Optimization of the treatment plan for the two-step empty field of inclined thick ore body

0 Preface

The goaf is generally the space left after the mining of the deposit by the mining method such as the room-pillar method, the comprehensive method and the retention method. If it is not treated or handled improperly, it will cause significant safety hazards.

The treatment methods at home and abroad are mainly divided into five categories: filling treatment empty area, caving ore processing empty area, leaving permanent pillar support empty area, isolation and drainage space area and joint method processing empty area. Each method has its own specific conditions and advantages and disadvantages. The two-step open-field mining method is used to divide the ore body into a mine room and a mine column. Generally, the mining room is first used, and then returned to the mining column and the goaf is treated at the same time. With the mining work in the mining area, the exposed area of ​​the empty area is getting larger and larger, and the stress concentration phenomenon is increasing. There will be ground pressure such as local caving of the empty area, deformation and destruction of the pillar, and difficulty in maintaining the stope in the adjacent operation area. It is possible that a large area of ​​sudden rock mass caving and movement will have serious consequences for production and safety, and it is necessary to return to the mining column in time and simultaneously treat the goaf.

1 empty area treatment plan and cost estimate

According to the existing goaf treatment methods at home and abroad, combined with the hydrogeological conditions, mining status and current situation and stability of the No. 70 vein of a large rock gold mine, the two-step empty field mining is adopted in the middle section of the 1304m mine. It is divided into a panel every 100m along the direction of the ore body, consisting of four one-step stopries with a width of 10m and three two-step stopries with a width of 20m. After the completion of the deep hole recovery in the first step, a 10m wide goaf is left, and the second step stop adopts a segmented fan-shaped medium-deep hole lateral collapse ore post-placement plan, and the stope is forced to release the empty area at the same time. Three kinds of schemes were proposed: top-deep hole topping, diverticulum strip pack topping, and small well medicine room topping. A large amount of surrounding rock collapses to fill the goaf or form a buffer layer with a thickness of 20 m or more below the goaf, thereby avoiding or reducing the hazard of air shock waves.

1.1 Strip drug pack chamber forced ceiling plan

The top chamber is arranged in two layers, which are a top chamber layer and a strip-shaped drug coating. In the roof road of 1334m level, three layers of diverticulum are designed by using the original project to lay a top chamber, and the maximum resistance line of the chamber is 38m. The strip-shaped ceiling chamber of 1337m level was cut from the middle of 1334m to the level of 1337m, and the length of the two-shaped drug packs was 38m and 40m respectively. The structural design section of the strip-shaped drug chamber is shown in Figure 1.

The strip charge is used to strengthen the loose blasting calculation of the charge. The calculation formula is shown in (1). The estimated amount and cost of the chamber discharge are shown in Tables 1 and 2.

Where: Q———calculate the dose, kg;

e———the conversion factor of explosives, which is 1.0 for the No. 2 rock explosive;

K'———— Loose blasting dose coefficient, the value of the loose blasting of the flat terrain is 0.44K, and the value of the multiple vacant surface or collapse blasting (0.125~0.4)K, where the value is 0. 4K;

K———standard unit consumption, kg/m3, syenite is 1.4;

L—the length of the strip chamber, m;

W———the minimum resistance line, m.

After calculation, the maximum dose of diverticulum is:

Q 硐=1×0.4×1.4×282×35=15360kg

1.2 medium and deep hole forced ceiling plan

The medium-deep roofing scheme is to use the down-the-hole drilling rig to lay the hole in the top plate of the 1344m middle section of the gently dumping mining body. For the panel test stop, 23N22, 21S13, 21N2, 19S33, 19S18, 21N2 are used as the mining quarry, and the mining is only after the topping. The middle and deep holes are divided into the north and south areas, and the north area is 23N22 and 21S13. The top of the stope, the southern section is the top of the 19S33, 19S18 two stope. A medium-deep hole forming method is used to form a cutting well, and a parallel downward direction is made in the cutting cross-section, a cutting vertical groove is formed by blasting the cutting well as a free surface, and a fan-shaped medium deep hole is cut in the rock drilling lane to cut the vertical The trough is a free-surface one-time detonation collapsed roof. The estimated amount and cost of the project are shown in Tables 3 and 4.

The top hole deep hole construction adopts the downhole hole drilling machine with a hole diameter of 90mm, the hole bottom distance is 4~5m, and the row spacing is 3~4m. The medium and deep hole topping project is large in quantity, the explosive consumption is large, and the cost is high.

