Abstract: 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.

Key words: mine blasting,blasting dust,explosion water mist,delay time,numerical simulation