explosives,' in: ullmann's encyclopedia of industrial...

� 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Article No : a10_143

Explosives

JACQUES BOILEAU, Consultant, Paris, France

CLAUDE FAUQUIGNON, ISL Institut Franco-Allemand de Recherches de Saint-Louis,

Saint-Louis, France

BERNARD HUEBER, Nobel Explosifs, Paris, France

HANSH.MEYER,Federation of EuropeanExplosivesManufacturers, Brussels, Belgium

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . 621

2. Physical Properties andChemical Reactions 624

2.1. Detonation . . . . . . . . . . . . . . . . . . . . . . . . . 624

2.1.1. Ideal Detonation . . . . . . . . . . . . . . . . . . . . . 624

2.1.2. Deflagration and Detonation. . . . . . . . . . . . . 625

2.2. Prediction of Detonation Data . . . . . . . . . . 625

2.2.1. Complete Calculation . . . . . . . . . . . . . . . . . 625

2.2.2. Approximation Methods . . . . . . . . . . . . . . . 625

2.3. Nonideal Detonation Waves and Explosives 626

2.3.1. Nonideal Explosive Compositions . . . . . . . . 627

2.3.2. Detonation of Cylindrical Cartridges . . . . . . 627

2.3.3. Low- and High-Order Detonation Velocity . . 628

2.3.4. The Effect of Confinement. . . . . . . . . . . . . . 628

2.4. The Buildup of Detonation. . . . . . . . . . . . . 629

2.4.1. Combustion – Deflagration –

Detonation Transition (DDT) . . . . . . . . . . . . 629

2.4.2. Shock-to-Detonation Transition (SDT) . . . . . 629

2.4.3. Shock and Impact Sensitivity . . . . . . . . . . . . 630

2.5. Classification of Explosives . . . . . . . . . . . . 630

2.6. Functional Groups . . . . . . . . . . . . . . . . . . . 631

2.6.1. Nitro Group . . . . . . . . . . . . . . . . . . . . . . . . 631

2.6.2. Other Groups . . . . . . . . . . . . . . . . . . . . . . . 631

3. Application . . . . . . . . . . . . . . . . . . . . . . . . 632

3.1. Energy Transfer from the Explosive to the

Surroundings . . . . . . . . . . . . . . . . . . . . . . . 632

3.1.1. Shock and Blast Waves . . . . . . . . . . . . . . . . 632

3.1.2. Casing and Liner Acceleration . . . . . . . . . . . 632

3.2. High Compression of Solids . . . . . . . . . . . . 633

3.3. Metal Forming and Welding . . . . . . . . . . . 633

3.4. Rock Blasting . . . . . . . . . . . . . . . . . . . . . . 634

3.5. Perforators, Shaped or Hollow Charges . . 634

4. Primary Explosives . . . . . . . . . . . . . . . . . . 634

5. Secondary Explosives. . . . . . . . . . . . . . . . . 636

5.1. Production . . . . . . . . . . . . . . . . . . . . . . . . . 636

5.2. Specific Secondary Explosives . . . . . . . . . . 637

5.2.1. Nitrate Esters . . . . . . . . . . . . . . . . . . . . . . . 637

5.2.2. Aromatic Nitro Compounds . . . . . . . . . . . . . 639

5.2.3. N-Nitro Derivatives . . . . . . . . . . . . . . . . . . . 641

6. High Explosive Mixtures . . . . . . . . . . . . . . 643

6.2. Desensitized Explosives . . . . . . . . . . . . . . . 643

6.3. TNT Mixtures . . . . . . . . . . . . . . . . . . . . . . 644

6.4. Plastic-Bonded Explosives (PBX) . . . . . . . . 644

7. Industrial Explosives . . . . . . . . . . . . . . . . . 645

7.1. Dynamites . . . . . . . . . . . . . . . . . . . . . . . . . 645

7.2. Ammonium Nitrate Explosives

(Ammonites) . . . . . . . . . . . . . . . . . . . . . . . 646

7.3. Ammonium Nitrate/Fuel Oil Explosives

(ANFO/ANC Explosives) . . . . . . . . . . . . . . 647

7.4. Slurries and Water Gels . . . . . . . . . . . . . . 647

7.5. Emulsion Explosives . . . . . . . . . . . . . . . . . 647

7.6. Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 648

8. Test Methods . . . . . . . . . . . . . . . . . . . . . . . 649

8.1. Performance Tests . . . . . . . . . . . . . . . . . . . 649

8.2. Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650

9. Legal Aspects and Production . . . . . . . . . . 651

9.1. Safety Regulations . . . . . . . . . . . . . . . . . . . 651

9.2. Production of Military Explosives . . . . . . . 651

10. Toxicology and Occupational Health . . . . . 652

References . . . . . . . . . . . . . . . . . . . . . . . . . 652

1. Introduction

An explosion is a physical or chemical phenome-non in which energy is released in a very shorttime, usually accompanied by formation and vig-orous expansion of a very large volumeof hot gas:

1. Mechanical explosions are caused by thesudden breaking of a vessel containing gasunder pressure

2. Chemical explosions are caused by decompo-sition or very rapid reaction of a product or amixture

3. Nuclear explosions are caused by fission orfusion of atomic nuclei

4. Electrical explosions are caused by suddenstrong electrical currents that volatilize metalwire (exploding wire)

5. Astronomical explosions are caused by solarflare activity on most stars

DOI: 10.1002/14356007.a10_143.pub2

6. Natural explosions are caused, e.g., by volca-nic eruptions when evaporation of dissolvedgas in the magma results in a rapid increase involume

Only chemical explosions are treated in thisarticle.

For an explosion to occur, the reactionmust beexothermic; a large amount of gas must be pro-duced by the chemical reaction and vaporizationof products; and the reactionmust propagate veryfast. For example, gasoline in air burns at a rate ofca. 10�6 m/s; a solid propellant, at ca. 10�2 m/s;and an explosive detonates at a rate of ca. 103 –104 m/s (detonation velocity).

The two different modes of decomposition aredeflagration and detonation. Deflagration exhi-bits two characteristics: 1) the combustion is veryrapid (1 m/s up to a few hundred meters persecond) and 2) the combustion rate increaseswith pressure and exceeds the speed of sound inthe gaseous environment, but does not exceed thespeed of sound in the burning solid. Thematerialsare often powdered or granular, as with certainpyrotechnics and black powder. Detonation ischemically the same as deflagration, but is char-acterized by a shock wave formed within thedecomposing product and transmitted perpendic-ularly to the decomposition surface at a very highvelocity (several thousand meters per second)independent of the surrounding pressure (seeChap. 2).

Explosive substances can be divided intothree classes. Members of the first class detonateaccidentally under certain conditions. These areexplosible substances, some of which are used inindustry as catalysts (e.g., peroxides), dyes, andfertilizers. This class includes products or mix-tures whose formation must be avoided orcontrolled, e.g., firedamp, or peroxides in ethers.In the second class are products normally used fortheir quick burning properties but which maydetonate under some circumstances, e.g., pyro-technic compositions, propellants, and somekinds of hunting powder. In the third class aresubstances intentionally detonated for variouspurposes.

For reasons of safety, acquaintance with thefirst group of materials is necessary. The secondgroup is described elsewhere (! Propellants;! Pyrotechnics). Pure substances and mixturesof the third class are described here.

The distinctions between these three classesare not clear-cut because most explosives burnsmoothly if they are not confined. However, ifsome fine hunting powder burns under certainconfined conditions, combustion may becomedetonation. Dry nitrocellulose fibers can easilydetonate, but this tendency is significantly lowerin the gelatinized form. Some compositions, suchas mixtures of cyclotrimethylenetrinitramine(RDX) with a binder, can be used as a propellant,gunpowder, or high explosive, depending on thetype of initiation.

The third class consists of primary and sec-ondary explosives. Primary explosives like leadazide (initiator explosives) detonate followingweak external stimuli, such as percussion, fric-tion, or electrical or light energy. Secondaryexplosives such as pentaerythritol tetranitrate(PETN) or 2,4,6-trinitrophenyl-N-methylnitra-mine (Tetryl) are much less sensitive to shock.However, they can detonate under a strong stim-ulus, such as a shockwave produced by a primaryexplosive, which may be reinforced by a boostercomposed of a more sensitive secondary explo-sive. The various secondary explosives are usedmilitarily or industrially as shown in Figure 1.

