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Xu S.,Nanjing University of Science and Technology | Xu S.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | Tan L.,Nanjing University of Science and Technology | Liu J.-P.,Nanjing University of Science and Technology | And 5 more authors.
Journal of Loss Prevention in the Process Industries | Year: 2016

Emulsion explosives (EE) have been widely used in the mining industry for their comparatively high detonation performance and exceptionally good safety characteristics. However, an accidental spontaneous burning of an emulsion explosive occurred in March 24, 2014. The investigation of the accident showed that the reaction between crystalloid sodium nitrite and ammonium nitrate (AN) was likely the cause of the spontaneous burning. To investigate the stability of the EE mixed with crystalloid sodium nitrite, AN, crystalloid Sodium nitrite, and EE, were analyzed by differential scanning calorimeter (DSC), accelerating rate calorimeter (ARC) and Dewar test. The results indicated that crystalloid sodium nitrite could decrease the onset decomposition temperature of AN and EE and the induced thermal runaway is the reason for the accident. © 2016 Elsevier Ltd.


Cai G.-W.,Nanjing University of Science and Technology | Xu S.,Nanjing University of Science and Technology | Xu S.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | Chen X.,Shanghai Entry exit Inspection and Quarantine Bureau | And 3 more authors.
Journal of Beijing Institute of Technology (English Edition) | Year: 2016

Using the cook-off oven, the experiment at setting heating rate of 3℃/h with different charge volume ratios studied influence of charge volume on temperature field distribution in slow cook-off oven, the results showed that the average deviations of heating rates were less than 5% basically and charge volume ratio isn't the main factors to temperature field distribution. The experiment on 64% charge volume ratio with five different heating rates explored influence of heating rates on temperature field distribution in slow cook-off oven, it could conclude that the uniformity of temperature field distribution become worse with the increase of heating rate, the average deviations were 1.8%, 3.7%, 4.6%, 8.0% and 10.4% at the heating rates of 3℃/h, 10℃/h, 60℃/h, 180℃/h and 300℃/h respectively. To ensure uniformity of temperature field distribution in the slow cook-off test oven, the heating rates need to be lower than 60℃/h. © 2016 Beijing Institute of Technology.


Cao W.,Nanjing University of Science and Technology | Gao W.,Dalian University of Technology | Liang J.,Nanjing University of Science and Technology | Xu S.,Nanjing University of Science and Technology | And 2 more authors.
Journal of Loss Prevention in the Process Industries | Year: 2014

To reveal the flame-propagation behavior and the thermal-radiation effects during coal-dust explosions, two coal-dust clouds were tested in a semi-enclosed vertical combustion tube. A high-speed video camera and a thermal infrared imaging device were used to record the flame-propagation process and the thermal-radiation effects of the fireball at the combustion-tube outlet. The flame propagated more quickly and with a higher temperature in the more volatile coal-dust cloud. The coal-dust concentration also significantly affected the propagation behavior of the combustion zone. When the coal-dust concentration was increased, the flame-propagation velocity and the fireball temperature increased before decreasing overall. Based on the experimental results, a dynamic model of the thermal radiation was employed to describe the changes in the fireballs quantitatively and to estimate the thermal-radiation effects during coal-dust explosions. © 2014 Elsevier Ltd.


Qiu S.,Nanjing University of Science and Technology | Qiu S.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | Wei J.,Jiangsu Academy of Environmental Sciences | Pan F.,Nanjing University of Science and Technology | And 4 more authors.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