1.3 small well drug room forced ceiling plan

In order to reduce the single-dose dose, multi-chamber segmented millisecond blasting was used to force the collapse of the roof, and 12 small well chambers were arranged at the level of 1337m and 1344m. The cross section of each diverticulum is 1.2m×1.2m. In order to find out the location of the empty area and the thickness of the roof and construction safety, firstly, a 3m×3m×3m chamber is placed in the position where the medicine room is arranged. The geological core drilling rig is used to detect the position of the empty area downwards, and the thickness of the actual roof is detected. The depth of the small well chamber is determined according to the actual situation of the empty area to ensure that the distance of the minimum resistance line meets the design requirements and provides safety for the construction process. . The design section of the small well drug room topping project is shown in Figure 2. The excavated waste gangue is piled up in the roadway of 1344m level to ensure the material supply of blasting backfill plugging and reduce the amount of transportation engineering. According to the actual situation of the blasting, the blasting blockage is blocked according to the blasting regulations of the chamber. The estimated amount and cost of the small well medicine room are shown in Tables 5 and 6.

2 empty area treatment plan optimization

Compare the engineering quantity, construction difficulty and safety of the forced topping area treatment plan.

(1) Forced placement of the strip-shaped drug chamber. The amount of engineering is small, the amount of caving is large, and the construction of the project is simple; however, the topping seismic wave has a destructive influence on the surface structure, and the safety is poor.

(2) Forced topping in the middle and deep holes. The safety is good. The impact on the roof is small and the amount of collapse is large. However, the cost of roofing is high, the amount of work is large, the construction time is long, and equipment needs to be purchased.

(3) Forced placement of the small well drug room. The topping has little impact on Dongping Village, the cost is low, and the safety is general; but the amount of caving is small, the construction is difficult, and the blasting organization is difficult.

By comparing the economic cost estimates, advantages and disadvantages, and safety risks of the three types of forced headspace treatment schemes, it is known that the blasting site is closer to the village due to the large amount of explosives in the roof of the strip roofing chamber. The blasting will have a devastating effect on the surface buildings, and it is difficult to ensure the safety of the surface villages. This scheme is not suitable. In the construction of medium and deep hole topping scheme, the deep hole needs to use the downhole drilling rig. The construction task is tight and the engineering quantity is large. The existing drilling equipment of the mine cannot meet the construction requirements, and the topping cost is the highest. This scheme is also not desirable. The small-cylinder pharmacy forced topping scheme has a small amount of single-stage detonation, which can meet the requirements of safe construction and production. The construction period is short and the production cost is the lowest. The technical feasibility of the scheme is economical and reasonable. Therefore, it is recommended to use the small well pharmacy to force the roof as the inclined thick. The implementation plan of the two-step empty field mining area of ​​the ore body.

3 conclusions

Aiming at the two-step empty field recovery and rear caving, three kinds of forced topping schemes for medium-deep hole topping, diverticulum strip topping and small well medicine chamber topping are proposed, and the advantages and disadvantages of the mining process and technical economy are adopted. The rationality comparison is to determine the optimal treatment plan for the goaf in the small well drug room, and provide reference for the treatment of goaf in similar mines.

references:

[1] Liu Dunwen, Gu Desheng, Xu Guoyuan. Evaluation and optimization of treatment methods for goaf in underground mines [J], China Mining, 2014, 13 (8): 52-55.

[2] Yan Hongjian, Chen Xingming, Yang Zaigao. Practice of goaf treatment combined with diverticulum and medium-deep hole blasting[J], Modern Mining, 2014, 1(1): 165-167.

[3] Liu Ling. Research and application of large complex goaf treatment methods [J], Mining Technology, 2008, 8 (1): 75-77.

[4] Yan Yurong, Liu Wutuan, Guo Shengmao. Application of Chamber Blasting in Empty Zone Treatment [J], Chemical Minerals and Processing, 2004(2): 30-32.

Author: Douzhi Ming; Song County Taurus limited liability company, Henan Song County 4,714,351;

Sheng Jia, Li Xiangdong, Zhou Yilong; Changsha Mining Research Institute Co., Ltd., Changsha 410012, China; National Metal Mining Engineering Technology Research Center, Changsha 410012, China;

Zhang Huatao, Gong Yicai; Jixian Jinniu Co., Ltd., Yanxian County, Henan 4714351;
Source: Mining Technology 2015, 15(5);
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