Mt. Zijinshan Gold Mine in 1992 were industrial pilot production, using underground mining methods, multi-mid adit trackless main mode of transport, mechanization, large-scale production by the end of 1999 formed the production scale of annual output of 1.8 million t of ore. In order to achieve greater economic benefits, since the beginning of 2000, the Zijinshan gold mine has been completely converted from open mining to open-pit mining, and the amount of ore is further increased. By 2005, the amount of ore processed has exceeded 10 million tons, and the output of gold exceeded 10 tons. Due to the high-steep operation technology used in open-pit mining, the roads in the stope are steep and steep, and the stope and the yard are far apart (about 3km). In order to save production costs and ensure safe transportation, the relative height difference of Zijin Mountain is utilized. Large-scale features, the choice of the slippery - Pingyu joint transport mode [1] .
At present, the Zijinshan Gold Mine has designed 6 large-scale high-level slides (see Table 1). The specification is 4m×4m. Among them, 3 lines are arranged with 301 and 305 two ore slides, and 4 lines are equipped with 402 or 403 two ore slides. ore greater than 0.5 × 10 -6 to 520m transport track grade adit, transported to a second electric locomotive beneficiation plant; 9 and 8-wire 901,801, respectively, disposed waste rock chute two gold, which is less than 0.5 × 10 -6 grade gold-bearing waste rock is transported to 500m tape flat, transported by tape and transferred to the third concentrator [2] . In the future, within the scope of the new planned expansion of the mine field in 2005, two new ore shafts will be drilled, and the project may not be completed until the end of 2006.
In March 2002, the Zijinshan Gold Mine had a small-scale running accident in the 403 chute, with a running volume of about 60m3. In June 2002, a small-scale running accident occurred in the 305 chute, and the ore volume was about 80m3. Seriously affected the normal operation of production. These mining accidents occurred during the rainy season, when the daily rainfall was 35 to 45 mm. In this paper, the prevention and control measures in the process of using the high-grade chute in Zijinshan Gold Mine are proposed for prevention and treatment.
I. Hydrogeological profile of the mining area
Zijinshan Gold Mine is located in the main peak of Zijin Mountain in Shanghang County. It belongs to the middle and low mountain eroded mountainous terrain. The terrain is steep and the regional tectonic activity is very strong. It is mainly northwest and northeastward, and has experienced geosyncline and quasi-ground. The multi-cycle tectonic evolution stage of the Pacific continental marginal activity. The fault structure is relatively developed within the mining area, with north-east and north-west faults as the main fault, followed by north-north and east-west faults. In addition to the fault structure, the two groups of jointed fissure structures in the northeast and northwest are very developed, intersecting each other and spreading throughout the whole area. All kinds of rocks in the ore section are subject to different degrees of fragmentation and strong silicification. The rocks are mainly hard and semi-hard blocks, and the IV and V-level structures are especially developed, and the II and III structures are less.
The Zijinshan Gold Mine is located at the north of the intersection of the provincial river Tingjiang and the old county river. The water system of the mining area is developed. The main stream is the Tingjiang River, which is the source of the Hanjiang River. It originates from Jiangxi and flows from north to south to Sanheba and Mei of Guangdong. After the river merged, he entered the South China Sea in Shantou. The old county river and Huangtan River in the territory are all tributaries of the Tingjiang River, which constitute an asymmetrical water system. The Zijinshan gold deposit is mainly buried in the oxidation zone above the 650m submerged surface. The main water-filled water zone of the deposit is the weathered zone fissure diving water zone. Its water-richness is mainly weak, and seasonal fissure water is present. In the wet season, a small part of the main ore body is buried in the diving water zone. The groundwater in the mining area is near the 650m elevation surface and below the diving surface. The main movement is mainly to the drainage point, and the local flow along the structural fracture zone is downward. The water inflow is generally 0.01~0.20L/s, and the minority amount is 1.102～1.218L. /s.
Second, the open pit mining conditions
Due to the high altitude and complex terrain, the mining climate belongs to the subtropical high mountain and rainy climate. It is rainy and foggy every year from March to June, and there are many storms and rains in summer. It is often caused by catastrophic wind and rain. Especially in August, it is easy to cause flash floods. The annual average precipitation of the mining area is 1676.6mm, the maximum annual precipitation is 2501.1mm, the minimum annual precipitation is 1048.5mm, the recent continuous rainfall is 31d, and the total rainfall is 440.3mm.
