Abstract: Controlling the rate of blasting powder ore is an important way to reduce ore loss and promote high quality development of aggregate mine.Taking a limestone aggregate mine as an example,firstly, rock dynamics tests were carried out through on-site mine sampling,and the crushing characteristics of limestone under dynamic load were analyzed in combination with the screening test of broken rock,and the range of energy consumption density and corresponding dynamic load intensity which control powder ore production were explored.Secondly, based on the test results,the dynamic load strength and particle vibration velocity peak criterion were introduced to carry out numerical simulation of bench blasting with different delay time between holes,aiming at reducing the rate of blasting powder mineral and taking into account the yield of controlling blasting bulk,the delay time between holes was optimized.Finally,the optimized delay time is applied to mine production blasting to verify its optimization effect.The results show that the reasonable energy consumption density for control of powder ore is in the range of 1.85~2.05 J/cm³,and the corresponding dynamic load strength is in the range of 200~205 MPa.The numerical simulation results show that when the delay time is 20 ms,the blasting powder ore rate and bulk rate are relatively low, and the blasting effect is the best.When the delay time between holes is adjusted to 20 ms,the blasting powder ore rate decreases by 6.12%,and the blasting bulk rate and average crushing size also decrease correspondingly.

Key words: aggregate mine,blasting powder ore rate,delay time,dynamic test