Caving mining method

It is rare to use the caving method to fill the top pillar of the mine. It is allowed to collapse on the surface and the mine can be used to mine low grade ore with non-cemented filling.

Figure 1 is an arrangement of the Yangjiazhangzi molybdenum mine used to recover the top pillar of the mine by stratified caving. A 1.5 m thick roof pillar is retained on the first layer.

Figure 1 Stratified caving mining method mining top pillar

When the top and bottom columns are recovered by the sub-column sublevel caving method, they can be recovered together with the inter-column. Copper Mountain copper mine official contact with hydrothermal metasomatic skarn copper pyrite deposit. The ore body is like a layered output, the upper part is relatively large, and the deep part is gradually narrowed and branched, and the thickness of the ore is 2 to 33 m. The inclination angle is 32 to 82°. The upper plate is quartz diorite , which is very stable. The lower plate is quartz shale , which is stable to moderate stability, but it is soft and brittle and has poor stability due to the influence of the fault at the contact of the rock. The ore is stable and the copper grade is 0.71%. The surrounding rock contains very little copper. Pyrrhotite, pyrite ores easily oxidized under certain conditions, spontaneous combustion and agglomeration. In the past, due to open-pit mining and underground mining, the upper horizontal stratified dry filling method was used to return to the mining room. The vertical ore body of the mine is arranged in a direction of 12 to 14 m in width and 6 to 8 m in width. The height of the top column and the bottom column is mostly 4.5 to 5.5 m. The mine is filled with 80% loess and 20% stone. After the end of open-pit mining, except for the pillars of the old temple base more than zero meters have been exploited by the open pit, the remaining pillars are mainly recovered by the sublevel caving method. In the deep mining, since the height of the stage is increased from 30m to 40m, the inclination of the ore body is slowed to about 30°, thus changing the layout of the electric raft and the structure of the stope accordingly.

As the inclination angle of the ore body changes, the stage division and the number of segments (2 or 3) and the electric ramp arrangement are different. When the dip angle is slow, the last section of the ramp is often arranged along the strike to recover the top and bottom columns. The ramp can be 1 to 3, depending on the horizontal area and the amount of the top pillar. The distance between the ramps is 10m and the length is about 40m. The second subsection electric ramp has two arrangements of horizontal and inclined: when the ore body inclination angle is ≥40°, the horizontal electric ramp is arranged along the axial direction of the inter-column at half of the stage height, mostly double-sided funnel; When the inclination angle is about 30 to 35°, the inclined electric raft is arranged on the lower plate, the inclination angle is less than 20°, and the funnel is arranged on one side. The last section of the electric ramp is located 1 to 2 meters away from the stage transportation lane, and is mostly a single-sided funnel. When unilaterally arranged, the electric ramp deviates from the centerline of the inter-column by 1 to 2 m, so that the center of the funnel is located on the centerline of the inter-column.

Usually the above two sections are combined. Use a down-the-hole drill to drill a deep hole with a diameter of 100 to 110 mm. 28kW and 55kW electric rafts for mining.

It can also be picked up separately. The following are several arrangements for separate picking.

Figure 2 shows the top and bottom columns of the thick mining ore body. Along the center line of the width of the mine, the artificial electric raft is constructed with reinforced concrete in the filling and connected with the stage roadway. The upper middle and deep holes are used for falling ore. This arrangement can improve the recovery rate, but the manual irrigation electric raft has a large workload, and it is necessary to take out a part of the filling material.

Fig. 2 Schematic diagram of reinforced concrete artificial ramp sublevel caving method

1-reinforced concrete electric roadway; 2-filling body; 3-top bottom column

Figure 3 shows that the Hongtoushan copper mine was used for the mining of the top and bottom columns with a thickness of 3 to 5 m and a mine along the strike. Dig a road outside the electric circuit along the lower plate, and arrange the ore discharge on one side. The location of the electric ramp is determined by the requirement to release as much ore as possible. Before mining, the cemented packing should be discharged first, and then harvested by shallow hole retention method to 2~6m from the top of the upper stage column. The ore will be released, and then the deep hole will be drilled in the deep hole chamber. The remaining ore is mined under the overburden.

Figure 3 Schematic diagram of mining and caving mining method

1-gel filling body; 2-slip mine; 3-person ventilation shaft; 4-stage transportation lane; 5-level discharge port;

6-top column; 7-bottom column; 8-an ore mine roadway; 9-branch roadway; 10-passing roadway;

11-falling rock; 12-unexpanded sulfide ore (coated)

Fig. 4 is an example of a top and bottom column with a thicker deep hole collapsed ore body and a larger exposed roof area of ​​the Hongtoushan copper mine. In order to reduce the ore loss on the side of the upper plate, the tailings were used to form the ore slope, but the ore was lost due to the small angle. First, the top column is collapsed, and after being released, the bottom column is collapsed and the ore is discharged under the loose filling.