The open pit of Zijinshan Gold Mine is operated by high-steep operation with a height of 12m. Above 772m, it is a hillside open pit mine, and below 772m is a hollow open pit. During the rainy season, the prevention and drainage of the stope is mainly atmospheric precipitation. The total catchment area of ​​the stope is about 1.15km 2 with the current mining boundary and the direction of the flow after the mining. 772m catchment area above the platform of the mining area east about 0.7km 2; 19 wire catchment area of about 772m above the platform west 0.25km 2; middle (Bottom) 772m internet catchment area of the central region of approximately 0.20km 2 According to the 2005 new open pit mining and stripping plan, the catchment area will be expanded later.
According to the safety regulations related to the Zijinshan Gold Mine: in order to ensure the safety of the north exit dump site and the lower Yanzigou road and yard in the south, it is strictly forbidden to transfer the catchment in the open pit into the dump (North Exit) and Yanzigou (Southern ravine). The southern 24 lines are southeast of each ravine, 8 line ditch, and Yanzigou; the steps of the open pit form a 3% to 5% anti-slope surface from the central part to the north and south ends, so that the stop water can be collected along the middle of the step or the road. To the lowest working platform, the minimum working platform enters the flood control system of the well along the exposed underground goaf.
Third, the cause analysis of mine accidents
The diving surface of the mining area is at an elevation of 650m, while the discharge opening of the slipping well is at an elevation of 520m, meaning that all the wells penetrate the aquifer. In the routine inspection of the normal slippery well, it was found that there was a very small amount of dripping in the crack around the drifting well above the diving surface, and no obvious flow of water was formed, which had little effect on the ore in the chute. Mainly because the fissure water below the diving surface is fully absorbed by the ore during the ore transport process, and no crack water seeps out on the platen of the vibration discharge port. Only when the chute is not used for a long time, a large amount of fissure water seeps on the platen of the vibration discharge port, and the amount of water inflow is about 0.1 to 0.18 L/s. In actual production, when the chute is not used for a long time, the ore in the chute is generally emptied, and almost no mining accident occurs.
According to the characteristics of running shafts in the past years, the ore flow plasticity is small, and the amount of self-slip is small. It can be judged that the main reason for running the mine is that the Zijinshan Gold Mine was mainly underground mining before 1999. There are a large number of goafs left by underground mining around the chute; during the rainy season, most of the surface water in the open pits is developed. The fissure penetrates into the goaf, which often causes serious water accumulation in the underground goaf. A large amount of accumulated water seeps into the chute through the empty area or rock layer fissure; if the ore in the chute encounters excessive water, the ore (the ore silt rate is generally greater than 15%) in the state of fluid flow, the ore fluidity increases, when encountering blasting vibration or the vibration of the concentrating machine, the ore containing water supersaturated will spurt or slip away, resulting in a runway accident [3] .
Fourth, the main prevention measures
Because the joint fissures of the surrounding rock are very developed and have many structures, this provides conditions for water penetration. During the rainy season, surface water can penetrate into the well through cracks more or less. When the surface water forms dripping water in the surrounding rock of the slippery well, most of the rock mass flowing through it has reached water saturation state, that is, under the original condition (before excavation). The deposit has been filled with water, and it is almost impossible to completely eliminate the water damage; at least, atmospheric precipitation that falls directly into the well is unavoidable. The solution to this hazard is mainly to prevent or eliminate some of the surface water that flows through the empty area or fissure.
(1) Improve the overall flood control system of the open mining and keep the drainage system of the mining area unblocked. Drainage channels are arranged reasonably in open pits and the water flows are collected in a certain location or several locations, and then concentrated to a safe zone, so that most of the surface water can be prevented from seeping into the empty area. For example, the flow direction of the eastern mining area above the 772m platform, the north (or south) of each platform → the middle of the platform → the middle part of the lower platform → the total drainage ditch of the 772m platform → the total drainage ditch of the western area → the mining dew drainage channel; 772m platform above the western area, 19 line repair yard → 19 line development road ditch → 796m west area total drainage ditch → mine dew mining and drainage channel; and the central area (pit bottom) 772m platform below, the water is led to the southwest side of the bottom of the pit → 730m Middle section empty area → 730m flood discharge chute.
