The research on scraper in China has been for a long time, mainly focusing on high power, high strength, long service life and high safety. Now, the focus of research is the high-performance components and high-efficiency equipment of scraper machine. At the same time, it develops and integrates information technology, such as working condition detection, remote control and corresponding startup software. Zhang Jianwen L in order to effectively solve the chain clamping problem of scraper conveyor, the optimization design is carried out by enhancing the driving torque and changing the sprocket. Generally, the driving torque and design angle can effectively solve the problems of large slope transportation. At present, China is relatively lack of technology in CST starting system and AC motor governor, and some power scraper machines still use foreign products.
A large amount of dust will be produced in the process of coal mining, especially at the joint of scraper conveyor and corresponding belt conveyor, which is more serious, and there is the phenomenon of mechanical injury. At present, China has put forward new requirements for occupational diseases, so the traditional scraper conveyor rotor point can not meet the engineering needs, so it is necessary to develop a kind of equipment that can solve this problem.
1. Current situation of underground transportation in coal mine
In the main transportation system of coal mine, the transportation system of fully mechanized mining face is a very important equipment. According to the mechanism of equipment operation, it can be divided into the following categories: first, continuous motion; Second, back and forth movement. For continuous motion, it is characterized by continuous operation after startup, which is widely used in belt conveyor and scraper conveyor. For the round-trip transportation equipment, in the process of transportation, it can make periodic movement in the form of round-trip. At the same time, it also needs to operate the commutator to realize commutation. It is widely used in locomotive transportation and single rope traction transportation equipment. In order to achieve efficient production, coal mining enterprises mainly use continuous transportation equipment.
In the main transportation system of the mine, the equipment transfer point is the hardest hit area producing coal dust. The use of fully enclosed dust prevention and protection devices can not only have an effective dust reduction effect, but also protect the workers. Therefore, it is necessary to develop safe and reliable dust prevention and protection devices, which provides a reference for dust reduction in fully mechanized mining face.
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2 Coal dust hazard
2.1 Links of coal dust generation
Coal mine dust is defined as various fine particles produced during coal mining. Due to the existence of primary dust in the coal seam itself, the mining coal mine will produce dust due to cutting and crushing. It will also produce a certain amount of dust during coal mine transportation, especially when unloading at the transfer point.
2.2 Hazard of coal dust
Usually, coal mine dust will be suspended in the air due to its own characteristics, and it can diffuse to various mining points under the action of wind. When underground workers go deep into the production environment, coal dust is very easy to enter the lung through the worker’s respiratory system, forming lung disease. According to the statistical report of relevant occupational diseases, it is found that among the top 100 coal enterprises, 2.05 people suffer from pulverized coal pneumoconiosis on average in the output of 100 tons of raw coal. For non top 100 enterprises, 73.41 people suffer from pulverized coal pneumoconiosis on average in the output of 100 tons of raw coal. In addition, coal dust can also lead to explosion. When the concentration of dust in the floating air exceeds a certain value, the coal dust will explode when there is enough heat source. Coal dust explosion often produces serious explosion wave, resulting in larger dust, which leads to large-scale explosion. When coal dust explodes, its explosion temperature will produce a flame of 2300 ~ 2500 ℃, which will move forward at the speed of 1120 MLS, which is very destructive.
3 Mechanical hazards
3.1 Damage of running scraper and chain
When the scraper conveyor works, it transports the coal gangue of the working face under the drive of the motor. In this process, there is a situation that workers cross the scraper conveyor, so it is very easy for people to fall into the chute. If the maintenance of the scraper is unreasonable, the phenomenon of floating chain may occur, which may cause casualties.
3.2 Cargo injury caused by scraper conveyor operation
When the scraper conveys grinding and other materials, the materials are often stuck in the scraper and chute. What’s more, the materials are cheap at high speed, which may lead to personnel safety problems.
4 Application of fully enclosed dust protection device for scraper conveyor
In order to effectively prevent the generation of a large amount of dust and personnel stepping into the conveyor slot, the traditional scraper conveyor is installed with “armor”, that is, an inverted U-shaped shield of the scraper conveyor is added, which can effectively reduce the amount of dust generated by the scraper conveyor and prevent the staff from entering the conveyor slot by mistake.
Two totally enclosed devices are set in each middle groove and connected in the form of pin shaft. The adjacent middle groove must be installed in a straight form, and the bending degree in the horizontal and vertical directions must be less than 3°. The scraper chain shall be set in the middle groove, and the scraper chain shall be moderate. An observation window is set at the head frame of the fully enclosed device to observe the operation of the head sprocket half drum. An observation window is reserved in the middle groove to observe the operation of the scraper chain. In addition, the fully enclosed device is convenient for separate disassembly and replacement.
The device can effectively reduce the labor intensity of coal cleaning. For the operation unit, the fully enclosed form is adopted for protection, which can effectively avoid the potential safety hazards caused by machinery. Because the water spray device is installed at the retransmission point, it can form water droplets and water, some of the dust will fall, and some of the dust will collide with each other to form larger dust and fall, which will prevent the transfer point from forming more dust.
5 Field application effect
In order to verify the application effect of the device, five dust sources are selected as samples in the experiment, and their positions with the head of the scraper conveyor are 1 m, 5 m, 10 m, 15 m and 20 m respectively. The sample points shall be tested on site for 10 days, and the average value of the test points shall be taken at the same time. When the device is installed, the dust mass concentration decreases from 3.9 mg / m3 to 1.5 ~ 1.7 mg / m within 5M and 1.3 ~ 1.7 mg / M ‘within 20m. Therefore, it can be seen that the dust reduction effect is great.
The fully enclosed dust prevention and protection optimization design of scraper conveyor shows that when coal is produced, the scraper conveyor operators enter the working face of roadheader for support operation, which can reduce the coal cleaning work. The water mist combined with dust in the steam spray device installed at the re-transmission point can make the dust fall, and some of the dusts collide with each other, which will further improve the dustfall effect due to heavy falling. In addition, all-round closed protection is implemented for the operation unit, which can effectively eliminate the safety problem of mechanical injury. Therefore, it can be popularized in the whole industry and provide comprehensive protection for the health of employees.
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