In China, due to the extensive use of open field mining, a large number of unidentified, untreated layered goafs have been formed. Under the condition of complex group space, many mines were forced to change from underground mining to open-pit mining in order to achieve full mining of the pillars and ensure safe production of mines [1-2]. In recent years, a large number of scholars have carried out the control factors of the relevant processes such as the goaf treatment method in the open pit mining, the thickness analysis of the safety isolation layer in the empty area roof, and the stability analysis of the open slope under the influence of the empty area treatment [3-8]. In-depth research and fruitful results. The wear Wengfu phosphorus ore from underground cavern by the open segment ore mining process, for distribution through the rock Diaphragm goaf using forced caving lane filled gob caving process to force goaf, roof coating The rock chamber blasting method forced the topping treatment of the goaf, and the effect is remarkable; the Sandaozhuang mining area of ​​Luoyang Luanchuan Molybdenum Group Co., Ltd. combines the open mining production and explosion process to treat the underground goaf, that is, in the production process. According to the occurrence scale, size and state of the underground goaf, lithological conditions, roof height and other specific conditions, the empty area is treated by the caving of the caving area, the lateral horizontal (tilt) drilling and blasting, and the VCR method. Achieved the purpose of eliminating hidden dangers. In this study, the characteristics of multi-layered group empty area of Zijin Gold copper mine, considering that the empty area to eliminate hidden dangers, from underground and open-pit mining smooth transition aim to maximize resource recovery pillar, to take "low-grade ore filling the middle of + 460m The comprehensive treatment method of “empty zone†and “collapsed isolation pillar filling +520m middle section empty area†discusses the control factors in the process of empty area treatment. Commonly used goaf treatment methods include closure, caving, reinforcement and filling [1]. The purpose of the treatment of the mined-out area of ​​Zijinshan Gold-Copper Mine is to: 1 control the ground pressure and eliminate safety hazards; 2 smooth transition of the lower copper resources in the open-pit mining and reasonable recovery of the pillars. Taking all factors into consideration, the treatment of the goaf of Zijinshan Gold-Copper Mine adopts the idea of ​​“disintegration + fillingâ€, that is, filling the 460m middle goaf with the low-grade ore of the stope, and filling the 520m goaf with the collapsed ore pillar, in the 2 After the completion of the mid-section goaf, the large-scale open-field mining above 100m elevation is carried out [4]. The maximum elevation of the underground space of the mine is 577m. After leaving 35.4m, the lowest elevation of open pit mining is 612.4m. According to the current design and mining status of open pit mining, the 612.4m elevation is set to 616m in open pit. At this time, the isolated pillar is 39m thick, that is, when the open pit is mined to 616m, the underground goaf is started. Trolling Motor Parts, Trolling Motor Accessories, Trolling Motor Reviews, 24 Volt Trolling Motor Wiring Diagram Ningbo Haibo Group Co.,Ltd. , http://www.hbtrollingmotors.com
1 Project Overview
The Zijinshan Gold-Copper Mine is a symbiotic deposit of extra-large gold and copper. The gold ore body is produced above 600m. In order to reduce production costs, the gold ore body is open-pit mining, and the copper ore body is underground. The mining area is mainly 460. , 520m middle section. With the progress of production, the elevation of open pits has been declining, and the goafs left by the mining have brought serious safety hazards to open pit mining, which has become an important problem that restricts the development of mines. At the same time, in order to comprehensively utilize the resources of Zijinshan Copper Mine and improve the production capacity of the mine, in the case that the current mining can not achieve full recovery of the copper ore surface, it is necessary to achieve open mining of the copper ore body above 100m, which is 460. The gob area in the middle section of 520m is comprehensively processed.
The underground of the mine is mined by the stage empty field method. The characteristics of the goaf left after the stop mining are as follows: 1 The shape of the goaf in a single mine is regular, approximate to the cuboid, the scale is small (<100,000 m3), and the goaf in the middle is large. , reaching millions of cubic meters, the distribution of the mines in the empty area, the long sides are nearly parallel (Figure 1, Figure 2); 2 the upper part of the goaf is an open pit, when the exposed height drops to a certain height, There are safety hazards in the production operations in the goaf; 3 the existence of goaf affects the production connection of underground open-pit mining and the realization of the ultimate open-air boundary. At present, some mines in the middle of the mine have been mined in the middle of 460 and 520m. In the plane position 0#～15#, more than 100 mine houses have been arranged. The mine is 15m wide and varies in length from 120m. There are 36 mining houses in the middle section of 460m, the area of ​​goaf is 27470m2; there are 55 mining houses in the middle of 520m, the area of ​​goaf is about 54232m2; the total volume of goaf is 410×104m3. 
