Study Of Thermal Decomposition Characteristics Of The Typical Components Of A Mixture Of Ammonium Nitrate And Emulsion Explosives

The safety investigation about the emulsion explosive and ammonium nitrate (AN) has been never terminated since many accidents about the explosion of emulsion explosive and AN have happened in the history, most of which suggest that the explosion is because of the heat accumulated by their decomposition during the course of production and storage.This thesis mainly directs at the investigation into the kinetic mechanism of the thermal decomposition of emulsion explosives. As a basis ingredient of commercial explosives, the decomposition of AN must be considered at first.In this paper, the kinetic mechanism of the thermal decomposition and kinetic parameters of neat AN, commercial grade AN and mixtures of neat AN and NaNO₃, NaCl, H₂O, engine oil, wood powder, NH4Cl, Al powder etc. has been investigated by means of non-isothermal DSC and TG(Differential Scanning Calorimetry and Thermalgravimetry) at various heating rates (2K/min, 4K/min, 6K/min, 8K/min) through the SDT-2960 thermal analyzer under the condition of dynamic atmosphere of nitrogen. The process of the decomposition of them are described, the activation energy( E , kJ/mol ), the pre-coefficien(A/s^-1), the reaction constant(k/s^-1), and the initial decomposition temperature (T_i/K) are determined, and the reaction micro-mechanism (f(α)) and the kinetic equations are also given. For the emulsion explosive, the critical temperature T_B (K) and the critical lag t_B (s) of thermal explosion is calculated.The results suggest that AN is a kind of material with relative safety and, simultaneously, is very sensitive to the impurities during thermal decomposition. Different materials have various effects on the decomposition behaviors of AN. It shows that NaNO₃, NaCl and Al powder are helpful in improving the stability of neat AN under open experimental conditioa But the Cl has some effect on accelerating the decomposition neat AN. The oil, wood powder and H₂O, NH₄Cl can not only decrease the physical stability of neat AN but also its reaction constant from the point of the kinetics of chemistry. Wood powder and NH₄Cl have complex influences on the decomposition of neat AN. What' more, neat AN is also exhibited a poor comparability with the impurities.For the water-content explosives, the heat is released after the water is vapored during the heating. After water escaping, The average activation energy of coal-permitted emulsion explosive is 124kJ/mol and the critical lag (t_B) is 0.7113s.By synthesizing and analyzing the achievements of the documents, the kinetic mechanism of AN and the typical ingredients of emulsion explosives is investigated, which is valuable for the solution to the safety problem in the production and storage of AN and emulsion explosives.