Application of mining environment reconstruction in the recovery of hidden danger resources

Hidden resource refers to the difficult resource that is difficult to mine due to natural conditions or human factors, and the recovery rate is low.

The 0# stope of the middle section of Sh-320 in Fankou Mine is located in the upper middle section, which is the main ore body area. The ore body is thick and high in grade. The VCR method is used for mining, and a large gob is formed after the blasting of the stope. The remote-controlled scraper performs remote-controlled shovel mining. Due to the factors such as the mining sequence, the rock structure, the fault, the ground pressure, the mining blasting, and the exposure time of the empty area, the gangs of the stopway have a cross-help, which leads to the peripheral phase. Large area instability occurs in the adjacent area, and the technical conditions for resource exploitation within the scope of its impact become extremely complicated, and resource recovery is extremely difficult. It must be rebuilt through the recovery environment to achieve safe and efficient recovery of resources.
1 mining environment analysis
Among the many factors that plague the recovery of hidden danger resources, the stability of the stope is undoubtedly the primary factor. It is accompanied by the whole process of recovery of hidden danger resources, which is an important guarantee for the safe recovery of hidden danger resources. Therefore, it is necessary to conduct on-site investigation, drilling, and mechanical analysis. Methods such as numerical simulation, analyze the impact range of collapse, determine the scope of impact and the reserves and occurrence of hidden resources, so as to provide a basis for the development of feasible schemes for the management of hidden danger areas and resource recovery.
1.1 Site investigation and investigation
After the occurrence of the stope, the site investigation of the local mine and mine, the comprehensive exploration of the surrounding operation area and the operation stop, the design and construction of the exploration hole to investigate the collapse area, and initially determined the scope of influence (see Figure 1).

1.2 Numerical simulation analysis
In order to further determine the scope of influence after the 0# stope collapse, the stress field analysis, displacement field analysis and plastic zone analysis were carried out by cooperation with scientific research institutes. The analysis results show that the maximum tensile stress of the two gangs in the goaf reaches 1 MPa, the maximum displacement of the two gangs is 11.6 cm and 11.1 cm, the displacement of the top plate is 8.0 cm, and a large range of shear failure occurs. Tensile damages the plastic zone and the plastic zone penetrates. Therefore, it can be known that in the case of laterally being pulled in the empty zone, the gangs and collapses are generated, and the roof is also subjected to different degrees of landslides, which eventually leads to large-scale instability failure of the entire empty zone, such as As shown in Fig. 2, the influence range of the site survey is within the dotted line, and the influence range is estimated by the numerical simulation within the solid line. The affected areas of the two analyses are basically consistent.

2 Mining environment reconstruction
2.1 Regional grouting reinforcement
The results of on-site investigation and numerical analysis show that the 0# stope has a great influence on the adjacent areas and the stope after the collapse of the stope, and it is necessary to comprehensively control the hidden danger area to meet the requirements of recovery safety.
On the basis of basically determining the scope of hidden danger resources, the overall hidden danger management plan will be formulated, the grouting holes will be constructed, and the grouting reinforcement will be carried out to comprehensively control the hidden danger areas, creating favorable conditions for resource recycling.
According to the actual project, the grouting method is used to fill and grout the collapsed area. The slurry diffuses along the chamber or crack under a certain grouting pressure gradient. When it is away from the grouting hole and the pressure gradient is reduced to the critical pressure, the slurry flow rate is reduced, and the hydraulic material in the slurry will solidify and become viscous. Increase, the flow rate is very low, and finally stop flowing. After the slurry solidifies, it fills the collapse zone, cracks and cements the debris.
A total of several kilometers of drilling holes were drilled, and the grouting amount was about 22,000 m3. The on-site investigation found that after grouting and strengthening the entire working area, the fallen area basically reached a stable state, which created favorable conditions for further further treatment and mining.
2.2 Stope grouting reinforcement
On the basis of effective management of the entire hidden danger area, further grouting and reinforcement of the main mining areas and stope will be carried out to achieve safe mining conditions. The down-stage grouting method is adopted for the stope, and the orifice pressure grouting is performed for each section of the stop. After the design end standard is reached, the next section of construction is carried out, and each grouting section is controlled at 8-10 m.

3 mining planning
The resources within the influence range of the main ore body collapse zone can be roughly divided into resources outside the slip surface range and within the slip line range. Since the stope in the range of the slip surface is likely to have moved to the goaf of the 0# stope, the mining of the stope in this range is difficult and dangerous, and the stope outside the slip line passes. Mechanical analysis and on-site exploration show that the mining of these stope is relatively difficult and the risk is low. Therefore, the overall mining sequence is planned as follows.

(1) It is easy to make it easy, first and then inside, and then proceed from the two sides to the middle, that is, firstly mining the stope at the periphery of the slip surface, mining the stope at the boundary of the slip surface, and finally mining within the slip surface. field.
(2) The stope within the slip surface, because the mining environment is extremely complicated, it is necessary to complete the above-mentioned mining of other mining sites and fill it with high quality, then do the necessary mechanical analysis to optimize the mining sequence and achieve safety and efficiency. Picking up. In addition, before mining, drilling, grouting and reinforcement should be carried out, and then reasonable mining methods and layout of roadways should be selected according to the actual project.
(3) Only after the slip surface is completely safely mined and high-quality filling is completed, the mining surface can be mined on the boundary of the slip surface.
4 mining field mining
According to the overall mining planning, take the S1-2# stope as the entry point, carry out the mining design after the grouting reinforcement, pay attention to the edge exploration and mining, and combine the mining and exploration. According to the mining requirements, the first stop of the S1-2# Mining - 320m four-segment to -280m two-section ore section, the section is basically below the collapse and slip surface, mining by VCR. The upper chamber is arranged in the -280m two-section section and the lower chamber is arranged in the -320m four-section. The second section is along the S1-2# mining site in Nanbang. The construction is 2.6m high and 3m wide. The bottom road is explored and the bottom road is formed. After the formation of the bottom road, according to the grouting reinforcement design and grouting construction requirements, the roadway Beibang The cutting is carried out, and the upper chamber is cut and the two holes are constructed and the grouting is strengthened to achieve the requirements of safe recovery. The section collapses in the mining site, and the length of each section is controlled within 30m. After the end of the blasting in the east, it is filled in time to strengthen the protection of the two fillings. Use the remote-controlled scraper to mine and ensure safety and efficiency.
5 results achieved
At present, the stope has entered the recovery stage. From the point of view of the recovery, the pre-grouting reinforcement has achieved good results. The overall treatment area is stable, no gangs and landslides have occurred, and safe recovery has been achieved. Accumulated valuable experience, further grouting reinforcement through mining, and re-engineering of the mining environment has created favorable conditions for subsequent recovery.
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