Application of Deep Hole Caving Method in Strong Pulling Groove in Underground Space Treatment
After more than 30 years of underground mining in the history of the Sandaozhuang mining area, a large number of underground empty areas have been formed in the open-pit mining boundary. The total empty area is 1.2 million m2, and the empty area is 18 million m3, while the geological resources affected by the empty area account for The total resources of the entire Sandaozhuang mining area are 30% to 40% [1]. Because large-scale mined-out areas exist in the open-air boundary of current production, multi-level goafs are extremely complicated, and the existence of a large number of irregular and multi-level overlapping goafs seriously affects the normal production of mines, and the personnel for mine construction and The equipment brings great security threats, and the recovery of residual mineral resources is difficult and dangerous.
In response to the problem of governance in the goaf within the boundary, the mine cooperated with the Changsha Mine Research Institute to carry out a large number of research on the treatment plan of the goaf. Some methods such as surface drilling and gravel filling, deep hole caving in the surface, concrete filling method, and open step slope rebuilding are studied [2]. Among them, the deep hole caving method in the surface is used. The method has wide application range and strong flexibility. In view of the mining conditions of the Sandaozhuang mining area, this paper mainly introduces a special form of deep hole caving in the earth's surface. - Strong deep groove caving method to control the goaf.
1 explosion area situation introduction
The explosion area is located in the south of the D district of the Sandaozhuang open-pit mining area, with a line of 5-11, between the vertical XVII and XVIII lines. The blasting steps are 2378 horizontal and 1390 horizontal. The surrounding area is mainly 1350 and Two large empty areas of 1330 were drilled and monitored in the empty area of ​​the explosion area.
1.1 Explosive area geology
The stratum in this area is diopside garnet skarn (zjs2-2). There is a large broken belt exposed in the perforated area, the width is 3~5m, and the structural belt is 133°∠89°. The ore body is mainly distributed in the diopside garnet skarn, and the average grade molybdenum is expected to be 0.118%, tungsten is about 0.094%, and no magmatic rock is exposed [3-4].
1.2 Empty area within the explosion area
1350 empty area: In 2012, the 1350 empty area and the lower 1300 empty area were filled, and the filling amount was relatively large. From the hole area drilling detection and 3D laser scanning analysis, 85% of the upper part of the 1350 empty area was 1376 empty area. The imaginary mulch is covered, the thickness of the false raft is 14~16m, the thickness of the roof rock is 22~26m; the shape of the 1350 empty area is simple, the elevation of the floor area is 1343～1346m, the elevation of the roof is 1352～1356m, and there are 2 pillars in the empty area. The empty area spans 20~30m, the mining height is 8~14m, the horizontal top plate to 1378 horizontal thickness is 23~26m, and the thickness to 1390 level is 34~36m (including imaginary 碴14~16m). There is a large broken belt at the 9th line that divides the entire empty area from south to north.
1330 empty area: From the original data analysis, there are 1330 empty areas below the 1350 empty area. The height of the empty area is 4m, 6m and 8m. The floor area of ​​the empty area is 1328~1332m, and the elevation of the top area of ​​the empty area is 1334~1338m. The thickness of the partition between the level and the 1350 empty area is 10 to 15 m, and the area of ​​the overlap area is 550 m 2 . However, from the analysis of the drilling data, except for the 1402-2# detection hole, the 1330 empty area was detected, and the surrounding detection holes failed to detect the 1330 empty area. Therefore, it can be inferred that the 1330 empty area is not large and will not have a major impact on the processing of this empty area.
1.3 Empty area monitoring
In this blasting area, there are currently four monitoring holes 1390-53#, 1390-54#, 1378-23#, and 1366-31#. According to the monitoring situation, there is no large ground pressure activity event recently [5- 6]. In general, it can be preliminarily concluded that the ground pressure in the through-space area is not obvious and is temporarily relatively stable.
2 empty area treatment plan
Since 85% of the 1390 level in the upper part of the 1350 empty area is covered by the virtual turbulence after the 1376 empty area treatment, the 1390 horizontal treatment perforation is difficult, the hole formation rate is low, and it is difficult to ensure that the empty area is successfully collapsed; To the level of 1378, and then treated by the medium-deep hole caving method, although the imaginary shovel can be shoveled to solve the problem of perforation, but the steps are all reduced to 1378 level, the thickness of the top plate to the step surface of the empty area is only 22 to 26 m, and The span of the empty zone is up to 30m, and it is difficult to be secured during the perforation process due to the influence of the structural belt.
In order to carry out the 1350 empty space treatment under safe conditions, it is planned to arrange deep holes at the 1378 level (corresponding to the 1350 empty area), and at the 1390 level (corresponding to the 1376 empty area processing range), the cutting deep holes are arranged, 1390 and 1378 Two steps were simultaneously blasted, and the 1350 empty area was cut and collapsed (see Figure 1 for the layout of the hole). The total area of ​​the blasting area is 5,528 m2, of which 1390 horizontal blasting area is 3,108 m2, and 1378 horizontal blasting area is 2,420 m2.
