__FORCETOC__ When heated,

ammonium nitrate Ammonium nitrate is a chemical compound with the chemical formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is ...

decomposes non-explosively into

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

es of

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

, and

water vapor (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous p ...

; however, it can be induced to decompose explosively by

detonation Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with s ...

into

nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...

and water vapor. Large stockpiles of the material can be a major

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames a ...

risk due to their supporting

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

, and may also detonate, as happened in the Texas City disaster of 1947 which led to major changes in the regulations for storage and handling. There are two major classes of incidents resulting in explosions: * In the first case, the explosion happens by the mechanism of shock to detonation transition. The initiation happens by an explosive charge going off in the mass, by the detonation of a shell thrown into the mass, or by detonation of an explosive mixture in contact with the mass. Examples are Kriewald, Morgan, Oppau,

Tessenderlo Tessenderlo (; li, Loei) is a municipality in the Belgian province of Limburg. It is where the three Belgian provinces of Limburg, Flemish Brabant and Antwerp meet at the front gate of the Averbode Abbey. The municipality Tessenderlo encompass ...

, and Traskwood. * In the second case, the explosion results from a fire that spreads into the ammonium nitrate (AN) itself (

Texas City Texas City is a city in Galveston County in the U.S. state of Texas. Located on the southwest shoreline of Galveston Bay, Texas City is a busy deepwater port on Texas's Gulf Coast, as well as a petroleum-refining and petrochemical-manufacturing ...

Brest Brest may refer to: Places *Brest, Belarus **Brest Region **Brest Airport **Brest Fortress * Brest, Kyustendil Province, Bulgaria * Břest, Czech Republic *Brest, France ** Arrondissement of Brest **Brest Bretagne Airport ** Château de Brest *Br ...

Tianjin Tianjin (; ; Mandarin: ), alternately romanized as Tientsin (), is a municipality and a coastal metropolis in Northern China on the shore of the Bohai Sea. It is one of the nine national central cities in Mainland China, with a total popu ...

Beirut Beirut, french: Beyrouth is the capital and largest city of Lebanon. , Greater Beirut has a population of 2.5 million, which makes it the third-largest city in the Levant region. The city is situated on a peninsula at the midpoint o ...

) or to a mixture of an ammonium nitrate with a

combustible A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...

material during the fire. The fire must be confined at least to a degree for successful transition from a fire to an explosion (a phenomenon known as "deflagration to detonation transition", or

DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...

). Pure, compact AN is stable and very difficult to initiate. However, there are numerous cases when even impure AN did not explode in a fire. Ammonium nitrate decomposes in temperatures above . Pure AN is stable and will stop decomposing once the heat source is removed, but when catalysts are present, the reaction can become self-sustaining (known as self-sustaining decomposition, or SSD). This is a well-known hazard with some types of

NPK Many countries have standardized the labeling of fertilizers to indicate their contents of major nutrients. The most common labeling convention, the NPK or N-P-K label, shows the amounts of the chemical elements nitrogen, phosphorus, and potas ...

fertilizers and is responsible for the loss of several cargo ships.

Timeline of major disasters

The column AN states the amount of ammonium nitrate consumed in the disaster in metric tonnes.

References

{{Ammonium nitrate disasters * Nitrates Explosives Industrial fires and explosions Chemical disasters

Timeline of major disasters

See also

References