwing effect of 14 m step andϕ310 mm large diameter deep hole in a mine is numerically simulated and analyzed under the conditions of hole by hole,row by row step,sequence across the ore-rock interface and long time delay.The following conclusions:①Across the ore rock boundaries are throwing speed and large displacement.Lateral throwing movement speed and displacement caused by stress superposition offset smaller,so the boundary is mainly forward movement while effectively avoiding the ore-rock mixing phenomenon.The instantaneous free surface condition is created around the cross boundary hole due to the first initiation of the hole group,which leads to the whole broken rock particles are thrown forward and forward and also thrown sideways,which is conducive to the throwing and separation of the ore mass.From the characteristics of each monitoring point,it can be seen that the displacement and velocity of the overall vertical height of the step are the largest at the minimum resistance line,and decrease to both sides in turn.②Under the same row of perforation initiation mode across the ore-rock interface,the simulation results of perforation group under different delay time of 110~150 ms show that with the increase of delay time,it is beneficial to provide sufficient throwing space for the perforation across the interface,reduce the collision during the throwing process of ore and rock mass,and increase the width of the separation trench.At the same time,the explosion height of the rock mass is relatively increased.③On the basis of the blasting separation technical plan of orderly long-delay initiation across the ore-rock interface in the mixed explosive zone,the center of the mine(rock)area in the explosive zone is taken as the initiation point,and the V type initiation plan of the respective region is adopted,which can realize the accumulation of the respective center of the ore and rock,and also strengthen the instantaneous free surface effect of throwing across the ore-rock interface,which is more conducive to the generation of deep grooves.Fully reduce the dilution rate of mixed blast ore.The study provides theoretical basis and creates favorable conditions for the blasting of rock separation in metal open-pit mine.