Functions and Constraints. Explosivescan be either pure substances or mixtures. Theyfunction in such systems as munitions, wherethey are a component of a complex firing system,or as firing devices in mining, quarries, demoli-tion, seismic exploration, or metal formingequipment. With such systems, the ingredientsmust fulfill one or more functions, while meetingvarious constraints arising inmanufacture or use.Therefore, tests that represent these functionsand constraints are required.

When an explosive detonates, it generates ashock wave, which may initiate less sensitiveexplosives, cause destruction (shell fragments,blast effect, or depression effect), split rocks andsoils, or cause formation of a detonation wave. Adetonation wave of special geometry (hollow-charge effect) may modify materials by veryrapid generation of high pressure; for example,shaped charges, metal hardening, metal-powdercompaction, or transformation of crystallineforms. Shaped charges can be applied for thedestruction and demolition of large obsoletestructures by causing inward collapse. Shapedcharges (so-called perforators) are also used in

622 Explosives Vol. 13

the exploitation of petroleum and natural gaswells to perforate the metal casing of the welland thus allow the influx of oil and gas. A shockwave may be used to transmit signals, e.g., forsafety devices or in seismic prospecting.

In general, constraints are related to safety,security, stability, compatibility with other ele-ments of the system, vulnerability, toxicity, eco-nomics, and, more recently, environmental anddisposal problems [21].

History [1, 4, 88]. Explosives were proba-bly first used in fireworks and incendiary devices.The admixture of saltpeter with combustibleproducts such as coal and sulfur produced blackpowder, already known in China in the 4thcentury A.C., described in 808 A.C. by Qing-Xu-Zi, andmentioned as amilitary gunpowder ina book published in 1044. The use in shells duringthe Mongolian wars around 1270 and a severeexplosion in a factory in 1280 were described.The first correct description of the phenomenonof shock waves in air seems to be in a book by thescientist Song-Ying-Xing in 1637. Around 1580first descriptions in Europe are known (siege ofBerg-op Zoom). However, the difficulties ofinitiation upon impact against the target werenot overcome until 1820 when fulminate capswere developed. In the early 1600s, black powderwas used for the first time to break up rocks in amine in Bohemia. This technique spread

throughout Western Europe during the 1600s.Ammonium perchlorate was discovered in 1832.

The development of organic chemistry after1830 led to new products, although their explo-sive properties were not always immediatelyrecognized. These include nitrocellulose andnitroglycerin.

The very important contributions of ALFRED

NOBEL (1833 – 1896) include the use of mercuryfulminate in blasting caps for the safe initiation ofexplosives (1859 – 1861), the development ofdynamites (by chance NOBEL found that whennitroglycerin was mixed in a ratio of 3:1 with anabsorbent inert substance like Kieselgur (diato-maceous earth) it became safer and more conve-nient to handle, and this mixture was patented in1867 as Dynamite), and the addition of 8%nitrocellulose (gun cotton) to nitroglycerin(Gelignite or blasting gelatine, 1876).

Many new products were developed between1865 and 1910, such as nitrated explosives,mixtures in situ of an oxidizer and a fuel, ex-plosives safe in the presence of firedamp, chlo-rate explosives, and liquid oxygen explosives.Organic nitro compounds for military uses in-cluded tetryl, trinitrophenol, and trinitrotoluene.

Between the two world wars, RDX, pentaer-ythritol tetranitrate (PETN), and lead azide wereproduced. After 1945 cyclotetramethylenetetra-nitramine (HMX), 1,3,5-triamino-2,4,6-trinitro-benzene (TATB), and hexanitrostilbene (HNS)

Figure 1. Differentiation of explosible materials

Vol. 13 Explosives 623

were developed (see Chap. 5), as well as ‘‘fuel –air explosives’’. Ammonium nitrate – fuel oil(ANFO/ANC) explosives, slurries, and emulsionexplosives were developed for industrial uses;some were improved by adding glass bubbles(microspheres), micropores, and/or chemicalgassing.

In the 1880s BERTHELOT described the phe-nomenon of detonation.About the same time thehollow-charge effect was discovered, and thefoundations of the hydrodynamic theory of deto-nation were established. In 1906, the first accu-rate measurements of velocities of detonationwere made. After World War II, the science ofdetonation was further developed and perfected[17].

Recently, new explosive compositions of lowvulnerability (LOVA ¼ low vulnerability am-munitions) are being developed. Major effortsare being made to use predicted properties (e.g.,density, DHf, sensitivity, themal stability) toavoid unnecessary experiments [18, 19, 95, 103].

2. Physical Properties and ChemicalReactions

2.1. Detonation

The detonation process needed for most uses ischaracterized by a shock wave that initiateschemical reactions as it propagates through theexplosive charge. The shock wave and reactionzone have the same supersonic velocity; a frac-tion of the chemical energy is used to support theshock.

2.1.1. Ideal Detonation

A model of ideal detonation (ID) is shown inFigure 2, with steady flow to the end of thereaction zone.

Stationarity requires the plane correspondingto the end of the reactions to be locally sonic. Thiscondition, termed the Chapman – Jouguet (CJ)condition [23, 24], yields the relation D ¼ uþcneeded to solve the equations of conservation offlow (where D ¼ detonation velocity, u ¼ par-ticle velocity, and c ¼ sound velocity).

The structure of the reaction zone of the IDplane detonation can be ignored, and the me-chanical and thermodynamic data can be calcu-lated by solving equations between the non-reacted and fully reacted states. The descriptionof the ideal detonation is given by the model[25–27] represented in Figure 3 by the p – Vplane (Fig. 3 A) and the pressure p vs. distancex profile at a given instant of time (Fig. 3 B). Thismodel relates the explosive at rest (V0), theshocked nonreacted explosive [ZND spike (*)],and the end of the reaction zone [CJ plane ð Þ].This model has been experimentally ascertained[28].

In Figure 3 A the three states are located on astraight line (Rayleigh line), with slope equal to�D2=V0

2 . The loci of the shocked states aretermed Hugoniot curves: H0 for the unreactedexplosives, and H for the completely reactedexplosives.

Some relations at the CJ plane can be ex-pressed as a function of D and the polytropiccoefficient of the detonation products:

G ¼ qlog r

qlogV^

!s

Figure 2. Ideal detonation

Figure 3. Development of the ideal detonationA) The p – V plane; B) The pressure vs. distance profile;p pressure; V specific volume; D detonation velocity; H0

Hugoniot curve of nonreacted explosives; H Hugoniot curveof reaction products; (0) explosive at rest; (1) reaction zone oflength a, an arbitrary quantity; (2) isentropic release of thedetonation product


The notation ( )s represents the derivativealong the isentrope at the CJ point.

u¼ D

Gþ1p¼ r0

D2

Gþ1

c¼ GGþ1

D r¼ r0Gþ1

G

where r ¼ densityThese relations are valid for most condensed

organic explosives G � 3, with the assumptionsthat p0 ¼ 0 and u0 ¼ 0.

2.1.2. Deflagration and Detonation

In a thermodynamic diagram such as Figure 3 A,there is another point that satisfies the Chap-man – Jouguet condition in the region p <p0(not drawn in the figure). It represents the Chap-man – Jouguet deflagration, in contrast to thedetonation:

Detonation Deflagration

p> p0 p< p0U > 0 u< 0

V < V0 V > V0

Unlike the detonation wave, the deflagrationwave is subsonic, and consequently a precursorshock is propagated in front of the reaction zone.Its intensity and velocity depend on the chemicalenergy released and on the boundary conditions;in contrast to detonation, a specific explosivedoes not provide a unique solution fordeflagration.

A precursor shock that is strong enough can, inaddition to compressing the explosive, also heatit sufficiently to initiate reactions just behind itsfront; a progressive buildup of a completelystationary process identical with the ZND modelof the detonation is observed. Consequently, adetonation is equivalent to a shock followed by adeflagration.

2.2. Prediction of Detonation Data

2.2.1. Complete Calculation [29]

The quantitiesD, p, u, V , and T in the Chapman –Jouguet state are needed to evaluate further the

effectiveness of the explosive on the surround-ings in a given action. The calculation of thesequantities requires the equation of decomposi-tion, the heats of reaction, and an equation of statefor the reaction products, which may be theoreti-cal (virial expansion) [30, 31], semiempirical[32], empirical [33], or a constant G law. Inaddition, the equilibrium constants for the reac-tion given as a function of V and T are needed.

