0 Preface
The essence of the deep hole section blasting method is to drill a set of parallel deep holes along the full height of the patio between the upper and lower middle sections with a deep hole drilling rig , and blast the well from the bottom to the top, and the blasted ore falls to the lower part. The middle section is shipped away. In the deep hole blasting well formation technology, the gutter form and the gutter parameters are the key factors affecting the well formation effect. In this paper, we use the large-cavity spiral grooving blasting technology to fill the empty space in the upper part of the underground goaf, and then fill the empty area with the ore through the patio to support the surrounding rock, avoid large-scale collapse and eliminate the ground. The purpose of the pressure activity.
1 project status
405m a horizontal copper pit mine stope out area (see FIG. 1), two roadway at an upper level of 405m 455m level remains after recovery to a level of 455m stope approach and long-term use; gob roof It is 15~17m away from the 455m horizontal transportation lane. In order to avoid the damage of the 455m horizontal stopway in the goaf of the goaf, and to combine the actual production needs of the Tongkeng mine, the blasting well method is used to fill the joint in the upper part of the goaf. Construction of a filling well, timely backfilling the goaf to ensure the safety of the 455m horizontal stop.
2 common blasting well formation methods
The 455m horizontal transportation mode of Tongkeng Mine is non-rail transportation. The waste rock is dumped into the filling well by car or scraper to realize the filling of the goaf. According to the actual situation of the Tongkeng mine, the filling well specification is generally 3m×3m. The layout of the blasting wells in Tongkeng Mine is shown in Figure 2. There are 21 lower parallel holes in the diameter of 90mm, including 5 grooving eyes, 8 auxiliary eyes and 8 peripheral eyes. - Auxiliary Eyes - The blasting sequence of the peripheral eyes is blasted, each blasting depth is 2 to 3 m. The blasting and well-forming method has large blasting property, and has high requirements on the control of the blasthole construction, the charging structure, the detonating sequence and the like. If these factors are not well controlled, the blasting quality will be affected.
3 large hole spiral grooving blasting technology
At present, the domestic deep hole blasting wells use large holes as the free faces of the parallel blastholes, and the free holes are preferably larger diameters.
A large-diameter hole is arranged in the center of the cross-section of the patio, and is drilled vertically and drilled through the entire patio, which is both a free surface and a compensation space for the blasting of the slotted hole during deep hole section blasting. The large holes increase the area of ​​the holes, improve the blasting conditions, increase the allowable deviation of the charging slots, and improve the reliability of the blasting.
In this test, the large-hole spiral grooving blasting method is adopted (see Figure 3), which is based on the common blasting and well-forming method of Tongkeng Mine. A total of 12 parallel-medium-deep holes are arranged, including one central hole. There are 3 sulcus eyes and 8 peripheral eyes. The diameter of the central hole is 300mm, and the aperture of the sulcus and the peripheral eye are both 90mm.
3.1 Determination of blasting parameters
According to the rock drilling equipment used in Tongkeng Mine, the 1# hole is first drilled with a drill with a diameter of 165mm. After completion, the drill bit with a diameter of 300mm is replaced for reaming.
The distance from the first cannon hole to the hole is calculated according to the following formula:
Where: D—the diameter of the hole, mm;
D———slot diameter, mm;
n———compensation coefficient;
L———the distance from the first bullet hole to the slot, mm;
After calculation, take L = 500mm.
Arrangement of the slotted holes. According to the nature of the rock and considering the previous engineering experience, the distance between the 2# slotted hole and the center of the center hole is 500mm, and the distance between the 3# slotted hole and the center of the center hole is 600mm, and the distance of the 4# slotted hole is from the center hole. The center distance is 650mm. 2#, 3#, 4# The angle between the center of the groove and the center of the hole is 120°.
The arrangement of the peripheral holes. In order to ensure the design section specification of the filling well, there are 8 peripheral holes, which are evenly arranged around the design section of the patio.
3.2 Charge structure and blasting construction
Charge structure: The height of the designed patio is 16m, divided into two blasts, each section height is 8m. When the parallel hole is used as the free surface, the minimum resistance line of the groove should not be too large. To avoid the excessive lateral impact dynamic pressure when the groove is collapsed, the hole should be blocked, and the charge density of the groove should be correctly determined. . A spacer charge method is used to reduce the charge per square meter of the well. The slotted hole is divided into sections, and the bamboo tube is used for spacing. According to the resistance line and the free surface size, each medicine bag is separated by 400 mm, and the detonating cord is placed on the full length of the charge. The peripheral hole is made of continuous column charge, and the charging method is adopted. They are all charged from top to bottom. The filling height of the lower part of the filling should not exceed the minimum resistance line of the hole, and the lower packing height is generally 0.8 to 1 m, and the peripheral hole is 0.4 to 0.5 m. The upper packing height is 1 to 1.2 m, and the packing material is river sand. The charging structure of the groove is shown in Figure 4. The structure of the surrounding hole is shown in Figure 5. The parameters of the hole are shown in Table 1.
Detonation network: The detonation sequence is shown in Figure 3. The slotted hole adopts the hole-by-hole detonation technology. The peripheral hole is detonated by two segments. The detonator is a half-second tube, the interval is 500ms, and the detonator is connected to the detonating cord at the orifice. Yue Yang, et al.: The application of large-hole spiral heaving blasting technology in Tongkeng Mine 81 is a double-shot connection. The clusters are detonated in parallel, all the detonating tubes are caught together, and then the two detonators are used to detonate.
4 Conclusion
The filling well is boring by means of large-hole spiral grooving and blasting into a well. Each blasting height is 8m, and blasting is performed twice. After the first blasting, the average shot depth is 7.5m, and each blasthole is a through hole. The bottom of the hole is neat and the blasting effect is good. After the second blasting, the filling well successfully broke through the top, and there were fewer throwings around the wellhead and the wellhead was regular. The deep hole blasting without a large hole in the center is more difficult and dense. The blasting is 1~2m, and the hole is easy to be blocked after blasting, and the construction period is long. In contrast, the large-hole spiral grooving blasting method has the advantages of reduced cloth holes, no clogging after blasting, high blasthole utilization, improved blasting depth, short construction period and reduced construction cost.
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Mo Supeng , Hunan Nonferrous Metallurgical Labor Protection Research Institute, Changsha 410014, China;
Source: Mining Technology: 2016, 16(3);
Copyright:
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