Experts interpret Kunshan explosion accident: the hub is polished with a lot of dust

Kunshan Network Kunshan August 2 news (Reporter Du Ximeng) According to the Voice of China, "News Night" reported that the cause of the accident was caused by dust, so how does the dust cause the explosion? Why is the destructive power so Big?

How does dust cause an explosion?

Xiao Qiuping, a researcher at the Shanghai Research Institute of Chemical Industry: There are several conditions for dust explosions. When these conditions are met at the same time, a dust explosion will occur. The first point is that dust is present and the dust is flammable dust. It is impossible for a dust explosion to occur when the sand on the roadside is raised because it is not flammable. Starch is a flammable powder in daily life, and dust explosion may occur. The second point in a dust explosion is to have an oxidant, or oxygen in the air, that is, oxygen must be supplied. The third is to have an ignition source. If there is no ignition source, all conditions are sufficient and there is no way to trigger the dust explosion.

Dust explosion has a special phenomenon. It needs to form premix in the air. The dust explosion is more accurate. It should be called a layer cloud explosion, because the dust is scattered in the air, forming the feeling that we see the sand layer in the air. . The powder layer cloud has an upper and lower limit, not to say that it can explode when flying, and the dust explosion will occur only after the five conditions are met.

Why does the explosion produce such a great power?

A dust explosion is actually a violent burning, or a deflagration. Why is this violent explosion? This is actually the intensity of the reaction. To make an analogy, wood charcoal is to burn wood into an open hearth. It is a slow burning and does not form a violent reaction. When the wood powder is turned upside down, after the wood is broken into dust, the particle size is lowered, the contact with the air is more sufficient, and the surface area is increased, resulting in a more intense reaction.

In the actual production process, the dust explosion occurring in the production accident is likely to be a secondary explosion, and the amount of dust involved is large, which may also lead to a drastic effect. What is a second explosion? It is the first explosion at a certain point. The power may not be very large, but the shock wave of the first explosion gathers the dust accumulated on the pipe surface and inside the factory. This amount is very large. Forming a violent second explosion, even three or four explosions, which is why the dust explosion is so intense.

According to the understanding, Kunshan Zhongrong Metal Products Co., Ltd. was established in 1998 and is located in Kunshan Economic Development Zone. The company employs 450 people and its core business is electroplated aluminum alloy wheels. A person in charge of a domestic tire wheel manufacturing company said in an interview with China Voice that the aluminum alloy wheel wheel may actually burn or explode due to the increase in dust concentration during the electroplating and polishing process:

Responsible person: There will be a lot of dust in the polishing process. One kind of dust is the thing that comes down on our wheels. That is aluminum powder. Once the aluminum powder is ignited, the reaction force is very very large. Another grinding material itself has to be consumed. Sand dust, aluminum powder dust, he is easy to mix, so it accumulates all the year round, and it will be more and more accumulated without timely cleaning. The concentration is high, let alone use open flame, as long as there is Static electricity will explode. The moment of the explosion will happen and it will not be able to control it.

According to industry statistics, since 2010, domestic metal polishing dust explosions have occurred frequently, accounting for almost 30% of dust explosion accidents. The person in charge also said that if the country requires, the company needs to carry out a variety of explosion-proof disposal to ensure safe production:

Responsible person: Like this manufacturer, artificial masks should be used to prevent him from developing silicosis. Secondly, the protective clothing, shoes and gloves that you wear must be antistatic, including lights, anti-static lamps, everything. All have to be anti-static, but also have to regularly ventilate, you have to have a vacuum cleaner, you have to ensure the air flow, the requirements are very strict.

According to the Kunshan Municipal Government of Jiangsu Province, the two business leaders of Kunshan Zhongrong Metal Products Co., Ltd., whose explosion occurred, have been controlled, and the cause of the accident is still under investigation.