Classification of the development method

According to the relative position of the main Pingyi and the ore body, the development of Pingshuo is divided into three types : the development of the lower plate, the development of the plate, and the development of the wing . According to the mining system, it can be divided into stages and development. Pingyi develops and combines Pingyi to develop three kinds.

The lower plate is suitable for mining deposits whose ore body orientation is consistent with or consistent with the slope direction and tends to be opposite to the slope tendency. The flat is generally perpendicular to the ore body. Pingyi and related auxiliary development wells are located in the surrounding rock of the lower plate. They are generally not affected by the movement of the rock formation in the goaf, and the maintenance conditions are good, so they are widely used.

The upper plate is suitable for mining deposits with ore body orientation and hillside trend, ore body inclination and hill slope tendency. A flat vertical ore body. The auxiliary development wells related to this development method must be far away from the ore body, and can be located outside the moving range of the mined-out rock formation, and the amount of development engineering is large ; if the ore body is deeper than the horizontal level, the flat raft itself will also be affected by the rock movement. The impact of the protection is poor ; sometimes it is necessary to leave the security pillars.

The flank flat shovel is suitable for deposits where the ore body intersects with the hillside. The shoal is located in the surrounding rock of the vein or the lower plate, and the direction is consistent with the direction of the ore body. This method of development makes the underground transportation a one-way transportation, and the transportation of the rock is large. If Pingyi is located in the surrounding rock of the lower plate, Pingyu has no prospecting effect and needs to open a roadway leading to the ore body. If it is located in the vein, Pingyu can play a role in prospecting, and there is a by-produced ore during excavation, but it must be left in the security pillar ; if there is a quantity below the level, the flat is itself located in the movement range of the goaf. Maintenance is more difficult.

At the stage level, a flat raft is set up at each stage, and the ore collected at each stage is shipped out at this stage. Generally, there are no chutes and no auxiliary wellbore. The mid-1950s, China in the 20th Century there are still many mines continue to follow this pioneering approach. The advantage of this method is that it can be constructed from the top to the bottom in stages, and the initial construction investment is small and the production is fast. The disadvantage is that the transportation of material equipment to the underground often requires manual transport, otherwise it is necessary to construct a winding road or a slope hoistway. If the various stages of beneficiation ore concentrate, the more prominent shortcomings, ore shipped down to the foothills of the concentrator, often use the car, chutes, ramps or slopes rail tramway transport, low efficiency and poor reliability. This kind of development method is scattered in the pit, the transportation distance is long and the links are many, the operation cost is large, the output is small, and the use is not extensive, and it is mostly used for small mine development.

The basic flat development main level is located at the lowest level of development depth, generally equipped with an auxiliary wellbore, 1 to 3 main chutes, 1 to 2 wind flats or wind shafts. The auxiliary wellbore can be an open shaft, a blind shaft, a blind inclined shaft or a blind ramp. The ore and waste rock excavated in the above stages are discharged to the main level by the main chute, and then transported by motor car, belt conveyor or car ; personnel, equipment and materials are sent by auxiliary wells or trackless ramps. To the upper stages ; there are also stages on the ground using rail ramps or car connections. The fresh air flow enters from the main flat, rises to the various stages through the auxiliary well or the special wind well, and the dirty air is discharged by the return air or the return air well ( Fig. 1) . This type of development is more widely used.

Figure 1 Basic diagram of the development of the flat

1 — basic leveling ; 2 — auxiliary well ; 3 — main chute ; 4 — return air level ;

5 — transporting alleys ; 6 — returning to the wind alley ; 7 — measure wells

The combination of flat and open development uses two or more flats to develop a well field, as shown in Figure 2 . The ore produced at each stage of the upper stage is transported to the lowermost flat raft through the 1st to 3rd sloping wells ; the personnel, equipment and materials are lifted to the upper stage by the auxiliary wells of 1 to 3 stages. The main advantage of this method is that the length of each flat and main chute is small, which can reduce the construction difficulty ; the auxiliary wellbore, the main chute and the concrete can be gradually scrapped with the decline of the mining stage, thereby reducing the maintenance cost of the well. However, the ore needs to be transported in multiple stages, with many transportation links, complicated management and low efficiency . It is only suitable for groups of mineral veins parallel to the direction of the hillside, and the distance between the vein groups is large, and the special values ​​of each pulse group are raised and lowered with the mountain potential. Under conditions.

Figure 2 combination diagram

Compared with other pioneering methods, the use of current status and trend development methods has great advantages, and Chinese mines use more. Due to the disparity in topographical heights in southwestern China, the most developed mines are developed by Pingyi, followed by the Central South. Which uses the footwall Adit open up more, the length of the main adit is generally 400 ~ 1500m, for some length of up to 3 ~ 5km, such as the main adit length Pang Jiabao Chinese iron ore up to 5100m. In the development of the main flat, in order to speed up the construction, it is possible to excavate inclined shafts or shafts in places with favorable terrain to increase the tunneling face. Due to the deep mining depth in western countries, there are fewer mines developed by Pingyu, and there are more mines for shaft development and joint development. US Henderson (Henderson) molybdenum employed to develop long adit, main adit length of 15.8km. With the increase of mining depth in China, there is a growing trend of shaft development and joint development.