Research On Reutilization Of Waste TNT

With the rapid development of modern military technology and its weapons systems,the disposal of waste explosives that have been stored for long periods of time or ammunition that has been decommissioned for a number of reasons has become a key concern for countries around the world.The traditional methods of disposing waste explosives,such as open burning,open detonation,and dumping to ocean,have many defects,cause great pollution to the environment,and waste the potential value of energetic components.It has become an inevitable trend to explore an efficient,environmentally friendly,and energy-saving treatment method.TNT has the characteristics of insensitivity to impact and friction,good thermal stability,etc.It is often used as one of the components of military mixed explosives(Composition B and TNT-RDX-Al Explosive),and occupies a large proportion of the recovered explosives,comparing the performance of recovered TNT with that of pure TNT,we found that the performance of recovered TNT is almost unchanged and meets the requirements of reuse.Therefore,it is of great significance to study the resource reutilization of waste TNT.The safety and stability of explosives stored for a long time will be changed,and at the same time there is a high temperature environment in the separation and recycling process of waste explosives,so it is necessary to study the thermal decomposition reaction of composite explosives containing TNT before the research on the the resourceful reuse of TNT to provide corresponding theoretical support for the future storage and safety assessment of mixed explosives.In this paper,we first investigated the thermal decomposition mechanism of composite explosives containing TNT(Composition B and TNT-RDX-Al Explosive),and then explored the problem of resource reutilization of waste TNT.Make the groups on TNT participate in the reaction to obtain intermediates that are more prone to chemical reactions,and then use the intermediates as raw materials to synthesize high-value energetic compounds,realizing the resource reutilization of waste TNT.The main researches are as follows:(1)A supercell model of TNT/RDX was constructed in accordance with the actual proportions of B explosives,and molecular dynamics simulations were carried out using the Reaxff/lg(C/H/O/N)reaction force field to investigate the thermal decomposition behaviour of B Explosives at different decomposition temperatures.We found that the decay rate of RDX molecules was significantly faster than that of TNT molecules during the thermal decomposition of B explosives,and the decomposition rates of TNT and RDX were significantly accelerated as the temperature rises.The higher the temperature,the shorter the difference in time between the TNT and RDX molecules to be completely decomposed.The behaviour of the thermal decomposition at different temperatures is similar.The main small molecules produced are NO₂,NO,N₂O,H₂O,CO₂,N₂,H₂,HNO₂ and HNO.the reaction force field(Reax FF-lg)containing C/H/O/N/Al parameters was used to simulate the thermal decomposition of the TNT-RDX-Al Explosive by reaction kinetics simulation.And the results were compared with the thermal decomposition behaviors of the binary systems TNT/Al O,RDX/Al O and TNT/RDX.The results show that:aluminium nanoparticles are easier to diffuse in the ternary system,the diffusion range is wider,the joint action of Al and RDX molecules reduces the decomposition temperature of TNT,prompting ring-opening reaction of TNT can occur earlier,advance the time of complete decomposition of TNT molecules,the system of large carbon-containing clusters significantly reduced.(3)A variety of technical routes were designed to synthesise the existing high performance heat resistant explosives 2,2',4,4',6,6'-hexanitroazobenzene(HNAB)and2,6-dibutylamino-3,5-dinitropyridine(PYX)using waste TNT as raw material,and the explosive intermediates 4,6-dinitrobenzofurazan(DNBF),the products of each step in the experiment were characterized by melting point,IR,DSC and NMR to verify the feasibility of the route.Finally,TNT was oxidized,Schmidt rearranged and amino oxidation azo to obtain HNAB;the target product DNBF was successfully synthesized by oxidation,decarboxylation halogenation,azidation and denitrogenation cyclization;and PYX,a heat-resistant explosive with excellent performance,was successfully obtained by oxidation,decarboxylation halogenation,nucleophilic substitution and nitration.(4)The TNT was used as the basic structure,and the new energetic materials were designed with the energetic groups such as trinitromethyl triazole and trinitromethyl tetrazole as the main functional groups.The performance parameters were predicted by Gaussian09and Explo5.The target compounds were selected and the synthetic technical route was designed using TNT as the raw material.The products of each step were analyzed and characterized by IR,DSC and NMR.3-trinitromethyl-5-nitro-1-(2,4,6-trinitrophenyl)-1H-1,2,4-triazole was successfully synthesized by oxidized,decarboxylated halogenated and substituted from TNT.The results show that the decomposition temperature of3-trinitromethyl-5-nitro-1-(2,4,6-trinitrophenyl)-1H-1,2,4-triazole is 327°C,?=1.89 g·cm^-3,D=9.01 km·s^-1 and OB=-30%?with a high heat of generation,a high crystal density,a good oxygen equilibrium,and thermal resistance,which indicated that this compound may be applied in the future as an environmentally friendly and high performance nitrogen or oxygen enriched material.