Bottomless sublevel caving method and pillar size

For the pillarless sublevel caving method, there is no obvious sign of dividing the nugget. For the convenience of production management, it is generally divided into a nugget by the scope of a chute service.

The size of the gap between the wells, the average distance is 40 to 50 meters, (refer to the use of the loader), generally up to 50 to 60 meters. The maximum can not exceed 60 to 80 meters. (in individual cases). If a scraper is used, the track distance is generally 150 to 200 meters (individually up to 300 meters), so the spacing of the chute can generally be 150 to 200 meters. Usually the gap between the wells can be arranged in 4 to 5 ways. The spacing of the chute should not be too large, otherwise it will affect the transportation efficiency. ZYQ-14 type loader, dragging long wind ropes, is inconvenient to walk and has a long transportation distance, which reduces the shipping efficiency.

2) Location of the slippery well

The chute is arranged in the ore body and the amount of minerals lost is large. The chute is generally arranged outside the vein. This makes the production flexible, convenient and reduces the workload of the slip seal. If the chute is placed outside the vein, it should leave the ore body boundary more than 15 meters, otherwise it will affect the safety.

When the thickness of the ore body is large and the ZYQ-14 type loader is used for mining, the chute has to be placed in the vein. When the slipper is arranged in the vein, attention should be paid to the wear and expansion of the well. It is necessary to control the amount of ore discharged by the chute and the closure of the chute when the section is lowered.

3) The form of the slippery well

There are two kinds of chutes: straight chute and chute. When the angle of inclination of the ore body is slow, the inclined shaft should be used as much as possible. Its advantages are: 1 It can reduce the amount of excavation work; 2 In addition, it does not affect the production capacity of the ship due to the increase of the distance of the lower section.

4) Other requirements for the chute

1 The lower ore loading port of the chute should be located on the straight section of the transportation horizontal roadway to facilitate loading.

2 If it is necessary to classify ore out or to mine separately according to different varieties, the well can be appropriately increased.

3 If there is a large amount of stone in the ore body, or when the amount of extra-pulmonary engineering is large, it is necessary to dig a special waste rock.

4 When determining the spacing of the chute, the passing ability of the chute should also be considered to avoid affecting the production due to the excessive wear and tear of the chute.

5) About the closure of the slippery well

When mining thick ore bodies, most of the chutes are placed in the ore body. When the mining work is retreated to the vicinity of the chute, when the chute is no longer used in this section, the chute should be closed to prevent the overburden from falling into the chute. There are many ways to close the well. The specific examples are as follows:

1 First expand the chute into a platform to catch the materials used for sealing, so as not to move after being subjected to external force. When sealing the wellhead, the lowermost layer is installed in a grid shape with scrap rails, and a layer of garden wood is placed on the upper part, and a layer of waste rock is pressed on the top of the garden wood. The quality of the closed work should be guaranteed, otherwise a vibration during the blast will impact the bad sealing material. At the same time, the waste rock in the upper part will be mixed into the chute, which will not only have a serious impact on production, but even cause the chute to be scrapped in advance. Therefore, the chute should be placed as far as possible outside the pulse, as conditions permit, to reduce the workload of the closed chute.

2 Double-layer garden closed-hole method.

As with 1, the wellhead is also built into a platform, except that two layers of garden wood are placed on the platform, and the waste rock is placed on the top to serve as a buffer.

This construction method is fast and simple. Applicable to the conditions of the smaller section of the slide. When the wellhead is large, it is easily damaged. This method is not reliable.

3 oblique row garden closed flow method

When the upper section is closed for some reason, the upper wellhead is enlarged and cannot be closed. When the lower level is to be used for mining out of the well, it can be closed by this method. The garden is arranged obliquely in the chute. (see illustration)

4 Horizontal and oblique mixed row garden wood closed slip method

If the third case is not reliable, in order to be safe, the lower horizontal wellhead will be locked and a mine outlet will be left.

5 reinforced concrete closed slip method

In order to be more robust, this method can be used. That is, a number of 0.8 meters deep eyes are placed around the wall of the slippery hole, and steel bars are inserted, and a steel mesh is placed on the steel bars, and the template is supported by the net. Then cast concrete. After the moist soil is well maintained, it can be used.

This closed-flow method improves ore recovery. However, the concrete has a long curing time (if it is added to the accelerator, it will take half a month to use it. It is not safe to work. But it is more reliable once it is well maintained.

6 Concrete sealing method

When a slippery shaft is not used, it is not necessary to release the ore of the chute, and the ore is required to be filled with ore, leaving only the height of the concrete layer to be cast. With the remaining ore as a support, the stirred concrete is poured into it. After the health is good, the ore in the chute will be released.

The method is simple, the construction safety is good, the steel bar is saved, and the mining of the lower section is favorable, and the steel bar and the wood are not stuck.