超硬岩露天深孔台阶爆破参数优化研究

为解决在新疆金宝铁矿露天深孔台阶爆破过程中存在的大块率高、留有根底等影响铲装效率与后续生产的问题，通过现场调查统计与分析，摸清大块产出部位，剖析大块产出与出现根底的原因，并提出相应对策。基于矿岩物理力学性质与矿山现有条件，提出针对超硬岩露天深孔台阶爆破的小孔排距爆破方案，对孔网参数及起爆网路进行了优化提升，采用115 mm孔径，孔排距3.5 m×3.0 m、堵塞长度2.5 ~ 3.0 m，孔间毫秒延期时间为11、13、18 ms，排间毫秒延期时间为21、29、37 ms。工程实践表明，小孔排距深孔台阶爆破适用于铁矿石等超硬岩的深孔台阶爆破，相比原爆破方案大块率降低约8.7%，爆后无根底，大大提高了露天矿山采剥效率，很好地满足了生产要求。爆破振动速度降幅约为28.1%，减少了对边坡岩体的扰动和破坏。小孔排距深孔台阶爆破在超硬岩露天矿山矿岩采剥中体现了良好的适用性，能够有效减少大块和消除台阶根底，可为露天矿山超硬岩深孔台阶爆破提供借鉴与参考。

Blasting parameters optimization of deep-hole bench blasting in open-pit mine with extra-hard rock

In the process of deep-hole bench blasting at the Jinbao open-pit iron mine, some problems come into being after blasting, such as high bulk rate, multi-foundation. Through the statistics and analysis of field investigation, we find out the position of bulk output, analyze the root causes of bulk output and multi-foundation occurrence, and then put forward corresponding countermeasures. Based on the physical and mechanical properties of ore and the existing conditions of Jinbao open-pit mine, a optimized scheme with small spacing and burden is proposed aiming at deep-hole bench blasting for extre-hard rock, whose blasting parameters and detonating network are improved. The scheme adopts 115mm borehole diameter, spacing and burden being 3.5m×3.0m, plugging length being 2.5~3.0m, interhole delay time of 11ms, 13ms and 18ms and interrow delay time of 21ms, 29ms and 37ms. The field tests show that the optimized scheme with small spacing and burden get results well for extre-hard rock deep-hole bench blasting. Compared with the original blasting scheme, the bulk output is significantly reduced, which the bulk rate is reduced by about 8.7%. After blasting, there is no multi-foundation, which greatly improves the stripping efficiency of open-pit mine and meets the production requirements well. The reduction of blasting vibration velocity is about 28.1%, which reduces the disturbance and damage to rock mass of the slope. The deep-hole bench blasting scheme with small spacing and burden reflects the good applicability for extra-hard rock blasting in open-pit mine, which could reduce bulk output and eliminate multi-foundation effectively, and it can provide some reference for extra-hard rock deep-hole bench blasting in open-pit mine.