Mining work of shallow hole retention method

The mining work of the shallow hole retention method includes: rock drilling, charge blasting, ventilation, partial ore deposit, bristles, flat field and large amount of ore mining.

Mining mining is carried out from the bottom up, and the height of each layer is generally about 2-3 meters. Use shallow hole collapse.

( 1 ) rock drilling

1) Rock drilling method—The rock drilling method of the shallow hole retention method has two types, namely, an upward hole and a horizontal hole.

1 Upward hole: Can be used when the ore is relatively stable.

[Advantages] The rock drilling efficiency is high and the workers are easy to manipulate.

[Disadvantages] Workers work directly under the vibrating ore body, with poor safety and poor working conditions (water flows down when rock drilling). At the same time, there are many times of changing the drill rod during rock drilling, which affects the rock drilling efficiency.

For the hole, the 01-45 rock drill is generally used, and the blasthole collapse is 75°-85°.

2 Horizontal hole: When the ore is less stable, use horizontal holes as much as possible.

[Advantages] The working surface formed after rock drilling and blasting is relatively flat and smooth, and the safety during work is better.

[Disadvantages] The rock drilling efficiency is lower than that of the upward hole; the large ore is larger than the upward hole.

Currently used in mining and mining in thin and very thin veins. Most use uphole blastholes. In recent years, some mines have promoted the use of horizontal eyes in veins with relatively stable conditions. (Such as iron ore using Gongchangling play horizontal eye, type 7655 with a drilling machine).

2) Work surface layout

There are two types of working faces for the shallow hole retention method. Straight and step type. The length of the step is different depending on the horizontal blast hole and the upper hole.

1 When hitting the hole: the length of the step is generally 10-15 meters, the height of the step is 1.2-1.5 meters, and the depth of the upward hole is about 1.3-1.8 meters. The upward hole is generally inclined forward by 75°-85° (convenient for eye opening). When the blasting property of the ore is poor, the blasthole can be deeper by 0.05m-0.1m.

2 Horizontal blasthole: The length of the ladder is generally 2-4 meters (2 is deep in the hole). The height of the ladder is 1.5-2.0 meters.

The horizontal hole has a depth of 2 to 3.5 meters, and the horizontal hole is generally inclined up to 5 to 8 degrees (to facilitate the discharge of rock powder)

[Reference to thin ore parameters: blasthole diameter - currently used 32-36mm

The diameter of the blasthole is 1.0-1.2 m; the distance between the blastholes is 0.8-1.0 m; the minimum resistance line is W=0.6-1.6 m.

3) Hole arrangement

1 "One" shape arrangement - suitable for the condition that the ore is well broken and the amount of ore is separated.

2 "Zigzag" arrangement - suitable for the conditions of better blasting of ore, and for the condition of the ore vein thickness of 0.7-1.2 meters, this form can better control the width of the mining.

3 Parallel arrangement - suitable for thick ore veins where the ore is hard and the boundary between the ore body and the surrounding rock is not obvious or difficult to separate.

4 staggered arrangement - (ie plum blossom arrangement)

It is suitable for ore bodies with hard or thick ore, and the ore block used for this type of collapse is relatively uniform. This form is widely used in production practice.

( 2 ) Charge blasting work 1) The consumption of unit explosives in shallow holes is as follows:

2) Shallow hole charge coefficient:

The actual experience proves that the charge factor in the blasthole should not be too small, and it is best to reach 60-70%. If the charge factor is too small, the explosives are unevenly distributed in the ore, and the ore that collapses is relatively large.

3) Detonation method

The first method is to use a fuse to ignite the detonation method of the first firing sequence of the fire detonator. Less use of electric detonators to detonate.

Many mines now use thin iron sheets to make tees.

A triangular groove is cut across the outer end of each of the fuses to expose the core, and the 1-3 hole of the tee penetrates into the tee, so that the exposed portion of the core is opposite to the hole of the tee.

4) Explosives:

Use ammonium explosives or ammonium nitrate explosives.

5) Detonation kit:

Place it at the bottom of the hole from the second drug pack and manually charge it.

( 3 ) Ventilation work

Ventilation should be strengthened after blasting so that gunpowder and dust can be quickly discharged from the work surface. The air volume of the working face should be guaranteed to meet the needs of dust removal and smoke exhaust. To this end, the wind speed required for mining work should not be less than 0.15 m / s, and the oxygen content of air should not be less than 20%.

Ventilation system in the mine. Generally, the fresh air flow enters from the patio in the direction of the upper wind, and after passing through the working surface of the mining room, it is discharged through the patio to the upper return airway.

Ventilation of the electric ramp should form an independent system to prevent contamination from entering the mine.

( 4 ) Local mining work

After the ore has collapsed, some ore must be released in order to ensure a certain working space due to the ore swell. According to the regulations, one third of the collapsing ore should be released, and 2/3 should be dug as a temporary workbench to continue working. (The general hard ore has a coefficient of expansion of 1.5)

It should be noted that: 1 In the case of local mining, personnel are not allowed to work above the discharge funnel to ensure personal safety.

2 When partial ore mining, there should be a plan to reduce the workload of the flat field and prevent the formation of open space. If it is found that there is an empty space, it should be dealt with in a timely manner.

( 5 ) Pingyi work (brief description)

After the local mining, after the workers enter the stope, they should first go to the pumice at the working place, otherwise it will directly affect the workers' safe production.

The work of Pingyi is both important and cumbersome. So far, there is no good mechanized equipment to carry out these tasks. When the angle of inclination of the ore body is slow, the workload of the flat field also increases (a large amount of ore accumulates on the lower side).

The equipment of the pumice stone has been made abroad, but not yet in China.

Some mines have thought of some measures to solve the problem of flat work. If some of the explosives are buried in the piles under the plate, the ore is thrown to the upper plate by blasting. However, this method consumes a large amount of explosives and the throwing effect is not good. (The effect of burying is not good, the depth of the work is large, and there are difficulties).

Therefore, properly arranging the funnel is important to reduce the amount of work in the flat field. Therefore, as the inclination of the ore body becomes slower, the position of the funnel should be arranged as far as possible in the downward direction of the disk. (Some mine electric tweezers are flat).

In thick ore bodies, the ore area of ​​each funnel is preferably controlled within 36 ^m2 and the maximum should not exceed 50 ^m2 .

( 6 ) Massive mining work

After all the ore in the mine has been collected, a large amount of ore mining work is required, and all the 2/3 gravel left behind is released.