Practice of Underground Mining-Interval Artificial Inter-column Mining and Mining in Yanjin Deposit (Sujiadian Gold Mine)

Su store gold ore deposits in accordance with its conditions, the use of artificial distance between pillars in comprehensive mining law mining.

First, mining technical conditions

The deposit is a quartz vein type formed by a gold-containing hydrothermal fluid filled along the fault structure. The ore body and the surrounding rock show a gradual relationship, which is determined by sampling and testing. The structure in the mining area is not very developed, and the NE and NNE-oriented faults control more than a dozen veins, of which the No. 1 vein is the main mining body. The No. 1 vein is layered and vein-like, with a dew on the surface and a slope of 150m.

The mining bed is developed with an inclined inclined shaft with an inclination of 29°. The slope length is 174m. The stage height is 20 to 25 m and is divided into four stages, namely 125 m, 100 m, 80 m and 55 m. Among them, the 80m level is mined by the room-column method. The ore content (including the top column, the bottom column and the inter-column) accounts for 33% of the ore minerals. The pillars are basically not recycled, and the resources are wasted.

In order to improve the mining recovery rate, the mine has achieved good results for the inclined medium-thick ore body test of the No. 1 vein 55m level and the use of the interval artificial column-column mining comprehensive mining method.

The vertical thickness of the No. 1 vein at the 55m level is 2-8m, with an average of 4m, the inclination angle is 35°~45°, and the ore grade is 5g/t. The surrounding rock of the ore body is moderately stable, and the ore body and the surrounding rock are stable, and the rock hardness coefficient f=12-17. Hydrogeological conditions are simple.

Second, mining method structure and mining cutting

The ore blocks are arranged along the strike, with a length of 8 to 10 m, of which the mine is 6 to 8 m long (6 m when the ore body is thick, 8 m when the thickness is thin), and the column width is 2 m (replaced by artificial columns). The height of the nugget is 25m high and 32-44m long. The thickness of the ore block is the thickness of the ore body. The top column is not left (80m horizontal low column has been manually replaced), the bottom column is 5m high, and it is retained for mining in the next stage.

The mining method structure and the mining engineering arrangement are shown in Figure 1. The 55m horizontal prospecting along the vein roadway is used as the stage transportation lane. Every 8 to 10 m, the roadway is drilled into the tunnel of the ore body through the roadway. The tunnel is used for prospecting first, and then used as the loading and unloading lane during mining. The tunnel is drilled up to the level of the bottom of the tunnel, and the electric winch winch is excavated in the surrounding rock near the slip hole. At the level of the bottom, the adjacent two wellheads are connected to each other to form a bottomed alley. From the middle of the pull-down roadway, the tunnel is drilled into the lower part of the ore body, and the open hole is drilled along the lower plate. The diameter of the patio along the ore body is 3m, and the vertical ore body strike size is equal to the thickness of the ore body. The construction is completed in two steps. The first direction of the ore body is 3m, and the thickness of the ore body is 1.8~2m. The patio reaches 80m. The second step is to pick up the full thickness of the ore body to form a 3m wide full-section patio. . In the patio. One side of the artificial column with a width of 2m is built on one side, and the other side (1m wide) is used as a pedestrian, ventilation and double-cutting well. The artificial columns in the mining patio are spaced and built with excavation waste rock. The dimensions are: 2m along the strike width (40cm stone on each side, 1.2m gravel watered inside), 3m along the slope, thickness equals The thickness of the ore body is 2m along the slope.

Figure 1 Sujiadian gold mine interval artificial column retention ore mining method

1—transportation alleyway; 2—mineral crossing lane; 3—slip mine; 4—electric winch winch chamber;

5—Picking the patio; 6—Pedestrian and ventilation wells; 7—Intervaling artificial columns;

8—pull space; 9—recovery blasthole, 10—temporary ore

Third, mining work

After completing the various mining projects and the artificial columns on both sides of the mine, the mining can be carried out.

(1) Falling mine

The bottom level is extracted from the bottom to the step surface. When mining, it is divided into 2 to 4 layers along the thickness direction of the ore body, and each layer is about 2 m thick. Between adjacent two layers, the lower layer is one shot ahead of the upper layer (about 1.8m), and each layer forms a stepped working surface. At the time of mining, each step is blasted according to the net width (6~8m) of the mine, and each time the mine is pushed upwards by about 1.8m. The 7555 rock drill is used for eye drilling with an eye depth of 2 m, a minimum resistance of 0.6 m (row spacing), and a blasthole spacing of 0.7 to 0.8 m. When the ore body is divided into two layers for recovery, in the stratification close to the lower plate, the blasthole is arranged parallel to the inclined direction of the ore body, and the blasting is performed by using the mining patio as a cutting groove; in the stratification close to the upper plate, The blasthole is arranged perpendicular to the oblique direction of the ore body. When the ore body is thicker and divided into four layers for mining, the blastholes parallel to the ore body are arranged in the two layers close to the lower plate, and are arranged perpendicular to the ore in the two layers close to the upper plate. Tilted blasthole.

(2) Mining

After each fall of the mine, the ore is used, and the ore is transported away by the mine. Each part of the mine discharges about one-third of the ore-mining amount, and the rest is reserved for the workbench that continues to be harvested until the mine is completely mined and a large amount of ore is discharged.

(three) roof management

Each mine has been built with artificial columns on both sides before mining, and the top plate is mainly supported by artificial columns during the mining process. The maximum exposed size of the roof of the mine is 6-8 m wide and 32-44 m long. If the roof is unstable during the mining, when the low-grade ore is encountered, the local pillar can be left to support the roof. After a large number of mines have been mined, the empty area will let it collapse on its own. Because there is an artificial column to support the roof, it will not cause a large area of ​​the roof to fall.

Fourth, technical and economic indicators

The main technical and economic indicators of the mining method of the Sujiadian gold mine are shown in Table 1.

Table 1 Main technical and economic indicators of mining methods in Sujiadian gold mine

V. Evaluation

The practice of the interval between the artificial column and the mining method in the Sujiadian gold mine shows that the main advantages are:

(1) Replacing the mine room column with artificial columns, significantly improving the ore recovery rate;

(2) The working face of the mining face is stepped, with many free faces, good mining effect, large amount of mining, and high production capacity of the mining house.

The main disadvantage is that the masonry wall has a large workload, heavy labor and high mining cost; the ore body needs to be layered and recovered, and the process is complicated; the ore needs to be retained in the mining process.

The mining method is suitable for the mining of stable rock thin and medium thick gold deposits.