Thermal Stability of Fertilisers Containing Ammonium Nitrate

Keywords: Ammonium nitrate safety, Self-sustaining decomposition, Ammonium nitrate.

In the last decade fertilizers have shown a steady increase in the content of ammonium nitrate and in the quantities handled in transport and storage. Because of this trend to more concentrated fertilizers a number of accidents has happened in the past. As a consequence much attention was paid to the safety aspects in manufacture. Much research was done and published by the industry, the international organizations and governments and made available via publications.

In this respect the valuable work of ISMA and APEA have to be mentioned.

As a result this paper has to be seen merely as a review of earlier work completed with some new contributions.

Fertilizers containing AN possess a very complicated hazardous character. The following hazardous properties, which are regarded as the most important, will be dealt with in this paper:

– explosibility

– self-heating

– self-sustaining decomposition (cigar burning)

– oxidizing capacity (support of combustion).

In the past the danger of explosibility and self-sustaining decomposition were classified in transport codes by the ability to show these phenomena.

However, it should be understood that the chance that an accident will happen is determined by the situation; i.e. that e.g. CAN 33% will detonate only if the necessary energy is supplied from the outside. As a result the chance of an event is determined by the minimum energy to start off a detonation or a self-sustaining decomposition. In this paper this subject will also be dealt with. Further will be discussed the various factors such as chemical composition which govern the self-sustaining decomposition.

G Perbal, VKF Mekog-Albatross NV, Utrecht, Netherlands.

63 Pages, 26 Figures, 5 Tables, 22 Refs.