[Enthalpy]

Hi everyone, thoughts for the victims and relatives.

How do you understand the colour of the smoke cloud over the explosion in Beirut's port on 04 August 2020?

I know NO₂ with that colour. A few uncommon metal oxides would resemble but not so closely.
https://www.aljazeera.com/indepth/inpictures/pictures-lebanon-capital-beirut-shaken-massive-explosion-200804162150133.html
https://en.wikipedia.org/wiki/Nitrogen_dioxide

A Lebanese minister claimed 3750t of ammonium nitrate NH₄NO₃ exploded. Newspaper reported that as an obvious explanation. I doubt.

First, the exploded amount was not in the thousands of tons, not of a single-molecule explosive. The silo tens of metres away resisted.

Second, do you imagine ammonium nitrate producing vast amounts of NO₂ in an explosion? Here's a video of 2t ammonium nitrate, apparently without a fuel, "disposed of" the military way. It disperses some dirt and makes no coloured cloud
https://www.youtube.com/watch?v=084GndZlew8 boom at 0:48

Unless someone proposes a better explanation, my present impression is that tens of tons of NO₂ deflagrated with a badly mixed fuel.

Here's a crash example of a rocket loaded with NO₂-N₂O₄ (and UDMH, which burnt a good part of the nitrogen oxide)
https://www.youtube.com/watch?v=ycRVAcZC5R4
this resembles better what happened in Beirut. Something like a rocket development gone wrong for internal or external reasons.

[wildfyr]

Fuel could be as simple as wood pulp product X (paper, cardboard, whatever)

[Enthalpy]

Sure! Flour too, and even dust.

Worse: ammonium nitrate needs a fuel only to start detonate, or something else that detonates, or enough heat. Once the detonation mode has started, pure ammonium nitrate suffices.

But for the red fume? Would you imagine anything else than big amounts of NO₂ for that colour? And how could NH₄NO₃ produce it?

[wildfyr]

Thermal decomposition of ammonium nitrate gives all the various small nitrogen gases possible

https://www.researchgate.net/figure/Modes-of-thermal-decomposition-of-AN_tbl1_263578419

I see ammonia, nitric acid, N₂O, NO₂, NO, plus water, oxygen and N₂. Various combinations of these can intercovert as well under heat, pressure, oxygen etc etc. I'd be more surprised if this explosion DIDN'T produce various nitrogen oxides. Especially since there could easily be some metal dust from steel getting heated to a liquid in the initial fire then particle-ized by the explosion.

[Enthalpy]

Thanks wildfyr!

Meanwhile I've looked for the damage after similar disasters, and ammonium nitrate isn't quite as destructive as TNT. 300t in Toulouse made as much damage as estimated 30t of TNT. The damage by 2300t of ammonium nitrate at Texas City in 1947 is similar to the destruction in Beirut
https://texashistory.unt.edu/ark:/67531/metapth11736/
https://carynschulenberg.com/2018/04/texas-city-disaster/

I still don't grasp the colour of the plume. In the decomposition of pure ammonium nitrate, Propep finds no NO₂ at all. In an expansion from 1kbar or 10kbar to 1atm, the initial concentration of NO₂ is about 10^-4 only, the final concentration is zero, meaning less than 10^-7. Starting at 10bar leaves 2*10^-7 and 1.02atm leaves 1.5*10^-6.
The molar composition after expansion from 1000bar is:
0.46 H₂O
0.29 N₂
0.14 O₂
0.12 H₂O liquid
Zilch, nada, niente -> Everything else, including N₂O, NO, NO₂

A limit of Propep: it computes equilibria. With 1245K reaction temperature, the hypothesis isn't too bad, but the fraction of ammonium nitrate dispersed before it detonates can undergo more subtle reactions, where the reaction path influences the products.

[Babcock_Hall]

https://cen.acs.org/safety/industrial-safety/chemistry-behind-Beirut-explosion/98/web/2020/08

Chemical and Engineering News has a story.

[wildfyr]

Enthalpy,

I fail to understand how your discussion disputes the idea that likely impure ammonium nitrate is haphazardly decomposing into various NOx molecues, some of which are red, especially NO₂. What is propep?  Is this some software that produces idealized reactions? How does it do better than the experimental data I found on research gate?

Its pretty clear to me that it is VERY well known that decomposition of ammonium nitrate gives NOx gases in the real world even under perfect conditions. The ratios are certainly going to be influenced by conditions.

Here is another paper showing ammonia, nitrous oxide, and nitric acid are decomposition products under their careful lab conditions with clean materials. Propep did not spit out any of those 3. Seems unreliable for this usage.

https://pubs.acs.org/doi/pdfplus/10.1021/ja01651a096

[Enthalpy]

I'm willing to believe that the incomplete detonation of ammonium nitrate produces red fume.

