Research And Application Of Millisecond Blasting In 24-m High Bench In Barun Mine

In order to meet the needs of modern large-scale open-pit mine blasting and the popularization of new blasting equipment and processes,a series of technologies such as large-aperture,high steps,gas separation,and intra-hole differential blasting have gradually entered the application stage of the site,but related blasting parameters and theories Further research is needed.The parameters such as differential blasting are determined based on theoretical research and field tests.It cannot reflect the impact of blasting parameters on the applicability of the project.Unreasonable parameter settings often cause bad effects on the foundation and large rocks.In order to optimize the step blasting effect,this article quantitatively analyzes the blasting effect from the combination of the position of the initiation point,the initiation distance,and the time difference.(1)Under the condition of the differential blasting parameters in the high-step hole,the numerical simulation calculation is performed by using the finite element analysis software after the basic settings such as columnar drug package modeling,JWL state equation parameter determination and debugging.Taking the open-pit blasting of Baotou Mine of Baotou Iron and Steel Group as the research model,and a combination of numerical simulation and field tests is used for analysis and research.According to the on-site process and technical conditions,9 groups of models with a step height of 24 m,an aperture of 310 mm,and an air-spaced charge were established.The digital gas detonator was used to conduct short-difference time intermediate gas interval initiation to conduct research the combination of the initiation point position at 3ms difference(Models 1,2,3,and 4 with a detonation distance of 0 m);Detonation distances with a 3 ms difference(models 5,6,7,8 with a detonation distance of 0.5 m,1.0,1.5,and 2.0);Digital electronic detonator conditions The down-difference time has a limited change(model 9,6 ms,and the low end initiation distance is 1.0 m).(2)Based on the detonation wave and tensile stress theory,considering thechanges in the effective stress peaks and the distribution of the full stress field at the top and middle spaced air grains and ultra-deep isometric observation points,the rock yield stress is used as a criterion for comparison.Whether the explosion load can reach rock failure and analyze the rock fragmentation.The theoretical results are verified by field industrial tests to achieve the purpose of comprehensively using computer analysis methods and blasting theoretical knowledge to guide production practice.The engineering test results show that the combination of the blasting stress wave in the rock body has the longest action time under the combination of the first initiation distance of 1.0m at the bottom of the lower grain column and the initiation of the interval of 3ms in the hole,followed by the explosion at the top of the upper grain column.It is confirmed that the simulation conclusion is combined with the field industrial test verification to achieve the purpose of comprehensively using computer analysis methods and blasting theoretical knowledge to guide production practice.