Due to the existence of a large number of empty areas left by the mining period, the drainage area or the retaining wall is arranged in the open area of ​​the open-pit mining area, so that the water does not directly flow into the empty area, especially the empty area near the running shaft. According to the characteristics of the north-south trend of the open mining platform, a 5% negative slope with a length of about 50m is formed on both sides of the south and north sides of the shaft, and 50m away from the south and north sides of the shaft, while avoiding the goaf around the shaft. A new catchment point is formed, and a water guiding channel is arranged on the slope retaining wall of the catchment point, and the water flow is drained through the water guiding ditch to the lower step, thereby reducing the flow of water to the surrounding of the chute and preventing the water flow from the chute. The surrounding cracks penetrate into the chute.
At the unloading port of the open pit, a retaining wall has been built and must be compacted and widened to ensure that it is impossible to directly flow into the chute.
(2) Strengthening the flood control conditions of the slippery itself. There are five main tasks in this respect: 1 When designing the chute, try to avoid the formation of rock formations, structural belts and empty areas with severe water flow. 2 Next to the contact road around the middle section of the underground well, the waterproof retaining wall shall be watered with concrete so that the water accumulated in the contact road around the middle section of the downhole cannot directly enter the chute (such as the 305 chute); or water is placed around the chute in the middle section of the well. Ditch, so that water does not flow into the slippery well and flow to the empty area or ditch away from the chute; if conditions permit, the main transport lanes in the middle section of the mining will be re-routed to the mouth during the in-situ mining, and the middle part of the catchment will be discharged to the raft. outer. 3 Install anti-slip gates at the ore discharge port, and process several water guide holes on the gate to act as a water diversion function. 4Using observation wells or inspection wells next to each chute, especially around the slip well below the diving surface, a circular 2m×1.8m circular diversion tunnel is constructed with a vertical spacing of 40m, and the fissure water below the diving surface is drained to the inspection well. , through the inspection of the wells to the transport level of concentrated emissions. 5 Because during the underground mining, the lowest mining middle section is the middle section of 670m. Due to the instability of the empty area in each mining section, small-scale rock movement activities are generated, resulting in many empty areas interpenetrating, and surface water is collected through the various empty areas. Middle section of 670m. Therefore, in the middle section of the original 670m mining near the surface of the diving surface, a complete flood discharge system should be established to discharge the accumulated water collected in the middle of the 670m section and reduce the infiltration of surface water into the well.
(3) Strengthen the management of mine drainage. According to the daily processing capacity of the chute, the ore storage capacity of the slip well is reasonably arranged, generally not exceeding 5000t. According to the weather forecast, before the rainy season, the open pits should try not to arrange the mines, and preempt the deposits of the shafts. After the heavy rain, it is strictly forbidden to run the wells under the excessively large amount of water ore to prevent ore from producing ore. Slipping accident.
V. Conclusion
The run-by-hole mine is the most serious threat to personnel and equipment in the production of slippery wells. It is the most dangerous and difficult to handle, but it is not terrible. The key is to have a correct understanding of its hazards. As long as we really start from the idea of ​​ensuring safety, different mines can analyze, summarize and summarize the hazards of running accidents according to their own characteristics, and formulate corresponding prevention and control measures, which will definitely minimize the losses caused by running mine hazards. of.
Since the occurrence of the mine accident in 2002, the Zijinshan Gold Mine has adopted the waterproof control measures proposed by the author. After nearly three years of practice, these prevention measures are correct and the effect is good. There has not been a corresponding situation since then. Running a mine accident. The author's experience is derived from production practice and has certain limitations. When it is promoted and applied, it should be analyzed in depth to be able to rise to the general law, and as the mine production continues to deepen, the work steps change, the stope The water guiding system should also undergo corresponding changes and improvements to meet the requirements of mine safety production.
references:
[1] Xie Dianchun. On the economics of open-pit mining Pingshuo well transportation [A]. Proceedings of the 6th National Mining Conference of China Mining Magazine [C]. Anshan: Anshan Metallurgical Design and Research Institute, 19991326～332 .
[2] Zeng Xianhui. Discussion on the evaluation, development and utilization of low-grade resources in Zijinshan Gold Mine [J]. Gold, 2002, 23 (8 increase): 38 ~ 40.
[3] Zhang Rongquan, Chen Yong, Zhang Yun. The process of plugging and mine discharge management [A]. Proceedings of the 6th National Mining Conference of China Mining Magazine [C]. Anshan: Anshan Metallurgical Design and Research Institute, 1999.336~339.
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