For organic explosives, the distinction betweenoxygen-positive or weakly oxygen-negative ex-plosives, which give only gaseous products, andthe strongly oxygen negative explosives, whichalso give free carbon, is important. In fact, theassignment to one class or the other is determinedby the values of the equilibrium constants for(V ; T) determined after a first calculation.

In asmuchas (V; T) are a functionof the loadingdensity r0, some explosives, for instance, pentaer-ythritol tetranitrate (PETN), produce free carbon athigh loading densities and only gaseous products atmoderate values of r0. Because of the complexityof the calculation, the number and formulation ofthe equations depend on the final result.

The thermochemical equations are solvedwith a priori (V,T) pairs to give gas productcomposition. The mechanical equations are thenapplied at the Chapman – Jouguet plane with thegeometric condition represented on Figure 3 A:at the CJ point, the isentropic and the Hugoniotcurves have the same tangent, with a slope equalto �D2=V0

2 .

2.2.2. Approximation Methods

A first prediction of the CJ data can be given byusing methods valid for condensed explosives.

Chemical Potential. For many organic ex-plosives, D and p can be expressed simply as afunction of a parameter F defined as [34]:

F ¼ Nffiffiffiffiffiffiffiffiffiffi�MrQ

q

N ¼ number of moles of gaseous productsper gram

�Mr ¼ average molecular mass of these pro-ducts, g/mol

Q ¼ enthalpy of the explosive minus theenthalpy of the products, J/g


The calculation of F is made under the as-sumption that:

OþH!H2O

OþC!CO2

i.e., the formation of water is considered beforethe formation of carbon oxides.

The following relations are then proposed:

D ¼ Að1þBr0ÞffiffiffiffiF

pp¼ K r20F

A good fit with experimental data is found fororganic explosives by setting

A ¼ 1:01 B ¼ 1:3K ¼ 15:58

This method, which requires only knowledgeof the equation of decomposition, is useful forcomparing organic explosives.

Rothstein Method. An empirical correla-tion has been found between the detonationvelocityD and a parameter F, which is a functionof the explosive molecule [35].

Dðr0Þ ¼F�0:26

0:55�3ðrTM�r0Þ

rTM ¼ theoretical densityThis correlation applies to both organic nitro

and fluorinated nitro explosives.

F ¼ 100

nðOÞþnðNÞþnðFÞ� nðHÞ�nðHFÞ2nðOÞ

0@

1A

*

Mr

þ100

A

3� nðB=FÞ

1:75� nðCÞ

2:5� nðDÞ

4� nðEÞ

5

Mr�G

where n (F), n (HF), and n (B/F) are the elemen-tal terms for fluorinated explosives, and whereG ¼ 0.4 for each liquid explosive component,G ¼ 0 for solid explosives, and A ¼ 1 if thecompound is aromatic; otherwise A ¼ 0. * Ifn (O) ¼ 0 or if n (HF) > n (H), this term ¼ 0.

For 1 mol of composition:

n (O) ¼ number of oxygen atomsn (N) ¼ number of nitrogen atomsn (H) ¼ number of hydrogen atomsn (F) ¼ number of fluorine atomsn (HF) ¼ number of hydrogen fluoride mo-

lecules that can form from avail-able hydrogen

n (B/F) ¼ number of oxygen atoms in excessof those available to form CO2 andH2O or the number of fluorineatoms in excess of those availableto form HF

n (C) ¼ number of oxygen atoms doublybonded to carbon as in a ketone orester

n (D) ¼ number of oxygen atoms singlybonded to carbon as in C–O–Rwhere R ¼ H, NH4, C, etc.

n (E) ¼ number of nitrato groups existingas a nitrate ester or as a nitricacid salt such as hydrazinemononitrate

Molecularmasses and atomic composition forexplosive mixtures must be derived as sums ofmass-average molecular mass and of elementalmole fractions. The prediction of the detonationvelocity is ca. 95% accurate.

2.3. Nonideal Detonation Waves andExplosives

A detonation wave is nonideal if the geometryand dimensions of the charge are such that thereaction zone is affected by lateral shock orrarefaction waves. Consequently, the nonidealitydepends strongly on the dimensions of the chargeand the explosive composition characterized by agiven reaction zone length.

An explosive composition consisting of com-ponents with different reaction kinetics does notsatisfy the ideal detonation model, which as-sumes all the exoenergetic reactions to be com-pleted simultaneously in the sonic Chapman –Jouguet plane. Such compositions are nonidealexplosives. The ideal detonation model appliesonly as an approximation to most multicompo-nent explosives; however, with data on reactionkinetics under pressure often lacking, calcula-tions are commonly based on the ideal detonationmodel.


2.3.1. Nonideal Explosive Compositions

An example of an organic explosive with ametallic nonexplosive additive is a dispersion ofaluminum grains or flakes in a cast organicexplosive. The process sequence is shown inFigure 4. The energy effectively supporting thedetonation wave has been delivered at time tA.The absorption of energy by aluminum reduces pand D, but the late combustion of the aluminumallows the pressure to be sustained behind the CJplane, thereby increasing the total impulse trans-mitted to the surroundings.

The possible sequence of an organic explosive(a) with a negative oxygen balance cast orpressed with a binder containing oxygen (b) isshown in Figure 5. The relatively slow decom-position of the binder produces oxygen gas,which shifts the reaction of the organic explosivetoward better oxygen balance, thus increasingenergy production.

A typical example of a mixture of two explo-sive components with different reaction kineticsis a mixture of trinitrotoluene (TNT) and ammo-nium nitrate (AN). The slower reaction of ANproduces energy and an excess of oxygen, whichshifts the equilibrium of the TNT reaction to ahigher energy release. Because the detonation ofthe nonideal explosives involves heat transfer

between components, the specific surface areasbecome important. Moreover, because the totalreaction zone is relatively long, detonation de-pends on the dimensions of the charges.

2.3.2. Detonation of CylindricalCartridges

In the detonation of cylindrical cartridges, thereactive flow is two-dimensional, stationary, andrelatively easy to model. Many military or engi-neering applications use cylindrical geometry.

The basic phenomenon is the interaction ofthe inwardly propagating rarefaction fan, origi-nating at the outer surface as it is reached by theshock wave, with the reaction zone. The firstconsequence of this interaction is freezing of thereactions by cooling, which reduces the releasedenergy. A second effect is a curvature of thedetonation front and a loss in energy through adiverging flow. The reaction zone length and theradius of the cartridge are two quantities that playopposite roles in the process.

The experimental determination of the deto-nation velocity as a function of the diameterproduces a curve limited in two ways:

1. As the diameter increases, the detonationvelocity D approaches a constant value Di

equal to that of the ideal detonation wave.2. Below a given diameter d, called the critical

diameter, dcr , the detonation is no longer self-supporting and fails.

Figure 4. Sequence of reactions: explosive and combustibleadditivea) Cast organic explosive; b) Aluminum grains or flakes

Figure 5. Sequence of reactions: explosive and oxygen-richbindera) Negative-oxygen-balance explosive; b) Oxygen-contain-ing binder


Many analytical expressions DDiðdÞ have been

proposed in which the explosive is characterizedby its ideal reaction zone length. The functionD (d) and the critical diameter dcr depend on boththe length and the structure of the reaction zone,i.e., on factors that affect this zone, such as theloading density r0, grain size g, initial tempera-ture t0, and composition, especially in the case ofmixtures.

As an example of the effects of these factorson ideal explosive compositions, the influence ofr0 is shown in Figure 6 for the conventionalmilitary composition 60 RDX/40 TNT (compo-sition B) [36]. In the case of energy-rich explo-sives, the effect of the cylinder diameterincreases with decreasing density, whereas thecritical diameter decreases with increasing den-sity and increasing temperature [37]. The influ-ence of mean grain size, e.g., that of powderedTNT, is shown in Figure 7 [29], and mostnonideal explosive compositions and some pureexplosives exhibit a particular behavior (seeChap. 6).

2.3.3. Low- and High-Order DetonationVelocity

Some explosives exhibit two different detonationvelocities, depending on the diameter of thecartridge and the initial ignition energy. Suchexplosives always have a relatively low energyand loading density, with great sensitivity to

shockwaves [36]. Conventional examples are thedynamites and highly porous explosives [38].

