1 Engineering geological conditions
Huili Zinc Mine Tianbaoshan ore deposits, construction nearly north-south and east-west near the main north east and north west to construct a smaller scale. The near-north-north structure of the mining area is a cap rock structure, and the east-west structure is the product of the inheritance and development of the basement structure. The folds and faults in the mining area have experienced long-term tectonic evolution, often with multiple periods of activity history, and complex constraints and cutting relationships. The distribution situation ore, geological and rock alteration, etc., combined with its physical and mechanical indicators of rock, ore and rock which are divided into the following three groups: dolomite, diabase, lead zinc. Lead-zinc ore and diabase are both poorly stable rock masses, and dolomite is a medium rock mass. The bottom structure works mainly in lead-zinc ore and diabase. Therefore, the stability of the project is poor, and it is not allowed to form a large horizontal compensation space before blasting. It is difficult to blast the blasting in the expansion and bottoming projects.
2 leaky bottoming scheme
According to the stability of the rock, the method of pulling the bottom is different. According to the hole depth, it is divided into a shallow hole bottoming and a medium-deep hole bottoming scheme. The shallow hole bottoming scheme requires more formation lanes or It is necessary to form a large compensation space in advance, so it is generally only applicable to mines with stable ore, and the efficiency is low, the labor intensity is large, and the production process is increased, which increases the difficulty in the production connection and production management of the stope. The medium-deep hole bottoming has many advantages such as high efficiency, safe operation and simple process. According to the unstable rock of the E806 and E807 mining sites, the bottom blasting can only be blasted in the same sub-segment as the mining project. According to the specific conditions of the stope, three technically feasible bottoming schemes have been developed, namely the horizontal medium-deep hole bottoming scheme, the fan-shaped hole bottoming scheme, and the medium-deep hole leaking bottoming blasting scheme.
2.1 horizontal medium deep hole bottoming scheme
The rock drilling project is arranged as far as possible in the rock drilling road and the rock drilling roadway. Generally, the special bottoming roadway is not dug, and the horizontal deep hole is drilled in the rock drilling roadway. The same type of differential blasting is used for the expansion and the large-scale blasting. First, the leakage is carried out, and then the bottom is pulled. When the bottom is pulled, the rock-rocking joint is used as the free-face differential blasting, and finally the large-scale blasting is carried out. The bottoming engineering layout is shown in Figure 1.
2.2 Sector-shaped deep hole bottoming scheme
The fan-shaped medium-deep hole bottoming scheme reduces the corner hole angle when designing the face, and designs the number of blastholes according to the requirements of the bottom space. Generally, it is designed to cut 2 holes in one side and blast before pulling the mine. Bottom hole to form a bottom space. The same type of differential blasting is used for the expansion and the bottom blasting. First, the blasting is performed, then the bottom hole is blasted, and finally the large blasting is carried out, as shown in Fig. 2.
2.3 Medium and deep hole expansion and drainage bottoming same blasting scheme
The leaking bottom hole is constructed together. When cutting, the funnel well is appropriately deepened; during the rock drilling project, the machine is supported in the funnel well, and the leak hole is deepened to a certain height according to the range of the leaking bottom. The leaking bottom is blasted with the funnel well as the free surface, and the leaking bottom is completed once, as shown in Figure 3.
3 expansion and leakage bottoming scheme comparison
The three schemes are technically feasible. The horizontal deep hole scheme is consistent with the direction of the blasthole and the bottom boundary. The boundary after blasting can meet the design requirements, and the amount of blasting can be increased. The medium-deep hole bottoming scheme is technically feasible, and the support machine is convenient and safe. However, whether it is parallel arrangement or oblique arrangement, a large number of horizontal holes need to be drilled, the amount of rock drilling is large, and the difficulty of drilling horizontal holes is difficult. Larger and less efficient. In the fan-shaped medium-deep hole bottoming scheme, it is necessary to drill near-horizontal blastholes, which is difficult to drill. With the same sub-stage blasting, the required detonator section is high and the blasting design is complicated, but the blasthole boundary and the bottoming range are easy to control, and the bottoming is regular and the effect is good. The medium-deep hole bottom-dumping expansion scheme is carried out in the same section of the same period. Without increasing the detonator section, the blasting is easier to implement, the amount of blasthole construction is small, and the damage to the bottom layer is small; The deep holes in the upper tribe have a greater impact and complex design.
After discussion and technical argumentation, on the one hand, the E806 and E807 mining sites are simultaneously blasted, and the blasting is divided into two times. The first time is 2064, 2074 layer blasting, the second time is the expanded bottom blasting, 2044, 2054 layer blasting. The number of blasting sections is large, and the requirements of the detonator section are relatively high. In order to ensure the smooth implementation of the blasting, the scheme of the medium-deep hole expansion and drainage bottoming sub-stage blasting scheme is better. On the other hand, considering the crushing of the ore bodies in the E806 and E807 mining sites, if the blasting of the blasting is carried out in stages, it is difficult to stabilize the ore body after the expansion, which will cause difficulties in the bottoming project. According to the construction disclosure and mine measurement results, the vertical height difference between the bottom layer of the eaves layer and the upper layer (2036～2044) is only 7.6m, and the height of the bottom column is less than the design height; during the tunneling process, due to rock fragmentation, The roof of the roadway fell seriously and the bottom column had been damaged. Considering the actual situation on site, the design uses medium-deep hole expansion and pull-out, and the two projects are combined. In addition, due to the long mining period of the stope, the 2044, 2054 layered roadway has collapsed many times during the excavation process, and the construction period should be tightened, and the blasting should be carried out in time under the premise of ensuring safety, and the engineering quantity of the scheme is relatively higher than that of the other two schemes. Smaller, the efficiency of chiseling the inclined holes is also higher. In summary, the same-stage same-stage blasting scheme is adopted.
4 leaky pull bottom parameters
(1) Rock drilling equipment. YG-40 pole drilling rig , Φ60mm drill bit, drilling Φ70mm hole.
(2) Rock drilling parameters. The leakage design should be designed so that the blastholes are evenly arranged, and the arrangement of small resistance lines is adopted, and the multi-holes are less charged, and the peach-shaped pillars are destroyed as small as possible. In order to reduce the resistance line, the design adopts two ring holes. The angle of the outer ring blast hole and the funnel slope angle is 50°, the inner ring is 59°, the inner ring is 8 holes, and the outer ring is 12 holes, totaling 20 holes.
(3) Charge blasting. The Φ32mm emulsion explosive roll was used, and the millisecond differential detonator was used to detonate. The inner and outer ring holes were divided into one section of blasting, and the deep hole of the 2044 layered and 2054 layered ore was blasted at the same time, but firstly, the leaking bottom blasting was carried out.
5 Conclusion
The bottom layer formed by the same-stage same-stage blasting scheme can achieve a good buffering effect on the blasting, avoiding the violent impact of the blasting on the bottom structure peach-shaped pillar, and reducing the maintenance amount and cost of the bottom structure later.
For the extremely unstable ore body of the rock mass, the mining method of the funnel bottom structure is adopted, the diffusion bottoming and the segmentation large blasting are the same time differential blasting, and the deep hole is used for the bottoming, and the bottom hole is expanded. Construction, leaking bottom blasting points to the funnel well, which is beneficial to reduce damage to the bottom structure caused by blasting.
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Lai Wei, Yang Ning, Yin Xiangang; Changsha Mining Research Institute Co., Ltd., Changsha 410012, China;
Source: Mining Technology: 2016, 16(4);
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