Why is the threat of an exposion occuring ever present at a grain elevator?

Answer 1

There are fine particles of grain dust suspended in the air space. The particles are flammable (just like wood is). Because the particles are floating, there is enough oxygen available to make each individual burst into flames. This causes the other particles around it to ignite and you get an explosion.

If you take a match and put it next to ordinary flour, you get nothing because of the lack of air. But if you sprinkle flour over a match, you'll see that they will ignite. Of course, I'd only recommend doing that in a safe manner (fire extinguisher, a more mature person around, etc.). :)

Answer 2

particle explosions.
a large object with a large surface area will burn slower,
a smaller object with less surface area will burn more quickly.
dust particles are very mobile, floating in the air. Dust particles also combust at a very high rate of speed. the more dense the dust cloud & wind vairiables, along with humidity play factors in the ease of ignition.
a detonation is when the shock wave of an explosion is faster than the speed of sound.
a deflagration is when the shock wave is slower than the speed of sound. A deflagration is what happens in a particle explosion.

Answer 3

due to two factors... static electricity and fine air-borne particles. If the grain is old then it can also rot making explosive gases