Completion time: March 2005

　　Project Location: Nantong Dantongkeng Mine

　　Completion unit: Beijing Mining and Metallurgical Research Institute, Huaxi Group Tongkeng Mine

　　Project host and participants: Sun Zhongming, Zhang Youbao, Li Shiqing, Chen He, Su Jiahong, Yao Genhua, Yu Ziqing, Liu Jiandong, Pan Jiaxu, Wu Guicai, Luo Xianwei, Yu Bin, Yu Yangxian, Wei Fangjing, Yang Weizhong, Cai Hanqian, Wang Huxin, Dong Weijun, Zeng Lunsheng, Mo Rongshi, Xia Hailiang, Wen Yanyu, Liu Menghong, Yuan Xiangquan, Xie Yuan, Wei Keli, Wu Zengqiang

　　Contributed by Sun Zhongming

　　In 2002, the Guangxi Academician Bank organized by the Chinese Academy of Engineering and the National Development and Reform Commission held a special discussion on the issue of the hidden dangers of the Tongkeng Mine. It clearly pointed out the urgency and possible treatment of the hidden dangers of the Tongkeng Mine. Technical approach. Based on this, the Beijing Research Institute of Mining and Metallurgy and Huaxi Group cooperated on March 28, 2005 to conduct a large-scale underground blasting with a charge of 150t at the Dantongkeng Mine in southwest Guangxi. This large blasting is a key project for the national key safety hazard remediation project, the hidden danger management of Tongkeng Mine, and the underground blasting of the largest blasting volume in China.

　　Huaxi Group Copper Pit Mine is a large underground mine with a mining history of more than 30 years. The three major ore bodies mined are the fine vein belts, the No. 91 and No. 92 ore bodies from top to bottom, and the three ore bodies are partially overlapped in the vertical direction. The earliest mined fine vein belt ore body spontaneously ignited since 1976, forming a fire zone that cannot be cured, causing disorder of the subsequent mining sequence, leaving a considerable number of irregularly distributed empty areas. With the development of mine production and construction, the main mining area of ​​the mine has gradually shifted to the lower No. 92 ore body, forming a group of upper and lower empty areas, and it is more difficult to control the ground pressure of the mine. Since 1998, local collapse of the stope and movement of the rock formation occurred, and then localized collapse began to occur. At the same time, the fire barrier column left in order to ensure the safety of the lower mining area has been in an incomplete state, controlling the spread of the fire zone and preventing it. The difficulty of ground pressure disasters is getting bigger and bigger, and the remaining 3.6 million tons of ore in the veins of the veins cannot be recovered. The mining operations of the lower 92 ore body are directly threatened. In 1997, it was listed as a hidden danger area for major accidents in Guangxi. In 2002, it was listed as a national key safety hazard remediation project.

　　In order to cure the hidden dangers and pressure disasters in the fire area and recover the ore resources, Huaxi Group adheres to the principle of “prevention first and safety first”, in the State Administration of Work Safety and the Safety Production Supervision Administration of Guangxi Zhuang Autonomous Region. Under the guidance, we will actively carry out the management of the hidden danger zone of the fine veins. The Beijing Research Institute of Mining and Metallurgy is a large-scale national comprehensive research institute. It has carried out long-term systematic work in the development and research of mining engineering technology, and many research results have reached the international advanced level. In particular, it has rich engineering practice experience and innovative technology in high-efficiency mining technology and large-scale blasting technology. In October 2003, Huaxi Group and the Beijing Research Institute of Mining and Metallurgy jointly cooperated to start a scientific and technological research project for the specific treatment of copper pit mines and related technologies. Since 2003, the Beijing Research Institute of Mining and Metallurgy has cooperated with the Huaxi Group Tongkeng Mine. After many investigations, analysis and argumentation, it has decided to adopt a partial filling, forced collapse, strong mining and strong out, closed coverage comprehensive treatment plan, and scope of treatment. It is divided into three explosion zones and blasting is carried out in stages.

