Example of underground mining-remaining mining method for rock gold deposit (Wenyu Gold Mine)

Wenyu gold ore deposits in accordance with its conditions, using a comprehensive Shrinkage mining method, and achieved good technical and economic results.

First, mining technical conditions

It is filled with the deposit account of epithermal gold sulphides quartz vein type, in addition to gold, but also contains a variety of metals as lead, copper, silver and the like.

The development of the deposit is to adopt the development method of Pingshuo, and the stage height is 30~38m. The mining technical conditions for the main ore body are:

No. 505 vein; dip angle 37 ° ~ 55 °; thickness 0.3 ~ 3 m, average thickness 1.7 m; gold containing average grade 6.98 g / t, lead 3.253%.

No. 530 vein: dip angle 38 ° ~ 67 °, thickness 0.6 ~ 3.5 m, average thickness 1.32 m; gold containing average grade 11.76 g / t, lead 3.026%.

The surrounding rocks of the two veins are mixed rock, gneiss and pegmatite, f=13～15, which is relatively stable and partially unstable. The ore f=6～10, stable.

Second, mining method structure and mining cutting

The ore blocks are arranged along the ore body, and the mining houses and pillars are harvested in two steps. The nugget is 50m long and the height is 30~38m, and the thickness is equal to the thickness of the ore body. The column of the mine room is 6m wide, the bottom column is 5m high, and the top column is 2m high. The structure of the mining method is shown in Figure 1. The stage transportation lanes are arranged in the veins, and the ore blocks are excavated in the room pillars every 50m along the roadway; as pedestrians, ventilation and transportation materials. In the patio, the horizontal contact road is drilled every 5m, and the ore patio is communicated with the mining face and used as an electric winch. At the two ends of the mine near the patio in the bottom column, the mining funnel is digged from the transport alley to the level of the bottom. Dig the bottom of the bottom of the bottom of the column and widen it to the full thickness of the ore body to form a bottom space.

Figure 1 Wenyu Gold Mine Remaining Mining Method

1—transportation alleyway; 2—lower down alley; 3—return airway; 4—top column exit; 5—mine block patio;

6—Electric winch winch; 7—contact passage; 8—leathering funnel; 9—local pillar

Third, mining work

(1) Falling mine

The bottom is pushed forward by the bottom of the bottom. The YT-27 rock drill for rock drilling has a hole diameter of 40 mm and a hole depth of 1.8 to 2.2 m. The blastholes are arranged in a plum-shaped or parallel arrangement with a row spacing of 0.6-1.0 m and a hole spacing of 0.6-1.2 m. When the thickness of the ore body is greater than 3m, the layer is layered along the thickness direction, and the lower layer is first collected, leaving part of the ore as a workbench, and then the upper layer.

(2) Mining

The electricity is mined and the electric winch is placed in the horizontal communication channel in the column between the two sides of the mine. As the working face of the mining is advanced, the electric winch is moved accordingly. The ore is transported to the top of the mining funnel on both sides of the mine. If the angle of the floor of the mine is larger than the natural angle of repose of the ore, the ore will be released from the slip; otherwise, the electric pick will be installed in the connecting lane near the funnel for relay. Each time after the mine falls, one or three ore of ore is mined, and the remaining ore is temporarily retained in the mine, and the electric field is used as a workbench to continue mining. After all the mines have been mined, a large amount of mining is carried out. After the completion of a large number of mines, the mine floor ore fines were manually cleaned.

(3) Roof management and ground pressure control

During the mining process of the mine, the top plate is supported by the column, the bottom column and the top column. According to the needs of the maintenance of the roof, it stays in the 3m×3m pillar; in the case of stone or low grade ore, the irregular pillar remains; when the local roof is unstable, it is supported by bolts or wooden columns.

As the depth of mining increased, the roof collapse accident increased, with a record of 168, listed in Table 1. According to the data in the table, under the original stope structure parameters and roof management technology conditions, the roof falling is a serious problem, especially in the sixth stage. In order to solve this problem, the mine carried out research on the ground pressure control of the full-mining mining method. The following measures were proposed: the size of the ore block was reduced from 50m to 25m to reduce the exposed area of ​​the roof; the artificial column (concrete structure) and the inter-column column were used to support the roof; the bolt was used to support the roof. And supplemented by point column support; centralized operation, rapid recovery. Among them, the artificial column has the function of reducing the ore content of the ore to increase the ore recovery rate. These measures were carried out in the 10th stage of the mine at the 1007 stop. The 25m wide ore was taken in 3 months. The test shows that these measures greatly enhance the stability of the roof of the stope and ensure the safety of the mining work. Smoothly carried out, reducing the ore loss rate and ore depletion rate (the ore loss rate is less than 1%, the ore depletion rate is 3.1%).

Table 1 Statistical Table of Roof Fall Accidents in Wenyu Gold Mine Stope

1 Stage 9 mining is not yet completed;

2 information is not complete.

Fourth, technical and economic indicators

The main technical and economic indicators of the comprehensive method for retaining minerals in Wenyu Gold Mine are shown in Table 2.

Table 2 Main technical and economic indicators of the comprehensive method of retaining minerals in Wenyu Gold Mine

V. Evaluation

The application of the full-mining mining method in the Wenyu Gold Mine shows that its main advantages are:

(1) Strong adaptability and flexibility. It has strong adaptability to the complex and variable mining conditions of the ore body. For example, when the dip angle of the ore body is large, gravity can be used for ore mining, and the dip angle can be used for electric ore mining. When encountering lean or rock interlayer, it can be selected. Don't pick it up, reduce the depletion, and when the roof of the mine is partially unstable, you can use the anchor to reinforce or leave the irregular column.

(2) The amount of mining and cutting works is small and the process is simple. The cutting is relatively small (8~19m/kt, average 14m/kt), and the mining, mining and roof maintenance processes are simple.

(3) The production capacity of mining houses is relatively high. The production capacity of the mine is generally 1800t/month. When the thickness of the ore body is 2~4m, it is 2500~4500t/month, with an average of 75t/d.

The main disadvantages of this mining method exposed in the application of the Wenyu Gold Mine are:

1. The pillars occupy more ore and the recovery is not safe. The pillars account for 23% to 25% of the ore mass. The recovery rate of the pillar is 40%, the operation is unsafe and the cost is high.

2. With the increase of mining depth, the roof falling accidents increased, the mine mining safety decreased, and the ore loss increased.

3. The electric winch wins more times and the workload is large. Each mine uses 2 electric rafts. During the mining period, each electric raft needs to move 4-6 times. Each movement requires more than a dozen working hours or dozens of working hours, which affects the mining and mining.

4. The empty area left after the mining house is harvested shall be specially treated.