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1. Dust prevention technology
Dust mining coal face. Including coal seam water injection, reasonable selection of coal mining machine cutting mechanism and spray dust reduction.
The working face is dust-proof. Including dustproofing on the face of the excavation work, ventilation and dust removal on the excavation face and dustproofing of the anchor spray support. Transport and transfer dustproof. Including mechanical control automatic spray dust-reducing device and electrical control automatic spray dust-reducing device.
Comprehensive dust prevention measures. Including wet drilling, flushing the wall of the well, using water cannon mud, shooting spray, loading rock (coal) watering and purifying the air flow.
2. Coal dust prevention and explosion prevention measures
Coal dust explosions must occur when three conditions are met at the same time, that is, the dust itself is explosive; the dust is suspended in the air and reaches a certain concentration; there is a heat source sufficient to ignite the dust.
If these conditions are not allowed to exist at the same time, or the conditions that have been formed are destroyed, the occurrence and development of coal dust explosion can be prevented. This is the starting point and basic principle for the development of various measures to prevent coal dust explosion.
First, take dust prevention measures. Under normal circumstances, the concentration of floating coal dust in the production site is much lower than the lower limit of the explosion. However, due to air turbulence (the shock wave of the shot), the deposited coal dust is re-flyed, and the concentration of coal dust at this time greatly exceeds the lower explosion concentration. It is estimated that on the periphery of the 4m2 section small roadway, as long as a layer of coal dust of 0.04mm thick is deposited, when it is all flying up, the lower explosion limit is reached. In fact, the deposited coal dust in the underground exceeds this thickness. Therefore, it is the simplest and most effective explosion-proof measure to reduce the amount of deposited coal dust in the roadway and remove the well.
Effective dust-proof and dust-reducing measures are adopted in each production process to reduce the generation of coal dust and reduce the concentration of coal dust in the air, thus reducing the amount of deposited coal dust. Therefore, comprehensive dust prevention measures are not only measures to reduce the health hazards of workers, but also measures to prevent coal dust explosions.
Second, put an end to the source of fire. The sources of ignition that can cause coal dust explosions are electric sparks, friction sparks, friction heat, high temperature points formed by spontaneous combustion of coal, deflagration in blasting operations, and high temperature products generated by gas explosion. The main technical measures to eliminate this kind of ignition sources are: to maintain the integrity of the mine explosion-proof electrical equipment, electrical equipment to strengthen management to prevent loss of critical phenomena; the choice of non-ignition of the light alloy material to avoid the risk of friction sparks; tape, wind Common non-metallic materials such as cylinders and cables must have flame retardant and antistatic properties; use resisting agent, gel or nitrogen to prevent self-ignition of coal pillars and residual coal in goaf, and strengthen gas management to prevent gas explosion accidents. .
Due to the complex natural conditions of coal mines and the randomness of coal dust explosions, in addition to the above-mentioned general safety technical measures, in view of the characteristics of coal dust explosions, countries have also studied the expertise to prevent coal dust explosions. The long-term, simple and easy-to-use technical measure to prevent coal dust explosion is the slag powder method.
Third, the method of spreading rock powder. This method is to periodically spray inert rock powder around the roadway to cover the deposited coal dust deposited on the periphery of the roadway. When the rock powder layer has a low wind speed in the roadway, its viscosity plays a role in hindering the re-lifting of the deposited coal dust.
3. Prevention of coal dust explosion propagation technology
The technology for preventing coal-dust explosion propagation is also called the technology for isolating coal-dust explosion propagation (hereinafter referred to as explosion-proof technology). It refers to the technical measures to control the explosion that has already occurred within a certain range and extinguish it to prevent the explosion from spreading outward. This technology is not only suitable for the control of coal dust explosion, but also for the control of gas explosion and gas coal dust explosion. The technology is divided into two categories, passive flameproof technology and automatic flameproof technology.
Passive flameproof technology (also known as flameproof measures). At the beginning of the explosion, the peak of the explosion flame is ahead of the explosion pressure wave. As the explosion reaction continues and strengthens, the pressure wave gradually catches up and advances ahead of the flame peak. There is a time difference between the two. Passive flameproof technology is to use this law, using the energy of the pressure wave to make the explosion-proof measures act, forming a flame-extinguishing flame cloud of flame extinguishing flame in the roadway, and then extinguishing when the flame reaches the inhibitor dust cloud, blocking The explosion continued to spread forward. The passive explosion-proof technology mainly includes: rock powder shed, water tank shed and water bag shed, collectively referred to as passive explosion-proof shed. There are three forms of passive explosion-proof sheds, centralized layout, decentralized arrangement and centralized decentralized hybrid arrangement. According to the role and protection scope of the explosion-proof shed in the mine roadway system, they can be divided into the main explosion-proof shed (heavy shed) and the auxiliary explosion shed (light shed). The function of the heavy shed is to protect the safety of the whole mine. The main transportation roadway and the return air main road connected to the wellbore of the mine are connected; the transportation lane and the return stone gate between the adjacent coal seams; the concentrated transportation lane and the return airway between the adjacent mining areas. The role of the light shed is to protect the safety of a mining area, the air inlet and return air passages in the coal mining face; the coal and semi-coal rock roadway in the mining area; and other roadways with independent ventilation and danger of coal dust explosion Settings.
Automatic flameproof technology. The principle of action of the passive explosion-proof technology determines that the technical measure can only suppress the explosion within the range of 60-200 m from the explosion source (300 m in the rock meal shed). Therefore, this technique was ineffective at the beginning of the explosion. In addition, the use in low, narrow and curved lanes is extremely unfavorable and does not exert a detonation effect. In response to these shortcomings, countries have studied and used automatic flameproof technology.
The sensor, controller and spraying device are the three major components of the automatic explosion-proof device. The explosion-proof system consisting of several automatic explosion-proof devices is the automatic explosion-proof device. The sensors used mainly have three types: the gas explosion is accepted. A power effect pressure sensor, a pyroelectric sensor that utilizes the thermal effect of the explosion, and a photoelectric sensor that utilizes the light effect of the explosion flame. The controller is an instrument that issues an action command to an actuator that sprays the inhibitor; the spray mechanism typically consists of an actuator, a sprinkler, and an inhibitor storage container. Its role is to diffuse inhibitors (rock powder, dry powder or water) into the roadway space to form dust clouds or water mist zones. Its movements should be fast, reliable, and adaptable to the rapid development of the explosion.
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