In the present work, the experimental and theoretical studies on the structure, vibrations, NMR and HOMO-LUMO analysis of 3,3′,5,5′- tetrabromobisphenol A (TBBPA) are presented. The FT-IR (400-4000 cm -1) and FT-Raman (100-4000 cm-1) spectra of TBBPA were recorded. The molecular geometry, vibrational frequencies were calculated by using density functional theory (DFT) method with the 6-31G(d) basis set. The optimized geometric properties, scaled vibrational wavenumbers, IR intensities, Raman activities show good agreement with the experimental data. The assigned vibrational modes of the IR and Raman spectra were compared with the corresponding properties of the polybrominated diphenyl ethers (PBDEs). Comparative analysis indicated that the red shift of C-Br vibration could probably be ascribed to the further electronic density equalization due to the p-π conjugation between O atom and the benzene. The natural bonding orbital (NBO) analysis demonstrated that the intermolecular hyperconjugative interactions are mainly formed by the orbital overlap between σ (O-H), σ- (C-C), π (C-C), π- (C-C) bond orbitals. Compared to the higher E(2) value (33.65-34.82 kcal/mol) originated from LP(2)O to π- (C-C), the one (E(2): 8.23-9.73 kcal/mol) from LP(3)Br and π- (C-C) contributes to the preferential tendency of C-Br breakage to the C-O breakage in the transformation. The calculated NMR results obtained on the 6-31G(d) level proves good agreement with the experimental data (r2 = 0.999). Analysis of isosurface of the related orbital shows that all the main excitation exhibit π-π- character localized on the benzene rings. © 2012 Elsevier B.V. All rights reserved.


Tan L.,Nanjing University of Science and Technology | Xia L.-H.,Nanjing University of Science and Technology | Wu Q.-J.,Nanjing University of Science and Technology | Wu Q.-J.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | And 3 more authors.
Journal of Loss Prevention in the Process Industries | Year: 2015

A study has examined the effect of urea on the thermal stability and detonation characteristics of ammonium nitrate (AN). The thermal decomposition temperature and surface morphology of samples were investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). For further research on the thermal sensitivity and shock sensitivity of the samples, the Koenen test and UN gap test were conducted. The results indicate that urea can substantially increase the thermal stability of AN (the greatest exothermic peak is increased by more than 100 °C) and reduce the thermal sensitivity of AN. However, AN-50wt. % urea mixtures can still produce a steady detonation in the UN gap test. Urea cannot reduce the ability to propagate a detonation. Possible explanations for these results are discussed. © 2015 Elsevier Ltd.


Jiao S.,Nanjing University of Science and Technology | Jiao S.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | Wang Y.,Nanjing University of Science and Technology | Chen C.,Nanjing University of Science and Technology | And 4 more authors.
Journal of Molecular Structure | Year: 2014

This study reports a Graphene Oxide Mediated SERS (GOMS) Substrate supporting silver nanoparticles (AgNPs), which is characterized with the relatively clean surface of nanoparticles and formation of stable suspension in the detection. Moreover the tight anchoring of silver nanoparticles on the platform by a multiple oxygen-containing groups on GO carbon grid favors for the generation of large number of "hot" spots. We demonstrate that anchoring of the 4-mercaptopyridine (4-Mpy) analyte at these system leads to a pronounced intensification of its Raman emission using described SERS assay. Most impressively, acting as a new type of SERS substrate, the GOMS Substrate can disperse well in water during the detection process, which makes the Raman signals very uniform. This work not only shows that target molecule such as 4-Mpy has a strong interaction with the nanoparticle surface can be detected quickly and accurately with high sensitivity and stability, but also show SERS activity successfully for Bovine Serum Albumin (BSA), which interaction with nanoparticle surface is weak, in about physiological saline of Label-free detection. The results reported herein may lead to many applications in SERS techniques. © 2014 Elsevier B.V. All rights reserved.


Cao W.-G.,Nanjing University of Science and Technology | Xu S.,Nanjing University of Science and Technology | Xu S.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | Liang J.-Y.,Nanjing University of Science and Technology | And 4 more authors.
Baozha Yu Chongji/Explosion and Shock Waves | Year: 2014

Two kinds of different volatile pulverized coal were tested in a semi-enclosed vertical combustion tube. And a high-speed video camera and an infrared imager were used to record the flame propagation process and the spatial flame temperature distribution, respectively. The changes of the flame propagation velocity and temperature with time were analyzed for the two different coal dust clouds during combustion. Experimental results show that the flame propagation velocity and flame temperature of the high-volatile coal dust cloud are higher than those of the low-volatile coal dust cloud under the same experimental conditions. And the volumic mass of coal dust cloud as well as ignition energy can affect the flame propagation. With increasing the volumic mass of coal dust cloud, the flame propagation velocity and the flame temperature increase at first and then decrease, oscillating phenomena appear in the next process. With increasing the ignition energy, the flame propagation velocity and flame temperature increase. Based on the experimental data, an empirical formula was proposed for calculating the flame propagation velocity and flame temperature under certain conditions. ©, 2014, Explosion and Shock Waves. All right reserved.


