Maggie Koerth-Baker has written a chemistry and combustion rundown of ammonium nitrate, the chemical believed to be behind the devastating blast yesterday in West, TX: “Ammonium nitrate fertilizer isn’t really a dangerous explosive (most of the time)”.
Ammonium nitrate, a primary ingredient in synthetic fertilizers, isn’t itself very explosive. Accidents involving it are actually pretty rare, although incidents like the Oklahoma City Federal Building bombing in 1995 have given it quite a reputation. However, like anything, it’s the dose that makes the poison.
When it burns, it creates its own oxygen, which can lead to a runaway fire. In those runaway fires, the chemical can bind together from pellets into a massive plug, allowing it to trap huge amounts of hot gases beneath the weight of burning material. You can guess what happens when hot gases build up with no place to go.
More details at Boing Boing. Stay strong, West, TX.
Source: Boing Boing