1 Mine status

Using a mine adit - + helper inclined chute to open up the system, the silver-copper lead-zinc ores and ore mining and handling points, mine production nearly 10a, copper and silver mining separate lead-zinc production design have now been reached ability. The mine is designed to the middle of 3886m. It is mined by the method of retaining ore and segmented empty field method. It has formed 3886m main transport flat, 4100, 4160, 4200, 4250m flat, and is currently preparing for the development of the middle section of 4000m.

Production practice shows that with the implementation of open field mining, the exposed area of ​​surrounding rock is getting larger and larger, and the amount of surrounding rock is increasing. Especially in the middle and late stages of mining, the amount of surrounding rock is Larger, local stope even produces large-scale caving, which causes the ore and surrounding rock to mix during the mining process, resulting in a depletion of ore loss. After the mining of the mine, some of the mines have suffered from large amounts of surrounding rock, and the mining conditions of the pillars have been seriously damaged. It is difficult to recover normally and can only be used for residual mining.
In addition, with the implementation of the open field method, there are more and more goafs, and the phenomenon of falling is becoming more and more serious. At present, the ground pressure problem of the mine is very prominent: the 4200m top column and the surrounding rock fall together, and some of the top and bottom columns fall in the middle section of 4160m, which makes the underground goaf area communicate with the surface, forming a large caving area; 4200m middle section The surrounding rock of the Cu1 ore body has fallen off on a large scale; at present, the west main roadway of the 4160m middle section is obviously narrowed, and the main roadway of the middle section of 4200m is continuously patched; the silver-copper ore body has been mined to the middle section of 4050m, and the independent lead-zinc mining is to the middle section of 4100~4160m. In the middle of 4050~4200m, there are still a lot of empty areas untreated.
The mining poverty index of the mine in recent years is not ideal. The mining method has the following proportions: 60% of the retention method and 40% of the segmentation method. According to the site investigation and communication with the mine engineering technicians, the depletion rate of the pillar recovery reaches 50%. More than %, or even higher, the comprehensive mining depletion rate is at least 22%; some of the pillars are unable to recover, all losses, the comprehensive loss rate of the stope is at least 18%. Due to the fact that some small veins are sandwiched between thick ore bodies, most of the thick deposits form large-scale multi-level empty areas. The technical conditions for the mining of small veins in the middle are destroyed, and the empty field method cannot be used for mining. The loss of this part of the veins is huge. Occupy a lot of resources. The mine urgently needs to solve the problem of the retention of the upper pillar.
2 The necessity of goaf disposal
If the area of ​​the goaf is too large and the volume of the empty area reaches a certain level, the safety hazard of the empty area will be formed. The existence of the goaf will constitute a serious threat to the safe production of the mine. If it is not processed in time, it may lead to The occurrence of mine safety accidents.
The current silver copper has been mined to the middle of 4050m, the independent lead-zinc mining to the middle section of 4100m, the middle section of 4100m and above has 4, 4200, 4200, 4250m middle sections, the distribution of the empty area is wide, the main empty area is 300-500m long from north to south, and the east-west width is 100. ~200m; the surface has formed a collapse pit of 380m long from north to south, 170m wide from east to west, and 80~100m deep. With the continued mining of 4100m independent lead and zinc, the volume of mine empty space and the number of pillars will further increase.
At present, the support of the mines in the mine goaf is supported by a large number of empty areas. The geological disasters such as sudden large-area empty area collapse and large-scale surface subsidence may occur. The consequences are very serious. It may form a downhole air shock wave, causing serious damage to personnel, equipment and roadway engineering. Therefore, while the mining method changes, the goaf must be processed.
3 primary selection of pillar recovery scheme
The mine design and retention method is mainly used for ore bodies with a thickness of less than 5 m. In practical applications, due to large changes in ore bodies, medium and deep hole rock drilling is often difficult to adapt and the loss of depletion is large. The actual retention method accounts for 80% of the total, and the bottom structure of the electric funnel is used. After mining, the column is 8~10m, the height of the top column is 4~6m, and the height of the bottom column is 10~12m. The spacing between the Yanlian Road and the layered contact road is different, and the rest are similar.
According to the mining technical conditions of the mine pillar and the characteristics of the mining technology, the mining method of the pillar can be regarded as the mining column under the condition of the empty space of the mine. According to the structure of the mining yard, the method of large blasting is generally adopted under the condition of the empty space of the mine. In the mining, the deep hole is used for blasting, and the ore column is collapsed to the open-pit mine, and the ore is discharged from the electric tunnel at the bottom of the ore block under the empty field or the falling cover rock. According to the actual needs of the mine, it is possible to blast a pillar that can collapse one to several ore blocks, which is beneficial to improve the mining strength and operation safety of the pillar. Since the middle section of 4100m and below is filled by the filling method, two mining schemes are preliminarily formulated for the pillars above 4160m:
(1) Scheme I, deep hole collapse column recovery scheme;
(2) Scheme II, measures for the recovery of deep hole caving pillars in wells.
3.1 Deep hole collapse column recovery scheme
After the mining of the mine, the rock mass is not stable, the empty area is stored for a long time, and a large number of pillars have been “slimmed down”, working in the original column patio, and the safety guarantee is poor. The scheme is built on the original column patio safe and reliable, and can be implemented and realized under the conditions of deep hole drilling in the inter-column patio. The intermediate column, the top column and the upper stage bottom column have deep blasting and large blasting. Wherein the bottom column above the electric ramp, when the electric ramp can be utilized, the fan-shaped hole is cut in the electric ramp, otherwise the rock chamber is dug at both ends of the electric ramp, and the horizontal chisel is horizontal or bundled; The top pillar and the bottom pillar of the electric ramp are horizontally fan-shaped deep holes in the rock chamber of the patio; the pillars are deep-holes in the rock chamber of the courtyard. This mining scheme has a small amount of mining and cutting work. As long as the construction of the rock drilling chamber and the deep hole rock drilling work are safe and reliable, the implementation of the scheme is relatively safe and reliable.
3.2 Measures well deep hole caving pillar recovery plan
When the original column patio is not safe and reliable, the construction patio and diverticulum are used as a working place for rock drilling and blasting in a safe position. The horizontal hole or bundled deep hole is chiseled in the pillar. According to the requirements of the recovery sequence, the corresponding column is required. , the top column and the upper stage of the upper stage are slightly blasted and dropped.
For some bottom pillars above the electric ramp, when the electric ramp can be utilized, the fan-shaped hole is cut in the electric ramp, otherwise the rock chamber is dug at both ends of the electric ramp, and the horizontal chisel is horizontal or bundled; The top column and the bottom column below the electric ramp are horizontally fan-shaped deep holes in the rock drilling chamber; the horizontal column is horizontally beam-shaped deep holes in the rock chamber of the measuring well. The program is safe and reliable, but the engineering volume is slightly larger.
3.3 Application of the recycling program
After investigating the distribution of the pillars, according to the similar ore body column recovery methods at home and abroad, two technically feasible schemes for deep hole caving pillar recovery scheme and measures deep hole caving pillar recovery scheme are developed. The shortcomings are compared in Table 1.

