Example of underground mining-remaining mining method for rock gold deposit (遂昌金矿)

Suichang gold ore deposits in accordance with its conditions, also adopted comprehensive mining law Shrinkage.
First, mining technical conditions
Deposits occur in the metamorphic Predevonian configuration alteration zone, the solution is warmed to build lean pale gold silver sulfide account vein quartz rock deposit. The gold and silver in the ore are symbiotic, and the average grade is Au11.5g/t and Ag270.27g/t. The boundary between the ore is not obvious, and the ore body is delineated according to the sampling analysis results.
The inclination of the ore body is generally 45° to 60°, and the portion is less than 40°. The thickness of the ore body is 0.33 to 11.0 m. Many ore bodies and surrounding rocks are disturbed by faults and interspersed with veins, but most of them are not developed. It is relatively stable, and some surrounding rock of the ore body has a set of fissures and smooth surfaces parallel to the ore body, and the stability is poor. The ore is vein quartzite , hard, f=19. The surrounding rock is mainly black mica slant gneiss , f=14~15.
Second, mining method structure and mining cutting
The length of the nugget along the strike is generally 50m, the height of the nugget (stage height) is 40m, and the thickness of the nugget is equal to the thickness of the ore body. The ore block is divided into a mine house and a mine column. The column width between the two sides of the mine room is 3 to 4 m, the height of the bottom column is 5 to 6 m, and the height of the top column is 2 to 3 m. When the ore nuggets are used, the existing prospecting and perforating tunnels (one per 25m) are used to transform into tunnels for tunneling and to dig up the mining patio (2.5m×1.5m) along the ore body, on both sides of the ore block. The central government has three courtyards. A 30 kW electric winch was installed in the corresponding perforated roadway at the upper end of the central patio. The bucket and steel were led through the guide wheel to the bottoming tunnel. A 2 m wide and 3 mm thick steel plate was placed on the bottom of the central patio as the chute floor. In the vein-transporting lane corresponding to the lower end of the central patio, the expansion is carried out upwards, and a self-made vibration concentrator is installed. 5m above the floor of the transport flat road to dig the bottom of the flat, connect the three patios inside the ore, and then expand to the full thickness of the ore body, forming a 2m high bottom space. The structure of the mining method is shown in Figure 1.

Fig.1 Schematic diagram of the comprehensive method for retaining ore in the Suichang gold deposit
1—extra-pulse transportation roadway; 2, 3—through-pulse transportation roadway; 4—mine body;
5—reservation of return air wells; 6—artificial column; 7— iron chute; 8—central patio;
9—Electric winch winch; 10—Artificial bottom column; 11—Vibration release funnel; 12—Block
Third, mining work
For the higher grade ore, in order to improve the ore recovery rate, the first mining column is used, then the concrete is poured to form the artificial column, and finally the mining sequence is returned to the mining room.
(1) Recovery of the bottom column and formation of the artificial bottom column
A further 2 m was taken over the formed 2 m high bottoming space to form a 4 m high space, and all the collected ore was thrown to the funnel. Spread a layer of insulation (waste plastic bags, etc.) on the floor of the space. The concrete conveyed from the concrete mixing station is transported from the upper stage through the central pipe to the bottom layer by the slide pipe, and is flattened by hand or electric raft to form an artificial bottom column of 1.6 to 2 m thick. When the thickness of the ore body is greater than 3m, use appropriate amount of steel or steel rope as appropriate.
(2) The recovery of the column and the formation of the artificial column
The patios on both sides of the ore block are harvested on the full thickness of the ore body, and the upper disc direction is 3 m wide and the lower disc direction is 5 m wide, forming a section as shown in Section 2. The mining method can be used for mining. After the completion of the mining, all the ore is discharged, and a spacer such as a straw bag is applied to the body to be mined. When mining in the lower direction, take 1m 2 on the outside of the 3m mining frame to reserve the vent. Applying the “sand core method” to form the venting port, that is, a steel wire rope is used to connect the rubber air duct with a diameter of 1 m through the wire, and the outer layer of the air cylinder is covered with a plastic cloth instead of the template, and two are placed close to the lower plate. In the 1m 2 space, the air cylinder is filled with yellow sand. After these work is completed, the mixed soil is poured into the occupied space to form an artificial column. After the concrete has solidified, the steel rope is vibrated, and the yellow sand, steel rope and air duct are recycled for reuse. Reserved vents are formed on both sides of the artificial column.

Figure 2 Cross-section of the column
(3) Mining house mining
After the concrete in the artificial bottom column and the intermediate column reaches the required strength, the mining room can be recovered.
At the time of mining, the central courtyard (slot) is bounded, and the mine is divided into two parts, one part is recovered, and the other part is sampled and analyzed to circle the ore body, and the two are alternately carried out. In this way, the mining work can be carried out on the basis of sampling analysis and correct delineation of the ore body, which can reduce the blindness of mining and reduce the loss of depletion.
The mining work was carried out from the bottom to the top, and the YT-27 gas-leg rock drill was used to hit the shallow mine. The mining working face forms an inclined surface of 10°~15° from the two sides to the central chute, so as to improve the electric tapping capacity. After each fall, the local mining is carried out. Partial mining is carried out with an electric raft installed on the central patio, and the ore is transported to the central chute and discharged through a vibrating ore concentrator. In order to control the ore on both sides of the central chute, a steel rope net is installed on both sides of the chute, and the steel rope net is fixed by anchor bolts buried in the upper and lower plates of the mining room, and gradually advancing with the work surface upward. When the mining is combined, a large amount of ore is discharged. At this time, the working line of the ore is pushed downward from the bottom, and the inclination to the chute can be increased to 25° to 30°, and the steel rope net is gradually removed.
The roof of the mine is mainly supported by the artificial column and the top column, and the local unstable section is reinforced with anchors. When the mine is mining IV-4 and IV-5 ore bodies, there are faults and fracture zones in the surrounding rock of the upper plate. There has been a roof fall accident in the stope. For this reason, the roof maintenance experiment was carried out and the temporary mine was proposed. The column is used to reduce the exposed area of ​​the top plate during the mining process, the strong mining force is used to shorten the exposure time of the top plate, and the technical measures such as applying the anchor bolt for roof protection are adopted.
Fourth, technical and economic instructions
The main technical and economic indicators of the comprehensive method of retention of the Minchang Gold Mine are shown in Table 1.
Table 1 Main technical and economic indicators of the comprehensive method of retention of minerals in the Suichang Gold Mine (1991)
Indicator name
Value
Indicator name
Value
Mine production capacity / t · d -1
80～90
Mining rate / t · work class -1
8.88
Mine depletion rate /%
18.25
Explosive consumption / kg · t -1
0.612
Mine loss rate /%
4.42
Direct mining cost / yuan · t -1
13.98
V. Evaluation
The spurt gold mine used the fan-shaped working face to retain the mine comprehensive method. In the production, it was found that when the mining work was advanced to the maximum shovel angle of the electric shovel, the left triangle ore body was difficult to recover. Later, it was changed to a central chute in the center of the mine, and the inclined working face on both sides was used to advance the law. According to the characteristics of high ore crystal position of the mine, the artificial gold column and artificial bottom column are used to improve the recovery rate and economic benefit of the ore. The use of electric rafts, iron chutes and vibrating concentrators combines the mining and improves the mine. The mining capacity of the house; the use of the post anchor to improve the stability of the roof of the mine and reduce the depletion rate of the ore. These production experiences have reference value for similar conditions.

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