2 Control factors of integrated treatment process in goaf
2.1 Mining area engineering geological conditions
The lithology of the goaf in the middle section of the mine is mainly weakly weathered medium-fine grain granite , accounting for more than 80%. The cryptoexplosive breccia, Ying'an porphyry and quartz porphyry are visible locally, mainly in vein or lenticular shape. Distributed in medium-fine grain granite. The joint fissures in the goaf are most developed with a tendency of 30°～60° and 60°～80°. The inclination angle is 45°～80°, the local part is slow, and the tendency is extended. The strike is nearly parallel with the vein roadway; the inclination is 110°～ 140° or 300°～330° and the tendency of 140°～170° or 330°～350°, the inclination angle is 60°～80°, the crack surface is steep and straight, and the direction along the strike 922 and the tendency are larger, the trend is The vein roadway is nearly parallel. The joint fissures in the empty area are relatively developed, which largely destroys the integrity and continuity of the rock and is the main factor affecting the stability of the surrounding rock in the goaf. According to the rock mechanics properties, quality indicators, and the degree of fracture development (Table 1), it is judged that the stability of the surrounding rock mass of the ore body and its roof and floor in the mined-out area is stable-substantially stable.
2.2 Gob area treatment plan
2.3 Thickness of the roof insulation layer in the goaf and the start of processing time
For the treatment of the gob area of ​​the Zijinshan gold-copper mine, the open pit operation and the underground goaf are used to treat the isolated pillars, effectively solving the mutual influence problem, that is, ensuring the open pit in the processing of the underground goaf. The production is not affected and the stability of the open pit slope is guaranteed by certain measures, while ensuring the independence and safety of the underground goaf. At present, there are mainly analytical methods, empirical methods and numerical simulation methods for calculating the thickness of the roof safety barrier in the goaf [6]. The calculation results of this method are shown in Table 2. It can be seen from Table 2 that the numerical analysis method fully considers various external factors and is more in line with the actual situation.
2.4 Stability of open slope under the influence of goaf treatment
Zhao Mengsheng et al [8] combined with the treatment process of the goaf in the mine, analyzed the stress change of the upper stop slope during the treatment of the goaf, and adopted four sections of AA, BB, CC, DD, etc. (Fig. 3) The stability analysis is carried out. It is considered that the distance between the slope foot and the goaf is the key factor affecting the stability of the upper slope. The shear stress value and the horizontal distance between the goaf and the slope are linearly reduced. The safety control distance from the empty area is 80m. If the distance between the foot of the slope and the goaf is less than 80m, the slope monitoring should be strengthened or necessary engineering measures should be taken for the slope. During the processing of the goaf, the upper slope of the goaf should be strengthened to monitor the stability of the upper slope of the goaf, ensuring the safe operation of the slope and the safe handling of the entire goaf.
3 conclusions
(1) The geological conditions of the surrounding rock in the goaf determine the treatment method of the goaf, which is the controlling factor of the integrated treatment process in the goaf.
(2) The thickness of the safety isolation layer is an important influencing factor of the integrated treatment process of the goaf, which determines the start time of the treatment of the goaf, and ensures that the treatment of the goaf does not affect the open air operation of the upper part.
(3) The horizontal distance between the upper slope of the goaf and the goaf can ensure its stability if it meets the safety distance, which is an important factor affecting the follow-up work of the integrated treatment process of the goaf.
references
[1] Li Junping, Qian Xinming. Research progress in goaf processing [J]. China Molybdenum Industry, 2002, 26 (3): 10-15.
[2] Jin Yunjun. Treatment method of underground goaf in the Yanfuyan mine section of Yanfu Phosphorus Mine [J]. Chemical Minerals and Processing, 2008 (8): 20-23.
[ 3 ] Liao Jiangnan . Study on the treatment of goaf in Sandaozhuang mining area [ J ] . Nonferrous Mine, 2000 , 29 ( 6 ) : 10-14.
[ 4 ] Lai Hongyuan . Comparative analysis of treatment schemes in the goaf of Zijinshan Gold and Copper Mine [ J ] . Modern Mining, 2015 ( 4 ): 223-255.
[ 5 ] Su Zhongjie, Yu Guangming . Numerical simulation study on mechanical mechanism of overburden deformation [ J ] . Chinese Journal of Rock Mechanics and Engineering, 2003 , 22 ( 8 ) : 1287-1290.
[ 6 ] Lin Chao, Hu Fuxiang . Study on reasonable thickness of isolated roof column for open and underground joint mining of high and steep slope [ J ] . Metal Mine, 2012 ( 1 ) : 51-54.
[ 7 ] Lai Hongyuan . Numerical simulation of isolated pillar thickness in open pit underground mining of Zijinshan Gold and Copper Mine [ J ] . Mining Technology, 2014 ( 3 ) : 42-44.
[ 8 ] Zhao Mengsheng, Yan Hu, Dai Yongxin, et al . Study on the influence of goaf treatment on the stability of upper stop slope [ J ] . Modern Mining, 2015 ( 4 ): 124-128.
Author: Shenqi Hong; Zijin Mining Group Co., Ltd. Purple Mountain gold and copper;
Article source: "Modern Mining"; 2016.6;
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