The effect of mixing methods on the phase transition of ammonium nitrate

A study has been undertaken on the effect of mixing methods on the IV <-> III transition of ammonium nitrate (AN). Potassium chloride (KCl) and monoammonium phosphate (MAP) were mixed with ammonium nitrate (AN) by different mixing methods. The results of differential scanning calorimetry (DSC) showed that the crystals have different transition behaviour. When the samples were mixed by mechanical mixing method,the temperature of IV <-> III transition was increased. For the solution mixing method. the IV <-> III transition of AN-8%KCl mixture was disappear. while the IV <-> III transition temperature of AN-MAP mixture was reduced to a lower temperature. The morphology changes and structural properties were further analyzed by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The present study showed that mixing methods, additives, thermal cycling and hydrogen-bond have an important influence on the IV <-> III transition of AN.