ABSTRACT
Terrorists often use ammonium nitrate and fuel oil (ANFO) or similar mixtures, mainly because ammonium nitrate and the organic ingredient are usually fairly widely available commercially and legally. Ammonium nitrate can release oxygen on heating to higher temperatures: Hydrocarbon fuels with long carbon chains need oxygen to burn, supplied by the ammonium nitrate. Once ammonium nitrate starts decomposing, the exothermic process is impossible to stop, not least because it produces oxygen, and the reaction gets out of control. Terrorists often use ANFO or similar mixtures, mainly because ammonium nitrate and the organic ingredient are usually fairly widely available commercially and legally. Sandia National Labs in the United States have developed a cheap mixture of ammonium nitrate and iron sulfate which is a cheap and effective fertilizer, but which, crucially, when mixed with fuel oil does not become an ANFO explosive.
