Impact Of Various Impurities On Thermal Stability Of High Temperature And High Concentration Ammonium Nitrate Aqueous Solution

According to the guidelines, ammonium nitrate aqueous solution used in industrial explosives production needs to meet the requirements that its storage temperature should be about 120℃ and the maximum concentration of it shall not exceed 93%. The solution is stable and safe in industrial use under normal condition. Moister helps to increase the stability in theory for it is inert material. But the weak oxidizability of ammonium nitrate aqueous solution makes it part of industrial explosives when it was mixed with diesel oil、wood powder and combustible agent. The physical/chemical properties and the reaction mechanism of the mixture are not clearly understood. Research on the problem is of great use to improve the safety in the processes of ammonium nitrate aqueous solution production、transportation and use.C80 micro calorimeter was used to analysis the thermal decomposition behavior of ammonium nitrate solution. The effects of different impurities on thermal decomposition of ammonium nitrate solution were presented by theoretical analysis and the calculation of experimental data, which are as follows:1. Ammonium nitrate is a kind of self reactive chemical, the intermolecular oxidation-reduction reactions needs no oxygen atoms outside, which makes it prone to fire and explosion incidents without external energy in any forms outside.2. The Tonset and Ea of ammonium nitrate aqueous solution declines when the water content is low. Within experimental range, the increase in moisture content helps to reduce the reaction difficulty of the hybrid system and accelerate the reaction rate. The sample heat (ΔH) increased gradually. Small amount of water could promote thermal decomposition of ammonium nitrate.3. Chloride leads an advance in crystal transition temperature of ammonium nitrate, and it can catalyze the thermal decomposition of ammonium nitrate solution, and the catalytic effect is increased with the increase of chloride concentration and temperature.4. Small amount of nitrate has a certain promotion effect on thermal decomposition of ammonium nitrate, the promoting effect decreases with the increase of nitrate concentration. The catalytic effect of aluminum nitrate is stronger than that of sodium nitrate.5. Organic compounds have catalytic effect on the thermal decomposition of ammonium nitrate. The Tonset of ammonium nitrate aqueous solution varies by the types of organic compounds. In this experiment, the content of acetic acid and Tonset are linearity, the initial reaction temperature of the samples which contains stearic acid decreased first, and riseswhen the content of stearic acid reached more than 3%.