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The mixture of ammonium nitrate (AN) prills and fuel oil (FO), usually referred to as ANFO, is extensively used in the mining industry as a bulk explosive. One of the major performance predictors of ANFO mixtures is the fuel oil retention, which is itself governed by the complex pore structure of the AN prills. In this study, we present how X-ray computed tomography (XCT), and the associated advanced data processing workflow, can be used to fully characterise the structure and morphology of AN prills. We show that structural parameters such as volume fraction of the different phases and morphological parameters such as specific surface area and shape factor can be reliably extracted from the XCT data, and that there is a good agreement with the measured oil retention values. Importantly, oil retention measurements (qualifying the efficiency of ANFO as explosives) correlate well with the specific surface area determined by XCT. XCT can therefore be employed non-destructively; it can accurately evaluate and characterise porosity in ammonium nitrate prills, and even predict their efficiency.
Ammonium nitrate (AN) prills are commonly used as an ingredient in industrial explosives and in fertilisers. Conventional techniques (such as BET or mercury intrusion porosimetry) can measure the open porosity and specific surface area of AN prill, but the closed porosity is not obtainable. This work was focused on evaluating X-ray computed tomography (XCT) as a non-destructive technique for the assessment of porosity in AN prills. An advanced data processing workflow was developed so that the segmentation and quantification of the CT data could be performed on the entire 3D volume, yet allowing the measurements (e.g.; volume, area, shape factor…) to be extracted for each individual phase (prill, open porosity, closed porosity) of each individual prill, in order to obtain statistically relevant data. Clear morphological and structural differences were seen and quantified between fertiliser and explosive products. Overall, CT can provide a very wide range of parameters that are not accessible to other techniques, destructive or non-destructive, and thus offers new insights and complementary information.
Experiments in this study reveal that the initiating capability of commonly used squibs is not high enough to initiate PETN in all cases. The fulfilment of the ‘new’ essential safety requirement 4 as set out in the European directive 2013/29/EU and the categorization of squibs as theatrical pyrotechnic articles (T2) can therefore be justified, as the explosive investigated belongs to quite a sensitive type (Initiation with low impulse energies possible). Underwater initiating capability tests according to EN 13763-15 led to meaningful results, showing that squibs are usually unable to initiate a secondary explosive. For a general assessment of the initiating capability of squibs and comparable (theatrical) pyrotechnic articles a threshold range of an equivalent initiation capability in grams of PETN on the basis of the performed underwater initiating capability tests was determined. It was found that squibs are generally not capable of initiating secondary explosives if the underwater initiating capability test showed an equivalent Initiation capability below 0.25 g PETN. As a consequence of this result, the underwater initiating capability test gives an effective and safer alternative to the experimental confirmation of the ‘new’ ESR 4 by direct contact of the article with the secondary explosive and should then be preferred to it.
The explosion and fire incidents with buried gas pipelines are increasing globally e.g. San Bruno (USA, 2010), East Godavari (India, 2014) and Ludwigshafen (Germany, 2014) are only a few to quote. There are a number of parameters involved behind the occurrence of these incidents such as human mistake, intended efforts leading to major or minor leak, ex-plosion due to depressurization, crater formation, spill of gaseous fuel in the nearby regions and pool/jet/crater fires. In continuation to [3] these parameters are investigated for Ludwigs-hafen incident in the present work. The semi-empirical and advanced CFD (Computational Fluid Dynamics) based models are utilized to assess the damages caused by the explosion overpressures. Recommendations are also provided on minimum safety distance to be consid-ered for such pipelines to avoid/foresee/mitigate similar hazards in future.
The explosion and fire incidents with buried gas pipelines are increasing globally e.g. San Bruno (USA, 2010), East Godavari (India, 2014) and Ludwigshafen (Germany, 2014) are only a few to quote. There are a number of parameters involved behind the occurrence of these incidents such as human mistake, intended efforts leading to major or minor leak, explosion due to depressurization, crater formation, spill of gaseous fuel in the nearby regions and pool/jet/crater fires. In continuation to [3] these parameters are investigated for Ludwigshafen incident in the present work. The semi-empirical and advanced CFD (Computational Fluid Dynamics) based models are utilized to assess the damages caused by the explosion overpressures. Recommendations are also provided on minimum safety distance to be considered for such pipelines to avoid/foresee/mitigate similar hazards in future.
Shock tube systems are non-electric explosive fuses employed in blasting and demolition applications to trigger the detonation of explosive charges. Their working principle is based on the explosive reaction of a fine explosive powder on the tubing's inner surface, generating a shock wave traveling at a velocity of 2,100 m/s along the length of the tube, without destroying it. One of
the key aspects of the manufacturing process of these shock tubes is the size and morphology of the explosive powder grains and their distribution on the inner wall of the tube, in order to propagate the shockwave efficiently and reliably. For the first time, synchrotron X-ray computed tomography has been used to characterize non-destructively the explosive powder grains, typically Al/HMX between 10 and 20 μm in size, in terms of morphology and 3D distribution but also to characterise the presence and location of defects
within the shock tube walls.
Die quantitative Bestimmung toxischer Gase, die bei der Umsetzung von Sprengstoffen entstehen können, ist für alle unter Tage verwendeten Sprengstoffe vorgeschrieben.
In der europaweit harmonisierten Norm DIN EN 13631 Teil 16 wird die Prüfmethode spezifiziert. Die wichtigsten Vorgaben und Anforderungen der Norm und deren Realisierung in der BAM - Prüfmethode werden erläutert. Der Aufbau und die Funktionsweise der BAM – Schwadenkammer, die eingesetzte Beprobungs- und Messtechnik und die Datenauswertung werden beschrieben.
Für die jeweiligen Sprengtypen (ANFO, Emulsionen, gelatinöse Sprengstoffe) werden die gemittelten Gaskonzentrationen für Stickoxide und Kohlenmonoxid diskutiert, die aus den bisher durchgeführten Prüfungen an der BAM resultieren.
Die nunmehr seit mehr als 10 Jahren an der BAM durchgeführten Schwadenprüfungen von gewerblichen Sprengstoffen zeigen, dass die Prüfmethode verlässliche und gut reproduzierbare Ergebnisse liefert. Konstante Prüf- und Umgebungsbedingungen ermöglichen die Vergleichbarkeit der Schwaden-Konzentrationen verschiedener Sprengstoffe.
Der Vergleich mit Werten anderer Prüfeinrichtungen ist jedoch nur eingeschränkt möglich. Insbesondere die Einschlussbedingungen haben einen großen Einfluss auf die Schwadenzusammensetzung. Dies zeigte sich an den alten Prüfergebissen, die noch in der Bergbauversuchstrecke „Tremonia“ oder im späteren Sprengbunker der DMT ermittelt wurden, sowie beim Vergleich mit Messwerten unter Bergbaubedingungen. Zu einem ähnlichen Fazit kam auch ein Ringversuch zwischen den Benannten Stellen, der im Jahr 2009 durchgeführt wurde. Die Messergebnisse der Schwadenprüfung in verschiedenen Versuchseinrichtungen werden vorgestellt und Übereinstimmungen sowie Abweichungen diskutiert.