Number of non-coal mine stope number of jobs o'clock, there are varying degrees of lack of air flow underground, and poor air quality, and with the increase of mining depth gradually intensified, threatening the health of mine workers and safety. Therefore, ventilation system optimization research is very necessary [1-5].
A large manganese mine construction in 2006, 2011 officially put into operation. The mine adopts the comprehensive development mode of Pingyi+Slope, and the production scale is 150,000 t/a. At present, there are main wells and facilities such as 1# Pingyi, 2# Pingyi, 460m middle section, 435m middle section and 420m middle section. The current mining projects are mainly concentrated in the middle of 420m. Based on the analysis of the problems existing in the manganese ore ventilation system, this paper proposes an optimization scheme, calculates the optimized ventilation parameters, analyzes the fan capacity and optimizes the cost, and finally proposes further improvement.
1 Optimized front ventilation system The manganese ore uses central side-by-side negative pressure ventilation. 2# There is an air intake duct next to the flat raft, and two extraction ventilators are installed, one for work and one for standby. The ventilation system is 1# flat wind inlet, 2# flat return air, and the tunneling face adopts partial fan ventilation. The mine ventilation equipment before optimization is shown in Table 1. The pre-optimized ventilation network is shown in Figure 1.
There are 6 ventilation lines before mine optimization: ventilation line 1 is fresh air→1#å¹³ç¡â†’main lane auxiliary shaft→1#下山→1#下山II cutting→3#下山→420m middle section→4#下山→4# Downhill I contact lane→5#下山→回风巷→460m middle section return wind lane→2#å¹³ç¡â†’ground; ventilation line 2 is fresh air→1#å¹³ç¡â†’main lane auxiliary shaft→1#下山→1#下山II cutting→3#下下→420m middle section→4#下山→4#下山II contact lane→5#下山→回风巷→460m middle section return wind lane→2#å¹³ç¡â†’ground; ventilation line 3 is fresh air→1 #å¹³ç¡â†’Main lane auxiliary shaft→1#下山→1#下山IV cutting→3#下山→420mä¸æ®µâ†’4#下山→4#下山I contact lane→5#下山→回风巷→460m middle section →2#å¹³ç¡â†’ground; ventilation line 4 is fresh air→1#å¹³ç¡â†’main lane auxiliary shaft→1#下山→1#下山IV cutting→3#下山→420ä¸æ®µâ†’4#下山→4#下山II Contact Lane→5#下山→回风巷→460m middle section return wind lane→2#å¹³ç¡â†’ground; ventilation line 5 is fresh air→1#å¹³ç¡â†’435m middle section→slope road→420m middle section→4#下山→4 #下山IContact Lane→回风巷→460m middle section backwind lane→2#å¹³ç¡Ground; ventilation line 6 is fresh air→1#å¹³ç¡â†’435m middle section→slope road→420m middle section→4#下山→4#下山II contact lane→5#下山→回风巷→460m middle section Huifeng alley→2# Flat → ground.
2 Problems before optimization (1) Series ventilation. At present, there are 8 working faces in the mine underground, which are 2 working faces in the middle section of 420m, 2 working faces in the middle of 420m, 2 working faces in the middle of 420m, 4 working faces in the middle of 420m, 4 working down in the middle of 420m, 3 in the middle of 420m. Working face. Combined with Figure 1, it can be analyzed that the wind flow from the 3# node to the 4# node has actually passed through 4 working faces, which is a dirty wind with more harmful components such as dust, and these sewage winds do not enter the return air alley, but After the fresh airflow of the 1# flat, 435m middle section and the ramp road meets at the 4# node, the wind source is provided to the 4 working faces of 4# downhill and 5# downhill through the middle section of 420m. Thus, there is a big problem in Series Ventilation ventilation system before optimization, both in violation of the "metal and nonmetal mine safety regulations" (GB16423-2006) requirements, but also greatly reduce the 4 # 5 # down and face down The quality of ventilation is harmful to the health of the workers and even their lives.
