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Pingdu gold mine-free stay pillar mining method, greatly reducing the ore loss and dilution, significantly improved stope production capacity and create a better economic efficiency.
I. Problems in the mining of the retained ore column
Pingdu City Gold Mine has more than 30 veins, of which the No. 1 vein is the largest. 1 gold-bearing quartz veins angle 70 ~ 85 °, the average thickness of 1.64m, average grade of 17.88g / t, ore and rock are stable.
In the past, the retention method of the top column and the bottom column has been used, and the mining lanes are all arranged in the veins. The ore block is 40m long along the strike, with a smoothing patio at its two ends, a common funnel bottom structure, a funnel spacing of 5m, a bottom pillar height of 5m, and a top pillar thickness of 3m.
In the production process, it was found that the ore retention column retention method has the following problems:
(1) There is no patio in the center of the stope. The cross bracing of the paved patio may be broken by the caving ore. It is quite difficult to restore the patio and the safety in the stope is poor.
(2) Due to the use of intrapulmonary transport lanes, when several miners are recovered at the same stage, they interfere with each other.
(3) The transportation lanes in the upper stage are used for transportation, pedestrians and ventilation. The retention time is long, the top and bottom columns cannot be recovered in time, the pillars are deformed greatly, the recovery is difficult, and the loss of high-grade ore is large.
In order to solve the above problems, the mine tested the non-mineral column retention method. After five years of production practice, it proved that the non-mineral column retention method was successful.
2. Test and application of no-mineral retention method
The method of retaining ore in the experimental study does not leave the top and bottom columns. The stage transportation roadway is arranged outside the lower plate vein. A reinforced concrete bottom column with a thickness of 0.5-1.0 m is constructed at every other stage, and the waste stone or tailings is used in the goaf. Filling.
The nuggets are 80 to 100 m long. The height of the stage is 40m, the structure of the flat bottom, the spacing of the ore discharge is 5~6m, the central part of the mine is arranged in the vein, the pedestrian and the prospecting patio, and the pedestrian walkway on both sides (see Figure 1).
Figure 1 Non-mineral column retention method
The main features of the mining method are: (1) using the first layer of mining along the vein roadway, 1.5m high, the ore that has collapsed is not mined, and after standing on the heap, the second layer of blastholes will be A layer of mineral remains out of the net, and then the funnel partition wall is made of stone or brick at the junction of the ore and the lower plate, the funnel is installed, and the second layer of blastholes is blasted, and the ore is basically filled and filled. In the field, one third of the ore in the third layer can be released from the funnel and taken up layer by layer according to this method; (2) when the mining room is recovered to 3.0~3.5m from the bottom of the upper stage, in the mine A tight safety platform is set up on the upper side of the Duan Shun Road, and a small well of 3.0~3.5m is drilled from the top of the road, and the bottom of the upper stage is connected with the floor of the upper stage. Then, the back road is retracted from the central well and is finished with the YSP-4P rock drill. The top layered blasthole, the hole depth is 2.7 ~ 3.2m, the section blasting, complete the mine mining work; (3) the ore remaining in the upper stage, released in a large number of ore.
The main technical and economic indicators of the non-mineral retention method are listed in Table 1.
Table 1 Main technical and economic indicators of non-mineral retention method
Mining method
Ore loss rate
/%
Ore depletion rate
/%
Stop production capacity
/t·d - 1
Class efficiency
/ t · Taiwan class --1
Standard ratio
/m·kt - 1
Retaining top pillar retention method
Non-mineral column retention method
17.5
2.16
23.31
9.42
30
100
30
50
14.7
15.8