1 Ways and characteristics of dust generation in coal mines
1.1 Ways of coal mine dust generation
Coal mine dust is mainly produced in the production of coal mines. Especially in the case of large wind speeds in coal mines, coal mine dust pollution will be more obvious when coal mining operations are carried out. The coal mining face is the main source of coal dust, and the amount of dust discharged accounts for about 60% of the total dust emissions. Doing a good job of dust prevention work in coal mining face can not only prevent gas and coal dust accidents, but also play an active role in the environmental improvement of coal mining face and the life safety of miners. Generally, coal mine dust mainly comes from: the coal cutting process of the coal mining machine, the moving process of the coal mine support, the coal discharging process of the coal discharging equipment, and the breaking process of the breaking equipment. Among them, the coal cutting process of the coal mining machine and the coal mining process of the coal mine support have the largest amount of coal dust. In addition, a large amount of dust is generated during the process of tunneling into the coal mine roadway. In order to do a good job in the prevention and control of coal dust in coal mining, it is necessary to take corresponding treatment measures according to the specific source of coal dust, and comprehensively carry out treatment to reduce the concentration of dust.
1.2 Hazard characteristics of coal mine dust
The main components of coal mine dust are micro-dust and debris dust. The characteristics and hazards usually have the following points: (1) In the air floating in the air for a long time, there will be a circle of air film around it. The appearance of the air film will hinder the interaction between the dust and the dust or between the dust and the tiny water droplets in the air, which will seriously affect the sedimentation process of the dust; (2) the oxygen molecules on the surface of the dust will follow The increase of dust diffusion increases, which will accelerate the oxidation rate of dust; (3) Silica in the fine dust of the cuttings, because of its large surface area, once the coal miners inhale into the body, it will be easy in the coal miners Deposition of sediment in the alveoli, long-term accumulation of time will cause coal mine workers to produce pneumoconiosis; (4) the instantaneous generation of dust on the coal mine working surface will bring more electricity than the dust that has entered the coal mine ventilation system, if If the dust concentration is too large, the dust explosion or burning will easily occur in the workplace, and even the operation of the mechanical equipment will be affected.
2 Control measures for dust in coal mining operations
2.1 Coal dust treatment measures
(1) Arrange the radial fog screen of the shearer.
By shearer drum is installed close to the swing arm welded straight and curved metal pipe coupling 6-9 ejection seat, the flow rate using the water pressure of about 10MPa or more and 5L / min to give the water jet seat A radial fog screen is formed on one side of the sidewalk to effectively reduce and control the dust generated by the shearer drum.
(2) Use high pressure spray to reduce dust.
High-pressure spray dust reduction mainly relies on the high pressure of water mist to disperse the dust to achieve the purpose of reducing its concentration. The dust reduction method of the dust reduction method is ideal, and the operation is relatively simple and easy to implement, and the dust reduction rate can be as high as about 90%. Its pressure requirement for water is controlled above 8~12MPa, and the flow control is required at 15L/min. The working principle is mainly to increase the flying speed of the water mist molecules and the amount of electric power of the eddy current by high pressure, so that the water mist molecules and the dust particles collide and coagulate at a high speed, so that the dust can be externally caused by the air film. The phenomenon of rejection is effectively avoided, and the degree of combination between the two is significantly improved to achieve the purpose of efficient dust removal. Five measuring points are set in the windward side of the shearer from 5m to 10m in the downwind side. The distribution of all dust in the case of headwind cutting and downwind cutting coal and the comparison before and after the high pressure spray dust removal technology are shown in Fig. 1 and Fig. 2. Shown.
Dust pollution problem and treatment in coal mining operations
It can be seen from Fig. 1 and Fig. 2 that the full dust concentration gradient before the high pressure water mist is sprayed is obvious, the total dust concentration is high, and the center position of the shearer drum is relatively high, and the concentration on the leeward side is relatively low. This is because the whole dust itself has large particles, it is difficult to suspend in the air, and it is easy to settle by itself. After spraying high-pressure water mist, the overall dust concentration gradient has been significantly reduced. It can be seen that the effect of using high pressure spray to reduce dust is still significant.
