Prilled/granulated ammonium nitrate is commonly used as a fertilizer and a basic ingredient of industrial explosives, especially of ANFO. One of the most important factors that affect the explosive properties of ANFO is the porosity of the prills/granules. This paper describes an attempt to manufacture ammonium nitrate prills of determined porosity in order to investigate its influence on the ANFO detonation velocity. A method of manufacturing porous ammonium nitrate prills with a high-level of oil absorption (up to 20% by volume) was developed. The relations between porosity and granulometric distribution of ammonium nitrate prills versus the detonation velocity of ANFO were examined. It has been proved that the detonation velocity of ANFO increases significantly with higher porosity and smaller size of ammonium nitrate prills/granules. The influence of ANFO oxygen balance (researched by changing the content of fuel oil in the mixture) on detonation velocity has been determined for two kinds of ammonium nitrate prills–one with a low and another one with a high level of porosity.

Influence of Ammonium Nitrate Prills' Properties on Detonation Velocity of ANFO

Synthesis and Desensitization of Nano‐β‐HMX

Ongoing research into new insensitive energetic materials with low sensitivity toward accidental stimuli, high thermal stability and high performance characteristics is undertaken in many research groups worldwide. In order to obtain promising compounds, which fulfil the sensitivity, stability, and performance requirements, researchers use many different strategies. One of the most promising approaches is the synthesis of novel explosives with tailored physico-chemical properties. In this review the synthesis and properties of some both covalent (NTO, TEX, FOX-7, ADNP, DNPPs) and ionic (salts of ANDP and DNPP) insensitive explosives are presented, which are of high interest to this field of research.

Covalent and Ionic Insensitive High-Explosives

To improve the safety of cryclotrimethylenetrinitramine (RDX), a novel method for the improvement of nano-energetic materials was reported in our research. Based on the mature microcapsule technology, nano-energetic materials are firstly fabricated by using RDX as core material and poly methyl metharylate (PMMA) as shell material via an emulsion polymerization method. The RDX/PMMA nano-composites were characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectra, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and impact sensitivity test, respectively. The SEM results indicated successful coating of the wall material PMMA on the surface of the core RDX, and the resultant particles by emulsion polymerization were regular solid spherical particles with smooth surface and dense coating layer, more importantly, it exhibits a very uniform particle size distribution with a narrower grain size. The XRD and FT-IR analyses did not show any change in the crystal structure after coating, thus indicating that PMMA could not change the crystal structure of RDX. Moreover, the characteristic height H50 of RDX/PMMA microspheres increased from 24.3 to 39.7 cm, significantly improving the safety performance. According to the DSC analysis, the Tb after core–shell coating increased by about 2 °C, and the Ea increased by 19.07 kJ mol−1, revealing desirable thermal stability. It is obvious that the emulsion polymerization method is an effective desensitization technique to prepare core–shell composite particles for RDX.

Synthesis, thermolysis, and solid spherical of RDX/PMMA energetic composite materials

Wpływ struktury fizycznej granul saletry amonowej na właściwości wybuchowe saletrolu (ANFO)

Mixtures of crystalline explosive and water have as a rule detonation properties different from the dry material. It has been shown that the character of those changes is closely related to the structure of the particles (crystals, granules) of the explosives. The critical diameters and detonation velocities have been measured for a range of explosive-water mixtures, and the results are interpreted in terms of the hotspot theory.

B. Zygmunt

Papers

The Detonation Properties of Explosive‐Water Mixtures