The high sensitivity to shock waves tends toallow the detonation to be sustained. This is trueeven when the development of the reactions isseriously limited by the size of the cartridge.Thus, under steady conditions, a state of shockplus reaction would correspond to that appearingin a transient regime in the buildup of heteroge-neous explosives to detonation.

2.3.4. The Effect of Confinement

Confinement usually delays the arrival of theexpansion waves on the axis. A confined chargeis equivalent to a charge having a large diameter.However, two anomalous effects should be not-ed: if the velocity of sound in the confinementexceeds the detonation velocity for the givendiameter, a foreshock is propagated ahead of thewave. This foreshock can accelerate the wave(increase the density) or stop the detonation, i.e.,desensitize a porous explosive by compaction,the explosive becoming homogeneous. An anal-ogous desensitizing effect can be generated ifthere is an air gap between the explosive and thecontainer. The expanding reaction products adi-abatically compress the porous explosive. Thiseffect can stop the detonation of mining chargesembedded in boreholes (so-called dead pressingprocess, especially observed in emulsionexplosives).

Figure 6. Detonation velocity D vs. diameter d for twodensities r of 60 wt% RDX – 40 wt% TNT

Figure 7. Detonation velocity D vs. diameter d for severalgrain sizes g of powered TNT


2.4. The Buildup of Detonation

2.4.1. Combustion – Deflagration –Detonation Transition (DDT)

Deflagration can generate a shock wave, which ispropagated in the unreacted medium, and ifstrong enough, can initiate reactions and becomea detonation wave. This transition can occur onlyif the explosive charge is confined or is of such asize that expansion waves do not prevent forma-tion of a shock wave. Accident reports haveshown that DDT affects a variety of explosivesand propellant charges.

However, different phenomena, which de-pend on the mechanical properties of the medi-um,may occur [39, 40]: if the explosive is porousor exhibits poor mechanical behavior, the gasformed and subjected to pressure is injectedbetween the grains or into cracks, increasing thecombustion surface. The resulting accelerationstops only when detonation occurs. The pathversus time of the observed ionization front iscontinuous. In the case of explosives stiff enoughto withstand an elastic wave, a steady deflagra-tion develops as soon as the pressure makes themedium impervious to the gas. The transition todetonation occurs as the pressure of the gasformed behind the deflagration zone becomeshigh enough to generate a shock wave. Detona-tion occurs when the shock wave reaches thefront of the deflagration wave. As a consequence,a discontinuity is observed in the path versus timeof the ionization front.

2.4.2. Shock-to-Detonation Transition(SDT)

If the end of an explosive charge is subjected to ashock wave, the steady detonation appears onlyat a distance s and with a delay t inside theexplosive charge [41]. For a given composition,s and t are inversely proportional to the intensityof the shock wave. There are two SDT processes:one for homogeneous (for instance, a liquid) andone for heterogeneous composition.

Homogeneous Explosives. The shockwave(a) in Figure 8 propagated at constant velocityinitiates decomposition reactions that are first

completed along the entrance side (b) at time t,the detonation appearing at point A. The detona-tion wave (c) travels in a compressed mediumheated by shock wave (a). Therefore, the deto-nation wave (c) travels with a velocity exceedingthe normal detonation velocity, which is attainedat point B (wave d) as soon as wave c has reachedwave a.

Heterogeneous Explosives. In Figure 9,the shock wave (a) is gradually accelerated bythe energy released upon its passage. Its acceler-ation ends with the appearance of a detonationwave at point B. This wave is characterized by itsluminosity, as seen on optical records. Some-times a second wave starts from point B andmoves backward in the explosive, which hasreacted only partially (retonation wave). Themacroscopic analysis can be explained by the

Figure 8. Detonation buildup (SDT), homogeneousexplosive

Figure 9. Detonation buildup (SDT), heterogeneousexplosive


microscopic heterogeneities of the explosive[42].

The energy of the shock wave is convertedinto heat energy by the implosion of occluded gasbubbles, the impact of microjets, or the adiabaticshearing of the powder grains. All the observa-tions allow for two successive phases, ignitionand buildup, that are accommodated by numeri-cal models assuming inward or outward combus-tion of the grains [43].

2.4.3. Shock and Impact Sensitivity

The sensitivity of the explosives to an appliedload is measured by the maximum load at whichno detonation occurs, or at which there is a 50%occurrence of detonation, i.e., a 50% chance offailure. The sensitivity to shock loading dependson the pressure p* and its action time t*. Sensi-tivity is defined with the aid of the curve p* (t*),which separates detonation points from failurepoints.

For a variety of explosives and for a certainpressure range, the sensitivity is defined by therelation ðp�Þ2t� ¼ e, where e is a constant thatdepends on the composition and exhibits thedimension surface energy per unit area [44].

Figure 10 shows that the concept of the ener-gy threshold is an acceptable approximation forsolid-state compositions [45]. For liquid explo-sives, which exhibit different behavior, the rela-tion t* (p*), based on an Arrhenius-type kinetic

theory (with initial temperature T * expressed asa function of pressure p*) accurately reproducesthe experimental findings. The critical time t* isequal, for a given shock pressure, to the time ofthe shock-to-detonation transition (see Fig. 8).Except for primary explosives, the sensitivity toshock-wave action and the shock-to-detonationtransition are both dependent on the homogeneityof the composition. Sensitivity is affected bygrain size [104] and internal grain defects[105]. The reaction of an explosive to impactloading depends on several factors. If the projec-tile is a large plate, the reaction is identical withthat observed in the preceding case: the shockwave induced by the impact depends on thevelocity and acoustic impedance, whereas theaction time is proportional to the plate thickness.In tests of sensitivity to shock-wave action, theimpacting plates are driven by explosives. If theprojectile is a small sphere or cylinder, the inter-action with the target becomes complex [41]. Ifthe shock wave cannot induce a shock-to-deto-nation transition, it degenerates into an adiabaticcompression. Frictional and shearing effects cancause ignition. Finally, a phenomenon analogousto the deflagration-to-detonation transition (seeSection 2.4.1) is observed, in which the mecha-nical properties of the explosive play a part.

2.5. Classification of Explosives

For many years the behavior of cylindrical car-tridges, as described in Section 2.3.2, was re-garded as typical of ideal explosives. A detailedanalysis has shown, however, that classificationof explosives into two groups is possible, takinginto account the influence of the loading densityr0 on the detonation velocity as a function of thecartridge diameter and the critical diameter [46].

The first group includes a variety of organicexplosives: TNT, RDX, HMX, and their mix-tures (see Chap. 5). The second group includesmixtures of an explosive and a combustiblenonexploding constituent (nonideal composi-tion). This group also includes some pure ex-plosives such as hydrazine mononitrate (HN),nitroguanidine (NG), ammonium nitrate (AN),dinitrotoluene (DNT), dinitrophenol (DNP), andammonium perchlorate (AP). The behavior ofthe second group is illustrated for ammoniumperchlorate in Figure 11.

Figure 10. Initiation energy threshold vs. shock pressurea, b) HMX plus binder; c, d) Cast RDX compositions


2.6. Functional Groups

Certain groups impart explosive potential.

2.6.1. Nitro Group

The nitro group is present in the form of salts ofnitric acid, ONO2 derivatives (nitrate esters),CNO2 derivatives (aliphatic or aromatic nitrocompounds), and NNO2 derivatives (N-nitrocompounds such as nitramines, nitroureas, etc.).

Salts of Nitric Acid. Salts of nitric acidinclude the alkali metal and alkaline earth metal

nitrates, ammonium nitrate, and the nitrates ofmethylamine, urea, and guanidine. These areusually low-density, water-soluble, sometimeshygroscopic compounds. With the exception ofsome salts of hydrazines, e.g., triaminoguanidineand hydrazine nitrates, they are insensitive toimpact and friction.

O-Nitro Derivatives, Nitrate Esters(RONO2). The low molecular mass represen-tatives are liquids or low-melting solids. They aresensitive to impact when the number of carbonatoms and �ONO2 groups are equal or nearlyequal. Densities are in the medium range, exceptfor symmetrical molecules such as pentaerythri-tol tetranitrate (PETN). Heat stability is moder-ate; they are subject to hydrolysis and autocata-lytic decomposition.