The two schemes have their own advantages. The 4160m middle section and the above two schemes are used together. When it is determined that the original patio can be safely utilized in the pillar, the deep hole caving pillar recovery scheme is adopted. Otherwise, the recommended measures deep well caving method for the pillar recovery scheme .
4 related projects
According to the distribution range of the empty area and the need for surface stripping and pillar recovery project construction, a intercepting ditch shall be set up 20m outside the mining subsidence zone and extended to 50m outside the mining area. The bottom of the drainage ditch is 1.5m wide and the upper mouth is 2,5m wide. The depth is 2m to meet the flood discharge demand of the mine during the rainy season.
When the safety of the original column is poor, the measures of the well pillar recovery scheme are adopted, and the tunnel is built in the stable rock of the lower plate with a distance of more than 5 m from the column ore body. The section is 1.5 m×1.5 m. The drilling chamber is drilled into the ore body at intervals of 10 to 12 m in the patio. The rock chamber is 5 m long and the section is 2.8 m × 2.8 m. For the mining of the top and bottom columns below the electric ramp, rock drilling is carried out in the measure well. The rock drilling chamber is drilled into the ore body at intervals of 5 to 7 m. The length of the rock drilling chamber is 5 m and the section is 2.8 m × 2.8 m.
5 Conclusion
The timely, safe and effective double recovery of the pillar recovery and goaf treatment is economic and safe, directly related to the production safety and economic benefits of the mining enterprise. The recovery of the pillars and the treatment of the empty area are carried out simultaneously. In the process of recycling the pillars, in order to ensure safety, it is recommended to establish a ground pressure monitoring system, conduct on-site monitoring in time, do a good job in ground pressure prediction and forecasting, and ensure the safe production of the mine.
references:
[1] Guo Shengmao, Liu Tao, et al. Bai Shanquan iron ore residue and recycling technology pillars out area [J]. Non-ferrous metals: mining section, 2014,66 (6): 18-20.
[2] Qin Xuekuan, Wang Zhiwen. Practice of mine column recovery in empty field mining method [J]. Gansu Nonferrous Metals, 2001 (4): 15-19.
[3] Zhang Fei, Wang Bin, Yan Yurong, et al. Stability analysis of surrounding rock in the recovery of goaf in No. 9 pillar of Dongshengmiao Mine [J]. Journal of Underground Space and Engineering, 2012 (06).