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Application of mining and mining method in Wulong Gold Mine (underground mining of rock gold deposit)
Wulong gold ore deposits in accordance with its conditions, with a shrinkage stoping method.
First, mining technical conditions
Wulong gold mining is gold-bearing quartz veins filling fractures in high-temperature hydrothermal deposits, sub-group and the North East, North West two groups veins. The average thickness of the veins of the Beidong Formation is 2m, the inclination angle is 75-85°, and the ore body shape is relatively stable. The average thickness of the North West Formation vein is about 1.5m and the inclination is 32~75°. The surrounding rocks of the two groups of veins are granitic gneiss and fine-grained diorite . The ore and surrounding rock are stable and relatively stable.
The veins are relatively flat along the strike, and faults and displacements occur in individual ore sections. The fault distance is generally 0.5-1.5 m and the maximum is 7 m. The geological grade of gold is 5-8 g/t. The ore is non-caking and pyrophoric.
Second, the bottom structure of the retention method and the characteristics of the mining
The Wulong Gold Mine is a mine dominated by the retention method. Since the 1950s, the structure of the bottom of the retention method has been continuously improved to create a variety of bottom structures of electrothermal ore (see Figure 1).
Figure 1 The bottom structure of the retention method
A—flat-bottom eel mine; b—funnel electric ramp;
C—the level of the ramp is lower than the level of the bottom; the d-flat bottom and the funnel are combined;
1—Electric sluice roadway; 2—Funnel; 3—Skiing well; 4—Transportation roadway; 5—Pedestrian patio; 6—Lowering roadway
The bottom structure of the flat-bottom electric slag mine is suitable for the rock mass with stable surrounding rock, small change along the strike of the vein, and thickness of less than 3m. The level of the ramp is lower than the level of the bottom, and it is applied to the nuggets that cannot be recovered by the bottom column. This form can reduce the loss of ore in the dead zone of the flat bottom. When the surrounding rock in the local section of the ore block is not stable or there is no ore in the local section above the level of the bottom, the bottom structure of the electric slag mine combined with the funnel is used.
The above four bottom structures are arranged above the transport level, leaving a bottom column of 3 to 5 m. In the nugget that does not need to retain the stage to transport the roadway, the bottom structure of the flat-bottomed eel mine can be arranged at the stage transportation level. At this time, the in-pulse prospecting road can be used as the bottom roadway, and the lower stage patio can be used for the chute. If the patio is available in the next stage, the electric loading platform can be used for mining and loading. The bottom structure is 40% to 50% less than the bottom structure of the bottom column, and the mining volume is increased, and the ore recovery rate is increased.
With the increase of mining depth and the influence of goafs, some of the roofs of the stope are flaky or plate-like, with sound. Such tension roof damage, affecting a certain thickness in the top plate, i.e., delamination of roof stone phenomenon. When the rock is shocked by the rock, the top plate is easy to fall.
In view of the above dynamic ground pressure phenomenon, the mine adopts horizontal blastholes, with a hole depth of 2.5 to 3.0 m and a layer height of 2.5 to 3.0 m. In order to achieve strong mining, the central courtyard of the nugget is pushed to both ends to increase the drilling face. Practice has proved that this method of falling mine can reduce the damage of the blasting to the roof, avoid the fall of the slab when the rock is rocking , and keep it intact because it does not damage the roof, which is also conducive to the stability of the roof. When the thickness of the vein is greater than 3m, the stability of the roof is poor, and the medium and deep holes are used to mine from the patio.
Third, the hydraulic transport and retention method
The inclination angle of the veins in the North West Formation varies greatly. The inclination of the ore body in the lower part of the ore block is 50-75°, and the upper part is 32-40°. In the past, when the ordinary mining method was used for mining, the dip angle of the upper ore body was slowed down, which was not only difficult to recover, but also after the large ore deposit, part of the ore accumulated on the bottom plate could not be released, resulting in permanent loss. In response to this condition, a hydraulic rushing method is created.
The hydraulic rushing and retaining method is to force the ore accumulated on the floor of the stope to be discharged to the bottom of the ore block by means of high-pressure water jet. The hydraulic rushing and retention method is shown in Figure 2.
