Explosives slurries

Many of the components used in slurry explosives and the functions are as follows ... 

Table 19. Cratering Characteristics of ANFO, Slurry Explosives, and TNT ...

Pollution Prevention. Procedures haven been developed for recovery of composite ammonium perchlorate propellant from rocket motors, and the treatment of scrap and recovered propellant to reclaim ingredients. These include the use of high pressure water jets or compounds such as ammonia, which form fluids under pressure at elevated temperature, to remove the propellant from the motor, extraction of the ammonium perchlorate with solvents such as water or ammonia as a critical fluid, recrystalli2ation of the perchlorate and reuse in composite propellant or in slurry explosives or conversion to perchloric acid (166,167). 

Oil-Explosive Combinations. See under Slurry Explosives in Vol 6, E469-R, and under Ammonium Nitrate Blasting Explosives in Vol 1, A341ff... 

M.G. Farey, The Gas Chromatographic Determination of Isopropyl Nitrate in Slurry Explosives , Rept No ERDE-TN-41, Waltham Ab bey (Engl) (1971) 4)J. Diederichse n ... 

Special authorisations are available for manufacture at the site of use of ammonium nitrate/fuel oil and certain slurry explosives provided that the equipment used and its position on the site are suitable. 

In the 1950 s a sudden and dramatic change affected the explosives industry in many parts of the world. This was the introduction in the U.S.A., Sweden and Canada of ammonium nitrate sensitised with fuel oil as a major blasting explosive. A slower but also important change started in the 1960 s with the development of slurry explosives in the U.S.A., Canada and other countries. 

Slurry explosives, also known as water-gel explosives or dense blasting agents, resulted from the work of M. A. Cook and others in North America and have now found world-wide application particularly for large scale operations. Whilst slurries are made in many forms to suit almost all types of use, they may be divided into two essentially distinct types ... 

This base is used to the minimum possible extent in the final explosive as the water it contains does not contribute to the power and indeed requires energy for its evaporation. All slurry explosives therefore contain further ammonium nitrate in solid form and also a fuel for combustion. The ammonium nitrate is usually in dense form similar to that used in nitroglycerine explosives as this gives the best physical properties. However, it is common practice to mix the explosive hot so that much or all of the solid ammonium nitrate results from crystallisation during cooling. 

The more widespread current use of slurry explosives is undoubtedly due to the development of aerated slurries. These have much greater versatility than the dense variety and can be made to a wide range of sensitivity, density and power. Moreover they are particularly suited to manufacture on site for pumping direct into a borehole without intermediate packing and transport. 

It has been pointed out that the water present in a slurry explosive must be vaporised during detonation and thus absorbs energy. Although the water vapour increases the total volume of gas produced the nett effect is still a reduction in strength. Many attempts have therefore been made to find a soluble additive which will replace part of the water to give both increased power and sensitivity. One such substance which has found success is ethylene glycol mononitrate. This when pure is explosive, but for... 

The ballistic mortar and lead block tests use only small amounts of explosive and are not applicable to slurry explosives which are too insensitive to detonate properly under such conditions. For these explosives it is useful to fire larger amounts of several kg under water and measure the period of oscillation of the gas bubble produced. The longer the period the greater the energy of the gas bubble and this part of the total energy of the explosive has been found to correlate well with the blasting effect of the explosive. 

Slurry explosive. An explosive made by sensitising a thickened aqueous slurry of oxidising... 

In preparing the second edition of this book the opportunity has been taken to add sections on slurry explosives and a short account of Nonel fuse. Parts which were badly out of date have been modernised, and the opportunity taken to correct some errors and ambiguities. Thanks are again due to my former colleagues in NEC. 

Decomposition of a 70% nitric acid-ammonium nitrate slurry explosive led to overflow, contact with wood and a fire. This spread to detonators, which initiated detonation of the slurry. 

Ammonium nitrate (AN NH4NO3) is a white, crystalline material, the crystal structure of which varies with temperature.melting point is 442 K and its heat of fusion is 71.4 kj kg . Though the mass fraction of oxygen of AN is 0.5996, it is highly hygroscopic and absorbs moisture from the atmosphere to form liquid AN acid. This limits its application in propellants and pyrolants. However, AN is widely used as an oxidizer of explosives such as slurry explosives and ANFO (ammonium nitrate fuel oil) explosives. 

The physicochemical properties of explosives are fundamentally equivalent to those of propellants. Explosives are also made of energetic materials such as nitropolymers and composite materials composed of crystalline particles and polymeric materials. TNT, RDX, and HMX are typical energetic crystalline materials used as explosives. Furthermore, when ammonium nitrate (AN) particles are mixed with an oil, an energetic explosive named ANFO (ammonium nitrate fuel oil) is formed. AN with water is also an explosive, named slurry explosive, used in industrial and civil engineering. A difference between the materials used as explosives and propellants is not readily evident. Propellants can be detonated when they are subjected to excess heat energy or mechanical shock. Explosives can be deflagrated steadily without a detonation wave when they are gently heated without mechanical shock. 

Slurry explosives consist of saturated aqueous solutions of ammonium nitrate with sensitizing additives.[i-3] Nitrates such as monomethylamine nitrate, ethylene glycol mononitrate, or ethanolamine mononitrate are used as sensitizers. Aluminum powder is also added as an energetic material. Table 4.15 shows a typical chemical composition of a slurry explosive. It is important that so-called micro-bubbles are present within the explosives in order to facilitate the initial detonation and the ensuing detonation wave. These micro-bubbles are made of glass or polymeric materials. 

Being partly aqueous, slurry explosives are not inactivated by water or humidity, and they are essentially insensitive to mechanical shock or heat. The strength of detonation is approximately equal to that of NG-NC-based explosives. Since slurry explosives are composed of a mixture of aqueous AN and an oil, they exist as emulsions and hence are also termed emulsion explosives. 

A mixture of AN and water forms a low-strength explosive referred to as a slurry or emulsion explosive. Since a mixture of AN and water cannot be detonated by initiation with a moderate detonation strength, to formulate practical slurry explosives nitrate esters such as monomethylamine nitrate, ethylene glycol mononitrate, or ethylamine mononitrate in conjunction with aluminum powder are added as sensitizers that facilitate the initiation of detonation. 

The major chemical components of emulsion explosives are fundamentally the same as those of slurry explosives, as shown in Table 9.4.[i l Instead of the sensitizers used for slurry explosives, a large number of hollow microspheres made of glass or plastics are incorporated to formulate emulsion explosives in order to obtain successive detonation propagation after the initiation of detonation. During detonation propagation into the interior of the explosives, an adiabatic compression results... 

Detonation in Slurry Explosives. Cook, in his book, pp 316-21, described under the heading "Water-Compatible Explosives properties of slurry explosives developed by M.A. Cook.St H.E. Farnam. These expls were intended for use in large diameter underwater blasting at Iron Ore Company of Canada s Knob Lake operation. The success of these expls brought out the importance of pressure and density on the products of detonation. Table 12.21 of Cook s book gave computed properties of three dry versus water soaked slurry mixtures at AN/TNT ratios of zero, 1.0 8c 3.25. It was of interest to note that the computed (dry basis) available energy A of the TNT in slurry with 27% water was 17% greater... 

In the late 1950 s and early 1960 s the entire explosives industry was intensively working on a new explosive system, which has since become known as water-gel or aqueous slurry explosives. Hercules was among the leaders in innovation and promotion of water gels. Packaged Flogel, an aqueous solution of oxidizing salts sensitized with smokeless powder became a forerunner of many such products. 

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