At about 7:37 on August 2nd, 2014, an explosion occurred in a flour factory. It caused several people hurt and die. But why did it explode without explosives. Because there was only dust? With this question in mind, let me first tell a little story.
During World War II, Hitler’s air force continued to bomb the UK. Bombs fell from the sky. The owner of a British flour mill was secretly grateful that the bomb did not hit her factory. However, almost at the same time as the bomb fell, a big explosion occurred in the workshop. Then the roof flew into the sky. Because the power of the explosion exceeded the effect of the bomb.
Why does flour explode?
1. The work done by the grinder consuming electrical energy converts and stores on the surface of the flour to form “surface energy”
2. The greater the degree of crushing, that is, the smaller the particles. Then the greater the surface area and the greater the surface energy.
3. After being crushed into flour, its surface energy can reach 2.7*106 joules. It’s the same work as lifting an object of the same weight 2,700 meters high. Then the surface energy increases by 100 million times.
4. Dust has such a high surface energy. Thus it is easy to undergo physical or chemical changes to release its energy. Therefore, once these tiny dusts fully mixes with the air, they will react rapidly and violently when exposed to fire. Then it will release huge amounts of energy in an instant. Then it causes dust explosion.
5. Not only flour, but any dust based on burning such as cocoa, cork, wood, light rubber, leather, plastics can explode. Besides, almost all organic compounds and various inorganic materials such as sulfur, iron and cobalt can also explode. Once these reach a certain concentration in the air, with an open flame, even a spark, it will cause explosion.