An example of mining of alpine deposits - mining of Danba mica mine

Danba Mica Mine is located in Danbaguo, Ganzi Tibetan Autonomous Prefecture, Sichuan Province. Geographical coordinates are 101°30' to 120° east longitude and 30°50' to 31°15' north latitude.

The mine has 10 mining areas, of which the Gaowa mining area is located at an altitude of 3000 to 4400 m with a distribution range of 55 km ² . The snow cover on the top of the mountain lasted for 7 months. The water source is abundant, and the mountain water is constantly flowing. It is difficult to use water above 4,200m, especially from December to January, and solve the problem of drinking water by dissolving snow.

The ore body is 30-100m long and 1~3m thick. The boundary between the vein and the surrounding rock is distinct, and it tends to be northwest to southeast, with a dip angle of 20-70°. The vein and surrounding rock are stable.

Ground transportation mainly uses ropeways and cars. A 4 ton car can only pull 2.5 tons.

It is developed by Pingyi, with a section of 2×2m, a height of 30×50m, natural ventilation, self-flowing drainage, freezing of groundwater in winter, and ice-discharging. The local fan uses JBT—51-2 and JBT—42-2.

The shallow hole retention method is used, and the YT-25 pneumatic rock drill , the Hua-I rock loader, and the 0.4-0.5 m ³ mine car are used.

When the production is stopped in winter, the water pipes and ducts should be cleaned.

The mine has a high elevation and works there. There are often headaches, hand swelling, joint swelling, heartbeat, etc., and the sunshine time is long, the ultraviolet rays are strong, the black is easy to be old, and the workers are generally under 40 years old.

The mine has a discontinuous work system. May to October is working hours, and other time is closed. Three months of pro-family leave and three months of preparation work (cleaning the ice in the stope and the roadway when starting work). Work two shifts a day, working 8 hours per shift. The organization is an integrated task force with 12 people per team and one cycle per day. The work efficiency is 0.6~0.8 ^m3 .

Due to the high altitude and serious lightning damage, the mine has adopted lightning protection measures:

1. Replace the ordinary transformer with the lightning protection transformer of SZ series Y/ZO-11 wiring, and the lightning arrester adopts high altitude equipment. The 55 type iron open fuse is used, and the rated voltage is 15kV.

Second, reduce the installation position of the FS-10 series arrester, shorten the grounding wire, reduce the residual voltage to improve the lightning resistance of the transformer.

Third, low-voltage electrical equipment. Due to the large amplitude of the rated voltage, the current rating needs to be increased by one step.

Fourth, the transformer low-voltage side pressure sensitive resistor (VYJ) limits forward and reverse transfer, over voltage.

5. Install a lightning rod to prevent direct electric shock.

6. Improve the insulation performance of high and low voltage overhead lines.