0 Preface
Guangdong Province, Baoshan Mines Ltd. where mining is a large multi-hole metal mine, due to the large number of people stealing team of mining, illegal mining, the formation of a large number of blind mined-out area in the open pit, which is nearly as much as the volume Articles These blind mining areas have seriously affected the safe production of open pit mining. The specific impacts are mainly as follows:
(1) Seriously affected the normal production schedule,
Brought great difficulties;
(2) Reducing the stability of the mining area and threatening the production safety of the mine;
(3) Increase in production costs;
(4) The quality of ore is difficult to guarantee.
1 detection of blind goaf
Due to the existence of underground blind goafs, the timeliness of geophysical methods cannot meet the needs of production. According to the long-term exploration of the mine, the combination of borehole detection and three-dimensional detection is currently used. At the same time, actively find suitable sites for geophysical exploration, find a reasonable method suitable for mine lithology and conduct a wide range of geophysical exploration.
2 safety control in blind space
For the proven goaf, after years of production practice, a set of mature technologies suitable for mine processing goaf has been explored, and different methods are adopted for single-layer gobs and multi-level goafs.
2.1 Single layer goaf processing
The most basic treatment method for single-layer empty area is to use deep hole or medium-deep hole blasting. If the actual situation on site is not suitable for gob area where vertical holes are directly blasted on the roof of goaf, conditional hole blasting can be created. For example, cutting holes around the goaf or tilting holes near the side slope. The single-layer empty zone treatment method is shown in Fig. 1. Fig. 1(a) is the single-layer empty zone treated by the medium-deep hole blasting using the step slope as the free surface on the premise that the thickness of the roof of the goaf is not less than the minimum safe thickness.
Fig. 1(b) shows that under the condition that the thickness of the top plate of the goaf is less than the minimum safe thick bottom, the drilling can not be carried out above the goaf, and the cutting hole is arranged around the gob to blast the goaf.
2.2 Multi-level empty area processing
For multi-level goafs, different methods can be used depending on the location and drilling conditions.
2.2.1 Hierarchical processing
If the detection result finds that the multi-layer empty interval partition is thick, and the upper empty area is not affected when the upper empty area is treated, the method can be adopted.
The method first processes the upper empty area, and then processes the lower empty area, and the gob area of ​​each layer is processed according to the processing method of the single layer goaf. During the treatment, certain measures must be taken to reduce the impact of blasting vibration. After the upper empty space is processed, the lower empty space must be re-detected to ensure the safety of the roof during the construction.
2.2.2 Multi-layer processing
If the overlapping layers of the plurality of empty spaces overlapping each other in the spatial position are thin, and the upper and lower sides interact greatly when the hierarchical processing is performed, a multi-layer one-time processing may be considered. When using the multi-layer one-time processing method, the following two methods can be selected according to the location of the goaf and the performance of the rig :
(1) The whole area is filled and filled in the deep hole cutting area of ​​the large area. This method can be used when the multi-level goaf is overlapped and complicated, and the shape is not equal. The top layer of the first layer is thick and cannot be blasted by the surface free surface. In the case that the drilling machine meets the drilling depth, dense cutting holes are drilled on the outer edge of the ground surface along the goaf of each layer (except the first goaf), and the first layer of empty space can be single layer empty The zone method is punched. During blasting, the groove is firstly opened at the thinner position of the top layer of the first-level goaf, and the other blastholes are blasted by the slotted surface as a free surface. The treatment method is shown in Fig. 2.
When handling, it should be noted that the grooved surface should be at least 5 holes to control the size of the area, and the slot is leading the other holes 1 to 2. After the completion of the blasting, the volume is calculated to determine whether the multi-level goaf collapses completely.
(2) The flank exposes the caving and filling method. When the multi-level goaf is completely overlapped and can not be used to perform the cutting hole operation, the existing step free surface can be created or utilized during the processing, and the inclined free hole or horizontal hole blasting treatment can be performed on the step free surface of the side wing of the goaf. The method can be combined with the overall collapse filling method of the deep hole cutting area in the large area, and the step free surface is used to punch holes in the side of the goaf to ensure that the column of the goaf collapses, thereby causing the roof to lose support and forcing it to completely collapse. The processing method is shown in Figure 3.
2.3 Security requirements
The construction of goaf should be strictly in accordance with the principle of first detection and then propulsion, to ensure that the thickness of the roof of the goaf can be constructed within the safe range. At the same time, the method of detecting the side of the construction is adopted, and the thickness of the roof is determined by the blasthole. If the thickness of the roof of a certain area is less than the safe thickness, the construction should be stopped immediately, and other treatment methods should be studied. At the same time, in order to ensure the safe construction of personnel equipment, the microseismic monitoring system is used for 24h uninterrupted monitoring. Delineate the alert area, control the number of personnel entering the alert area, and develop an emergency evacuation plan.
3 Conclusion
After long-term exploration and research, Dabaoshan Mining Company has formed a complete set of mature goaf treatment methods, and takes corresponding measures for the gobs of different positions and shapes:
(1) The single-layer goaf of the roof is safely treated by one-time blasting;
(2) The single-layer goaf of dangerous roof is treated by cutting hole blasting;
(3) The complex non-free surface multi-level goaf adopts the large-area self-grooving deep hole cutting area overall collapse filling method;
(4) The multi-layer goaf with free surface adopts the flank drilling method to cooperate with the large-area self-drawing deep hole cutting area.
From a practical point of view, this method can solve various types of goafs that appear, and achieves better results. The application of this method can not only quickly process the goaf, but also avoid the casualties and property losses caused by the collapse of the goaf, and lay a foundation for the subsequent production and mining, improve the processing efficiency of the goaf and ensure the production. .
references:
[1] Song Jiadong, Wang Jian. Open-pit mining technology of roof ore body in underground goaf [J]. Non-ferrous metals, 2000 (5) 14-18.
[2] Lan Yu, Zhao Xing. Discussion on safety control technology of underground complex goaf in Dabaoshan Mine [J]. Southern Metals, 2012, 6 (12).
[3] Yao Jian. Stability analysis and treatment technology of Dabaoshan underground goaf [D]. Changsha: Central South University, 2006.
[4] Chen Min. Research on risk assessment system for underground mined areas of metal mines [J]. Mining Technology, 2007, 7(3): 22-27.
[5] Liu Xiling. Research on stability analysis and safety warning of space based on laser three-dimensional detection [D]. Changsha: Central South University, 2008.
Author: Zhao; Dabaoshan Mining Co., Ltd., Shaoguan City, Guangdong 512127;
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