(2) The wind current is frequently short-circuited. 2# Pingyi is the return air well of the mine, which also serves as transportation and pedestrian access. 2# å¹³ç¡å£ only has a damper installed. When the personnel and the vehicle enter and exit from the 2# level, the damper needs to be opened. At this time, the ground wind flows through the 2# flat raft and the air intake duct, which is taken out by the main fan, and is in the main fan port and 2 #风ç¡å£ formed a short circuit between the winds. Since 2# Pingyi undertakes the transportation and pedestrian transportation of ore and waste residue in the entire second working area, the transportation task is heavy. On average, about 10 minutes, it is necessary to open a 2# flat sluice damper, which will cause short-circuit of the wind flow; since the 2# flat sluice damper is set throughout The key position of the mine ventilation system, the short-circuit of the wind current to the mine ventilation is global. When the wind current is short-circuited, the wind speed of each roadway and working face in the well is suddenly reduced, and even the wind flow is basically static. Frequent short circuit of wind current seriously affects the ventilation effect under the well, which has become an urgent problem to be solved in the optimization of the ventilation system of the mine.
3 ventilation system optimization
3.1 ventilation optimization program
Mine ventilation effectiveness is highly dependent on the installation and management of ventilation structures. The mine ventilation system has two major problems: large series ventilation and frequent short-circuit of wind current. It is because ventilation structures such as wind bridges, dampers and windshields are not installed according to the regulations. Therefore, the ventilation system optimization scheme is proposed:
(1) Construct a rubber tube wind bridge to prevent the sewage from being connected in series. When the air inlet and the return air passage intersect in the ventilation system, in order to separate the fresh air flow from the dirty air flow, a wind bridge needs to be constructed. The mine builds a rubber tube wind bridge in the middle section of the 420m section 3#, and the sewage from the 1# downhill and the 3# downhill is led to the return air lane through the wind bridge, avoiding the freshness with the 1# flat, 435m middle section and the slope road. The wind flow meets at the lower section of the 420m middle section 3#, thus ensuring that the wind flow of the 4# downhill and 5# downhill in the middle section of the 420m is fresh air, effectively solving the problem of large series ventilation. In order to make the wind bridge work better, add an 11kW auxiliary fan. Since the 3# Xiashankou is responsible for transporting pedestrians, an automatic damper is added to the 3# downhill. The wind bridge, supporting auxiliary fans and dampers after the implementation of the wind bridge plan are shown in Figure 2.
(2) Install the double damper to prevent short circuit of wind flow. In the ventilation system, where it is necessary to block the wind flow and the pedestrians are needed, it is necessary to establish the damper. In the roadway where pedestrians are not open to traffic or vehicles are scarce, ordinary dampers can be installed; in the lanes where pedestrians are frequently used, automatic dampers should be constructed. According to the actual situation of the manganese ore, an automatic damper is newly added at 8m from the 2# level, and a double damper is formed with the original damper (Fig. 3). When the pedestrian of the vehicle passes from the 2# level to the surface, the first damper near the air intake duct is opened first, and the vehicle pedestrian automatically closes after passing; after the first damper is closed, the vehicle pedestrian passes the second damper. The pedestrians of the mine frequently pass the 2# flat sluice, and the double damper scheme effectively solves the problem of wind short circuit between the main fan port and the 2# sluice port.
(3) Close the abandoned roadway to effectively reduce air leakage. In the production process, the mine will continue to form abandoned roadways and goafs. If it is not closed in time, on the one hand, people will easily enter the danger, and on the other hand, the downhole wind will be disordered and the mine leakage will increase. In order to make the underground wind flow circulate in the specified direction and effectively reduce the leakage of the mine, the non-production roadway should be built in time to build a closed wall to interrupt the wind flow. Permanently closed walls are made of brick or stone, and temporary closed walls can be made of wood columns, wood boards and used air duct fabrics. According to the actual situation of abandoned mine roadway and goaf in the mine, 16 closed walls (Fig. 4) were built with 25cm × 15cm × 12.5cm prefabricated bricks. The specific distribution position is shown in Table 2.
