You would have to be void of emotion and compassion to have not been shocked and saddened at what happened in Beirut, Lebanon on the 4 th August 2020.That afternoon, two explosions occurred at the port of Beirut city where a large quantity of ammonium nitrate was being stored.

This caused at least 177 deaths, 6,000 injuries, US$10–15 billion in property damage and left an estimated 300,000 people homeless. This avoidable tragedy raises numerous questions: what can I do to help? Has this happened before and could it happen here in Australia? Well as you can see from the diagram below care of Visual Capitalist, ammonium nitrate explosions are surprisingly common in a global context, happening a little over every two years on average, with 9 such explosions this century.

Source: Visual Capitalist

So: what is the amount of nitrate and what is it used for?

Ammonium Nitrate (NH 4 NO 3 ) is a white crystalline or granular material which is obviously rich in nitrogen, odourless and soluble in water.

  • It is the main ingredient in the manufacture of commercial explosives used in mining and construction, in a composition with fuel oil known as ANFO- ammonium nitrate fuel oil. This is bar far its greatest application in Australia.
  • It is a common ingredient of agricultural fertilisers.

What are the hazards?

Stability and explosion

  • NH 4 NO 3 is stable in solid, molten or in solution. It can become less stable due to the presence of contaminants or on exposure to high temperatures.

The following can cause NH 4 NO 3 to become less stable and at greater risk of explosion:

  • Exposure to contaminants including chlorides as well as metals such as chromium, copper, cobalt, and nickel
  • A decrease in pH (increased acidity)
  • If bubbles are permitted to form in molten states or solutions of NH 4 NO 3 .
  • Once NH 4 NO 3 becomes molten the risk of an explosion increases. This risk increases dramatically if the pH of molten NH 4 NO 3 falls or if it comes into contact with oxidisable material like oil, diesel, paper, etc.

NH 4 NO 3 may explode from:

  • Exposure to strong shocks (e.g. from shock waves of nearby explosions).
  • High temperatures under confinement (e.g. in a closed pipe).
  • A smaller detonation that can trigger an explosion in larger quantities stored nearby.

Heat, fire and combustion:

  • NH 4 NO 3 does not burn but will support and increase the rate of combustion in the presence of flammable or combustible materials even in the absence of oxygen.
  • When heated it will melt, decompose and release toxic gases including nitrogen oxides (NO x ) and ammonia gas (NH 3 ). When heated excessively (fire) it can cause an explosion in an enclosed space and rupture closed containers or vessels.

Physical propertie