　　The first explosion zone is located at the level of 570m to 650m in the fine vein zone, including the large 14th and 12th stopes and their corresponding upper fire barriers. Due to a large number of irregular vacancies, ballast damage and adjacent fire zones and other factors caused by quite complex blasting conditions and environment, for the different pillar conditions, the first blast zone adopts different stages of phase bundles such as linear, circular and square. The dense deep hole is mainly composed, and the blasting scheme of the local medium-deep hole and small diverticulum is supplemented to realize the overall collapse of the rock area.

　　The blasting resistance line of the bundle hole is 5 to 14 m. The beam hole blasting technology has the feasibility and applicability under special process conditions. Technically reliable, high efficiency and high strength. The large blasting design establishes the blasting vibration attenuation model and the downhole shock wave propagation attenuation model to accurately predict the harmful effects of blasting. The pre-cracking vibration reduction, flexible wave blocking wall, real-time monitoring and other technical means are used to effectively control the harmful effects of blasting.

　　The blasting rock chamber is located in the original mining approach or on both sides, 4m high. The beam hole has a depth of 30 to 62 m and is vertically parallel to the hole. The number of bundle holes is 3 to 9. Hole net parameters: beam spacing 6m × (6 ~ 12) m. The beam hole spacing is 825 mm. The deep hole blasting explosive is made of porous granular ammonium explosive, and the blast hole with high water hole and high temperature is selected from the emulsified ammonium explosive. The main detonation network is arranged in a double loop loop. Connection of the hole detonating cord: The annular beam hole is detonated by a ring-shaped double-type detonation, and the hole is detonated by means of a double detonating cord and a reinforcing drug pack.

　　According to the requirements of the predetermined plan, the first explosion zone mining and blasting technology design, blasting condition simulation test, blasting harmful effect calculation and safety scope delineation, as well as engineering construction and blasting construction organization design were carried out, and in February 2005. The blasting of the first explosion zone was carried out on the 28th.

　　The blasting area of ​​the first explosion area is 6500m2, the caving volume is 770,000 tons, the total charge is 150t, the blasting time is 20 seconds, the delay is 10s, and the total delay time is 2s. This is the largest underground mine in China. blasting.

　　The blasting operation is strictly carried out according to the technical requirements of the blasting design and the procedures of the blasting construction organization design, with a total investment of 1200 people. Completed the installation of the charging, blasting network and protective works from 8:00 to 28:00 on March 27, 2005, and detonated on time at 14:10. At the same time of blasting, the monitoring of blasting earthquake and air shock wave effect was carried out. The shock wave intensity generated by the large blasting is about 9.3 kPa in the explosion area, and the pressure reduction efficiency of a blocking wave wall is 77.2%. The effect of the blocking wall is remarkable. The large blasting shock wave did not cause damage to the mine production system, and the mine production system was intact. The burst pile is better. After the blasting, through the surface and underground inspection, the design area of ​​the entire explosion area collapsed completely, and no damage was caused to the adjacent stope, well engineering, facilities and structures, surface buildings and residential buildings near the explosion area.

　　After the successful implementation of the large blasting in the first explosion zone, the mine will organize a large number of ore mining, and the production capacity of the mining area can reach 2500-3000t/d. The ore recovery rate is 68% and the depletion rate is 20%. The annual benefit can reach 175 million yuan.

　　The successful blasting of the first blasting area basically eliminated the empty area of ​​the crater zone of the Tongkeng Mine, and formed a continuous caving body from the 560m level in the blasting area to the surface, which fundamentally eliminated the hidden danger of the ground pressure hazard and recovered the fine vein zone. The remaining ore resources of the ore body create conditions. After the blasting of the remaining two blasting areas, the mine closure will cause the safety hazards such as the fire area spread and the earth pressure disaster of the Tongkeng Mine to be eradicated. Economic and social benefits are very significant.

　　On August 16, 2005, China Nonferrous Metals Industry Association hosted a scientific and technological achievements appraisal meeting in Beijing, and completed the study on the "big blasting of cluster holes under complex conditions of underground mines" completed by Beijing Research Institute of Mining and Metallurgy and Huaxi Group's Tongkeng Mine. The results were identified. The expert group unanimously believes that the successful blasting of cluster holes under the complex conditions of underground mines will provide new technologies and means for the engineering blasting of underground mines in China. It has certain pioneering and innovative features, and the overall technical level has reached the international advanced level.