C-Nitro Derivatives (CNO2). Aliphaticand cycloaliphatic nitro compounds differ great-ly from the aromatic and heteroaromatic series.Members of the first group have limited explo-sive properties, except when the number of NO2

groups equals or exceeds the number of carbonatoms, as in some gem-dinitro compounds andderivatives of nitroform, HC(NO2)3. The latterare often shock-sensitive, with limited heat sta-bility. The compounds RCF(NO2)2 are stable toheat and rather insensitive [6, 7]. Members of thesecond group containing two or threeNO2 groupsper ring are valuable; they are often dense andinsensitive to impact, with good hydrolytic andthermal stability.

N-Nitro Derivatives (NNO2). N-Nitro de-rivatives are often difficult to synthesize. Theyexhibit high densities and detonation velocities,with some sensitivity to impact. RDX and HMXare representative.

2.6.2. Other Groups

Organic chlorates and perchlorates, peroxides,metal salts of some organic compounds (acety-lides and nitronates), and some organic com-pounds with three-membered rings or chains ofnitrogen atoms or triple bonds have only limitedapplication, except as primary explosives. Mostare very dangerous to handle.

Figure 11. Detonation behavior of ammonium perchlorate;h ¼ percent of the theoretical maximum density


Nitroso (NO) compounds are usually unstable.So-called hexanitrosobenzene is an exception;however, it is actually not a nitroso compoundbut a furoxan derivative (benzotrifuroxan). It is ofinterest because it is free of hydrogen (zero-hydrogen explosive). Other furoxanes and alsofurazanes have explosive properties [89].

The difluoroamine group imparts explosivecharacter, increased density and volatility, alower melting point and detonation velocity, andoften much higher impact sensitivity. Thesecompounds resemble primary explosives.

Many metal azides are primary explosives.Some organic azido derivatives are being studiedbecause of their high density and stability. How-ever, polyazido compounds can be verysensitive.

3. Application

3.1. Energy Transfer from theExplosive to the Surroundings

The energy available in the gaseous reactionproducts is transferred to the surroundings byshock waves. The mechanical effects depend onthe geometry of the charge and the surroundings,on the distance from the charge, and on theacoustic impedance of the media. The explosiveenergy is used either to create compression andtension for engineering applications or to accel-erate projectiles for military applications.

3.1.1. Shock and Blast Waves

The highest dynamic pressures are produced atthe exit end of the charge, where the detonationshock is transferred to the inert material. Theshock pressure is a function of the shock imped-ance. It is defined by the so-called shock polarcurve of the pressure (p) vs. particle velocity (u).By a graphical method (Fig. 12) the inducedpressure can be determined at the intersectionof a shock polar curve with the detonation gas-product curve passing through the CJ point.

Even higher pressures can be obtained byusing converging geometries or, indirectly, bya two-stage device. The explosive accelerates athin metal plate, which generates an intenseshock in the solid specimen as it strikes it in free

flight. During wave propagation in the surround-ing medium, the intensity of a shock wave de-creases and the pressure profile changes. At agiven distance from the charge, compressionalternates with tension. The mechanical effectsare a function of the maximum pressure and ofthe positive and negative impulses comprisingthe so-called blast wave. The maximum andminimum pressures are represented in Figure 13as a function of the reduced distance R/m1/3 fromthe charge.

3.1.2. Casing and Liner Acceleration

A casing or liner in contact with an explosivecharge is accelerated by a three-step process:

Figure 12. Determination of shock pressure p and particlevelocity u induced in an inert material by an explosive;PMMA ¼ poly(methyl methacrylate)

Figure 13. Front pressure pf and minimum pressure pmin inair vs. reduced distanceR/m1/3 fromTNT in air, whereR is thedistance in meters and m the mass in kilograms


1. u1 given by the shock wave2. u2 � 2 u1 given by reflection of the shock

wave in a release wave at the free surface3. u3 given by the further expansion of the

gaseous detonation products

The Gurney formula gives an approximate u3for a casing filledwith an explosive characterizedby the quantity E, which is given in J/kg [47]:

u3ðm=sÞ ¼ ð2 EÞ1=2 M

Cþa

� ��1=2

where

M ¼ mass of the casing, kgC ¼ mass of the explosive, kga ¼ 0.5 for a cylindrical charge anda ¼ 0.6 for a spherical charge

3.2. High Compression of Solids

Explosives provide the most powerful means forcompressing solids in spite of the fact that at highpressure the heating limits the volume reduction.

Production of New Crystal Phases. Thehigh pressure generated by shock waves may beused to transform one crystal phase into another(polymorphic transformation). The best-knownexample of this technique is the transformationof graphite into diamond. Unfortunately, theshort duration of the shock limits this techniqueto the production of small crystals used asabrasives.

Powder Compaction. The compression ofpowders by shock waves produced by explosivescreates high pressures and temperatures simulta-neously, resulting in grain welding. The mainproblem, which has been solved only recently, isthe explosion caused by the interaction of releasewaves, which follow the shock; special geome-tries are required [48]. Rapidly solidified amor-phous and metastable microcrystalline materialsand ultrahigh-strength ceramics are expected tobe produced by this technique.

Shock Hardening. The detonation of a thinsheet of explosive covering a piece of steelcreates great surface hardness by a sequence ofrapid compression, heating, and cooling.

3.3. Metal Forming and Welding

The detonation of an explosive charge is used toform a metal plate; the shock wave is moderatedby a liquid transmitting medium (Fig. 14). Tech-niques of free forming (Fig. 14 A) or bulkheadforming (Fig. 14 B) may be used.

A grazing detonation may weld two metalplates (even different metals such as titanium onsteel or aluminum on copper) with diffusion ofmetal through the interface (Fig. 15) [49]. Therequired collision velocity vc depends on thematerials and the types of explosives used. Thisprocess is called explosive welding or metalcladding.

Figure 14. Setups for metal formingA) Free forming; B) Bulkhead forming

Figure 15. Explosive welding or cladding


3.4. Rock Blasting [36]

In rock blasting the explosive systems are placedin blast holes, which are usually drilled in defineddistances and angles into the bench and/or thewall of the quarry. With strong confinement,which is usually achieved by stemming the bore-hole, most of the explosive energy is usefullyemployed, even though some of it is released byafterburning. Depending on the specific require-ments of the quarry, the geological/petrologicalconditions, the required rock fragmentation, thecost effectiveness, and the environmental para-meters (ground vibration, dust, noise, air blast),the blasting specialists determine which blastingsystem should be applied to optimize the overallperformance and results. This refers to selectionof the correct type of explosives, for example,cartridged products such as dynamites or emul-sions; bulk emulsion explosives which are man-ufactured from non-explosive substances on thebench by so-called mobile emulsion manufactur-ing units (MEMUs) and pumped directly intoblast holes on demand; ANFO in packaged formor from bulk trucks, and an appropriate initiationsystem (electrical, nonelectrical, or electronicdetonators, detonating cords, and delay relays orcombinations thereof). Various types of wedgecuts are used for underground blasting ope-rations.

3.5. Perforators, Shaped or HollowCharges

An explosive can be used to produce a thin,high-speed metallic projectile capable of perfo-rating armor [50]. Nonmilitary applications in-clude oil (perforators) and the demolition ofstructures.

A cavity in the explosive (Fig. 16) is linedwith a metal, usually copper. The detonationdivides the liner into two parts that move alongthe axis at different velocities. Most of the massof the liner forms the so-called slug at a velocityof several hundred meters per second. The re-mainder forms a thin projectile which is elongat-ed because of the difference of velocity betweenthe first formed elements near the apex (ujetmax. � 8000 – 11 000 m/s) and those formedlast (ujet min. ¼ 1500 – 2000 m/s). The ultimatelength of the projectile depends on the ductility of

the liner and can be > 10 times the diameter ofthe charge.

When the projectile strikes a solid or liquidtarget, it drills a deep, narrow hole. The holedepth P is given approximately by the expression

P ¼ L

ffiffiffiffirjrt

s

where L is the length of the projectile and rjand rt are the densities of the projectile andtarget.

4. Primary Explosives

Under low-intensity stimulus of short duration,primary explosives, even in thin layers, decom-pose and produce a detonation wave; the activa-tion energy is low. The stimulus may be shock,friction, an electric spark, or sudden heating. Thedeflagration – detonation transition occurs with-in a distance often too short to be measured. Thereleased energy and the detonation velocity ofprimary explosives are small. Their formation isoften endothermic.

