What are the dangers of Ammonium Nitrate?

Answer 1

Nitrate (NO3-)is a powerful oxidizer which can rapidly and explosively react with various organic compounds. For instance, a common explosive in the mineral mining industry is ANFO, or Ammonium Nitrate Fuel-Oil, which is ammonium nitrate mixed with a hydrocarbon such as kerosene or diesel fuel.

The ammonium (NH4+) in the compound contributes by combining with oxygen from the nitrate to create nitrogen gas (N2) and water (H2O). This process releases a large amount of energy, causing the gaseous products to expand dramatically.

The combination of rapid oxidation of the hydrocarbons and ammonium cause a rapid increase in pressure and temperature - an explosion.

Ammonium Nitrate can be dangerous because this reaction has a fairly low activation energy. At even mildly elevated temperatures, it's possible for a spark to start the reaction.

Additionally, at higher temperatures, the nitrate can decompose. When this happens, the ammonium can react with the oxygen, catching fire. This process is less explosive than when the ammonium nitrate is mixed with a fuel, but it can still start fires, possibly leading to secondary explosions.