Ammonium nitrate, which according to the Lebanese authorities theis an odorless crystalline substance commonly used as fertilizer that has caused numerous industrial explosions over the decades. This particularly includes one in a fertilizer plant in Texas in 2013, in which 15 people died and died , an explosion on the North Korean railroad that killed 161 people in 2004, and the Oklahoma City bombing in 1995.
In combination with heating oils, ammonium nitrate produces a powerful explosive that is widely used in the construction industry, but also by insurgent groups such as the Taliban for improvised explosives.
Two tons of it were used to bomb the bombthat destroyed a federal building and killed 168 people.
Lebanese Prime Minister Hassan Diab said 2,750 tons of ammonium nitrate, which had been stored in a warehouse at the port of Beirut for years, had exploded.and cause widespread damage in the capital.
Ammonium nitrate was among the chemicals stored in a warehouse in China’s northern city of Tianjin, which ignited in 2015 and triggered an explosion that killed at least 165 people and caused over $ 1 billion in damage.
An investigation found that improper storage of the chemicals was to blame.
In agriculture, ammonium nitrate fertilizer is applied in granular form and dissolves quickly under moisture, so that nitrogen – the key to plant growth – is released into the soil.
However, under normal storage conditions and without very high heat, ammonium nitrate is difficult to ignite, Jimmie Oxley, a chemistry professor at the University of Rhode Island, told AFP.
“If you watch the video (of the Beirut explosion), you saw the black smoke, you saw the red smoke – that was an incomplete response,” she said.
“I assume there was a small explosion that triggered the reaction of the ammonium nitrate – whether that small explosion was an accident or something I haven’t heard on purpose.”
This is because ammonium nitrate is an oxidizing agent – it increases combustion and makes other substances ignite more easily, but is itself not very flammable.
For these reasons, there are generally very strict rules about where it can be stored: for example, it must be kept away from fuels and heat sources.
In fact, many countries in the European Union require that ammonium nitrate be added to calcium carbonate to produce calcium ammonium nitrate, which is safer.
In the United States, regulations were tightened significantly after the attack on Oklahoma City.
For example, as part of the anti-terror standards for chemical facilities, facilities in which more than 900 kilograms of ammonium nitrate are stored are inspected.
Despite its dangers, Oxley said that the legitimate use of ammonium nitrate in agriculture and construction has made it essential.
“We would not have this modern world without explosives and we would not feed today’s population without ammonium nitrate fertilizer,” she said.
“We need ammonium nitrate, we just have to be careful what we do with it.”