Figure 2 Art diagram of hydraulic recharge and retention method
1—Pool; 2—water pump; 3—water supply pipe; 4—water gun; 5—workbench; 6—humane; 7—slipper
(1) Water supply system
The water supply system includes a temporary storage tank, a water pump and a water supply line. The old roadway near the stope is generally used as a storage tank. The pump type is selected according to the ore angle of the ore body, the thickness of the vein and the range of the jet. In the floor of the stope, the inclination angle is 40~50°, the thickness of the vein is less than 1m, and when the range of the water gun is short, the pump of 100D16×8 type (head 124m, flow rate 54m 3 /h) is selected; when the inclination angle of the floor is 30～40°, the thickness of the vein is more than 1m. When the water gun has a long range, the 4GC8×8 type water pump (head 260m, flow rate 30～55m 3 /h) is selected. Water supply pipe, welded pipe for the former type of water pump, seamless steel pipe for the latter type of water pump.
(2) Water gun and its installation position
The outer dimensions of the water gun are: 1350cm long, 500cm wide and 590cm high. Nozzle size: Ñ„18mm.
Water gun installation location. When the stope is used to retain the top column, the water gun is installed in the working column of the top column: the vein is very thin, and when the surrounding rock is stable, the water gun is installed on the workbench erected under the top column: the working well cannot be drilled, and the workbench cannot be set up. The water gun is installed in the communication channel of the column.
(3) Impact mining operations
The best effect is from the top to the bottom. At the beginning of the mining, the trough should be formed first, and then the trough should be layered into the two wings. The optimum layer thickness is selected according to the inclination angle of the floor of the stope, the ore block size and the compaction degree of the pile, and is generally 0.5 to 1.0 m. Figure 3 is a schematic diagram of the layered ore rushing to the two wings.
Figure 3 Schematic diagram of layered ore
1—water gun; 2—loose ore; 1-7—rushing stratification sequence
In order to recover the fine ore, before the rushing, the ore discharge well is filled with ore. The height of the ore house is more than 4m. In the intermittent operation of the water gun, the ore water enters the chute and is filtered by the ore. The fine ore remains in the chute, and the water flows out into the drain.
(4) Main indicators of hydraulic flushing and mining
The main indicators of hydraulic flushing and mining are shown in Table 1.
Table 1 Main indicators of hydraulic flushing and mining
Stope
Stope floor inclination
/(°)
Water gun working pressure
/MPa
Water gun nozzle diameter
/mm
Water gun production capacity
/t·h — 1
Water Consumption
/m 3 ·t - 1
361
35～40
2.1 to 2.4
18
147
0.314
6152
40～45
0.8 to 1.0
18
120
0.45
Fourth, double-layer ramp retention method
According to this occurrence condition, the double-drain method is used to solve the problem that the mining ore is high in the total loss rate caused by the digging of the ore in the dip angle. problem.
For example, the mine 5761 stope, the length of the ore block is 30m, the vertical height is 40m, the average thickness of the vein is 2.5m, the lower part of the ore body is 60°, the middle part is 45°, the upper part is 70°, and the ore is stable. The upper and lower mines are divided into two upper and lower mines (Fig. 4). The bottom of the stone is a flat-bottom electric shovel structure. When the dip angle is slowed down, the roof is leveled and the supplementary mining process of the upper mine is done. When the vein width is wide, the working face can be used as a double-layer ramp: when the vein is narrow, a double-deck ramp is required. The upper mine has a funnel bottom structure. After the mining of the upper mine is finished, the ore of the upper mine is discharged first, then the bottom pillar of the upper mine is recovered, and finally the ore of the lower mine is released.
Figure 4 Double-layer tunnel retention method
1—Electric Ramp; 2—Rowstone; 3—Funnel; 4—Pillars; 5-Patio;
6, 7 - middle section transporting alley; 8, 9 - smooth road patio; 10 - slipping mine
The production practice proves that the double-layer tunnel retention method is an effective mining method for the ore body with steep inclination and steep change. It obviously improves the ore recovery rate and reduces the ore depletion rate. Filled with mined ore, it has a good supporting effect on the surrounding rock.