(3) Specially designed automatic valve-controlled spray equipment for special areas.
For the dust generated in some special areas, such as the transfer process of coal mine supports, the coal discharging process of coal discharging equipment can achieve the effect of dust reduction and dust removal by designing special automatic valve-controlled spraying equipment. The method of installing a four-way valve or a magnetizer on the dust removing device can remove the dust generated during the movement of the coal mine support and the dust generated during the coal discharging process of the coal discharging device, so that the dust reduction work of the downwind adjacent frame can also be performed. Magnetized water spray dust reduction work of respiratory dust plays a very good role
2.2 Analysis of economic and social benefits
The on-site dust test after the comprehensive application of the above dust removal measures showed that the dust concentration at the driver of the shearer was reduced by about 72%, which met the expected dust reduction target. Since the above-mentioned dust reduction measures have been comprehensively used on March 11, 2014, the systems have been operating normally and no abnormalities have occurred. The production environment of the 3207 working face has been improved, the visibility of the working face has been improved, the misoperation of the workers in production has been reduced, and the production enthusiasm has been improved. In addition, the reduction in dust concentration protects workers from dust and protects workers' health.
2.3 Drilling dust control measures for excavation work
Mechanical rock drilling is the main operation mode of coal mine underground mining work. In the process of strong impact on rock by mechanical equipment, a large amount of dust will inevitably occur in this process. The main factors affecting the amount of dust in the coal mining work are: (1) the lithology and specific structural characteristics of the mined rock; and (2) the production intensity of the mined coal mine. The humidification treatment is a dust reduction measure usually used in rock drilling, and dust removal can also be carried out by carrying out dust collection work. With the development of science and technology, a more easy-to-operate and more economical dust removal method-foam dust removal method has been developed, which mainly adds a certain proportion of foam in water and then obtains a kind of water and foam through certain mechanical treatment. The new mixture, the volume of this new mixture is much larger than the volume of pure water, which can save a lot of water, increase the wet interface, and can more capture the dust, and its dust removal effect is also ideal.
3 Strengthen the application of scientific management and new technologies
(1) To ensure the smooth progress of the dust reduction work in coal mines, it is necessary to have a good dust management mechanism as the basis. Among them, the control of coal mine dust should focus on the control of respirable dust. Because this dust poses a direct threat to the physical health of coal mine workers.
(2) Based on the advanced dust removal technology in foreign countries, combined with the actual situation in China, develop a dust removal device suitable for the characteristics of coal mine production in China. For example, we can learn from the vacuum drums in the UK to develop our own vacuum cleaner rollers.
(3) In the aspect of protective respirable dust, the focus is on the development of filter dust materials, and try to avoid the direct all-round contact between dust and workers. Focus on the development of some small and convenient dust removal equipment.
(4) Focus on the use of advanced biotechnology and new processes on dust masks or appliances.
1 In the research and development of biotechnology dust-proof appliances, the government and relevant departments should increase investment to prevent some respiratory dust from causing direct harm to the first-line miners;
Development of early warning systems. The treatment mechanism combining early warning, treatment and prevention should be the development direction of dust prevention work in new mines in the future. It should be equipped with a special dust monitor in the dust generation line to effectively monitor dust concentration, composition, particle diameter and dust. The content of silica, set up relevant monitoring stations on the ground, once it is found that some dust in the air exceeds the standard and poses a hazard to the human body's personal safety, it should immediately organize the underground employees to evacuate the site, so that the body of the coal mine workers can be Safety is a guarantee, and it can also prevent a series of major accidents such as underground gas explosions and dust explosions.
5 Conclusion
Improve the awareness of coal mine practitioners on the source, characteristics and hazards of coal mine dust, start from the source of dust, prescribe the right medicine, take preventive measures, and actively introduce and adopt some new technologies and new techniques, especially to do respiratory dust. The prevention and control work will ensure the life and health of front-line workers and establish a new mine in the future that is quiet, clean, energy-saving and safe.
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