- September 28, 2020
- Posted in LOCAL
What started as a normal day in the port of Beirut, Lebanon ended in serious turmoil. A devastating explosion, on the 4th of August, 2020, suspected to have been caused by large volumes (2750t) of Ammonium nitrate (AN), stored unsafely in a warehouse, ripped through the city, and shook it to the core. Lebanese authorities say the giant blast, killed at least 200 people, injuring more than 5000 people, and left an estimated 300 000 homeless. The blast also left Lebanon in political limbo, the whole cabinet resigning amid widespread anger over the blast.
The Beirut disaster has left many people asking, what really is ammonium Nitrate?
Ammonium nitrate is a crystal-like white solid that is made in large quantities all over the world. Its common use is in agriculture, where it is used as a top dressing. The nitrogen-rich compound is also commonly used to make commercial explosives. Ammonium Nitrate acts as an oxidiser, supplying oxygen in the propagation of the explosive reaction. It is the most common ingredient in many modern explosives on the market, including emulsions, water-gel explosives, and the main component of the explosive composition known as ANFO- Ammonium Nitrate Fuel Oil.
Ammonium Nitrate has the chemical formula NH4+NO3–, which contains two nitrogen (N) atoms, four hydrogen (H) atoms, and three oxygen (O) atoms. In this formula, the ammonium (NH4+) ion and nitrate (NO3–) ion are bonded together by an ionic bond.
A closer look at the amateur video footage doing rounds on social media platforms, two explosions can be seen. At first, white smoke could be seen wafting from the roof of the warehouse, and a large initial explosion was heard. Seconds later, a second colossal explosion came, which sent a reddish-brown plume above the city’s port and creating a supersonic blast wave radiating through the city.
The reddish-brown fumes characterise all Ammonium Nitrate explosions. Upon ignition, Ammonium Nitrate produces lots of oxides of nitrogen (commonly known as nitrous fumes). Once initiated, a self-supporting reaction is sparked, ammonium nitrate explodes rapidly and violently decomposing into large volumes of nitrous oxides and water vapor.
In its pure state, Ammonium Nitrate is relatively stable and not classified as an explosive. However, ammonium nitrate is classified as an oxidiser according to the UN classification of dangerous goods. In simpler terms, ammonium nitrate increases the burning reaction of fuels by increasing the amount of oxygen available for the reaction. To initiate the reaction, ammonium nitrate needs to come in contact with an open flame or a source of ignition. In the case of the Beirut explosion, preliminary investigations are pointing to the presence of fireworks in the vicinity.
A quick trip down memory lane, ammonium nitrate is known to have caused serious accidental detonations in the past.
- The Texas City disaster of 1947, which is considered to be the deadliest industrial accident in US history, quickly comes to mind. At least 581 people were killed when more than 2300tonnes of Ammonium nitrate detonated on-board a ship that had docked in the port. The detonation is said to have been sparked by a carelessly tossed cigarette which started a fire aboard the ship.
- In 1921, in Oppau, Germany, about 4500tonnes of ammonium nitrate caused an explosion at a plant and more than 500 people were killed during the disaster.
- In China, more recently in 2015, a similar incident involving ammonium nitrate and other chemicals killed around 170 people in the port of Tianjin in Northern China
Not all disasters involving Ammonium Nitrate are accidents: Terrorists also take advantage of the readily available explosive ingredient to cause anarchy. The 1995 bombing of the Federal Building in Oklahoma City by terrorists, left around 168 people dead. In 2002, a nightclub bombing in Bali killed 204 people. In the 2011 Oslo bombing by Anders Behring Breivik, which killed eight people, and in numerous other terrorist attacks that use the product. All these attacks were perpetrated using ammonium nitrate as the main explosive ingredient.
Ammonium nitrate is relatively cheap to buy and usually safe to handle compared to other explosive ingredients, but storing it can be a problem. Overtime the prills combine to form lumps. The lumps are more sensitive and when subjected to the intense heat it can trigger a massive explosion.
In Zimbabwe, it is common to find ammonium nitrate stored in significantly large quantities by farmers, miners as well as in industries and other commercial depots or warehouses. Do people really know the hazards?
Many times I have visited my Grandpa in the rural areas, only to find his Ammonium Nitrate fertiliser for the coming season, stored together with other combustible materials such as grain, packaging material, and in some cases with diesel for tilling the land. In some instances, the deadly oxidiser is found in the open and not properly stored. In the event of a fire outbreak, the severity of that fire will be amplified. My Grandpa and others alike should be assisted with the basics of proper handling and storage of ammonium nitrate to avoid similar disasters in the future.
With proper handling, ammonium nitrate continues to play an imperative role in our lives, helping us feed the nations and unearthing wealth, but with a little laxity in our controls, the product can cause large scale destruction, the Beirut incident and history has taught us.
This article first appeared in the Mining Zimbabwe Magazine September 2020 issue