Texas Fertilizer Plant Explosion ?

[Point Conception]

It started as a fire at a Texas fertilizer plant where ammonia is produced and stored. Then
a massive explosion. What happened chemically ? Three possibilities : Ammonia produced
by the Haber process. N₂ + 3H₂ --> 2NH₃ -92 kJ/m
1. a hydrogen tank exploded.
2. With heat from the initial fire could above reaction been driven to left producing H₂ ?
3. Combustion/explosian of ammonia: 4NH₃ + 3O₂ --> 2N₂ + 6H₂O -1267kJ/m

 

[Borek]

Most likely it was an explosion of ammonium nitrate. Relatively common.

http://en.wikipedia.org/wiki/Ammonium_nitrate_disasters

 

[chemisttree]

I think it was a fire started after an ammonia leak, supported by the ammonium nitrate, which heated a large tank of liquid ammonia to the point of explosion. It was reported that there was a strong smell of ammonia just before the event. Typical fuel-air explosion boosted by the decomposition products of ammonium nitrate. From the videos I've seen just before the explosion, it is unlikely that the ammonium nitrate decomposition products (mostly NOx compounds) ever built up significant concentrations before they burned off. Probably just a fuel-air type explosion... ammonia plus oxygen.