Direct observation would be more convincing than some referenced papers of poor quality or not exactly related with a detonation. One paper makes essentially unsubstantiated claims, an other mistakes the detonation speed with the speed of the shockwave and pure ammonium nitrate with its mixture with a fuel. Decomposition by slow heating doesn't neither represent the products of a detonation.

At the Texas City disaster, testimonies reported red fume. I wish to know more, ideally see the exact colour on a video, but this is already convincing.

Propep is reliable within its intended use: compute equilibria in a rocket combustion chamber. Here, much ammonium nitrate must be dispersed before it detonates, so out-of-equilibrium decomposition can produce something else, especially NO₂.

==========

Today, Michel Aoun, the Lebanese president, considered publicly the hypothesis of a missile or a bomb
https://www.lesoir.be/317785/article/2020-08-07/explosions-beyrouth-le-president-du-liban-evoque-la-negligence-ou-un-missile
https://www.theguardian.com/world/2020/aug/07/beirut-explosion-former-port-worker-says-fireworks-stored-in-hangar
the article doesn't tell more. Shall a missile have started the first fire that let detonate the ammonium nitrate? The wording of the Belgian article would also be compatible with a missile being developed in the Beirut port, but Michel Aoun asked for images to determine if aeroplanes or missiles were present in the air.

It's practically unavoidable that a huge cargo of ammonium nitrate in Beirut would be misused by some Lebanese faction to tinker explosives.
https://www.aljazeera.com/news/2020/08/protests-lebanon-arrests-16-beirut-blast-live-updates-200807062157963.html
"Hezbollah denies storing arms at blast site".
30 to 40 bags of fireworks confiscated by the Customs were stored in the same hangar as the ammonium nitrate. Ignorance kills.

In the morning of the disaster day, before 11:00 CET (09:00 UT), I heard and saw a small dozen of four-engined US military transport planes flying here, near Ramstein. About as many planes of same model flew (back?) in the next and following morning. The same happened before US military interventions, for instance to destroy Syrian combat planes. I just wonder why the US armed forces would make such a fuss to blow a hypothetical clandestine lab, while any combat aircraft with its stock missiles would do the job.

[Enthalpy]

A newspaper has completely different figures about the power of the explosions in Beirut, Toulouse and others
https://www.lemonde.fr/les-decodeurs/article/2020/08/07/comparee-a-d-autres-catastrophes-quelle-a-ete-la-puissance-de-l-explosion-au-port-de-beyrouth_6048412_4355770.html
40 times more energy in Beirut than Toulouse, that's not what I expected from the pictures.

==========

Several countries developed laser weapons, the US had one (Jumbojet-sized) to destroy missiles from 500km distance and demonstrated the destruction of drones at short distance. It's unavoidable that these weapons serve to ignite fires in covert operations, because this is easier than stopping a missile and the action is hard to prove.

[Enthalpy]

Video of the damage made by a drone flying through the damaged buildings
https://www.youtube.com/watch?v=FMvBg7YIDAA
Impressive damage, and impressive flying skills too.

[Enthalpy]

[...] Several countries developed laser weapons, the US had one (Jumbojet-sized) to destroy missiles from 500km distance and demonstrated the destruction of drones at short distance. It's unavoidable that these weapons serve to ignite fires in covert operations, because this is easier than stopping a missile and the action is hard to prove.

Examples of multi-purpose laser weapons, maybe at different development stages and powers:
https://asiatimes.com/2020/08/israeli-firm-points-laser-sights-on-low-tech-enemies/
https://www.youtube.com/watch?v=GU2FV6mnL2M
https://en.wikipedia.org/wiki/Iron_Beam
Newspapers reported "against incendiary balloons" but if the laser really destroys mortars as Wiki suggests, the light power is completely different.

[wildfyr]

Here is a very detailed analysis done by the NYTimes.

https://www.nytimes.com./interactive/2020/09/09/world/middleeast/beirut-explosion.html?action=click&module=Top%20Stories&pgtype=Homepage

I really don't see this as some cloak and dagger operation. Use Occam's razor, ineptitude, greed, and laziness are much better explanations than fancy lasers.

A team of welders was sent by the gov't on the day of the explosion to a room full of fireworks, miles of fuses, and ammonium nitrate. Seems like an open and shut case.

[Borek]

ineptitude, greed, and laziness are much better explanations than fancy lasers.

https://en.wikipedia.org/wiki/Hanlon%27s_razor

[wildfyr]

Thanks Borek, that works even better!

[Enthalpy]

Thanks for the link to the informative article.

I take good note that some possible causes for the explosion need no external intervention.

I don't and won't follow heuristics to decide between explanations, because this fails. Giving a name to the heuristic, be it Occam or anything else, doesn't improve that.

And I maintain that military cargo planes moved at Ramstein as they did before military interventions. I ignore what the purpose was, just that the date coincides.