Effects of urea on the thermal decomposition behavior of ammonium nitrate: A reliable thermal safety performance enhancer

To address the actual disaster of thermal decomposition and explosion of ammonium nitrate (AN), a commonly used raw material, urea was selected as an additive to study its effect on the thermal decomposition of AN through experimental and theoretical methods. The thermal decomposition kinetics, energy release, self-reaction properties of adiabatic environments, and escaping gaseous products have all been discussed. It was found that urea has an inhibitory effect on the crystalline transformation of AN stored at room temperature, which is beneficial to its thermal safety. The results showed that urea increased the activation energy of the thermal decomposition of AN, raised the temperature of the initial reaction and reduced heat generation. Furthermore, the action mechanism of urea is suggested to be heat absorption by its thermal decomposition and the escape of ammonia. Finally, the study carried out an engineering assessment of the thermal safety of AN under the action of urea and found that the addition of urea greatly enhanced the thermal safety performance of stored and transported AN. The comprehensive analysis concluded that a small dose of urea could be added to enhance the thermal stability of AN without affecting its normal function.