Beirut blast: What is ammonium nitrate that causes 78 deaths in explosion

New Delhi, Aug 05: An massive explosion at a warehouse in the Port of Beirut, Lebanon, close to 80 people and left more than 4,000 people injured on Tuesday.

The blast sent shockwaves across the city. The blast appeared to be centred around Beirut's port and shattered windows miles away.

"It is unacceptable that a shipment of 2,750 tonnes of ammonium nitrate has been present for six years in a warehouse, without taking preventive measures," Prime Minister of Lebanon Hassan Diab said.

Videos uploaded to social media of the explosion show plumes of red-brown smoke and the apocalyptic extent of the destruction, with buildings levelled for miles.

The PM of the country said the explosion was fueled by a stockpile of over 2,700 tons of ammonium nitrate, confiscated and stored for approximately 6 years at the port.

What is ammonium nitrate and why it is explosive

Ammonium nitrate is a chemical compound containing the element nitrogen, as well as hydrogen and oxygen, and is commonly used in agriculture as fertilizer. Nitrogen is an essential element for plants and ammonium nitrate is particularly good, compared with other fertilizers.

Ammonium nitrate is also an explosive compound and is used around the world in mining and construction operations in the times of detonations.

The chemical is highly stable under normal conditions.

But it can explode after exposure to contaminants or fuel oil and then heated.

If the chemical heated with above 170 degrees Fahrenheit, it begins to undergo decomposition. With rapid detonation, chemical reaction can occur that converts ammonium nitrate to nitrogen and oxygen gas and water vapour. And the process releases huge amounts of energy.

Though burning ammonium nitrate in an open field is not likely to result in an explosion in confined space high energy explosion can occur.

In the Beirut explosion, not all of the ammonium nitrate used exploded in the explosion.

Some of it decomposes slowly creating toxic gases like nitrogen oxides which are responsible for the red-brown plume of smoke seen in the aftermath of the explosion, says specialists.

As ammonium nitrate is potentially explosive, countries and unions impose strict regulations on storing and processing it.

"It is generally kept under controlled conditions and modified volumes to minimize chances of explosion," says Brent Kaiser, a plant biologist at the University of Sydney.

Notably, in 2015, explosions partly caused by the detonation of around 800 tons of ammonium nitrate rocked the Beijing port in China, killing 173 people.

In 1947, the worst industrial accident in US history that killed 581 people when a ship in the harbour of Texas City, Texas, carrying approximately 2,300 tons of ammonium nitrate caught fire.