Flour explosion refers to the phenomenon that flour particles explode when exposed to open fire. In the production process, a large number of extremely fine flour dust will be produced. When the dust is suspended in the air and reaches a high concentration, such as 9.7g flour per cubic meter of air, it will burn instantly in case of fire, Mars, electric arc or appropriate temperature, forming a violent explosion, which is equivalent to a bomb. Dust becomes an "explosive" because of its large surface area.

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The difficulty of dust explosion is related to the physical and chemical properties of dust and environmental conditions. It is generally believed that substances with high combustion heat are more likely to explode, such as coal dust, carbon and sulfur. Substances with fast oxidation rate are easy to explode, such as magnesium powder, aluminum powder, ferrous oxide, dyes, etc. Dust that is easy to be charged is also easy to cause explosion, such as synthetic resin powder, fiber dust and starch. These substances with poor conductivity accumulate due to static electricity generated by friction with machines or air, and when they reach a certain amount, they will discharge to generate electric sparks, which will constitute the fire source of explosion.

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