Ultra deep hole blasting technology

I. Introduction

Domestic large and medium-sized open pit mines are basically drilled with a roller rig , and their maximum penetration depth can reach 25.0 m. If it is calculated by the conventional ultra-deep 2.0~2.5 m, the maximum section height of the blasting should be 22.5~23.0 m, which is 1~1.5 m away from the standard two levels (the general mine step height is 12.0 m). However, in the mining process, due to the influence of many factors, there are often objective cases where the high step reaches 13.0 m and the low step is 11.0 m. However, it has not affected the normal production of the mine. Therefore, the difference between the two levels of mining step errors of up to 0.75 m will not affect normal mining. At this point, the ultra-deep hole blasting technology has the possibility and feasibility of implementation from mining production to piercing equipment.

Second, the feasibility of ultra-deep hole blasting technology

(1) Shortening the filling height

Under the same blasting parameters, the packing length of ultra-deep hole blasting is reduced by 5.0-6.0 m compared with the ordinary medium-deep hole. This is because ordinary medium-deep hole blasting requires two cycles, which is a superposition of two packing heights. Table 1 lists the comparison of the filling heights of the two types of boreholes. The heights of the two types of blasting are similar, but the ordinary medium-deep blasting has an extra-deep, and the two extra-deep explosives are applied to the repeated blasting point. It doesn't make much sense. Therefore, the main reason for the ultra-deep hole blasting to improve the blasting quality is to shorten the packing height.

Table 1 Fill height comparison / m

(2) Reducing ultra-deep improvement of blasting efficiency

The ultra-deep hole blasting reduces the ultra-deep compared with the ordinary medium-deep hole, and the result is improved blasting efficiency. Table 2 shows the comparison of the comprehensive efficiency indexes of the three sets of standard blasting parameters.

Table 2 Comparison of blasting efficiency /t·m ^-1

(3) Reducing the consumption of explosives

See Table 3 for the comparison of the single-consumption consumption of the single-hole maximum dose average index under the three standard blasting parameters of the two types of drilling.

Table 3 Comparison of two blasting explosives consumption/kg·t ^-1

Third, the application of ultra deep hole blasting technology

(1) Excavation for drainage pits

Deep drainage facilities in mines are often fixed at a certain location, and the rate at which the drainage pits fall must be ahead of the rate at which mining production declines. Therefore, the greater the depth of the blasting of the drainage pit, the more favorable it is for mining production, so the full potential of the roller drill can be fully utilized, that is, the deep hole of the three-section rod.

(2) Used in mining and engineering blasting

Ultra-deep hole blasting technology to mining and blasting, the blasting on the basis of improved quality, improve blasting efficiency and reduce the cost of the blasting, has the following advantages: 1) the flexibility to design across the railway cutting step; 2) flexibility Exploring the car roads with more than two steps in succession; 3) Increasing the amount of ore blasting in a planned way, that is, increasing the storage capacity of high grade, good selection, and good grinding of ore; 4) increasing the amount of rock blasting in a planned manner, especially in When the working face is worn less. Therefore, it can accelerate the stripping and lay a solid foundation for the continuous ore production of the mine; 5) The application of ore recovery outside the boundary can reduce the number of cycles of rock blasting, increase the time of mining stripping, and increase production.

4. Safety assessment of ultra deep hole blasting

The safety that affects ultra-deep hole blasting is blasting vibration, individual flying stones, toxic gases and noise. The most important hazard is the seismic effect. The blasting adopts the hole-by-hole detonation technology, and the blastholes in the explosion zone simultaneously detonate no more than two. Calculate the formula based on the seismic safety distance:

R=(κ/ν) ^{1/ a} ·Q ^1/3

In the formula, the R-seismic safety radius, m; k-factor, take 150; a-coefficient, take 1.5; V-blasting mass velocity, take the national standard 2 cm / s; Q - the same section of explosive charge, take 2000kg.

It can be seen from the calculated radius of influence that the harmful effects of blasting vibration are in line with national standards. For a mine, the working area and living area are much larger than this distance.

V. Estimation of economic benefits of ultra-deep hole blasting

(1) Reducing the efficiency of explosives consumption

According to the total amount of blasting 15 million tons, the stripping ratio is calculated as 2.5 t/t, the blasting ore is about 4.3 million tons, and the rock is about 10.7 million tons. According to the explosive cost of 2 yuan/kg, the benefit is estimated as:

(4300 000×0. 0365+10700000 × 0.0324)×2.0=100.726 million

(2) Improving the efficiency of blasting efficiency

Improve the blasting efficiency, that is, reduce the blasting footage, according to the rock drilling cost of 66. 99 yuan / m, the benefit estimate is:

ore:

(4300 000/106. 31-4300000/116. 94)×66. 99=24. 650,000

rock:

(10700000/105.63-10700000/114.87)×66. 99=85.51 million

Total ore:

24. 65+85. 51=110.16 million

(3) Total benefits

The sum of the two benefit estimates:

100. 726+110.16≈2.1 million.

Conclusion

In summary, although the ultra-deep hole blasting technology has not been widely used, the technology has a good development prospect, which not only can improve the blasting effect, improve the blasting quality, but also improve the blasting efficiency and reduce the blasting cost. Therefore, it has a wide range of promotion and application value, and should be further explored and studied in the future blasting practice to make the technology more perfect and mature.