Figure 4 Schematic diagram of the deep hole collapse mining method

1- blasting the deep hole of the top column; 2-deep bottom hole of the blasting column; 3-cracking rock; 4-tail sand bag pile;

5-adhesive filling body; 6-deep hole rock drilling chamber; 7-electric roadway; 8-mining port

When the height of the top and bottom columns is not large, the working volume with the sub-column sublevel caving method is very large, and the structure and process of the sub-collapse method without the bottom column are relatively simple (Fig. 5).

Figure 5 Bottom-free sublevel caving mining method

1-slide mine; 2-Pedestrian patio; 3-stage transportation roadway; 4-gun hole; 5-cracked overburden; 6-filled body

Fig. 6 to Fig. 9 show the case where the Zhongshankeng of the Zhonglong Mine in Japan is used to recharge the bottom pillar of the mine with the caving method.

Figure 6 Filling mining method

1- bottom column; 2-top bottom; 3-cut groove; 4-stage transportation roadway; 5--mining drill car;

6-bolt; 7-gun hole; 8-filling; 9-scraper; 10-filling tube

Figure 7: Falling mining method

1-waste stone; 2-bottom column; 3-cutting trough; 4-bracket; 5-cracking ore; 6-remote scraper;

7-guard top skin; 8-to be collapsed top cover skin; 9-to be collapsed ore; 10-blast hole

Figure 8 Mine roof filling

1-top column; 2-filling pipe; 3-preparation filling pipe; 4-conveying pipe; 5-pressure rubber pinch valve (for checking pipe blockage)

Figure 9 Digging a way in the top column

A-drilling rock; b-cutting the filling material in front of the excavation work to form a free surface; avoiding blasting damage to the top plate;

C-Use the remote control shovel to mine; d-backfill, and support with 125mmH steel bracket; 1 - the original position of the bottom column;

2-stage roadway original position; 3-top column; 4-filler; 5-pillar

Long contact with the ore account lead-zinc skarn silver deposit. Zhongshankeng mines many small block ore bodies with high grades. Due to the irregular shape of the ore body, the thickness and the inclination change are large, so the mining room is opened by the upward horizontal layered filling method. The height of the mine is 40m and the height of the top and bottom columns is 3~7m.

According to the stability of the ore, the top and bottom columns are recovered by different schemes.

1. When the top plate is relatively stable, use the filling method to recover the top column and use the caving method to recover the bottom column.

The top column is first recovered by filling (Fig. 6). The recovery steps are as follows:

(1) The mining room continues to be harvested to a thickness of 3 m from the top pillar. 1.5 ~ 2.0m long mounting bolt and the metal mesh support stage transport tunnel. The filling surface of the mine is 4m high from the top column, and the upward inclined crater of 2.5~3.0m depth is drilled in the top column (Fig. 6a).

(2) Filling the mine room with mortar or waste rock, so that the filling surface is 1.0-1.5 m higher than the top column for charging and blasting (Fig. 6b).

(3) Blasting the blastholes in all the top columns (Fig. 6c).

(4) Mining with a scraper (Fig. 6d).

(5) After the ore is completely discharged, it is filled to the horizontal floor of the transportation.

The bottom column is recovered by the caving method, and the recovery step is as shown in FIG. The mining area will be widened and heightened, and the roadway will be transported in the metal or wood support stage (Fig. 7a); the 2~3 rows of holes will be returned to the mining step, and the upper part will be 0.5~1.0m thick. It collapsed with the next drop of the ore (Fig. 7b, c); it was mined with a remote-controlled scraper under the cover of the cantilevered topping (Fig. 7d).

2. When the ore rock is unstable, use the caving method to first collect the bottom column, then use the approach to recover the top column, and then use the caving method to retreat the top plate and the two gangs of the approach.

The steps of the caving method to recover the bottom column are:

(1) Filling the upper space of the mining room with a pressure mortar densely packed. The delivery pressure was 2.5 MPa (Fig. 8).

(2) The bottom column recovery method is the same as that shown in Figure 7. When the bottom column is recovered, the false roof is laid on the old rail, the old backboard or the metal mesh at the stage of the horizontal roadway to prevent the ore from being depleted when the top pillar is recovered.

(3) When the top column is recovered, the parallel approach is made on the filling surface and the top column, and the height is 2.5m. The steps are shown in Figure 9.

(4) At one end of the road, the caving method is used to return to the two gangs and the top column of the mining road. Practice has proved that no safety accidents have occurred in the mining process, and the expected ore recovery rate and depletion rate requirements have been met.