Ammonium nitrate: The chemical behind the massive Beirut explosion

The Lebanese capital was shaken in the afternoon of Tuesday , when a huge explosion swept through part of the city, leaving at least 135 dead – according to the latest figures – and thousands more injured. This explosion is now being referred to as the “Beirut explosion

Ammonium nitrate: The chemical behind the massive Beirut explosion

The countdown to disaster began more than six years ago, when a cargo ship chartered by the Bulgarian company Briar Wood Corporation, sailing under the Moldovan flag, made an unscheduled stop in the port of Beirut.

The ship was full of debt, with a poorly paid crew, and a small hole in its hull through which water leaked that had to be constantly pumped. 
In addition, it carried very volatile merchandise, more than 2,700 tons of ammonium nitrate, an unstable material used to make fertilizers – and pumps -, which was destined for Mozambique.

Ammonium nitrate: The chemical behind the massive Beirut explosion
The Rhosus anchored in the port of Varna, Bulgaria, in 2010.

The Rhosus never went its way. Enmeshed in financial and diplomatic disputes, it was abandoned there by whoever had rented it. 
The ammonium nitrate was transferred to a deposit in the port, where it would be stored for years as a result of negligence and bureaucracy … Until Tuesday of this week, when it was the origin of a devastating explosion that, according to the Lebanese authorities, left more than 135 dead, 5,000 injured, and several missing.

What is ammonium nitrate and how can it cause an explosion of the observed magnitude?

before and after comparison of the Beirut explosion

Ammonium nitrate has the chemical formula of NH₄NO₃. It is produced as small porous pellets, or “microcapsules,”.

It is one of the most widely used fertilizers around the world. 

It is also the main component of many types of mining explosives – where it is mixed with gasoline and detonated by an explosive charge.

For an ammonium nitrate industrial disaster to happen, however, it takes a lot of things to go wrong. Tragically, this is the case in Beirut.

What could have caused the Beirut explosion?

This chemical compound does not ignite by itself. Instead, it acts as a source of oxygen that accelerates the combustion of other materials.

For combustion to occur, oxygen must be present. Ammonium nitrate pellets provide a much more concentrated supply of oxygen than the air around us. 
This is the reason why it is both effective and explosive in mining.

However, at high enough temperatures, ammonium nitrate can decompose. This process creates gases, including nitrogen oxides and water vapor, which quickly release gases that can cause an explosion.

The decomposition of ammonium nitrate can be triggered if an explosion or fire occurs near where it is stored. The latter was what happened in 2015, when a blast in Tianjin killed 173 people after flammable chemicals and ammonium nitrate were stored together in a factory in eastern China.

And while we are uncertain as to what caused the explosion in Beirut, footage of the incident clearly shows a fire outbreak in a section of the city’s port, just before the catastrophe happened.

It should be noted that it is relatively difficult for a fire to set off an ammonium nitrate explosion. The flames must be constant and confined within the same area where the pellets are, whlol ich in turn need to be contaminated with, or packed in, another combustible material to produce a reaction.

Residents health in danger

In Beirut, 2,700 tons of this compound have been reported to have been kept in a warehouse for six years without respecting relevant regulations and security controls. 
This certainly contributed to the circumstances that led to an explosion of such a proportion, whose shock wave devastated everything in its path.

This is how the port was left after the explosion.

An ammonium nitrate explosion like this one generates massive amounts of nitrogen oxides. Nitrogen dioxide (NO₂) is a red, smelly gas. And the images that transcended reveal, precisely, a distinctive red color in the plume of gases from the explosion. High levels of this pollutant are of particular concern to people suffering from respiratory problems.

The smoke and gases in Beirut pose a health risk to residents until they dissipate naturally, which, depending on the weather, can take days.

Source: NY Times

Facebook Comments

Leave a Comment