The main function of primary explosives is toproduce a shock wave when the explosive isstimulated by percussion, electrically, or optical-ly (laser), thus initiating a secondary explosive.Primary explosives are the active detonator in-gredients. Some are used in primer mixtures toignite propellants or pyrotechnics. Because oftheir sensitivity, primary explosives are used in

Figure 16. Projectile formation


quantities limited to a few (milli)grams, and aremanufactured under special precautions to avoidany shock or spark. To be used in industry,primary explosives must have limited sensitivityand adequate stability to heat, hydrolysis, andstorage. Mercury fulminate, azides, and diazo-dinitrophenol are among the few products thatmeet these requirements and that can detonate asecondary explosive. Others, e.g., lead styphnateor tetrazene, initiate burning or act as sensitizers.

Properties of primary explosives are given inTable 1.

Mercury Fulminate [628-86-4], Hg(ONC)2,Mr 284.65, was first prepared in the 1600s andwas used by NOBEL in 1867 to detonate dyna-mites. It is prepared by the reaction of mercurywith nitric acid and 95% ethanol, in small quan-tities because the reaction is difficult to control.Mercury fulminate is a gray toxic powder, whichlacks the stability for storage. It reacts withmetals in a moist atmosphere; in most industrialcountries its use has been abandoned.

Lead Azide [13424-46-9], Pb(N3)2,Mr 291.26,discovered by CURTIUS (1891) [13], was developedafter World War I and is now an importantprimary explosive. It is produced continuouslyby the reaction of lead nitrate or acetate withsodium azide in aqueous solution under basicconditions to avoid formation of hydrazoicacid, which explodes readily. The crystal sizemust be carefully controlled, large crystalsbeing dangerous, by controlling the stirringand by using wetting agents. Demineralizedwater must be used. With thickeners such asdextrin, sodium carboxymethylcellulose, orpoly(vinyl alcohol), purities from 92% to99% are possible, the former containing 3%dextrin and 4 – 5% Pb(OH)2. The lower sen-

sitivity of the 92% lead azide to impact andfriction compared to purer lead azides facil-itates detonator loading. Lead azide has goodstability to heat and storage. Contact withcopper must be avoided because copper azideis extremely sensitive; aluminum is preferred.Silver azide is used at high temperature or inminiaturized pyrotechnic devices. It is pre-pared from aqueous silver nitrate and sodiumazide.

Diazodinitrophenol [28655-69-8], DDNP,C6H2N4O5,Mr 210.06, is obtained by diazotizingpicramic acid and purified by recrystallizationfrom acetone. It is sparingly soluble in water,nonhygroscopic, and sensitive to impact, but notas sensitive to friction or electrostatic energy. It isless stable to heat than lead azide. It is most oftenused in the United States.

Lead Styphnate [15245-44-0], lead trinitror-esorcinate, C6HN3O8Pb, Mr 450.27, is producedcontinuously by the aqueous reaction of themagnesium salt with lead acetate, sometimes inthe presence of agents that promote the formationof the correct crystalline form. Especially sensi-tive to electrostatic discharge, it is most frequent-ly used to sensitize lead azide and in primercompositions to initiate burning.

Table 1. Properties of primary explosives

Property Lead azide, Silver azide DDNP Lead Tetrazene

pure styphnate

Crystal density, g/cm3 4.8 5.1 1.63 3.0 1.7

Detonation velocity, km/s 6.1* 6.8* 6.9 5.2

at density 4.8 5.1 1.6 2.9

Impact sensitivity, Nm 2.5 – 4 2 – 4 1.5 2.5 – 5 1

Friction sensitivity, N 0.1 – 1 20 8 10

Lead block test, cm3/10 g 110 115 325 130 130

Explosion temperature,** �C 345 290 195 265 – 280 160

*Theoretical.**After 5 s.


Tetrazene [31330-63-9], C2H8N10O, Mr

188.07, is obtained by the reaction of sodiumnitrite with a soluble salt of aminoguanidine inacetic acid at 30 – 40 �C. It decomposes inboiling water. Its greatest value is for the sensiti-zation of priming compositions.

A current trend in research on new primaryexplosives is to replace compounds containinglead for environmental problem reasons.

5. Secondary Explosives

5.1. Production

Common high explosives are usually made byliquid-phase nitration. The overall mechanism isbelieved to be ionic, with NOþ

2 generally thereactive species. In some cases, N2O4 may beadded to a double bond or to an epoxy group. It isalso possible to nitrate gas-phase hydrocarbons.The most important nitrating agent is nitric acid(! Nitric Acid, Nitrous Acid, and NitrogenOxides).

Numerous end products of nitration are solu-ble in concentrated HNO3, andmay be recoveredby dilution. However, dilution below ca. 55 wt%acid is not economic.

To increase the NOþ2 content (3 wt% in pure

HNO3), lower the solubility of end products,reduce oxidative side reactions, and facilitate thetreatment of spent acids, mixtures of sulfuric andnitric acids (mixed acid) are used. The watercontent of a mixed acid may be reduced byadding oleum. In 50 : 50 wt% mixed acid, thenitric acid is ca. 15% dissociated.

However, sulfuric acid is difficult to removefrom products by washing. Furthermore, somesubstances (e.g., nitramines, nitriles, etc.) aredecomposed. Orthophosphoric acid or polypho-sphoric acid may be used instead of sulfuric acid;however, these phosphoric acids aremore expen-sive and more difficult to recover.

Mild nitration or nitrolysis can be conductedin mixtures of nitric acid and acetic anhydride or

acetic acid; the reactive species may beCH3COONO2H

þ. Mixtures of nitric acid andacetic anhydride containing between 30 and80 wt% HNO3 can detonate [51]. A high con-centration of acetic anhydride avoids this danger.More recent nitration methods use N2O5 as asolution in pure nitric acid (‘‘nitric oleum’’) or inchlorinated solvents (e.g., CH2Cl2). Three pro-cesses for the production of nitric oleum are inoperation or in development [89]:

1. Oxidative electrolysis of a N2O4 – HNO3

mixture2. Ozonation of N2O4

3. Distillation of an oleum (H2SO4 þ SO3) –NH4NO3 mixture [90]

Nitric oleum allows yields to be improved andpermits some syntheses to be performed that arenot possible by other routes; the organic N2O5

solutions allow nitration to be performed undervery mild and selective conditions [16, 91].These nitrating agents must be used at their siteof production.

Nitration. Reaction is exothermic. Dilutionof the nitric and mixed acids with water liberatesheat [52]. Normally, nitration is rapid. However,70 – 85 wt% nitric acid is also an oxidant, andfor this reason the reaction is best conductedcontinuously to limit the contact time of theproduct with the reactive medium. If the mediumis free of solid particles, a tubular reactor can beused; otherwise, reactors in cascade with effi-cient stirring are employed. These reactors aremade of highly polished stainless steel. Reactorsand stirrers must be carefully designed to avoiddead zones and friction with crusts of explosives.Reactors are often provided with a valve thatopens quickly to discharge reactants into a dilu-tion vessel in an emergency.

Product Isolation. If a precipitate is nothighly sensitive to friction, it may be centrifuged.For safe continuous filtration, the product mustbe stable in its mother liquor, and the filter designmust avoid introduction of the explosive betweenmoving and fixed parts. The precipitate is washedin two stages. The first uses only a small amountof water, which is recovered and mixed withspent acid. The acid is recovered from thismixture.


Purification. Treatment with boiling wateris sometimes sufficient to hydrolyze impuritiesand wash out nitric acid. Crystallization elimi-nates sulfuric acid and produces the desired grainsize. The solvent can be diluted with water orremoved by steam distillation. Very fine crystalsare obtained by dilution with high-speed stirringor by grinding in water or an inert liquid. A fluidenergymill may also be used. Size separation canbe effected by sieving under flowing water or in aclassifier. Drying is usually done as late as pos-sible in the process.

Recovery of Spent Acids. Acid recovery inan explosive plant is of great importance incontrolling production costs. These acids include55 wt%HNO3, 63 – 68 wt%H2SO4 from nitricacid concentration, and spent H2SO4 containingsome nitric acid and nitration products.

