1 Overview of mines and ventilation systems
Inner Mongolia Jin Tao Co., Ltd. belongs ore mine built in 1958, the mining area of mining 5.1km2, using the shaft, blind shaft jointly developing ways of mining method for the scarps filling mining method, external reclaimer fill mining method. The veins are densely distributed in clusters. 65 veins with industrial value have been identified. The single vein is 200-500 m long, with an average thickness of 0.20-0.5 m. The maximum length of the ore body is 23 to the middle. In 2015, it will continue to extend from the middle of the middle to the middle of the 22nd, with a mining depth of 744m. It is a multi-middle section and a large-scale mining operation. It is characterized by long ventilation distance and many windy locations. The mine initially used a diagonal diagonal ventilation system. Since 2005, it has adopted a multi-stage machine station partition independent ventilation system. The mines of Jintao Company are divided into three mining areas, namely, the first, second and third mining areas. Each mining area is interconnected independently in different middle sections, and the multi-stage station partitioning independent ventilation system is concentrated (Fig. 1). The system is mainly composed of 35# ventilation well, 26# ventilation shaft, 56# ventilation shaft, 4 rhubarb line ventilation wells, 4 lifting shafts and 3 blind shafts. A total of 8 main fan fans are continuously operated for 24 hours to ensure downhole production. . In order to prevent the lifting well from freezing, the whole mine ventilation system is divided into normal and two periods of ventilation in winter. Ventilation system 2#, 15#, 1#, 56#, 35# in the normal period and 35# blind shaft, blind paying well and 57# blind shaft below the middle section of the 7th stage are all in the wind, 35#, 56#, 26# , the rhubarb line ventilation well exhaust; in winter ventilation, the three wellhead fans of the rhubarb line, 35#, 56# ventilation wells reverse the ground fresh air into the well, 2#, 15#, 1#, 56#, 35 #å‡äº• has a small amount of hot air discharged, and the dirty air is discharged by 26# ventilation wells.
With the increasing depth of mining, the deep air volume in the mine is insufficient, so that the smoke cannot be discharged in time, and the temperature in some places is high. After analysis, the main problems are as follows: (1) Early construction wind shaft ventilation section is too small, there are many misaligned wells, and the ventilation resistance is large, and it is not treated by the retaining wall. The localized location collapses due to weathering and water flow, which is extremely dangerous when cleaning. The wind well is clogged, the danger of cleaning is high, and some of the ventilation wells are connected to the goaf. The air leakage is serious and cannot be blocked. The ventilation resistance is too large, which directly affects the air volume of the fan, causing the main fan operating point to shift, and then the fan appears. Problems such as easy damage and small air volume; 2 scattered work sites, involving many middle sections. When the ventilation system is running in winter, only one 26# ventilation well discharges the dirty air, the dirty wind line is long, the ventilation resistance is large, and the dirty wind line is turned back. It is easy to pollute other working places; 3 there are many working places, the air volume can't be dispersed, which makes it difficult for fresh airflow to go down to the middle part of the deep, which can't effectively eliminate the heat damage; 4 With the use of the handheld electronic CO detector, the downhole workers enter the working place The information on the CO content of the working surface can be obtained quickly and clearly before, and when the CO content reaches 24×10-6, it is forbidden to enter, resulting in a considerable part of the working place.
2 ventilation system optimization
2.1 Total mine air volume calculation
The actual required air volume at each operation site of Jintao Company's mine should be calculated according to the amount of harmful gas generated after blasting (no gas and carbon dioxide escaping), working surface temperature, wind speed and the maximum number of people working at the same time. Take the maximum value and the results are shown in Table 1. Combined with the data in Table 1, the required air volume of the first, second and third mining areas is calculated to be 55.7, 56.94 and 54.74m3/s respectively. The calculation results of the specific required air volume in each mining area are shown in Table 2.