2.1 cloth hole way
According to the lithology and empty area treatment requirements in the blasting area, the 1378 horizontal troughing area uses KY-310 cone drilling to construct a deep hole with a hole diameter of 310mm, using 5.0m×5.0m hole net parameters, square-shaped cloth holes, pulling The area of ​​the trough area is 500m2, and the rest of the 1378 level is constructed with a DTH drill with a hole diameter of 140mm. The parameters of the 5.0m×4.0m hole network (ie, the hole spacing is 5.0m and the row spacing is 4.0m) are presented. The triangle hole is arranged, the blast hole near the slope is arranged as the inclined hole (the blast hole inclination angle is 75°-80°); the 1390 level is constructed by the down-the-hole drilling rig with the hole diameter of 140mm, and the 4.5m×4.0m hole is adopted. The mesh parameters (that is, the hole pitch is 4.5m and the row spacing is 4.0m) are arranged in a triangular manner [7].
2.2 Perforation conditions 1378 horizontally arranged 30 slotted holes with a hole diameter of 310mm,
The average hole depth is 25 m, and 37 cutting holes having a hole diameter of 140 mm are arranged, and the average hole depth is 26 m. The 1390 horizontally arranges 76 cutting holes having a hole diameter of 140 mm, and the average hole depth is 31 m.
The perforation effect of the two steps was good. The hole penetration rate of the 1378 horizontal blasthole was 100%, and the pass rate was 96.3%. The hole penetration rate of the 1390 horizontal blasthole was 100%, and the pass rate was 90.6%.
2.3 Charge construction
The blasting explosive uses a porous granular ammonium explosive, and the water hole is an emulsion explosive.
The blasthole in the trough area is divided into two sections for charging. The lower charging section is 7-11 m, the middle interval is 2 m, the upper section is 8 m, and the upper part is filled with 5 m. The blastholes outside the troughing area are connected by a columnar charging structure. Duan Shuang initiated the explosive detonation, no interval in the middle, and the upper part of the blasthole was filled 3.5~4.0m. The through hole should be blocked by the lifting hole first, and the hole is densely packed with fine rock powder, and the length of the blockage near the stepped surface should be correspondingly increased. The structure of the blasthole charge is shown in Figure 2.
2.4 blasting network connection
The blasting is strongly segmented in the hole of the groove, and the other cutting holes are not segmented, and the continuous charging structure is adopted. The non-electrical millisecond delay detonator detonates, and the network is a row-by-hole detonation network. The control row uses double-issue 17ms, 25ms non-electrical millisecond detonator to blast, the common row uses 42ms, 65ms non-electrical millisecond detonator to blast, and the hole uses 400ms non-electrical millisecond detonator to detonate. The 1378 horizontal strong groove area is connected with the detonating cord at the orifice to connect the upper and lower stage detonating tubes. The blasting interval of the upper and lower sections is 300ms (see Figure 3 for the strong blasting area of ​​the trough area), and the blast hole of the 1378 horizontal cutting area is detonated by the hole. The detonation point is connected to the upper segment detonating cord through a 17ms non-electrical millisecond detonator. The 1390 horizontal blasthole detonation point is connected to the 1378 blasting network through a dual-issue 400ms non-electrical millisecond surface tube, and the V-type detonation. The 1378 horizontal strong pull zone was first detonated, followed by the 1378 horizontal cutting zone and finally the 1390 horizontal cutting zone. The total surface propagation time is 983ms. The flying speed of flying stones is much smaller than that of the upper step network. The upper and lower step blasting networks do not affect each other, and the network is safe and reliable.
3 blasting effect and evaluation
In this empty area treatment, the deep hole blasting was carried out simultaneously with 1390 and 1378 steps, with a total area of ​​5528 m2, of which 1390 horizontal blasting area was 3108 m2, and 1378 horizontal blasting area was 2420 m2; a total of 143 blasting holes were constructed, and the total drilling volume was 4052 m. The charge is 82.4t, the processing area of ​​1350 is 5200m2, the volume is 41600m3, the ore is 332,000 tons (104,000m3), and the cost is 3.63 yuan/m3.
After the blasting, the blasting situation was analyzed and analyzed on the spot. From the collapse of the step surface, the height of the slope of the 1390 step in the southern part of the treatment range was 8~9m, and the volume of the collapsed ore was calculated. The application of deep hole caving in the tank in the treatment of underground space is well filled with 1350 empty space; the subsidence area is 1140 m2, which is approximately equal to the 1350 empty area of ​​the treatment area. It can be concluded that the 1350 empty space has been comprehensively processed, achieving the purpose of the 1350 empty area collapse treatment, and eliminating the safety hazards of the 1350 empty area.
4 Conclusion
(1) Strong groove processing method As a new type of empty area treatment technology, it has the advantages of simple process and low cost. The processing cost of empty area is only 3.63 yuan/m3, and the comprehensive technical and economic indicators are advanced.
(2) The strong pulling groove method has a short construction period in the goaf, which can achieve the purpose of rapid and effective treatment of the goaf, and has positive significance for safe production of the mine and stable mine output.
(3) The successful application of the strong-groove method in the Sandaozhuang molybdenum-tungsten mine indicates that the technology has broad application prospects in the treatment of empty areas and can be applied to other similar mines.
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Author: James Jin, Luo Jia; Changsha Institute of Mining Research Co., Ltd., Changsha 410012; National Metal Mining Engineering Technology Research Center, Changsha 410012;
Source: Mining Technology 2015, 15(5);
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