The main technical and economic indicators of the double-layer ramp retention method are listed in Table 2. Under the similar conditions of ore body occurrence, the 3752, 463, and 7151 stope with single-layer ramp mining, the production capacity of the ore block, mining efficiency, and explosive unit consumption are all close, and the ore loss rate and depletion The rates are 18.8% to 30% and 35.4% to 40%, respectively.
Table 2 Main technical and economic indicators of double-deck ballast retention method
Nugget number
263
362
2761
Nugget production capacity / t · d - 1
Mining work efficiency / t · work class - 1
Explosive unit consumption / kg · t - 1
Ore loss rate /%
Ore depletion rate /%
55
11
0.49
6.6
13
90
11.5
0.5
12
25.5
50
12
0.55
7.8
15.8
The double-layer ramp retaining method still has the following shortcomings: the large amount of mining and cutting works, the double-layer ramp and the mining at the same time, the inconvenient contact, the safety is poor; the occupation of equipment, the electric pick-up winch handling, the installation workload is large. These problems need to be further improved and improved in production.
V. Mining method for simultaneous mining of mines and pillars
As a new process, the mine and the pillars of the retention method are used as a new process. The production practice is carried out in the C-51 block of the 8th-stage 32-1 vein of the No. 3 pit of Wulong Gold Mine (Fig. 5).
Figure 5: Mining method for simultaneous mining of mines and pillars
1—upper stope; 2—upper stop bottom column; 3—top column; 4—central well; 5—Gulu well; 6—single-sided column;
7—adjacent mining houses; 8—bottom columns; 9-middle section along the vein roadway; 10—electric ramps; 11—pant prospecting wells
The C-51 ore is 128m long, the ore body is inclined at 80-85°, the average thickness is 5.3m, and the average geological grade is 6.3g/t. Divided into two stopes; 2 stop length is 56m, and 3 stop length is 72m. The mining, cutting, mining, ventilation and pedestrian structures of the two stopes shall be designed and constructed according to the process requirements. The bottom structure is in the form of flat bottom of the electric shovel, the bottom column is 4.5m high, the top column is 5m high, and the middle column of the two stopes is 2.5m wide. The middle column of the column is only arranged to the side of the 2 stope. The height is 5m.
Firstly, the mining mining area of ​​the 2 stope is recovered. When the mining is carried out to the top column, the top stop column and the upper stage bottom column are retracted in the direction of each stopway until the boundary of the column. Part of the ore is removed from the edge end, and the ore is removed from the edge of the stope by the principle of not affecting the normal mining conditions of the stope.
At the same time as the mining in the 3 pits, the horizontal blasthole is used to recover the column. At this time, the amount of ore discharged from the lower part of the column should be strictly controlled, and it is required that the ore interface of the 2 stope will not fall. When the working space in the lower part of the column is insufficient, the ore discharge should be carried out from the ore discharge port adjacent to the inside of the column to complete the flat field work under the column.
When the mining and mining columns of the 3 stope are recovered to the top column, the top column of the 3 stope and the bottom column of the upper stage are recovered later. The recovery method of the column and the top column and the upper stage column is shown in Fig. 6.
Figure 6 Synchronous mining of mine and pillar
A—synchronous mining and mining of the mine column; b—reverse step type mining top column and upper stage bottom column;
1—gun hole; 2—active ladder; 3—has returned to the mining room; 4—is returning to the mining room; 5—intercolumn; 6—bottom column; 7—top column
After the end of the mining stop, use three electric rafts at the bottom to release all the ore deposits of the two stopes.
Synchronous mining technology of mining room and pillar, compared with the step-by-step mining process, eliminating the preparation work before the column recovery (such as setting the working platform and Fengshui pipeline, restoring the roadway, etc.), simplifying the process: weakening the pillar The stress concentration improves the working conditions and greatly improves the recovery rate of the pillars (the column recovery rate is only 25.5% in the step-by-step mining process, while the synchronous mining process reaches 90%, the top and bottom columns are synchronously harvested, and the recovery rate is increased by 10%. ~20%). However, the synchronous mining process has strict requirements on the ore-mining control, and the adjacent mining site recovery relationship requires uniform, appropriate and regular. In addition, the mining of long stope requires higher stability of surrounding rock. These need to be further refined in production practice.