Tan L.,Nanjing University of Science and Technology | Xia L.-H.,Nanjing University of Science and Technology | Wu Q.-J.,Nanjing University of Science and Technology | Wu Q.-J.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | And 3 more authors.
Combustion, Explosion and Shock Waves | Year: 2016

To better understand the detonation characteristics of ammonium nitrate (AN) and activated additives mixtures, potassium chloride (KCl) and monoammonium phosphate (MAP) are mixed with AN by different mixing methods. The UN gap test and scanning electron microscopy are applied to study AN and AN-additive mixtures. For the mechanical mixing method, the detonation velocity of AN-additives decreases with increasing the additive proportion, while the detonation velocity of modified AN prepared by the solution mixing method shows the opposite tendency. It is proved that the sensitivity to shock waves increases as the size of AN particles decreases. The type of additives, the mixing methods, and the particle size distribution are important parameters that affect the detonation characteristics of AN. © 2016, Pleiades Publishing, Ltd.


Cao W.,Nanjing University of Science and Technology | Huang L.,Nanjing University of Science and Technology | Zhang J.,National Quality Supervision and Inspection Center for Industrial Explosive Materials | Xu S.,Nanjing University of Science and Technology | And 4 more authors.
Procedia Engineering | Year: 2012

The parameters of explosive characteristics of the coal-dust are assessed systematically with the test device of minimum ignition temperature of dust clouds and 20L sphere explosion test units. The minimum ignition temperature of dust is a main safety index when handling combustible dusts in industrial production, and while hazard evaluation, the maximum explosion pressure and the explosion index are key parameters. Five kinds of coal-dust with different particle diameters were tested in order to determine the temperature sensitivity and the ferocity under the given conditions, which can be used as the criteria to classify dust explosion hazards. The experiment results indicate that the minimum ignition temperature of coal-dust cloud reduces with the decrease of particle diameter under temperature of (293 ± 5) K and powder spraying pressure of 0.08MPa, and when the particle size reduces to (25-48) μm, the minimum ignition temperature is between (793-803)K; Besides that, the results can also show that minimum explosive concentration of coal-dust cloud is between 20 g·m-3 and 30 g·m-3 under temperature of (293 5) K, powder spraying pressure of 2MPa and ignition energy of 10kJ, the maximum explosion pressure is 0.45MPa and the maximum explosion index is 11.14 MPa·m·s-1, which classifies coal-dust explosion hazards to Level I. The conclusions drawn from the experimental results are of great significance to the safe application of these combustible substances. © 2012 The Authors. Published by Elsevier Ltd.


Cao W.,Nanjing University of Science and Technology | Huang L.,Nanjing University of Science and Technology | Liang J.,Nanjing University of Science and Technology | Miao N.,Nanjing University of Science and Technology | And 3 more authors.
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2014

In order to investigate the explosion parameters of coal dust in the spherical sealed container, the explosion rule and explosion mechanism of two kinds of coal dust with different volatile, ignition quality and explosion suppression agent were studied in a 20 L sphere explosion test units. The results show that the explosion pressure increased with the increasing of ignition energy. Under the same ignition quality, the explosion pressure firstly increased and then decreased. The explosion pressure of high volatile coal dust is bigger than that of low volatile coal dust. The explosion severity of coal dust with 9% methane-air mixtures is stronger than that with air mixture. Adding inert material SiO2 and NH4H2PO4 can effectively reduce coal dust explosion pressure. The explosion suppression results adding NH4H2PO4 is better than that adding SiO2.

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