1 Mine Overview
At present, a gold mining ore production capacity of 2500t / d. The mine is now developed with main and auxiliary shafts + auxiliary ramps, and the middle section is mainly transported by diesel trackless equipment. The mining target is mainly the No. 70 vein, and the middle section of the mining currently has four middle sections of 1264, 1224, 1184 and 1136m. The mine now mainly uses the wind inlet to enter the wind, the auxiliary shaft and the auxiliary slope to assist the air intake, and adopts the 1520m return air to return to the wind. The ventilation method is single-wing diagonal extraction type, and the total required air volume of the designed mine is 150m3/s. A DK62(A)-10-No30 mine counter-rotating shaft flow fan is installed in the 1466m return airway. The motor power is 2×400kW.
2 problems in mine ventilation system
According to the site investigation and analysis of the mine, the ventilation system currently has the following four problems.
(1) The existing DK62(A)-10-No30 main fan of the mine has one motor damaged. It is currently operated by a single motor. The total return air volume of the mine is determined to be 79.62m3/s, with an annual output of 10,000 tons. The air consumption is only 0.97m3/s. Therefore, the supply air volume of the mine is seriously insufficient, and there are many diesel equipment operating underground. Diesel equipment exhaust gas, gun smoke, dust, etc. cannot be diluted and discharged in time, resulting in poor air quality of most working faces in the underground, which threatens workers' health.
(2) The mine reflects that the existing DK62(A)-10-No30 main Fan Motor has been damaged many times. The main fan needs to be suspended every time the motor is replaced, and the motor replacement is inconvenient, which affects the normal production of the mine. After preliminary analysis, the cause of motor damage may be: the main fan and the motor are not matched, resulting in motor overload; the original fan of this model is 2×450kW, the actual installation of the mine is 2×400kW; the motor protection level is too low, downhole The tail gas of the diesel engine causes corrosion to the motor; when the main fan is turned on, the Class I and Class II motors are not started step by step as required, or the motor is started without closing the electric butterfly valve.
(3) The actual measured sectional area of ​​most of the return air inclined shafts in the mine is 7.8~12m2, and the cross section of the return airway is too small, which causes the ventilation resistance of the return air section of the mine to be too large, and the ventilation capacity is limited. According to the total return air volume of the mine of 150m3/s, the total resistance of the mine ventilation reaches 3200Pa. According to the initial air volume and the total resistance of the mine ventilation, at least the main fan with a power of 2×560 kW should be selected, and the power of the main fan operating point should reach 1007 kW.
(4) Since the mining of the mine, the No. 70 vein has been in the late stage of mining, and the mine is currently planning to mine 2 ore belts. 2 The ore belt is located on the south side of No. 70 vein, and the boundary of the two ore belts is about 400m apart. The existing mine ventilation system has not yet considered the 2 ore belt. Therefore, the mine ventilation system needs to be modified to meet the ventilation needs of the 2 mines.
In view of the problems existing in the mine ventilation system, combined with the current situation of the mine and the future development needs, it is urgent to optimize the mine ventilation system at this stage, so as to provide a good working environment for underground workers and meet the needs of mine underground safety production. .
Study on Optimization and Reform of 3 Mine Ventilation System
When constructing a mine ventilation system plan, the principles of good technical effect, safe and reliable operation, low capital and operating costs, and easy management should be strictly followed [1-2]. This research will formulate the optimization and transformation plan of this ventilation system based on the above principles.
3.1 Determination of ventilation system optimization and transformation plan
After analyzing the problems of the mine ventilation system, the recommended scheme for the optimization and renovation of the ventilation system is: replacement of the main fan + return air inclined well expansion + new digging 2 ore belt through the pulse communication lane. The optimization of the ventilation system is mainly carried out from the following four aspects.
(1) Increase the total return air volume of the mine to achieve the design air volume value. To increase the total return air volume of the mine, the main fan problem must be solved. Considering that the existing DK62(A)-10-No30 main fan motor in the mine is often damaged, and the motor power is not matched with the main fan. This time, we recommend another return airway in the middle of the 1466m return air, and re-match one DK62(A)-10-No30 main fan, using the matching 2×450kW motor, and the motor protection grade adopts IP55.
(2) Reduce the ventilation resistance of the return air section of the mine. To reduce the ventilation resistance of the return air section of the mine, it can be realized by brushing the cross section of the return air passage and increasing the parallel return air passage. According to the actual situation of the underground mine, a return air return patio of the original stope was cleaned out in the middle section of 1344 and 1390m, and a parallel airway was formed with the existing middle-return inclined well. The optimum wind speed of the main return air shaft can be 6 ~ 8m / s, generally should not exceed 10m / s [3]. At the same time, it is considered that the cost of the roadway cleaning is relatively low compared to the excavation. After comprehensive consideration, this proposal proposes to brush the main return air inclined section between the altitudes of 1184 and 1466m to 20m2, and the total length of the returning inclined shaft to be brushed is 517m.
(3) The lowest middle section of the 2 ore belt to be mined is 944m, and the uppermost one is the middle section of the 1390m return air. In order to solve the problem of 2 ore belts entering and returning to the wind, the study considers that in the middle section of 1184～1390m, a vein roadway close to the 2 ore belt is selected from the No. 70 vein, and the tunnel along the vein of the 2 ore belt is drilled. In this way, the 2nd ore belts of 1184m and above can enter the wind through the tunnels of the two mine belts, and use the 1390m middle section to pass through the ventilation corridor. According to the mine plan, the development system below 1184m in the 2 ore belt is planned to use the extended slope road + auxiliary inclined shaft to develop. Therefore, in the middle section of the 2 ore belt below 1184m, the wind can be used to enter the wind by the slope road and the auxiliary inclined shaft, and the return air will return to the middle section of the 1390m return air through the return section of the middle section, and then collect the total return through the 1390m return airway. Return to the inclined shaft.
