露天台阶爆破粉尘的爆炸水雾场拦截降尘技术研究

露天台阶爆破粉尘具有瞬时性、浓度高和扩散快等特点，危害采场作业人员身体健康，增加机械设备进风系统损耗，并污染周边大气环境。由于爆破飞石和冲击波等危害使人员、设备无法靠近爆区污染源，导致传统洒水降尘措施无法同步实施。采用数值模拟与现场试验相结合的方法研究爆炸水雾降尘，结合白云鄂博铁矿实际情况，建立了露天台阶爆破三维流场模型，分析了爆炸水雾场及爆破粉尘生成的技术特性。依据爆炸水雾场和爆破粉尘模拟结果，提出了爆炸水雾场拦截降尘的技术方案，确定了水袋在台阶坡面前16~21 m的合理布置范围，得到了爆破粉尘横向动态运移轨迹和时间之间的函数关系，确定了水袋合理激发延期时间，即Δt=t-1.21。利用SPSS软件对水雾定型试验结果进行了极差分析，确定了水袋规格和爆炸荷载优化组合。试验显示，爆炸水雾场生成空间尺度达18 m×8.7 m，水雾至最大空间尺度用时1.2 s。现场爆破降尘试验结果表明：在台阶坡面前18.5 m位置铺设水袋，设置其激发合理延时1 100 ms，测得距爆区50、100 m处粉尘浓度分别降低了43.6%、40.9%，实现了爆炸水雾场与爆破作业的同步实施，降尘效果显著。

Study on the Technology of Intercepting and Reducing Dust by Explosion Water Mist Field in Open Bench Blasting

The dust from open-pit bench blasting has the characteristics of instantaneity,high concentration and fast diffusion,which will endanger the health of stope workers,increase the loss of the air intake system,and pollute the surrounding atmospheric environment.Due to the hazards such as blasting flying rocks and shock waves,personnel and equipment cannot be close to the pollution source in the blasting area,so the traditional means of sprinkling water to reduce dust can not be implemented synchronously with the blasting.In this paper,the method of numerical simulation and field test is used to study the explosion water mist dustfall,combined with the actual situation of Bayan Obo Iron Mine,the three-dimensional flow field model of open-pit bench blasting is established,the technical characteristics of bench blasting dust and explosion water mist field are studied,and the technical scheme of explosion water mist field intercepting dustfall is put forward based on the simulation results of explosion water spray field and blasting dust.The reasonable arrangement range of the water bag in the front of the step slope at 16~21 m was determined,the functional relationship between the lateral dynamic migration trajectory of blasting dust and time was obtained as Δt=t-1.21,and the reasonable delay time of the water bag excitation was determined.The optimal combination of water bag size and explosion load was determined by the range analysis of the water fog type test results using SPSS software.The test results showed that the space scale of the explosion water fog field was 18 m×8.7 m,and the time for water fog to reach the maximum space scale was 1.2 s.The field blasting dust suppression test results showed that the dust concentration at 50 m and 100 m away from the blasting area was reduced by 43.6% and 40.9%,respectively,when the water bag was laid at 18.5 m in front of the slope and the reasonable excitation delay was set at 1 100 ms.The simultaneous implementation of the explosion water mist field and the blasting operation was realized,and the dust reduction effect was remarkable.