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Bottomless sublevel caving cutting work
The cutting work includes: boring the cutting alley, cutting the patio and forming the cutting vertical trough. That is, before the recovery, a cutting vertical groove must be formed at the end of the mining roadway as the free surface and compensation space for the initial collapse. The area and shape of the cutting trough should be adapted to the area and shape of the collapsing.
The width of the cutting vertical groove is generally not less than 2 meters.
It is important to ensure the quality of the cutting vertical trough, which will affect whether the working ability of the mining is smooth and the ore recovery index is good or bad. There are several ways to form a cutting vertical groove:
(1) Combined drawing method for cutting roadway and cutting patio
1) When the boundary of the ore body is relatively regular, it is often used to dig the cutting lane along the boundary of the ore body at the end of the mining roadway, and dig one or several cutting patios according to the length of the cutting roadway and the need of blasting. In the cutting lane, parallel or fan-shaped holes are made upwards, and the cutting patio is used as a free surface to retreat and blast to form a cutting groove.
Generally, 3 to 5 blastholes are arranged in each row. During the troughing process, part of the ore should be shipped to loosen the caving ore and prevent over-squeezing when mining is lost.
Advantages: less cutting wells and wide use.
Disadvantages: When the quality of rock drilling and blasting is not good, it is easy to form a suspended ceiling. For this reason, the width of the groove can be appropriately increased to encrypt the blasthole.
2) When the ore body is irregular, or when the mining roadway is arranged along the strike, the cutting roadway and the cutting patio are to be dug at the end of each mining roadway. This method of pulling the cutting groove is of good quality. However, the amount of excavation work is large.
2) Cutting patio and fan-shaped blasthole groove method
This method of pulling the groove is not to dig into the cutting lane, but to dig the cutting patio at the end of each mining roadway.
The cutting patio is located in the middle of the end of the mining roadway, and the long side of the patio is aligned with the direction of the mining roadway (the section of the cutting patio can be 1.5 x 2.5 m2 ).
Three rows of fan-shaped deep holes are made on the sides of the cutting patio by a trolley, and the grooves are blasted once by milliseconds.
Advantages: 1 This kind of groove method can ensure the smooth formation of the cutting groove as long as the cutting patio has sufficient height.
2 Do not dig into the cutting alley.
3 The cutting blasthole is the same as the mining blasthole, which can be drilled with a trolley and has a simple process.
4 Each back lane can independently form a cutting groove at a reasonable position, which has great flexibility and adaptability. Therefore, this method is also widely used. This method is particularly suitable when the ore body boundary changes greatly.
Disadvantages: The number of cutting patios is large, and the workload is large.
(3) No-cutting well drawing method
The method of no-cutting troughing is essentially a method of drilling a plurality of fan-shaped blastholes with different angles in a mining roadway or a cutting roadway, and forming a cutting groove by division (or one time).
1) Non-cutting well blasting and drawing method
The troughing method is to drill a plurality of fan-shaped holes with different angles in the mining roadway, and to blast the mining roadway as a free surface, and release some ore after the blasting to create conditions for the next blasting. After all the blastholes are blasted, a cutting groove is formed.
The specific method is to cut 8 rows of fan-shaped blastholes at the end of the mining roadway 4 to 5 meters, each row of 7 holes, and blast according to the row. This is equivalent to forming a cutting patio. In addition, in order to ensure the cutting, the area and shape of the groove, three rows of cutting blast holes of 9, 10, and 11 are arranged.
The arrangement is the same as the method of cutting the patio.
[Disadvantages]: The effect of pulling the groove is poor, and it is impossible to form a groove at one time, and it is difficult to grasp the rockwork.
[Advantages]: It is safe to drill rock without having to cut the patio and cut the alley.
This method temple iron ore mine # 24 used, with 9-meter-high segment, they think high segment should not use this method, because of difficult to guarantee quality.
2) One-time blasting method for wedge-shaped gutters.
This method is to cut four rows of fan-shaped blastholes in the cutting lane. A method of forming a cutting groove by one-time blasting of a differential electric detonator.
This method of drawing is suitable for places where the ore is not stable or is not convenient for cutting the patio. For example, the Chengchao iron ore mine in China successfully used this method of pulling in the section of the broken and yellow mud.
[Parameters] Chengchao Iron Mine, due to poor ore stability, the cutting roofway often has a high phenomenon of local roofing, which makes it difficult to apply other cutting methods. According to this feature, the mine uses a YQ-100 drill or a trolley to cut a wedge-shaped slotted fan-shaped hole in the cutting lane, and has achieved good results. At present, the Chengchao iron ore is not used anymore. It is still used to cut the lane and cut the well to open the groove.