2.2 ventilation well resistance
After detailed investigation of the ventilation wells of 35#, 26#, 56# and Dahuang line, it was found that the ventilation section is small, easy to block, and the locations with large wind resistance are concentrated in the middle section of 3~15. For this reason, the study uses a patio reverse drilling rig. A 1.4-meter-diameter patio is used as a ventilation shaft. The well wall is smooth and stable. After calculation, the friction resistance coefficient of the ventilation shaft is small (0.005kg/m3), and the friction resistance of the early ventilation shaft The coefficient is large (0.01 kg/m3) (Table 3).
2.3 Local ventilation optimization
At the same time of mine production, while using the total negative pressure ventilation of the mine, the roadway tunneling working face, the mining cutting face and the mining site blasting are all reinforced by local fans. The exit ventilation is generally adopted, and the YBT52-2 type local fan is used for design. For the working face of the single heading, the local fan is equipped according to the length of the roadway. When the length of the roadway is less than 200m, one YBT52-2 type fan is used for the extraction ventilation; when the length of the roadway is more than 200m, the pressure is adopted by two local fans. Pump mixed ventilation.
The distance between the locally ventilated air duct and the working surface: press-in ventilation shall not exceed 10m; draw-out ventilation shall not exceed 5m; when mixed ventilation, pressurize the air duct shall not exceed 10m, and the extracted air duct shall be delayed by 5m.
3 dynamic ventilation
3.1 Required air volume analysis
It can be seen from Table 1 that the mining face has a large air volume. The main air volume requirements of the mine working face are divided into two categories: dust exhaust air volume and row smoked air volume. From the sequence of mining operations, it can be known that the drilling operation is 8 hours, only the dust volume is required; the blasting ventilation is 8 hours, only the volume of the gun smoke is required, and the mining operation is 8 hours, and only the dust volume is required. It can be seen that during the drilling and mining operations
The amount of wind is wasted. To this end, the production air demand is classified according to different operation conditions. The wind type and air volume required for the whole mine mining operation are shown in Table 4.
It can be seen from Table 4 that the air volume required for rock dust removal and demineralization is much smaller than that required for row gun smoke. Since the 8 main fans of the underground mine of Jintao Company are continuously operated for 24 hours, many of them are series relay fans, the total working load is 501kW, and the actual air volume is 196.6m3/s, which can be seen in rock drilling and mining operations. Within 16 hours, the air volume of 61.5 m3/s was wasted. Assume that a wind turbine generating 61.5m3/s air volume is continuously operated for 16h, resulting in an electricity cost of about 1664 yuan / d, and the electricity cost in 1a is about 607,000 yuan. The wasted electricity cost is equivalent to 1 small mine. Ventilation fee.
3.2 Fans are arranged in parallel
The original 35#, 26#, 56#, and rhubarb ventilation wells were re-excavated and directly reached the deep middle section by using a rig rig . The main ventilation route was dredged by section, and the local ventilation system and main ventilation system of each middle section and each operation site were used. Unicom, which constitutes a complete ventilation network, conducts operations for large-scale wind separation and elimination of heat damage in the middle of the deep. The eight main fans currently in operation are placed in four main ventilation wells, which are connected in series. The total working load is 553 kW. According to the current wind well conditions, the total wind resistance of the whole mine is 3295 Pa. According to the above, the new ventilation with the rig construction is adopted. Well ventilation conditions (smooth wall, small frictional resistance coefficient) estimate the ventilation resistance of about 2000Pa. Each of the 8 sets of 8 fans is placed in parallel in the ground position of 4 main wind wells in parallel. See Table 5.
Hypothesis 1: divide the downhole work shift into three, 8 to 16 o'clock for the blasting ventilating class, 16 to 24 o'clock for the mining operation class, and 24 o'clock to 8 o'clock the next day for the rock drilling class. It can be seen from Table 4 that the maximum required air volume of the whole mine is 168.38m3/s from 8 to 16 hours, and four sets of 8 fans need to be turned on at the same time; 16 to 24 hours, 24 hours to 8:00 the next day, the main demand for dust removal is 119. .1m3/s, only need to open one fan per group to meet the requirements, that is, open 4 fans of 2, 4, 6, 7 in Table 5, the total power is 349kW, and the air volume is 143.8m3/s. If the assumption 1 is established, the electricity cost for the fan operation can be saved at 1264 yuan/d, and 1a can save 460,000 yuan.