The optimized mine ventilation network is shown in Figure 5. There are 4 ventilation lines: ventilation line 1 is fresh air→1#å¹³ç¡â†’main lane auxiliary shaft→1#下山→1#下山II cutting→3#下山→风桥→460m middle section returning wind lane→2#å¹³ç¡â†’ Ground; ventilation line 2 is fresh air→1#å¹³ç¡â†’main lane auxiliary shaft→1#下山→1#下山IV cutting→3#下山→风桥→460m middle section returning wind lane→2#å¹³ç¡â†’ground; Ventilation line 3 is fresh air→1#å¹³ç¡â†’435m middle section→slope road→420m middle section→4#下山→4#下山I contact lane→回风巷→460m middle section return wind lane→2#å¹³ç¡â†’ground; ventilation Line 4 is fresh air→1#å¹³ç¡â†’435m middle section→slope road→420m middle section→4#下山→4#下山II contact lane→5#下山→回风巷→460m middle section return wind lane→2#å¹³ç¡â†’ ground.
3.2 Ventilation parameter accounting
3.2.1 Air volume calculation According to the “Safety Regulations for Metallic Non-Metallic Mines†(GB16423-2006), the air volume is calculated.
3.2.1.1 According to the actual required air volume of each required wind point in the well
According to the characteristics of mine production, the total air volume required is the sum of the maximum air volume required by each working surface and the air volume of the independent ventilation chamber, ie
Where, Q is the total air volume required for the mine, m3/s; Qs is the required air volume for the mining face, m3/s; Qd is the required air volume for the tunneling face, m3/s; Qr is the required air volume for the diverticulum. According to the Mining Design Manual, the air supply volume of the underground pumping station, the compressor station, and the power supply and distribution room is 1~3m3/s. According to the actual mine, 2m3/s is taken; Qq is except for the mining, excavation and diverticulum locations. The sum of the required air volume of other wells is 1m3/s; K is the reserve coefficient of the mine air volume, which is 1.2; Ss is the over-wind section of the working site in the stope, 7.7m2; Vs is the minimum row required for the mining face Dust wind speed, 0.25m/s; ns is the number of mining face, 4; Sd is the roadway section, 5.28m2; Vd is the minimum dust speed required for driving roadway, 0.25m/s; nd is the excavation work The number of faces, 4
Calculate the total air volume required by the mine Q=19.18m3/s.
3.2.1.2 Calculate the mine air volume according to the maximum number of people working underground at the same time.
In the formula, q is the required air volume per person, 4m3/min; N is the maximum number of people working underground at the same time, 54 people; k is the mine ventilation coefficient, taking 1.25. Calculated Q = 4.5m3 / s.
3.2.1.3 Calculated according to the required air volume of diesel equipment
Where, P is the power of the diesel tractor, 20.3 kW; N is the number of diesel engines working underground at the same time, 8; q' is the air supply per minute, 4 m3 / kW.
Calculated Q = 10.8 m3 / s.
The maximum air volume required for the mine calculated by the above three methods is 19.18m3/s, so the current required air volume of the mine is 20m3/s.
3.2.2 Wind pressure calculation According to the air volume distribution and roadway specifications of each wind tunnel in the mine, the calculation formula of mine ventilation friction resistance is [6]
Where, hf is the frictional resistance, Pa; a is the frictional resistance coefficient, Ns2/m4; P is the circumference of the netway of the roadway, m; L is the length of the roadway, m; S is the clear sectional area of ​​the roadway, m2; Q is the passageway The air volume, m3/s; Rf is the frictional wind resistance of the roadway, Ns2/m8.
It is calculated that the current ventilation resistance of the mine is 764.59Pa, and the detailed calculation results are shown in Table 3.