To concentrate nitric acid, water is removedby countercurrent extraction with 92 – 95%H2SO4. At the top, 98 – 99% HNO3 is pro-duced. At the bottom, 63 – 68% H2SO4 is ob-tained, which can be concentrated to 93% bystripping with combustion gases, or to 96 –98% by vacuum distillation. Nitric acid canalso be concentrated by distillation over mag-nesium nitrate.

Sulfuric acid is freed of nitric acid and nitrocompounds by heating or steam injection.

Pollution Problems. Gaseous pollutionmay occur during nitrations, with evolution ofred nitrous fumes. These can be absorbed incolumns by recycling water or dilute nitric acidto provide 50 – 55 wt% acid.

Liquid and solid pollution is created by wash-ing. Usually acids are transferred to decantingand settling basins, where product and othersolid particles settle and liquids are neutralized.Some liquid wastes require special treatment; forexample, the red liquors from TNT are bestdestroyed by combustion.

Safety [9, 11]. Accidents caused by detona-tion are usually very severe. In addition to thenormal precautions required in acid handling, theproduction and use of explosives obviously in-volves special risks. Loss of life and destructionof property by an accidental explosion must beprevented at all costs, and the detonation ofexplosives stored near populated areas must be

avoided. Minimum distances between plant andnearby structures are regulated.

The transmission of detonation by pipes orfeeding devices must also be prevented by ap-propriate arrangements. The danger of detona-tion by an accidental fire can be mitigated bylimiting vessel size. Detonations by shock andfriction in pipes, pumps, or valves are preventedby suitable measures.

The following principles apply: partition ofrisks (e.g., specific buildings for specific opera-tions); limitation of risks (limited number ofpersons present and limited quantities of explo-sives); and installation of two or three indepen-dent safety devices. Some of these measures aretaken by themanufacturers under the supervisionof professional organizations following govern-ment regulations.

5.2. Specific Secondary Explosives

Properties of secondary explosives are given inTables 2 and 3.

5.2.1. Nitrate Esters

Nitrate esters RONO2 are prepared from alcoholsand nitric acid, whichmay bemixedwith sulfuricor acetic acid. The reaction is reversible:

NOþ2 þROH�RONO2þHþ

In an anhydrous medium the equilibriumshifts to the right; with dilution, hydrolysis oc-curs. In 60–80% HNO3, the unreacted alcoholmay be oxidized. Furthermore, a catalytic effectof the nitrous acids produced causes rapid de-composition of the reaction medium. This de-composition either does not occur or occurs veryslowly with an acid concentration below 55%.Nitrate esters are usually less stable if traces ofacid are present. Traces of sulfuric acid aredifficult to remove from solid nitrate esters;therefore, mixed acid should not be used for theirpreparation. Acetic – nitric acid mixtures areused with sensitive or oxidizable alcohols.

Pentaerythritol Tetranitrate [78-11-5], PETN,C5H8O12N4,Mr 316.15, is scarcely soluble in 82%HNO3 (0.7 wt%). The nitration of pentaerythritolis practically complete in a few seconds and is


conducted continuously. Pentaerythritol andHNO3

(ca. 1 : 5.5) are fed into a well-stirred, jacketedreactor, with overflow in cascade into a secondreactor of the same design. The temperature ismaintained below 30 �C. PETN precipitates andmay be isolated in one of two ways:

1. In a third reactor the reaction mixture isdiluted with water to 55 wt% acid (cPETN0.1 wt%) and filtered. The PETN is washedwith water

2. The reaction mixture is filtered immediatelyand then the 82 wt% spent nitric acid isconcentrated, a cheaper process but less safe

Washed PETN is stable. It can be recrystal-lized by dilution of a hot acetone solution withwater, which removes traces of acid and someorganic impurities, and crystals of desirable sizeand flow properties for continuous feed purposesare obtained. Pentaerythritol tetranitrate is fairlystable above 100 �C and in alkaline medium. It isa powerful high explosive, with a small criticaldiameter, easy to initiate, and sensitive toimpact and friction. But that sensitivity dependson the crystal size: PETN is more insensitive ifultrafine or in form of a very big monocrystal.Nanometric PETN was recently obtained by asol – gel process. It is used in detonators, com-mercial detonating cord, boosters (with wax),sheet explosives (with an elastomeric binder),and plastic explosives. In a mixture with TNT, itis employed in some warheads and in industrialexplosives.T

able

2.Properties

ofsecondaryexplosives

Property

PETN

NG

TNT

HNS

TATB

RDX

HMX

DIN

GU

NTO

ADN

Sorguyl

CL20(e)

mp,� C

141.3

13.5

80.8

318

>452

204

283

260

255

92

190

decomp.

decomp.

decomp.

decomp.

Vaporpressure,Pa

0.0011

114

1.3�1

0�7

0.4

0.05

4�1

0�7

at100

� Cat

40

� Cat

100

� Cat

100

� Cat

175

� Cat

110

� Cat

100

� CCrystal

density,g/cm

31.77

1.654

1.74

1.94

1.82

1.907b

1.98e

1.91d

1.83d

2.03–2.04

2.04

1.591a

1.47a

at81

� CDetonationvelocity

at8340

7700

6960

7120

7970

8850

9100

8450

8520

ca.3900

9300

9300

max.density,m/s

f

Criticaldiameter,mm

0.4

0.4

6–8

6–8

4–8

<1

Leadblock

test,10g,cm

3520

520

300

480

480

Explosiontemperature

225

220–240

470

305

315decomp.

301

330

after5s,

� C520explodes

aLiquid.

bbform

.cCalculatedin

somecases.

daform

.ebyx-rays1.99

Table 3. Impact sensitivity of secondary explosives*

Explosive Value**

Insensitive

TATB > 2.5

TNT 1

Moderately sensitive

DINGU 0.8

HNS 0.6

NTO 0.8

Sorguyl 0.15 – 0.2

CL20 0.15 – 0.2

Sensitive

HMX, RDX 0.3

PETN 0.15 – 0.2***

NG 0.1

*Drop-weight impact test [7].**Based on TNT ¼ 1.***Values are dependent on particle size


Nitroglycerin [55-63-0], NG,C3H5O9N3,Mr

227.09, unlike PETN, is a liquid at room temper-ature, totally miscible with HNO3 of higher than70% concentration, sparingly soluble (3 wt%)in 50% HNO3, and sensitive to hydrolysis (anycontact with hydrolytic medium must be veryshort) [53]. It is prepared by continuous two-phase nitration of glycerol in anhydrous mixedacid. The mass ratio of pure anhydrous glycerol(H2O < 0.5%) and 50 : 50 mixed acid is 1 : 5.The product is washed with aqueous sodiumcarbonate or bicarbonate.

In the Schmid – Meissner andBiazzi process-es, the reactor is a vessel with overflow and goodstirring and cooling. The reactants are fed con-tinuously, while the temperature is kept at 10 –20 �C. The emulsion produced flows into a sep-arator, which in the Schmid process does nothave moving parts. In the Biazzi process, theseparator is conical with peripheral feeding,breaking the emulsion by rotation. The productis washed with alkaline water in columns(Schmid) or in mixer – settlers (Biazzi).

In the Gyttorp process, developed in the1950s, the feeding of acid and alcohol can beinterrupted simultaneously. The key feature isthe use of an injector with an axial flow of acid;the alcohol is sucked through the neck withexcellent mixing. For good suction and heatabsorption, a volume ratio of acid: alcohol of ca.8 is required; it is maintained by recycling part ofthe spent acid. The glycerol is heated to 48 �C toreduce viscosity. The emulsion that is formed iscooled to 15 �C, and centrifuged continuously toseparate the nitroglycerin from spent acid. Theproduct is emulsifiedwith alkaline washwater bypassage through an injector; it is separated andwashed again until neutral. Thefinal emulsion canbe safely transmitted through pipes. The quantityof nitroglycerin present at any given time can bekept low, and safety is further increased by pro-tective walls and the use of remote control.

Other liquid nitrates are produced by theseprocesses; the Gyttorp process requires a liquidalcohol reactant. The spent acid may be purifiedby heating. Nitroglycerin is used in propellants,gunpowder, and dynamites.

5.2.2. Aromatic Nitro Compounds

The most common nitro-aromatic explosivescontain the picryl (2,4,6-trinitrophenyl) group

and are usually obtained by nitration. The Ingoldmechanism involves nitronium ion, NOþ

2 ; elec-trophilic attack occurs with formation of a s-complex intermediate [22].

