How to choose the deep hole blasting parameters in the underground?

In the deep hole blasting in the well, there are many parameters to be selected such as the diameter of the blasthole d, the minimum resistance line W, the hole distance b, the explosive consumption of the explosive, and the length of the packing.

The diameter of the blasthole is related to the rock drilling equipment and tools, the power of the explosive and the lithology. The larger the d, the more the blastholes per metre collapse. Of course, the increase of the diameter makes the rock mass rate increase and the rock drilling efficiency decreases. At present, the existing mine-type rock drilling in China is 55-65mm, and the diameter of the boring hole is 90-110mm. Of course, the mining method is different, and the diameter is not the same. For mines with soft or broken ore, such as Chengchao iron ore on the use of large diameter, which is easy displacement and deformation process for the blast hole blast hole. With a large aperture, it is easy to make a manual charge, and it is very efficient.

Minimum resistance line W: It is related to the strength of the rock, the diameter of the blasthole and the size of the compensation space.

Generally speaking: hard ore rock W=(25-30)d

Medium hard rock W=(30-35)d

Soft ore rock W=(35-40)d

Of course, the above formula is for reference only, and the specific situation needs to be adjusted according to the principle of dose balance.

Pitch b: For parallel holes is the distance between the same row of holes. For scalloped holes, the blasthole spacing varies, as shown in Figure 1.

Figure 1 The blasthole spacing of the fan-shaped deep holes

According to the empirical formula:

b=(1.1-1.5)W

É‘=(0.4-0.7)W

Explosive unit consumption q: The explosive unit consumption of deep hole falling ore is generally 0.3-0.6kg/t.

Blocking length: For fan-shaped deep holes, the length of the blockage is generally (0.4-0.8) W. For mines with sub-column-level caving method, the mud and wood wedges are mostly blocked, and the mine without the bottom column is only used. Block the mud, no wooden wedges.