Erdaogou gold mine using a local filling Shrinkage Method, mine waste rock filling in the well effectively support the surrounding rock, to improve the ore grade, mining to ensure the safety of operations.
I. VI vein geology and the problem of mining with ordinary retention method
The VI vein in the Erdaogou mining area is a medium-temperature hydrothermal fissure-filled deposit, and the ore body is present in the quartz diorite . The strike length is more than 500 meters and the inclination angle is 70-80°. The average thickness of the ore body is 1.0m, the average gold content is 7.6g/t, ore is kaolin and chlorite. The surrounding rock has parallel joints with the veins and oblique to the veins. It is very developed and is easy to fall after exposure.
Since 1987, VI veins have been recovered using a flat-bottomed retention method. In the process of mining, due to the unstable surface of the surrounding rock, the mining area is as high as 3m, the ore depletion rate is very high, and the ore grade is less than 1g/t. The 122 stope was forced to stop mining due to the seriousness of the surrounding rock fragments. The practice of recovery through three stopes proves that the retention method must be improved to increase the ore recovery rate and reduce the depletion rate.
2. Experimental study on local filling and retention method
The mining method is a combination of the retention method and the dry filling method, and the test was carried out at the 212 stop of the mine.
The mine has a length of 35m, a height of 40m, a width of 1m, a top pillar thickness of 3m, and a flat-bottomed rock loader. Two waste rock filling wells are set up between the mining and crossing roads in the stope. The wood cross bracing and the wood-structured waste rock wells are 2m long along the strike, and the horizontal distance between the cross braces is 1m (see Figure 1).
Figure 1 Local filling and retention method
1—middle section roadway; 2—shun road patio; 3—waste stone filling body; 4—cross bracing;
5 - 2nd middle roadway; 6 - mining and crossing road; 7 - along the vein contact road
In the mining, because the veins are thin, some surrounding rocks are taken, and the waste stones selected by hand in the stop are put into the filling wells. A partial filling body is composed of cross bracing and waste rock to support the surrounding rock of the upper and lower plates. The ore that was collected, after the selection of some waste rock, reduced the depletion rate. Each filling well can hold 144t of waste rock and the wood consumption is 2.2m 3 .
Since the veins are thin and the ore and surrounding rock are extremely unstable, it is important to use controlled blasting technology. The shape of the blasthole is 60°, the minimum resistance is 0.6m, the hole spacing is 0.8m, the row spacing is 0.5m, the hole depth is 0.8m, the charge factor is 50%, and the layer height is 0.7m.
The local filling and retention method has been successfully tested, and the test stop has achieved good technical and economic effects:
Production capacity of ore block /t·d - 1 40
Mining efficiency / t · work class - 1 5.7
Ore loss rate /% 7.5
(mainly the top column)
Ore depletion rate /% 17.35
The construction of filling wells consumes a large amount of wood, although it can be compensated for by the saved transportation and mineral processing costs, but due to the tight source of wood, it needs to be further improved in the future.
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