Ammonium nitrate emulsion explosives

Inorganic oxidizers are widely used as blasting agents in mining and construction explosives and also in improvised explosive devices utilized by terrorists. Ammonium-nitrate-based explosives (e.g., ammonium nitrate and fuel oil — ANFO) have almost completely replaced the majority of dynamites. In addition, slurry and emulsion explosives, which contain mosdy ammonium nitrate and a small amount of other oxidizers, have become widely used. 

B.1.3.1 Explosives shall be classified as unstable explosives or shall be assigned to one of the six divisions identified in B.1.2 in accordance with the three step procedure in Part I of the UN ST/SG/AC.10 (incorporated by reference See 1910.6). The first step is to ascertain whether the substance or mixture has explosive effects (Test Series 1). The second step is the acceptance procedure (Test Series 2 to 4) and the third step is the assignment to a hazard division (Test Series 5 to 7). The assessment whether a candidate for ammonium nitrate emulsion or suspension or gel, intermediate for blasting explosives (ANE) is insensitive enough for inclusion as an oxidizing liquid (See B.13) or an oxidizing solid (See B.14) is determined by Test Series 8 tests. 

Water-in-od emulsion explosives have been made as typified by a formulation containing 20% water, 12% oil, 2% microspheres, 1% emulsifier, and 65% ammonium nitrate. The micro droplets of an emulsion explosive offer the advantage of intimate contact between fuel and oxidizer, and tend to equal or outperform conventional water-based slurries. 

Experimental results of underwater explosion tests using an emulsion explo-sivecomposed of ammonium nitrate and hydrazine nitrate showed 0.85 MJ kg for the shock wave energy and 2.0 MJ kg for the bubble energy. The shock wave energy of underwater explosions is increased by the addition of aluminum powder to the explosives. The aluminum powder reacts with H2O molecules in the bubble. Large amounts of Hj molecules and heat are produced by the oxidahon of the A1 with H2O according to ... 

Civil explosives are further sub-divided into permitted or permissible explosives and non-permitted explosives. Two types of civil explosives namely ammonium nitrate-fuel oil (ANFO) and emulsion explosives dominate the rock blasting scene in the USA. 

An important group within the ammonium nitrate explosives are emulsion explosives, which consist essentially of a water-in-oil emulsion of an aqueous solution, supersaturated at room temperature, in an oil matrix which is a fuel. The oil phase is the continuous phase and includes small droplets of the supersaturated solution of the oxidizing agent. 

Commercial blasting explosives contain ammonium nitrate, wood meal, oil and TNT. A mixture of ammonium nitrate, water and oily fuels produces an emulsion slurry which is also used in commercial blasting explosives. Small glass or plastic spheres containing oxygen can be added to emulsion slurries to increase its sensitivity to detonation. 

For mud-like ammonium nitrate explosives - Slurries and -< Emulsion Slurries. 

Intermediate for -> Emulsion (blasting) explosives. These emulsions are non sensitized and are intended to produce an emulsion (a blasting) explosive only after further processing prior to use. Emulsions typicallyconsist of ammonium nitrate (partly replaced by other inorganic nitrate salts), water, fuel and emulsifier agents. 

Explosive emulsions are minute droplets of ammonium nitrate solution emulsified to the texture of margarine in a fuel (often diesel). Because the ammonium nitrate remains in solution, it is not an explosive and maintains an inherent high degree of safety during transportation. Emulsions are sensitized just prior to use by the introduction of gas bubbles or glass microballoons which create voids around which ammonium nitrate solidifies (the explosive form). Initiation is caused by the shockwave of a high explosive detonator. 

A suspected water gel is examined on a microscope slide to identify the microspheres used in slurry and emulsion explosives. The gel is directly extracted with methanol, which dissolves the amine salt, and a small amount of NH4NO3. TLC on a cellulose plate using a chloroform-methanol-water system separates the sensitizers. The plate is sprayed with ni-nhydrin and heated to visualize the amine salt. A second spray with diphenylamine in ethanol followed by long-wave UV irradiation visualizes the NFi4N03 if desired. Alternatively, the methanol extract may be evaporated to near dryness, redissolved in water, and analyzed by IC to identify the sensitizer. An intact sample can also be extracted with water using either a small homogenizer or ultrasonic agitation to disrupt the gel structure. Microspheres float on the surface and are removed for examination by SEM-EDX to characterize the manufacturer. Spot tests and IC identify ammonium, calcium, and nitrate ions in the water extract. Flake aluminum, if present, is identified as described above. 

Equation 10 with the fia replaced by the slope, fiafi of the Kissinger relation (Eq. 7) was appHed also to a study of explosive mixtures (Fig. 24) a thermal reactivity of several oxidizing systems of emulsion explosives and some commercial explosives with different nitrate ester content were specified in paper [153]. The main component of the oxidizing systems in all the studied materials was ammonium nitrate (AN). In Fig. 24 the line A corresponds to classical emulsion explosives W/0, the fine A to W/O emulsions fortified by addition of high explosives in the amount of at least 30% w/w, and the line C to gelatinous explosives with the nitrate esters content be-... 

Blasting agents—explosive materials that cannot be initiated by a No. 8 Test Detonator when unconfined, but which will detonate with a stronger stimulus. Typical examples include ammonium nitrate/fuel oil (ANFO), blends, and certain emulsions, water gels, and slurries. ... 

For a more in-depth discussion of the physical and chemical characteristics of emulsion explosives, see Blasters Handbook, 77-84 and Bampfield, Howard A. and John Cooper. 1988. Emulsion explosives. Chapter 7 in Encyclopedia of Emulsion Technology. New York and Basel Marcel Dekker. Mixtures consisting of a water-based explosive material matrix or an oxidizer matrix, and ammonium nitrate or ANFO, may also be referred to as blended explosives, blends, or heavy ANFO. 

The latest significant development in industrial explosives actually was invented only a few years after slurries, but full commercialization has occurred only within about the last fifteen years. Water-in-oil emulsion explosives involve essentially the same ingredients that slurry composite explosives do, but in a different physical form. Aqueous solutions of oxidizer salts, primarily ammonium nitrate, are emulsified into a relatively small amount of oil and emulsifier. Because of oxygen-balance constraints the volume ratio of the two liquid phases is about 90 10 for the aqueous and oil phases, respectively. This... 

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