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(1) Returning the mining along the slope and leaving the mined area in the upper part. The passage of personnel and materials does not need to pass through the goaf, which is conducive to the safety of the operation and the normal operation of the mining work;
Underground mining of Yanjin deposit—application of inclined roof mining method under inclined inclined mining bolt (Linghu Gold Mine)
Spirit Lake gold ore raw applying ordinary room and pillar method, a reverse recovery is inclined upward, leaving 3 × 3m 2 rules in stope pillar, a large loss and dilution of ore, job insecurity. From 1988 to 1990, the mine carried out a test study on the “slope-retracting mining bolt roof protection house column mining methodâ€, which was successful and was applied in the whole mine.
First, mining technical conditions
The ore deposit is a layer-controlled magmatic hydrothermal reclaimed ore deposit. The ore body is mainly produced in the F5 ore-bearing fault zone. The ore-bearing tectonic belt has multiple structural complexes. After the mineralization, there is a compression-torsion fracture superposition, so that the fault zone The structural fractures of the surrounding rocks on both sides are extremely developed. The surrounding rock of the roof is mixed rock and mylonite, and the surrounding rock is not stable. The allowable exposed area is about 50m 2 , the ore body inclination angle is 25° to 50°, and the average thickness is 2.63m. The average gold content of ore is 5.39g/t, which is moderately stable.
Second, mining method structure and mining cutting
The stope is 10~12m wide along the strike, with a slope length of 50~60m and a stage height of 25m. The thickness of the bottom column is 3m and the height of the top column is 2.5m. A mountain (2m × 2m 2 ) road is arranged in the center of the stope, which serves as a mine roadway and serves as a pedestrian, ventilation and cutting road. The upper part of the uphill mountain has a ventilation contact small well connected with the upper stage horizontal roadway, and the lower end of the uphill mountain is arranged with a power raft than a rutting room. The two adjacent stopes communicate with two intermediate links. Figure 1 is a schematic diagram of the mining method of the test stop. The uphill I and II are the mining roadways of the two stopes respectively. Since there is no ore belt in each stope, there is no room for the mine.
Fig.1 The Linghu gold mine along the inclined receding mining bolt roofing method (testing stope)
Third, mining work
(1) Recovery order
From the upper end of the upper side of the pick-up, it is tilted back and harvested. First, a 40° working line was opened at the upper end of the mountain, and it was moved down in turn. Figure 2 shows the two stopes of the test nugget and recovers at the same time. Back to the mining swindler: 1I on the mountain to help the top, retreat 4 to 6m; 2 to anchor the roof; 3 to the lower mine of the No. I mining; 4II up the top anchor; 5II stop mining upper mine 6 hit the anchor roof; 7 back mining the second mine. as shown in picture 2.
Figure 2 Test stop mining sequence
(2) Falling mine
The YT-27 rock drill was used for drilling, with a hole diameter of 40 mm, and blasted with ammonium nitrate explosive. The direction of the blasthole is 140° to the axis of the mountain, and the blasting surface is formed after blasting.
(3) Mining
The electric raft is applied down the mountain to the mine, and directly loaded into the mine car located in the stage transportation lane. The electric winch winch power is 30kW, and the bucket volume is 0.26m 3 .
(four) roof maintenance
Due to the development of joint fissures in the surrounding rock, the roof is not stable, and it is necessary to maintain the roof in time as the mining is carried out. The top plate maintenance uses wedge-shaped anchors.
The wedge-type anchor is rolled with A3 steel, as shown in Figure 3. The lower part of the rod body is a thick slit pipe with a diameter of 40 mm and a length of 1000 to 1100 mm. The upper part of the rod body is a slitted pipe, which is 36 mm straight and 900-1000 mm in length, and two triangular wedges are mounted on the upper end. When the anchor is used, the YSP-45 rock drill and the 38mm one-head drill bit are used to drill the anchor hole. The hole depth is 150-200mm longer than the anchor. The anchor rod is fitted into the hole and anchored in the rock by means of a YSP-45 rock drill and a bolt hammer. The results of the test of the mining stop rod are as follows: the maximum anchoring force is 13t, the minimum anchoring force is 5.2t, and the average is 7.3t.
Figure 3 wedge-type anchor structure
1—slotted thick pipe; 2—slotted thin pipe; 3—upper wedge body; 5—positioning pin; 6—gear ring; 7-pad
The bolt installation net degree is generally 1.0m×1.0m, and 0.8m×0.8m when the top plate stability condition is worse. After the wedge-type anchor is used to protect the roof, the exposed area of ​​the top plate is expanded from 50 m 2 to 258 m 2 and the maximum is 500 m 2 .
Fourth, technical and economic indicators
The main technical and economic indicators (test stope) of the Linghu gold mining method are shown in Table 1.
Table 1 Main technical and economic indicators of mining methods (test stope)
Indicator name
Value
Indicator name
Value
Production capacity / t·d -1
65
Ore: depletion rate /%
11.9
Acquisition coefficient /m·kt -1
twenty two
Explosive consumption / kg · t -1
0.462
By-product ore proportion /%
16.4
Bolt consumption / root · t -1
0.159
Ore loss rate /%
10.9
Anchor rod production and construction fee / yuan·root -1
20.5
V. Evaluation
Compared with the reverse sloping up-back mining room column method used in the mine, the inclined recoil type anchor roofing method has the following advantages:
(2) Applying a wedge-type anchor to protect the roof, avoiding roof collapse, achieving safe operation, and expanding the control top area of ​​the stope;
(3) reducing ore loss and depletion;
(4) Applying electricity to mine, improving the mining capacity and reducing the labor intensity of workers.
The mining method is suitable for the mining of gently inclined thin ore bodies with unstable roof.