It can be seen from Table 3 that the total wind resistance of the roadway is R=3.63Ns2/m8>1.42Ns2/m8, and the hole in the well roadway is
It is calculated that A=0.63<1, the mine can be analyzed as a large resistance mine, and as the mining project continues, the ventilation line will continue to expand, the ventilation resistance will continue to increase, and the difficulty of ventilation will increase.
3.3 main fan capacity analysis
3.3.1 Main fan air volume Due to the inevitable air leakage around the wind damper and the main fan, the air volume Qz passing through the main fan must be greater than the total air volume Q of the return air well. Withdrawable fan air volume is
In the formula, kf is the air leakage coefficient of the extraction fan, and the extraction fan takes 1.05 when there is no lifting task, and 1.10 when there is lifting task.
Calculated Qz = 22m3 / s.
It can be seen from Table 4 that the air volume of the K45-NO-11 working main fan can meet the mine demand, while the upper limit of the FBCZNO10 standby main fan is close to the mine demand but cannot be fully satisfied.
3.3.2 The static pressure generated by the main fan wind pressure fan is not only used to overcome the total resistance hf of the mine, but also to overcome the reverse natural wind pressure hz of the mine and the ventilation resistance hr of the fan unit, ie the static pressure of the fan for
In the formula, hz is calculated according to the Komalov empirical formula to obtain 30.43 Pa, and hr is 100 Pa by experience.
Calculated hj=895.02Pa.
It can be seen from Table 4 that the wind pressure of the K45-NO-11 working main fan can meet the demand (895.02Pa<1295Pa×90%=1165.5Pa); the wind pressure of the FBCZNO10 standby main fan is close to the upper limit (895) .02Pa<1100Pa×90%=990Pa).
In summary, the current K45-NO-11 working main fan can meet the mine air volume and wind pressure requirements; the wind pressure of the FBCZNO10 standby main fan basically meets the needs, but the air volume cannot fully meet the mine demand and should be replaced.
3.4 Bureau fan duct capacity analysis by friction wind resistance formula
That is, the frictional wind resistance of the air cylinder is inversely proportional to the 5th power of the radius of the air cylinder. If the 20cm air cylinder of the mining work surface is replaced by the cm40cm air cylinder, the wind resistance of the air duct will be reduced to 1/32 of the original, which can greatly improve the local ventilation effect of the mining working face, especially the long-distance ventilation effect.
4 Ventilation optimization cost analysis This ventilation system optimization project involves the construction of a rubber tube wind bridge, the production and installation of 2 dampers, and the construction of 16 closed walls.
(1) Wind bridge construction. The erected wind bridge is two idle plastic air ducts of 35cm mines, and the auxiliary fans installed are 11kW mine idle fans. The cost of wind bridge construction includes about 0.4 million yuan for roadway repairing, about 0.1 million yuan for wind bridge and auxiliary fan installation, and a total of 0.5 million yuan (excluding wind bridge maintenance airway system security fee).
(2) Wind door production and installation. The mine installed 1 supporting damper at the 3# lower mountain wind bridge in the middle section of 420m, and added 1 damper to 2# Pingyukou, totaling 2 fans. The cost of manufacturing and installing each damper includes the cost of materials and equipment such as steel and electric motor, which is 0.2 million yuan, and the labor cost of damper, which is 0.8 million yuan, totaling 10,000 yuan/fan.
(3) Construction of closed walls. Each closed wall requires pre-made bricks of about 280 pieces (5 yuan / piece), cement 2 bags (30 yuan / bag), sand 1m3 (150 yuan / m3), artificial 2 (200 yuan / labor), a total of 0.2 Ten thousand yuan / road.
The cost of ventilation optimization engineering is shown in Table 5.
In summary, the total cost of the ventilation system optimization project is about 57,000 yuan. The optimization scheme makes full use of the idle equipment materials such as local fans and air ducts in the mine, and completes the ventilation system optimization project with less cost, which obviously improves the ventilation effect and is beneficial to the health and safety of the underground workers.
