Ammonium Nitrate

The explosion of 200-300 tones of ammonium nitrate in a warehouse on September 21st 2001 at the AZF-La Grande Paroisse plant of Toulouse is the biggest disaster of the French chemical industry of the last decades. 30 persons died, 60-70 persons were severely injured and hundred of people were hospitalized for few days. Thousands of houses were blasted in a perimeter of 2-3 kilometers.

This fertilizer plant was build in 1921 in the vicinity of an explosive production plant (SNPE), but far away from the city. Years after years, the empty land between the city and the chemical plants has been urbanized. Due to the proximity of the buildings (houses, shops, ...), the explosion of the nitrate stock generated a disaster within the city. It should be noted that the production units of ammonia, nitric acid (AZF) and phosgene (SNPE) were not damaged by such large explosion, demonstrating the high safety level of these chemical units.

One month after the disaster, many questions on the origin of the explosion have not been answered. Several experts are working on site to prepare reports for officials (Justice Department, Ministry of Environment, ...). Ammonium nitrate is stable in normal conditions of production, storage, transportation and use, but can be explosive in conditions that have been summarized by our colleague Georges Guiochon (see text below).

Georges Guiochon graduated at the Ecole Polytechnique. He is recognized as an international expert on the versatile properties of ammonium nitrate since his PhD thesis on the decomposition of ammonium nitrate (see below the list of his publications directly related to this topic). During this period, he worked with L. Médard (expert on explosives) and P. Chovin (former director of the forensic laboratory of the Police in Paris). After a professorship at the Ecole Polytechnique and at the University Pierre et Marie Curie (Paris VI), he moved to the United States in 1984 to continue his research. He is currently Distinguish Research Professor at the University of Tennessee and Senior Scientist at the National Laboratory of Oak Ridge. He is the author of more than 800 publications, 4 books and he received many awards.


Bernard Meunier
(President of the Inorganic Chemistry Division
of the French Chemical Society)

Société Française de Chimique de France.