Experimental and theoretical study of the effect of typical halides on thermal decomposition products and energy release of ammonium nitrate based on microcalorimetry and FTIR

Ammonium nitrate (AN) is widely used as a raw material in industry and agriculture. However, the Beirut explosion in Lebanon once again shows that AN has a risk of thermal runaway during storage, especially long-term storage or when some possible substances are mixed therein. This paper focuses on the effect of halides additives, such as sodium fluoride, sodium chloride, sodium bromide and sodium iodide, on the thermal decomposition products and energy release of AN. Especially, the thermal decomposition of AN added with 5% sodium halide and the evolved gases in the thermal decomposition process are investigated by C80 microcalorimetry and FTIR. The results show that all kinds of sodium halides have an effect on the thermal decomposition of AN, although these effects are different. The addition of the halide not only changes the timing of the formation of the AN thermal decomposition characteristic product, but also reduces the heat of the reaction. Combined with optimized kinetic parameters, the engineering prediction of thermal safety was carried out for each type of sample. It is found that sodium iodide is beneficial to the safety of large-scale storage of AN. The research results can provide a reference and guidance for revealing the thermal decomposition mechanism of halide-containing AN and thermal decomposition simulation of AN with additives.