(1) Technical conditions for mining. System shallow ore deposits deposited native manganese, layered or stratiform, an average thickness of about 2m, steeply inclined angle from horizontal to a depth of 300m buried. The direct roof of the ore body is a blade-like black shale , which is extremely unstable, with a thickness of 0.5 to 8 m, and then a shell-like black shale with a thickness of 2.5 to 6 m. The direct bottom plate of the ore body is a soft line, containing carbon and scattered stars. like pyrite, roof backward Inflammable, ore processing and mechanical properties of the fuel are shown in Table 1.
Table 1 Physical and mechanical properties of ore
project
Shell-like black shale
Leaf-like black shale
Manganese carbonate ore
Line-like black shale
Quartz sandstone
Platts firmness factor (f)
body weight
Fragmentation coefficient
5
2.5
1.31
1~2
3~6
2.9
1.41
2.7
8
2.62
1.43
(2) The structural parameters of the ore block. The length of the nugget along the strike is 60-150 m, and within this length, it is further divided into small nuggets of 10-20 m. The determination of the length of the slope of the ore block generally takes into account the spontaneous combustion period of the rock in the goaf (generally 40 days) and the production capacity of the ore block. According to calculations and experience, it is appropriate to have a slope length of about 37 m. [next]
(3) Picking and cutting. In the middle of each small nugget, a courtyard is drilled up to the ore body for use as a mine and pedestrian ventilation; right at the entrance of the atrium, the mountain is cut along the ore body and cut up the mountain; every 10~ in the mountain 15m to excavate the section roadway on both sides, the purpose is to facilitate ventilation and increase the pedestrian exit. Both the uphill and the section roadway need to be supported by wooden shed, and the spacing of the wooden shed is 0.7~0.8m. The layout is shown in Figure 1.

Figure 1 Approach single-layer caving
1-patio; 2-uphill; 3-wood shed; 4-dense wood column
(4) The order of recovery. In the upper part of the mountain, the slope is plunged from top to bottom. In the direction of the mining direction, in the middle of each nugget, the mining is carried out on one side or both sides by way of approach to the boundary of the nugget. [next]
(5) Recovery. Rock mining with a light rock drill, shallow hole blasting. Before carrying out the first cannon mining in Shangshan, the original wooden shed beam in the upper mountain should be supported from below, the shed legs of the original wooden shed should be removed, and the rock blasting work should be carried out. The blasthole arrangement is shown in Figure 21-16. The first access road is 2.4~2.6m wide and the blasthole depth is 0.8~1.0m (one class completes rock drilling, mining and support work); after the first road advances 2~3m, it can start mining second The ore of the approach, rock drilling from top to bottom to prevent the collapse of the first approach to the wooden shed.

Figure 2 Schematic diagram of the hole layout
1-Uphill; 2-gun hole; 3-wood shed; 4-dense pillar
It is transported by electric raft, and the electric winch winch is 14kw, box type bucket, and the bucket capacity is 0.1~0.2m 3 .
Roof support. With a beam and three columns of incomplete sheds, the shed spacing is 0.7 to 0.8 m.    
Put the top. The top control distance is not retained when the top is placed, and the top distance is generally 4.8 to 5.2 m. The roof cut line is located at the edge of the ore body that will be mined in the future. A dense column is cut along the top plate to prevent the rock falling from the roof from being squeezed into the mining face during the next approach. The dense column can adopt round logs with small diameter, the wooden columns are spaced 0.2-0.3m apart, and the bamboo rafts are added on the wooden columns on the side of the topping area to prevent the gravel from entering the working surface, and the tops are manually or mechanically returned to the column. [next]
Ventilation in the stope. Due to the absence of a return air passage in the upper part of the stope, the ventilation conditions are poor. A local fan is generally used to supply air to the mining face. The partial fan can be installed in the section roadway, and if necessary, a partial fan fan is installed in the stage transportation lane. After the dirty wind reaches the transportation lane, the main fan of the mining area is discharged outside the well.
Mining site pressure activities. According to the actual measurement, when the inclination angle of the ore body is 15° and the thickness is 1.6m, when the mining site is about 20m away from the surface, the roof will fall behind, and the surface will sink in 1~3 days. The subsidence speed will increase sharply in the next few days, and finally in 3~4 The subsidence decreased gradually during the month; when the mining span was 4.8m, the maximum load of the pillar was 78.4×10 3 N. When the twist increased to 7.2m, the maximum load of the pillar was 196×10 3 N. From the fireproof drill hole after the collapse of the roof, when the average height of the mining is 1.5 to 2 m, the roof collapse height is 6 to 9.5 m.
(6) Prevention of internal fires. The black shale of the mine contains carbon and fine-grained pyrite, and the roof is lagging behind. The black shale spontaneously ignites due to oxidation and heat accumulation, forming a fire in the pit. For the prevention of internal fires, the following measures are taken: preventive yellow mud grouting to prevent black shale from being in contact with air. The yellow mud is stirred with 1:3 yellow mud and water. The amount of mud is 10~ in the goaf. 15%, drilling grouting from the surface or under the pit; closing the goaf, sealing the goaf, cutting roadway, return air well, etc. in the goaf, using red brick or wooden board to seal the wall with yellow mud; speeding up the mining speed , improve the recovery rate of pit wood and so on.
(7) Labor organization. It adopts the form of a comprehensive task force for drilling blasting, roof support and parallel operation in each class. Each mining team has a total of 30 to 33 people.
(8) The main technical and economic indicators are shown in Table 2.
 
Table 2 Main technical and economic indicators for the application of single-layer caving mining method in China
Mine name
Mining method
Acquisition workload (m/kt)
Ore production capacity (t/d)
Mining labor productivity (ton / work class)
Ore recovery rate (%)
Ore depletion rate (%)
Explosive consumption (kg/t)
Pit wood consumption (m 3 /kt)
Raw ore cost (yuan/ton)
Remarks
Pangjiabao Iron Mine
Longwall single layer caving
39
128
5.61
82.08
6.04
0.31
7.4
16.13
Ming shallow water bauxite mine
Longwall single layer caving
25.96
194
5.42
80
5
0.21
7.0
7.58
Zunyi manganese mine
Short wall single layer caving
69.71
47.1
50~60
2.23
2.16
85.8
90.8
6
8
0.27
0.26
3.04
23.5
38.54
42.67
Advancing along the trend
Xiangtan Manganese Mine
Approach single layer caving
30~50
3.2~3.8
94
5~9
0.3
18.0
Baiyukou Clay Mine
Approach single layer caving
45
60
2.5
67
3
0.2
9.0
twenty four

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