Dust explosion refers to the combustible dust in the encounter of heat source (open fire or high temperature), the flame instantaneously spread throughout the mixed dust space, chemical reaction speed is extremely fast, while releasing a lot of heat, forming a high temperature and great pressure, the energy of the system into mechanical energy and light and heat radiation, with strong destructive power.

The principle of dust explosion

The reason why dust is explosive is that there are strong reducing agents H, C, N, S and other elements exist, and when the peroxide and explosive dust coexist, it decomposes, resulting in a large amount of gas generated by oxidation reaction, such as in the process of open fire or high temperature, an explosion or fire occurs instantly, while releasing a large amount of heat.

Second, which dust can cause explosion

1, aluminum powder is also known as silver powder, aluminum powder has the characteristics of wet flammable, small explosion limit range, and aluminum powder can form an explosive mixture in the air. It can be seen that aluminum powder is particularly harmful. Aluminum powder will produce an oxide film in the air, and when it encounters an electric spark breakdown, a violent oxidation reaction will occur and rapidly spread, causing explosion and combustion.

2, magnesium powder is a silver-white powder, is a kind of active metal, in the event of water or moisture produces a violent reaction, releases hydrogen, produces a lot of heat, causing combustion or explosion. Magnesium powder is used as sulfur removal agent in metallurgy, and is also used in organic synthesis, lighting agent and so on.

3, flour production process, produce a large number of flour of very fine dust, when these dust suspended in the air, and reach a high concentration, encounter the fire source will burn up instantly, forming a violent explosion, its power is no less than a bomb.

3. Typical dust explosion accidents

Magnesium dust

On December 26, 2018, the Municipal and Environmental Engineering Laboratory of Beijing Jiaotong University exploded and burned, killing three people. In the process of mixing magnesium powder and phosphoric acid with a mixer, the sparks generated by metal friction and collision ignited an explosion, resulting in the death of three students at the scene.

Aluminum dust

On August 2, 2014, an explosion occurred in the polishing workshop of automobile wheel hub of Zhongrong Metal Products Co., LTD., Kunshan City, Jiangsu Province. The accident killed 69 people and injured nearly 200 others. It was preliminarily determined that it was an enterprise safety production responsibility accident, suspected to be caused by a dust explosion.

Stearic acid dust

An explosion and fire broke out in Shuangma Hua stearic acid granulation workshop in Dongchen Town, Rugao City, Jiangsu province. Eight people were killed and nine others injured in the blast, which collapsed to three stories after the explosion.

4. Explosive workplace

The pharmaceutical industry, food processing plants, power plants, steel casting industry, flour processing plants, cement plants, textile factories and other industries have dust, which will produce a large amount of combustible powder in the production process, and the higher the concentration value of dust in the space, the more dangerous.

Five, how to prevent dust explosion

Family: Keep away from open flame when using dust, be sure to stay away from open flame area such as stove gas when making flour or wheat flour, and it is best to open window operation.

Factory: Prevent dust deposition and clean up dust in time. Prevent dust from flying around, set up special protective cover and local exhaust hood and maintain a ventilated environment. Relevant enterprises need to install dust concentration measuring instrument to monitor dust concentration in real time.