Ammonium Nitrate Fertilisers: Analysis and Appraisal of Classification Categories

Keywords: ammonium nitrate, fertiliser safety, product stewardship, fertiliser storage, fertiliser transport, manufacturing, classification, safety testing

Decisions regarding the classification of ammonium nitrate-based fertilisers are made mainly based on their composition. Today it is somewhat unclear on what basis previous classifications were made. This paper summarises (based on present knowledge) the safe compositions of fertiliser mixtures. The theoretical high temperature calculations used are compared to experimental results and published literature. Several fertiliser raw materials such as carbonates and sulphates can be regarded as energy sinks, which is in line with calculations and experiments. The oxidation of ammonia is discussed for ammonium sulphates and ammonium phosphates. The inclusion of secondary reactions (the oxidation of ammonia) correlates well with present classification limits. However, previous experiments were to a large extent based on small scale experiments. Those test methods and results are summarised in this paper. Modifications to the Detonation Resistance Test were made in an attempt to confirm those past findings on a larger scale. The main finding confirms the importance of density of the fertiliser materials as a major relevant safety parameter. Modern fertilisers have much higher densities than those tested in the past and therefore guidelines on bulk density are discussed.

H Kiiski, Phil. Lic., Yara Suomi, Helsinki, Finland.

55 pages, 31 figures, 10 tables, 79 references.