ANFO

Abstract: A pourable blasting agent of high water resistance, having controlled density and bulk blasting strength greater than that of conventional ammonium nitrate-fuel oil (ANFO) mixtures, comprises two main essential components, i.e. (1) 40 to 60% by weight of a dry or essentially dry, solid, particulate oxidizer salt, with or without added fuel oil for oxygen balance and (2) 60 to 40% of a water-in-oil emulsion containing oxidizer salt dissolved in water and combined with an oily vehicle held in stable emulsion condition with a small quantity of water-in-oil emulsifier, the emulsion also containing a density controlled sensitizer such as hollow glass beads, polystyrene beads, microballoons or equivalent. The first component is preferably a fertilizer grade prilled ammonium nitrate, with or without added oil; the second is of heavy oil or grease consistency having high resistance to the extraction of salt therefrom in water and being of substantially higher bulk density than the particulate material. The components are thoroughly mixed together to substantially eliminate voids between the solid granules. The oily or greasy emulsion contains enough oil, with or without other fuels, to give substantial oxygen balance to the whole mixture. The required quantity of a highly effective emulsifier is minimized by high shear mixing to insure a stable emulsion of the second component.

Abstract: The Jones-Wilkins-Lee (JWL) equation of state parameters for ANFO and emulsion-type explosives have been obtained from cylinder test expansion measurements. The calculation method comprises a new radial expansion function, with a non-zero initial velocity at the onset of the expansion in order to comply with a positive Gurney energy at unit relative volume, as the isentropic expansion from the CJ state predicts. The equations reflecting the CJ state conditions and the measured expansion energy were solved for the JWL parameters by a non-linear least squares scheme. The JWL parameters of thirteen ANFO and emulsion type explosives have been determined in this way from their cylinder test expansion data. The results were evaluated through numerical modelling of the tests with the LS-DYNA hydrocode; the expansion histories from the modelling were compared with the measured ones, and excellent agreement was found.