When the mine is filled with water sand or waste rock, the column is recovered by the caving method. The ground pressure control principle and use conditions of filling and caving are different, so the supporting use is very rare, but it is used to mine ore with low grade in the following special cases: (1) filling mines left over from history; (2) open air Mining underground at the same time, using the filling method to return to the mining room for the protection of the open pit, and returning to the mining column after the open pit mining; (3) In some cases, the loss of the ore is caused by the large blasting to the empty field, and the ore is placed too much. Top or first recovery of the top and bottom columns to transfer the upper part of the overburden or filling, and then recover the column.
A layered caving method, a sub-column-free sublevel caving method, and a sub-column sublevel caving method may be employed.
The stratified caving method has the advantage of strong adaptability. When the rock is unstable and the burial conditions are complicated, a high recovery rate can be obtained, which can be used for ores that do not need to protect the surface, high value and high grade. When used for the recovery of the column, appropriate measures should be taken to prevent the influx of the filler from causing loss and depletion. For example, if the adhesive filling material is used, the side of the compacted part can be exposed to a certain area without collapse; if the non-bonded filling material is used, the “mineral skin” is left on the side of the inter-column. deep drilling should lead, to identify the actual size of the stud; also when stope mining i.e. both safety wood stud or metal mesh, sheet or pouring concrete wall (Fig. 1).
Figure 1 Mining the column with stratified caving mining
1—Patio; 2—Advance; 3—Pavement along the vein to transport the roadway; 4—Phase to transport the roadway; 5—Fake top
In China, the pilling-free sublevel caving method is used to initially use the wooden false top scheme. The width of the column and the height of the section are generally not more than 5-6 m. Although it is superior to the stratified caving method in terms of saving pits and improving the recovery intensity, the loss and depletion increase. The loss rate of the Yangjiazhangzi molybdenum mine with this method is 25% to 30%, and the depletion rate is 7% to 9%. Currently, there is a sublevel caving method without a false top (Fig. 2). When it is used to recover the column, the approach can only be overlapped. In order to reduce losses and depletion, the relationship between the column width and the segment height should be reasonably determined. When the column is wide, the filling material is cohesive and compacted. When the depth of the tapping device is large, a larger segment height should be used, which is generally 10 to 12 m to 15 m.
Figure 2 Columnless sublevel caving mining method mining column
1—concrete false bottom; 2—filled mine; 3—recovery approach; 4—deep hole in the back of the mining column; 5—falling surrounding rock and filling;
6—disintegrated ore; 7—external transport laneway; 8—intra-pulse transport lane; 9—pulse outer patio; 10—slipper
When using the bottomed column sublevel caving method to recover the inter-column, the stage is usually divided into 2 to 3 sections, and the funnel can be arranged on one side or both sides. When the mine is placed vertically, the top and bottom columns can be combined. At this time, the first section must be arranged on both sides of the funnel, and the filler in the range of the funnel can be discharged before the falling of the mine.
Table 1 is a summary of some mines using the caving method to recharge the mine room column.
Table 1 Data of several mines using the caving method to recover the filling of the mine room column
mine
(section)
Mining method
Inter-column mining method
Main index of mining pillar mining
Remarks
Recovery rate
(%)
Depletion rate
(%)
Nugget production
Ability (t/d)
Mining efficiency
(ton / work class)
No. 5 ore body of Yangjiazhangzi Molybdenum Mine - above 160m
Upward horizontal layered dry filling mining method
Layered caving mining method
90.5
30~40
High ore grade
Ibid.
Bottomless sublevel caving mining method with false top
70-75
7~9
70～80
4.6~5.0
SKS lead zinc ore crows soap 6,8 stud
Upward stratified filling method and retention method for post-harvest filling
Bottom column sublevel caving mining method
59.8
2.9
Copper Copper Mine officer
Upward layered dry filling method
Sub-column sublevel caving mining method combined with top and bottom column mining or separate mining
79.4
77.8
22.7
20.2
When returning to the mining room, it is simultaneously mined in the open air and underground.

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