3.3 Estimating electricity price factors Optimizing dynamic ventilation methods
The electricity prices of the mines where Jintao Company belongs are shown in Table 6. It can be seen from Table 6 that the peak electricity price is the highest, according to the hypothesis 1 analysis, 8 to 16 o'clock is the blasting ventilating class, the maximum mine air volume is 168.38 m3 / s, and 4 sets of 8 fans need to be turned on at the same time. The peak value is 4h, and the flat value is 4h. Although the fan can be saved according to the time-sharing operation of the hypothesis 1, the electricity cost is saved according to the peak-valley electricity price calculation, and the ventilation method is still unreasonable.
Hypothesis 2: The downhole work shift is divided into three parts, 22 to 5 hours for the blasting ventilating class, 6 to 14 hours for the mining operation class, and 14 to 22 hours for the rock drilling class. It can be seen from Table 4 that the maximum required air volume of the whole mine is 168.38m3/s from 5 to 22, and four sets of 8 fans need to be turned on at the same time; 5~13 hours and 14~22 hours are mainly dust removal, and the required air volume is 119.1m3. /s, you only need to open 4, 4, 6, 7 and other 4 fans to meet the requirements. If the hypothesis 2 is established, the electricity cost for the fan operation can be saved at 1903 yuan/d, and 1a can save 695,000 yuan.
The principle of the variable frequency fan is to adjust the input frequency of the motor and change the number of revolutions of the motor to adjust the air volume and wind pressure generated by the fan. When the motor input shaft power is 51% of the rated motor power, the fan speed will drop by 80% and the air volume will drop by 80%. If the downhole fan motor is completely replaced with a variable frequency motor, it is possible to adjust the air volume on time.
To the purpose of saving electricity.
Hypothesis 3: Change the fan motor and power distribution cabinet to frequency conversion type. According to Hypothesis 2, set the ventilation time, adjust the fan frequency and reduce the air volume in time. The actual preparation time and finishing stage of the mining class and rock drilling class need not be arranged. Dust, the fan dust frequency can be used to adjust the dust removal time of the two shifts to achieve the best ventilation effect. If the assumption of 3 is established, the electricity cost for wind turbine operation can be saved at 3,896.28 yuan/a, and 1a can save 1.422 million yuan.
4 Conclusion
Aiming at the problems existing in the mine ventilation system of Jintao Company, combined with the type of wind required by the working face, a new ventilation idea is proposed, in which the main fan is grouped in parallel, the main fan is dynamically turned on, and the single main fan is operated in frequency. The analysis shows that the ventilation method can not only greatly reduce the mine ventilation cost, but also distribute the wind source to the underground working points more reasonably, which helps to improve the safety, practicability and scientificity of the underground ventilation system.
references
[1] Wang Deming. Mine ventilation and safety [M]. Xuzhou: China University of Mining and Technology Press, 2007.
[2] Liu Qizhi, Sun Yufeng. Mine ventilation [M]. Beijing: Coal Industry Press, 2007.
[3] Jia Hongjie. Research on the optimal ventilation system of Jinchanggouliang Gold Mine [J]. Mining Express, 2001 (13): 9-11.
[4] Cui Shicheng. Study on the ventilation system of the non-independent multi-stage station of Jinchanggouliang Gold Mine [J]. Nonferrous Mining and Metallurgy, 1999 (5): 49-53.
Author: Wang Shiqiang, Wang Chenglong, the East Kong; China National Gold Group Co., Ltd., Inner Mongolia Jin Tao;
Article source: "Modern Mining"; 2016.6;
Copyright:
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