Application of Hole-by-hole Blasting Technology in Taihe Iron Mine (1)

Since the mining of Taihe Iron Mine, the continuous charging in the hole has been adopted, and the row is detonated in a row. The amount of a primer is large, and the height of the charge is low, resulting in a high block rate (more than 50%). In order to control the ore block rate and improve the blasting effect, the original blasting method was improved, and the bulk rate was effectively reduced.
First, the characteristics of the hole -by-hole detonation technology The hole-by-hole detonation technology means that the blastholes in the same row in the explosion zone are detonated in accordance with the designed delay time. At the same time, the blastholes in the row of the explosion zone are successively backward according to another extension period. The blasting is performed, that is to say, in the horizontal plane of the pre-explosion area, the blastholes in the horizontal row and the longitudinal column respectively adopt different delay times, but the blastholes usually located in one row or one column have the same surface extension. time interval. In the two-dimensional plane, the detonation time of each blasthole is sequentially accumulated according to the length of the holes and the inter-rows, and each of them is detonated independently with respect to the surrounding blastholes. In this way, the blasting process advances in time and space according to a certain explosion isochronal line until the blasting process is completed. Compared with the multi-row hole differential detonation, the hole-by-hole detonation has the following characteristics:
(1) Firstly, the blasthole is created to create a free surface for the post-explosive blasthole. Increasing the free surface of the blasting can greatly increase the energy of the blasting explosive and improve the efficiency;
(2) The explosion stress wave is fully reflected along the free surface to strengthen the broken rock;
(3) The ore blasting of adjacent blastholes collides and squeezes each other to enhance the secondary crushing of the ore, which can reduce the blasting block degree, the large block rate is low, and the secondary blasting amount is small, which can greatly improve its subsequent work (shovel Loading and transportation) efficiency;
(4) At the same time, the amount of explosive charge is only a single hole charge, and the amount of primer is small, which can effectively control and reduce the occurrence of damage such as seismic waves, shock waves and flying stones.
Second, the hole-by-hole detonation blasting parameters design Taihe iron ore mainly using KQ-200 type down-the-hole drilling rig for drilling, drilling diameter 220mm, using triangular and square cloth holes two ways, using mixed emulsification ****, with 2 ^#岩emulsified **** manufactures a primer pack. The blasting parameters are shown in Table 1.

Table 1 Explosion parameters

(1) Detonation time and detonation network by hole 1. Selection of differential time In order to improve the blasting effect and reduce the blasting vibration, the micro-blasting is performed between the blastholes. The detonation sequence and delay time of each blasthole are determined by calculation and combined with the nominal time of each segment of the non-electric detonator.
In order to improve the crushing effect, the time between the holes is mainly the delay time of the detonator in the hole and the minute interval of the detonator outside the hole. The delay time of the detonator in the hole should ensure that the detonator can be detonated when the detonator is far away from the hole. Therefore, the detonator with high delay section is selected in the hole, and the detonator with low section is selected outside the hole.
According to practical experience, the inter-hole differential time is calculated according to the hole spacing of 3 to 8 ms per meter. The hole spacing is 7 m, then the t hole = (3 ~ 8) × 7 = 21 - 56 ms. Three types of detonators of 17, 25, and 42 ms were selected. The row difference time t is calculated by 8 to 15 ms per meter row, then t row = (8 ~ 15) × (4 ~ 5) = 32 ~ 75 ms. A total of 42, 65, 100ms three types of detonators were selected. Since the Taihe vanadium iron ore is generally blasted within 40 holes each time, the 16-segment 400-ms non-electric detonator can be used to meet the demand. In the actual work, 17~42, 25~65, 42~100, 25~42ms are used for pairing. For the explosive type, the matching effect is similar, but for the easy to produce large block, use 17~42 The effect is better when the two modes are 25 to 42 ms.