Abstract: Due to the small network parameters and high explosive consumption in trench blasting of open-pit mine,compared with normal bench blasting,the blasting dust produced by the trench blasting is higher in concentration,faster in diffusion,and more harmful in pollution.The traditional method of surface sprinkling in the blast area can only wet the superficial rock mass.Affected by the harmful effects of blasting flying rocks and shock waves,remote spraying dust reduction methods such as mine water cannons cannot be implemented simultaneously with blasting dust production.In addition,the passive treatment of blasting dust after diffusion is difficult and ineffective.In this paper,Fluent numerical simulation was used to study the formation and initial expansion characteristics of trench blasting dust in open-pit mine,and the technical scheme of in-situ dustfall was proposed by laying explosive water mist field around excavation trench blasting area.Through the orthogonal test of explosive water bag and explosive water mist field,the important dust-settling technical parameters such as the composition of explosive water bag,the spatial scale and the stagnation time of explosive water mist field were determined.Explosive water mist field was set up based on the principle of "surrounding interception,synchronous generation and in-situ adsorption" in the field dustfall test of Bayan Obo Iron Mine.On-site high-speed photography analysis showed that the explosive water mist field was generated at a high speed in the early stage of mushroom dust cloud formation,the blasting dust was intercepted and adsorbed simultaneously to achieve the environmental protection goal of dust reduction at the source.The test results showed that the mass concentration of blasting dust was reduced by 40%,which provided a new environmental protection technology for low dust trench blasting and green mining of open-pit mines.

Key words: mine blasting,blasting dust,explosive water mist,water mist dustfall,trench blasting