Study On The Influence Of Precise Delay Of Digital Electronic Detonator On Blasting Effect In Open Pit Mine

Millisecond blasting technology has been proved to be able to improve the blasting effect in open-air bench blasting.With the popularity of digital electronic detonators,accurate determination of delay time is an important issue in open-air bench blasting engineering.In this paper,the influence of blasting delay time on rock size and explosion pattern of the steps of the open-pit coal mine in Beskuduk,Xinjiang.It is mainly used the method of theoretical analysis,indoor experiment,field test and numerical simulation.The following work was mainly accomplished:(1)Using drone technology to obtain the rock blocks on the surface of the blast reactor,the image is analyzed by Split-desktop 3.0 block analysis software.The results show that the range of large block rate under the test conditions is 3.11%to 6.29%,and the average block size range is 44cm to 59cm.When the delay time between the holes is4ms/m,the rock block rate and average block are the lowest so that the blasting effect is the best.(2)Using the GPS-RTK technology and the measurement point is modeled by3Dmine mine engineering software.The loose coefficient range of explosion reactor under test conditions is calculated from 1.175 to 1.304.When the inter-row delay time is13ms/m,the loose coefficient of the explosion reactor is the highest and the pattern of the burst reactor meets the safe production conditions.At the same time,the Weibull model is used to fit the profile of the explosion reactor.The results show that the value range of?is 0.8764 to 0.9616 and the value range of?is 1.317 to 1.546.By comparison,it is found that the Weibull distribution function model can be better matched with the explosion pattern.(3)Based on the ANSYS/LS-DYNA finite element software,the stress wave propagation law in the disadvantageous crushing area is analyzed.The results show that when the delay time between holes is 22ms,the tensile stress at the measuring point reaches the maximum and is greater than the tensile strength of rock.Under this delay time,the blasting effect is the best.(4)Combined with the millisecond blasting technology of large hole spacing and small row spacing,the optimal millisecond time between hole rows is used to adjust the hole network parameters of beskuduk open pit coal mine.The test shows that the unit consumption of explosive is reduced from 0.4kg/m~3to 0.37kg/m~3by properly increasing the loading area of single hole.Good economic benefits have been achieved by using this scheme.