(4) In order to improve the safety and reliability of the main fan operation, it is recommended to establish an on-line measurement and control system for the main fan in the mine [4-6]. Real-time monitoring of ventilation system parameters, environmental parameters, ventilator performance parameters, motor electrical parameters, Bearing temperature, motor vibration, etc. through online measurement and control system, and data management, report management, performance testing, and remote communication. The mine safety management personnel can grasp the operating state of the fan at any time during the production process, and remotely control the fan according to the real-time status of the fan, thus ensuring the safe and reliable operation of the main fan. The modified ventilation system is shown in Figure 1.
3.2 Ventilation network solution after optimization and renovation of ventilation system
The computer software can be used to solve the mine ventilation network, which can realize the simulation of the mine ventilation system, and provide technical support for the optimization of the mine ventilation system and the technical transformation of the mine ventilation system. In order to test the feasibility of the proposed ventilation system optimization and transformation plan, the most convenient and effective method is to solve the ventilation network after the transformation of the ventilation system to verify the decline of the total ventilation resistance of the mine and the distribution of the air volume of the mine.
This ventilation network solution mainly uses the Hardy-Cross algorithm for iterative calculation. The essence of solving the ventilation network by Hardy-Cross iterative method is: according to the initial air volume of each branch air passage in the network, the increment ΔQk of each loop air volume is approximated, and as the correction value, the air volume of the branches in the loop is respectively performed. Correction. The iterative calculation is performed until the correction value ΔQk satisfies a predetermined precision. In order to improve the convergence speed of the iteration, the Gausscide technique is applied to the Hardy-Cross iteration method [7-8].
The computer ventilation network solution steps are as follows:
(1) initialization parameters;
(2) Creating a ventilation tunnel;
(3) Edit the lane parameters;
(4) Check the ventilation network;
(5) Iterative calculation of the ventilation network;
(6) Air volume adjustment;
(7) The result of the solution is displayed;
(8) Ventilation solution report output.
Through the network solution of the modified mine ventilation system, the total resistance of the mine ventilation after transformation is H=2272.17Pa. Optional DK62 (A)-10-No30 type axial flow fan 1 set, with YB630S-10 type motor (IP55) 1 set, power 2 × 450kW, speed 590r / min. The operating point of the fan is Q=166m3/s, H=2451.62, α=40°, η=75%, and the shaft power N=665kW. Another spare motor of the same model.
3.3 Comparative analysis of ventilation system before and after optimization
(1) The modified ventilation system takes into account the need for simultaneous mining and ventilation of the 2 ore belts and the 70th vein.
(2) The total ventilation resistance of the mine after the transformation is significantly lower than that before the transformation. The total ventilation resistance of the converted mine was reduced by 927.83Pa before the transformation, and the main shaft operating point required for the design reduced the shaft power by 342kW, which was far lower than before the transformation. If the power consumption of the main fan is calculated according to the working period of the main fan, that is, the working system of 330d/a and 24h/d, the energy consumption of the mine ventilation system can be saved by about 270.86×104kW·h per year before the transformation, and its indirect economy is generated. The benefits are considerable.
(3) This time, the main fan with higher motor protection level is re-selected, which not only makes the total return air volume of the mine reach the design air volume value, but also ensures the safety of underground production and improves the safety protection performance of the main fan motor. Through the establishment of the main ventilator online measurement and control system, the safety and reliability of the fan operation is improved.
4 Conclusion
Aiming at the problems existing in the ventilation system of a gold mine, the corresponding optimization and transformation plan is proposed. The ventilation system was simulated and verified by the ventilation network solving program. It has been verified that the modified mine ventilation system takes into account the needs of the future development of the mine, reduces the total resistance of the mine ventilation, saves energy, and improves the economic efficiency, safety production level and automation level of the mine. This study has certain reference significance for the optimization and transformation of similar mine ventilation systems.
references:
[1] Hu Hanhua. Mine ventilation system design - principle, method and example [M]. Beijing: Chemical Industry Press, 2010.
[2] Wang Deming. Mine ventilation and safety [M]. Xuzhou: China University of Mining and Technology Press, 2012: 158.
[3] AQ2003.1-2008. Technical specification for metal non-metallic underground mine ventilation [S].
[4] Zhao Tao. Research and Design of Online Monitoring System of coal miners Ventilator OPC and PLC [D]. Based on Taiyuan: Taiyuan University of Technology, 2010.
[5] AQ2031-2011. Construction specification for metal non-metallic underground mine monitoring and monitoring system [S].
[6] Si Junhong. Dynamic monitoring of air flow parameters and optimization of air volume adjustment in mine ventilation system [D]. Xuzhou: China University of Mining and Technology, 2012.
[7] Wu Chao. Mine ventilation and air conditioning [M]. Changsha: Central South University Press, 2008: 135.
[8] Zhi Xueyi, He Jinlong, Zhang Hongying. Mine ventilation and dustproof [M]. Beijing: Chemical Industry Release, 2009: 137-150.
Source: Mining Technology: 2016, 16(4);
Copyright:
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