Ammonium Nitrate Fuel Oil Research Articles

Scanning electron microscopy of ammonium nitrate prills in relation to their application in ammonium nitrate-fuel oil systems

Detailed scanning electron microscopic studies were conducted on ammonium nitrate prills collected from different sources. The prills were classified as porous, irregular or dense. Based on their morphology, they were evaluated for their caking, rheology, friability and explosive characteristics in ammonium nitrate-fuel oil applications.

Reparameterization of the Becker-Kistiakowsky-Wilson equation of state for water-gel explosives

This paper describes the results of the reparameterization studies on the Becker-Kistiakowsky-Wilson (BKW) equation of state (EQS) for water-gel explosives. The original set of BKW parameters (α = 0.5, β = 0.1, κ = 11.85, and θ = 400) predicts a higher detonation velocity and detonation pressure and a lower detonation temperature compared with the experimental values for these explosives. Among the several combinations of parameters examined, the following set-α = 0.5, β = 0.1, κ = 8.85, and θ = 1850—is found to give realistic values for the various detonation properties. Moreover, the predicted and the experimental detonation velocities are seen to be in fair agreement. A comparison of the computed and the experimental (obtained from Crawshaw-Jones measurements) fume characteristics shows that (1) inclusion of the wrapper material in the explosive composition increases the concentration of fumes and gives correspondence between the two for products such as CO, H 2, NH 3, and CH 4, (2) the measured NO X concentration is difficult to get in these computations, and (3) calculations of the product compositions for the isentropic expansion of detonation products along the Chapman-Jouguet (C-J) isentrope give freeze-out temperatures in the range of 1000–1800K. These computations were also performed for two ammonium nitrate-fuel oil mixtures and are found to be in good agreement with the experimental data.

Detonation calculations with a Percus-Yevick equation of state

Chapman-Jouguet detonation calculations were conducted for pentaerythritol tetranitrate (PETN), TNT, and ammonium nitrate-fuel oil (AN-FO) explosives using the compressibility form of an equation of state of hard spheres based upon the Percus-Yevick (PY) theory, and a chemical equilibrium detonation code called TIGER. Similar calculations also were conducted with the Becker-Kistiakowsky-Wilson (BKW) equation of state. For PETN, the BKW equation gives somewhat better agreement with experimental values of detonation velocity and pressure. However, in terms of experimental temperatures and concentrations of the minor product species (NO), the predictions of the PY equation are shown to be more satisfactory. Similar comparisons of experimental and theoretical results for TNT and AN-FO indicate that the PY equation has general utility in predicting the detonation properties of condensed explosives at moderate loading densities (rho/sub o/ < 1.3 g/cu cm). (21 refs.)

Spectral analysis of cavitation noise in cryogenic liquids: Mosse, A., Finch, R.D. Vol 49, No 1 (January 1971) pp156–165

Detonations in explosive mixtures of ammonium-nitrate-fuel-oil (ANFO) confined by aluminum allow for transport of detonation energy ahead of the detonation front due to the aluminum sound-speed exceeding the detonation velocity. The net effect of this energy transport on the detonation is unclear. It could enhance the detonation by precompressing the explosive near the wall. Alternatively, it could decrease the explosive performance by crushing porosity required for initiation by shock compression or destroying confinement ahead of the detonation. At present, these phenomena are not well understood. But with slowly detonating, non-ideal high explosive (NIHE) systems becoming increasing prevalent, proper understanding and prediction of the performance of these metal-confined NIHE systems is desirable. Experiments are discussed that measured the effect of ANFO detonation energy transported upstream of the front by a 76-mm-inner-diameter aluminum confining tube. Detonation velocity, detonation front-shape, and aluminum response are recorded as a function of confiner wall thickness and length. Detonation shape profiles display little curvature near the confining surface, which is attributed to energy transported upstream modifying the flow. Average detonation velocities were seen to increase with increasing confiner thickness, while wavefront curvature decreased due to the stiffer, subsonic confinement. Significant radial sidewall tube motion was observed immediately ahead of the detonation. Axial motion was also detected, which interfered with the front-shape measurements in some cases. It was concluded that the confiner was able to transport energy ahead of the detonation and that this transport has a definite effect on the detonation by modifying its characteristic shape.

SHOOTING FOR DEEP REFRACTION EXPERIMENTS

Ammonium Nitrate—Fuel Oil explosive loaded into an abandoned mine shaft can be a convenient energy source for a deep refraction seismic experiment. Two such sites have been shot successfully in Australia.