The main factors affecting the height of the stage are:
1 Type of deposit exploration (exploration and mining)

Under normal circumstances, the higher the exploration type of the deposit, the denser the trenching network and the smaller the height of the anti-exploration phase. In order to make full use of the pit roadway as a mining roadway, in principle, the mining stage should be highly consistent with the pit exploration stage. Therefore, the higher the type of exploration of the deposit, the smaller the stage height. According to China's experience, the fourth type of deposits should be mined by the method of retention and mining, and the stage height of 40 to 50 meters should be adopted.

2 The stability of the surrounding rock

Generally speaking, when the stability of the surrounding rock is good, a higher stage height can be used; when the stability of the surrounding rock is not stable, a smaller stage height should be used because: the rock on the upper part of the mine The exposed area should not be too large, and the exposure time should not be too long, so a lower stage height should be used.

The exposed area of ​​the rock on the upper plate is determined by the height of the stage and the length of the mine along the strike. Therefore, the stage height is large. On the one hand, the volume of the mine is large. On the other hand, the advancement speed of the mining face decreases with the increase of the stage height. . Therefore, under the condition that the surrounding rock is not stable, it is only suitable to adopt the stage height of 30 to 40 meters; under the condition that the surrounding rock is very stable and the veins are relatively regular, the stage height of 40 to 50 meters can be adopted, and the base is larger. .

3 ore body inclination

The size of the dip angle of the ore body has a great influence on the ore-mining, and the impact is more obvious when the stage height is larger. Therefore, for a deposit that is not too steep, but it can also be mined by the method of retention, it is suitable to use a low stage of 30 to 40 meters.

(For example, the Dajishan tungsten mine, the stage height is 50 meters, and the mining body with a dip angle of 60°~70° is used. The mining and ore-mining are very smooth, but the mining veins of 60°-65° are often 30m in the mining room. When it is left and right, it is difficult to release the ore.)

4 Other mining methods for stage height requirements

There are many deposits, and due to the inconsistent conditions of the ore bodies and the technical conditions of the mining, a variety of mining methods are often used. At this point, when determining the stage height, take care of the needs of other mining methods.

5 patio excavation conditions

When using the common method to dig into the patio, the difficulty of tunneling increases as the height of the patio increases. Under normal circumstances, when the heading face rises to 25 to 30 meters, the transportation of ventilation and materials and equipment becomes more and more difficult, and the efficiency of tunneling is reduced.

For thin vein mining, the current tunnel excavation is still excavated by ordinary excavation. (A thickness of about 20 m ore, mined also useful in common, such as iron ore Gongchangling). Because it is difficult to track the veins by the hanging tank method, not only the prospecting effect is poor, but also it is not easy to use when picking up. Therefore, when mining thin veins, it is generally not appropriate to use too many stage heights.

Overall, there are many factors that influence the height of the stage. However, under conditions that ensure safe and smooth recovery, a larger stage height should be used to increase the mine's ore volume and thus reduce ore losses. The smaller the stage height, the larger the ore content of the ore. In the future, as the degree of mechanization increases, the mining intensity increases and the stage height increases.

(2) The length of the nugget - generally not more than 40 ~ 60 meters

The thin ore veins and medium-thick ore bodies are mined by the retention method, and the length of the ore blocks is slightly different. In China, the length of the ore deposit method is only between 25 and 120 meters, the most commonly used is 40 to 60 meters, and the medium and thick ore body is 20 to 80 meters. There are many factors affecting the length of the nugget, mainly in the following aspects:

1 Ore and surrounding rock stability (main factors)

From the majority of the situation in China, the ore bodies that can be mined by the mining method can generally reach an exposed area of ​​300-400 ^m2 . When the ore is particularly stable, it can reach 500-600 ^m2 or even larger. some.

The exposed area of ​​the rock on the upper plate varies with the length of the nugget when the stage height is determined. From the perspective of most of the mines in China, when the stage height is 40 to 50 meters, the length of the ore block can be as much as 40 to 120 meters. For medium and thick ore bodies with poor stability of surrounding rock, the method of retention or not should not be used. For thin veins with poor stability of surrounding rock, if the method of retaining ore is used, the length of the ore should be greatly reduced.

2 Limitation of ventilation and dustproof conditions

When a patio is opened at each end of the ore block, the wind flow enters the working surface through a patio from the wind into the working surface. After passing through the mine, it rises through the other patio and exits to the return airway. The length of the nugget of this kind of ventilation should be 40 to 60 meters. If it is too long, the resistance is increased, which is not good for dust removal. In addition, many rock drills are also working at the same time, otherwise the necessary mining intensity will not be achieved, which will inevitably cause workers in the downwind direction to be affected by the dirty wind.

3 Restricted by the effective transport distance of the electric tweezers

When electricity is used for ore mining, it is limited by the distance of the antimony ore, and the effective transportation distance of the electric raft is within 50 meters. Therefore, the length of the nugget should be within this range.
(3) pillar size

The size of the pillar has so far been determined primarily by experience.

1 Top column thickness - For thin veins, because the span of the mine is small, it is enough to leave only 2 to 3 meters if the top column is left.

For ore bodies above medium and thick, it is generally necessary to leave the top column. When the ore is relatively stable, and the span of the mine is not too large, it usually stays 3 to 6 meters. If the ore is less stable, or if the mine span is large, it should be 5 to 6 meters.

2 The height of the bottom column - the height of the bottom column is related to the type of bottom structure and the spacing of the funnel. Because the triangular pillars between the two adjacent funnel flares become higher as the distance between the funnels increases.

The bottom column and height also depend on the thickness of the ore body and the stability of the ore and surrounding rock. When the ore body is relatively thin, an artificial bottom can be used instead of the ore bottom column. Generally, the height of the bottom pillar of a thin ore body can be 4 to 6 meters (in some cases, it can be smaller, 2.5 to 3.5 meters) and 8 to 10 meters above the medium thickness.

3 column widths - the width of the columns depends on the thickness of the ore body, the stability of the ore and surrounding rock, and the service life of the patio. Also related to the span of the mine. Medium-thick upper ore body, when the ore is very stable, and the span of the mine is not too large, the column can stay 8 meters. (between 8 and 12 meters) The thin ore body is 2 to 6 meters.

4 pedestrian contact spacing - generally about 5 meters

5 Funnel spacing - generally 5 to 7 meters, section 1.8 x 1.5 ^m2 , and 1.8 x 1.0 ^m2 (when the conditions are good, the spacing can be smaller, 3 to 5 m).

The principle of the funnel arrangement:

1 In order to reduce the workload of the flat field, the funnel should be dug as close as possible to the lower part of the ore body;

2 When the width of the mine is less than 7 meters, a row of funnels can be arranged. When the width of the mine is more than 7 meters, 2 or more rows of funnels can be arranged. However, the area required for each funnel is not more than 50 m ² ;

3 When the angle of inclination of the ore body is small, the funnel should be placed as close as possible to the lower plate;

4 When the inclination angle of the ore body is <60°, the funnel can be omitted from one plate, and only the lower funnel can be opened, and the triangular pillar left behind will be collected together with other pillars. (Because in fact most of the ore is released from the lower funnel at this time, the ore released by the upper funnel is very small, so it can not be opened to reduce the workload.)

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