A grain elevator is a tower that contains a bucket elevator that scoops up and then transports grain into a silo.  However, this elevator turns into a dangerous situation when it runs into some chemistry.  An important aspect of the kinetics of a reaction is that the more crushed a substance is (greater number of surface areas), the more chance of having collisions and therefore, a reaction occurs much faster.

So when a large amount of dust is in one confined place (like the elevator), one little spark can ignite a combustion reaction.  The combustion reaction releases large amounts of heat and the rapid increase of temperature increases the pressure and kaboom.  A huge explosion.

Many have died in such explosions.  A famous historical example of the destructive power of grain explosions is the 1878 explosion of the Washburn “A” Mill in Minneapolis, Minnesota, which killed eighteen, leveled two nearby mills, damaged many others and caused a destructive fire that gutted much of the nearby milling district.  In a ten year period up to 1997, there were 129 such explosions in the United States.  (Wikipedia)

To demonstrate this, I use a highly combustible powder and spray it in an enclosed paint can with a candle in it.  Awesome explosion that has actually put some dents in my ceiling.  It’s so fast, you may have to watch it a few times.