5 Conclusion By optimizing the ventilation system of a large-scale manganese ore, building a rubber tube wind bridge effectively prevents the sewage from being connected in series, installing a double-channel damper to effectively prevent short-circuit of the wind flow, closing the abandoned roadway to effectively reduce air leakage, and analyzing the capacity of the main fan to obtain replacement of the standby main fan. The analysis of the fan air duct capacity indicates that the large diameter air duct should be replaced to reduce the wind resistance. The practice shows that the optimization scheme significantly improves the ventilation effect and the safe working conditions in the underground, and has certain reference significance for the optimization of other similar non-coal mine ventilation systems. At the same time, the following suggestions are proposed for similar non-coal mine ventilation management:
(1) Continuously optimize ventilation lines. The underground ventilation line of the mine is subject to dynamic changes with the advancement of the underground mining project. It is recommended that the ventilation technicians follow up and analyze, continuously optimize the ventilation route, and timely construct the ventilation structures such as the closed wall, the damper and the wind bridge to ensure that the wind flow flows in the specified direction and reduce the wind loss. .
(2) Strengthen the management of ventilation facilities. Many mines lack management of ventilation structures, often do not set dampers or other structures as required, or set the dampers not to close in time, resulting in a lot of wind leakage, and there is no wind flow in places where ventilation is required. To ensure the ventilation effect of the mine, it depends largely on the setting and management of the ventilation structure, and reduce the air leakage and short circuit of the ventilation system.
(3) Strengthen ventilation monitoring and monitoring. All fans must be equipped with on-off sensors. The main fans must be equipped with wind pressure sensors. Wind speed sensors must be installed in the return air ducts. Portable gas detection alarms must be provided for each working group in the well. Before entering the mining face, personnel must be tested for toxic. Harmful gas, it is strictly forbidden to enter when an alarm occurs. The main ventilator room should be equipped with measuring instruments such as wind pressure, air volume, current, voltage and bearing temperature. Each class should check the operation of the fan and fill in the operation record. The mine must be equipped with a sufficient number of wind gauges, dust gauges and gas analyzers, and calibrated according to national regulations.
(4) Improve mine emergency response capabilities. Each self-rescuer must be equipped with self-rescuer and ensure that it is carried around; the main passage in the underground is clearly marked with a disaster avoidance route, and the safety exit is ensured; the on-site disposal plan for poisoning asphyxiation accidents is established, and the ventilation personnel are regularly operated and safely guarded. Special training on poisoning suffocation accidents, carry out emergency drills for anti-poisoning suffocation accidents; formulate anti-wind exercise programs and conduct anti-wind exercises regularly to improve emergency response capacity in the event of fire in the vicinity of the wind tunnel or downhole yard.
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[2] Qiu Jifa. Discussion on several problems of mine ventilation [J]. Coal Technology, 2008, 27 (4): 151-152.
[3] Yan Changfu, Tian Meizhi, Li Leinong. A copper mine ventilation system optimization scheme [J]. Nonferrous Metals Science and Engineering, 2011, 2(4): 34-38.
[4] Xi Longan, Yang Zhen. Reconstruction of Ventilation System of Qujiashan Manganese Mine in Zhenba, Shaanxi Province [J]. China Manganese Industry, 2010, 28(3): 41-44.
[5] Wang Yuming, Shen Xianling, Wu Aixiang. Optimization and application of ventilation system in Tangdan Copper Mine [J]. Modern Mining, 2014 (7): 132-139.
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Article source: "Modern Mining"; 2016.12;
Author: Qin Hongliang; Guizhou Provincial Bureau of Geology and Mineral Resources Geological Team 102;
Da Quanchang; 103 Geological Brigade of Guizhou Provincial Bureau of Geology and Mineral Resources;
Luo Wei; Yu Fu (Group) Co., Ltd.);
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