After dust explosions, secondary explosions often occur. This is because in the first explosion process, a large amount of dust is piled up together, and its concentration exceeds the upper limit of dust explosion and cannot explode. However, when the shock wave or air wave formed by the first explosion lifts the deposited dust again and mixes with the air in the air, and the concentration is within the dust explosion range, a second explosion may occur immediately. The disaster caused by the second explosion is often much more serious than the loss caused by the first explosion.

Precipitator dust explosion can be much more complicated than combustibles and combustible gases. Combustible dust is suspended in the air and forms a dust cloud within the explosive concentration range. Under the action of the ignition source, part of the dust in contact with the ignition source is ignited to form a small fireball. Under the action of the heat released by the burning of this small fireball, the surrounding dust will be heated, the temperature will rise, and the phenomenon of fire will appear. In this way, the fireball will expand rapidly, forming a dust explosion. .

The difference between dust explosion and combustion. The combustion of large solid combustibles, such as coal, is propelled inward in an almost parallel layer. The release of this combustion energy is relatively slow. The heat and gas generated can be quickly dissipated. In the case of good ventilation, the accumulation and combustion of combustible dust will form an open flame, and in the case of poor ventilation, it will form smoke.

Mechanism of dust explosion. Combustible dust in the air will release energy when burned in the air, and will produce a large amount of gas, the rate of energy release, that is, the burning speed is related to the area of dust exposed to the air. Therefore, for the same solid powder, the smaller the particle size, the larger the specific surface area, and the faster the combustion and diffusion. If the solid particle size is very fine, once a large amount of energy can be ignited in a short time. This energy has no time to dissipate into the surrounding environment, causing the gas in the space to be heated and expand adiabatically. On the other hand, the large amount of gas generated during the combustion of the powder will cause the system to form a local high pressure, leading to explosion and spread, commonly known as dust explosion.