Ammonium nitrate fire forces mass evacuation

KXXV.com ^ | Posted: July 30, 2009 07:11 PM | by Patrick Tolbert

[Cindy]

Bryan, Texas

SNIPPET: "As the situation eased, officials scaled back the number of mandatory evacuations. As of 8:50 p.m., only about 1,000 people were affected by the evacuations."

SNIPPET: "John Carver with El Dorado Chemicals reports the plant on Highway 21 is a "typical dry blend fertilizer" facility. He reports a crew was welding in an empty ammonia nitrate storage bin when a spark started a small, smoldering fire.

Two workers were in the building at the time of the fire; both escaped uninjured.

Firefighters quickly responded to the scene only to discover they could not use water to battle the fire."

[Attention Surplus Disorder]

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

[NonValueAdded]

Code maroon?

[Peanut Gallery]

As a matter of fact, yes. It did get a code maroon..

[MyTwoCopperCoins]

I didn’t know ammonium nitrate could burn. Explode, yes, but burn? Slow burning?

Even for it to become explosive, it needs things like fuel oil, correct?

[Cindy]

LOL...I was going to say something about that and decided not to.
I’ll leave it there.

[HiTech RedNeck]

http://en.wikipedia.org/wiki/Ammonium_nitrate#Disasters

[Cindy]

Yes, and this fire was caused by welder’s sparks.

Thanks for sharing history, though.

[chuckles]

I was raised from 1951-1969 in Texas City. It becomes a part of your psyche if you live there. The Van Camp smoldered for some time before exploding. I suppose it could have been mixed with fuel oil if a bulkhead split, but as for my memory of the tale from my father, it just exploded when it got hot enough. Maybe generated gases, maybe ship fuel, who knows. I think the explosion was pretty efficient as the ship anchor was almost blown to the north end of Moses Lake about 20 miles from Monsanto. I'm inclined to believe it was just the ammonium nitrate reaching critical temp.

Now if you are reading the Anarchist cookbook, yeah, diesel fuel is recommended.

[Attention Surplus Disorder]

Ammonium Nitrate is rated “very slightly” flammable, but can definitely burn and (though it “helps”) it doesn’t even need oxygen from the air to burn, because the nitrate NO3 radical contains sufficient oxygen in and of itself to support (at least partial) combustion. It can start to decompose from shock, heat, or both. Impurities, particularly organics, tend to lower the shock > combustion threshold. NH4NO3, you might think of it as being 1/3rd oxygen = 3 oxys out of a total of nine atoms. Once it gets going, it can be hard to extinguish and can runaway react.

(NH4)2SO4 Ammonium Sulfate which is 4/15 oxygen = substantially *less* oxygen per molecule than A-N, is practically non-combustible and non-explosive. Maybe someone else can weigh in on why, but less oxy per molecule is certainly a major factor.

[bondjamesbond]

The Kansas City Ammonium Nitrate fire that killed all those firemen did not have fuel oil in the mix. In think it just blows under the right conditions, all by itself.

[wafflehouse]

the nitrogen is what makes it so unstable.. think of triple bonded N2

[wafflehouse]

2 NH4NO3 -> 2 N2 + 4 H2O + O2

[Redbob]

"... crew was welding in an empty ammonia nitrate storage bin..."

Sounds like a Darwinian moment to me.

[Cindy]

I agree.