The introduction of a second and third nitrogroup requires increasingly severe conditions, in-cluding more anhydrous mixed acids and elevatedtemperatures (above 100 �C for trinitration).

Some of these aromatic nitro compounds arenot used or are abandoned as explosives: amongthem:

1,3,5-Trinitrobenzene [99-35-4], TNB, ben-zite C6H3O6N3, Mr ¼ 213.11 (I, R ¼ H), attrac-tive as high explosive, cannot be obtained bydirect nitration of benzene, but only by indirectsyntheses giving an expensive product used onlyfor preparations of fine chemicals.

2,4,6-Trinitrophenol [88-89-1] C6H3O7N3,Mr ¼ 229.11 (I, R ¼ OH) TNP, picric acid,melinite, was extensively used in France duringWorld War I because of lack of toluene, but waslater replaced by trinitrotoluene (tolite), cheaperand nonacidic. In some ammunitions, ammoni-um picrate is still used.

2,4,6-Trinitrophenyl-N-methylnitramine[479-45-8] N-methyl-N,2,4,6-tetranitroaniline,Tetryl, C7H5O8N5,Mr¼ 287 (I, R¼N(CH3)NO2)has been used since 1905, notably for the pro-duction of boosters, after lubrication by graphiteor calcium stearate. But it is now practicallyabandoned because some allergic incidents ofdermatosis, and replaced mostly by RDX – waxmixtures.

Three nitro-aromatic products with a picrylgroup remain for use as high explosives: TNT,HNS, and TATB.

2,4,6-Trinitrotoluene [118-96-7], TNT, to-lite, C7H5O6N3, Mr 227.13 (1, R ¼ CH3), isproduced by successive nitration of toluene,producing mono-, di-, and finally trinitroto-luenes. The mononitration products are 60%ortho, 35% para, and 3 – 5% meta derivative.


The o- and p-nitro compounds give 2,4- and2,6-dinitrotoluenes and then 2,4,6-trinitrotolu-ene (meta-directing effect of NO2). However,m-nitrotoluene does not give the 2,4,6-trinitroderivative; other products are formed that reducethe stability or lower the melting point of theTNT. These impurities can be removed by the so-called selliting process or by fractional distilla-tion of themononitration products. Them- and p-nitrotoluenes are used as chemical intermediates,and the o-nitrotoluene is further nitrated to TNT.This method gives a product that is more easilypurified.

For reasons of safety, quality, and cost, mod-ern high-capacity plants use a continuous pro-cess. The solubility of organic products in mixedacids can be quite low, 0.5 – 15 wt%, dependingon temperature and sulfuric acid concentration.Nitration is believed to occur in the acid phase.Consequently, the rate of interphase transfer andthe intensity of stirring are important.

The plant employs a series of 8 – 16 mixer –settlers. The organic phase is transferred from thepreceding settler together with the acid phasefrom a following or preceding settler (counter-current or parallel nitrators) into a mixer main-tained at a constant temperature (50 �C formono-, 80 �C for di-, and 100 �C for trinitration).Acids may be added to adjust the composition.From the last settler, molten TNT overflows intoother mixer – settlers that are used for washingand selliting.

The spent sulfuric acid can be concentrated toca. 96% but not to oleum. Using oleum in theprocess leads to a higher yield, a shorter startingtime, and a more rapid reaction; consequently,fewer mixer – settlers are required for a givenoutput, but a use or customer must be found forthe spent acid.

Selliting is a process of washing with aque-ous Na2SO3. A preferential reaction with theunsymmetrical TNT isomers gives deep-red wa-ter-soluble products. Selliting is applied to crudemolten TNT above 80 �C, but with some losses.A continuous process may also be employed at50 �C, with TNT suspension produced by cool-ing an aqueous emulsion with vigorous stirring[54]. The resulting spherules contain pure 2,4,6-TNT at their center, and a mixture of isomers inthe outer layer. The use of MgSO3, rather thanNa2SO3, has been proposed [55]. The most eco-

nomical treatment of the red spent waterfrom selliting is concentration followed bycombustion.

Trinitrotoluene is used alone or mixed withPETN,RDX, or ammoniumnitrate. It is also usedin some industrial explosives.

Hexanitrostilbene [20062-22-0], HNS,C14H6O12N6, Mr 450.24, is formed by oxidationof TNT in methanol – tetrahydrofuran solutionwith aqueous NaOCl [58]:

Yields of 40 – 50% are obtained in a contin-uous tubular reactor [59, 60]. Hexanitrostilbenecan be crystallized from HNO3 or acetone.

Hexanitrostilbene has the following unusualproperties: the presence of 1% HNS in moltenTNT prevents the formation of cracks and crazesduring solidification. With its low critical diam-eter (0.4 mm) it can be used as the core in silveror other metallic explosive cords. It remainsstable and explosive over a very wide tempera-ture range (�200 to 250 �C) and is thus usable inspace [61].

1,3,5-Triamino-2,4,6-trinitrobenzene[3058-38-6], TATB, C6H6O6N6, Mr 258.15, isobtained by the following sequence:

The proximity of nitro groups favors thedisplacement of chlorine by ammonia. The reac-tion is conducted under pressure at 150 �C intoluene containing a little water. The product iswashed with water to remove NH4Cl. It has lowsolubility and is difficult to recrystallize [62, 63].Although discovered in 1887, it first attractedattention after World War II. Since the 1950sinterest has increased because of its thermalstability and outstanding insensitivity. Mixedwith HMX and a fluorinated binder, it is usedas a booster. It is, however, expensive (ca. 65 $/kg in the mid-1980s in the USA) because of the


high cost and low availability of trichloroben-zene. Therefore, alternative synthetic routes havebeen developed. An extensive review of TATB isgiven in [9].

5.2.3. N-Nitro Derivatives

N-Nitro derivatives include primary nitraminesRNHNO2, secondary nitramines RR0NNO2,nitramides, nitroureas, nitrourethanes, and nitro-guanidines. There are no general synthetic meth-ods. Sometimes it is possible to nitrate theprecursor with HNO3 alone as with tetryl. Oftenan N-acetyl, N-tert-butyl, or N-nitroso derivativeis used as starting material. In some cases, nitricoleum is effective. The nitration of hexamethy-lenetetramine (hexamine) to RDX and HMX ismore complicated.

1,3,5-Trinitro-1,3,5-hexahydrotriazine[121-82-4], C3H6O6N6, Mr 222.12, cyclotri-methylenetrinitramine, Hexogen, RDX.

Both RDX and HMX are stable in nitric acidover awide temperature and concentration range,but are destroyed by aqueous sulfuric acid and areattacked by alkaline substances. Sulfuric acidshould not be present during the synthesis.

1,3,5-Trinitro-1,3,5-hexahydrotriazine wasfirst described by the German chemist and phar-macist G. F. HENNING [64]. It is manufactured bynitrolysis of hexamine with nitric acid alone orwith acetic anhydride.

The main process, called the Woolwich pro-cess, which does not use acetic anhydride, wasdeveloped in the United Kingdom and is usedthere and in France. The raw materials are hex-amine and 98 – 99%HNO3 free of sulfuric acid.The reaction is complex and not completelyunderstood.

Hexamine dinitrate is probably formed first,followed by intermediates that are oxidized ordecomposed, exothermically and often violently,to produce RDX, which precipitates. Largeamounts of nitrous gases and CO2 are evolved

along with water. The process must be continu-ous with careful control of temperature and flowconditions. The plant consists of three groups ofstainless steel cascade-type reactors with effi-cient stirring and cooling devices (jacket or coil).Nitric acid and hexamine are fed into the firstgroup at a temperature of 20 – 50 �C. The ho-mogeneous mixture overflows from the last re-actor into the first one of the second group (thedecomposers); this reactor is equipped with alarge pipe for the escape of gases and a waterfeeder. The temperature is maintained between75 and 82 �C, and water is continuously added tomaintain a HNO3 concentration of 55 wt%. Thegases evolved are condensed in towers, produc-ing 50 – 55 wt% HNO3, which is reconcen-trated. This first decomposer is the key to theoperation. Foammust be avoided as well as thickcrusts on which the stirrer could scrape, causingan explosion. In the third group of reactors, thesuspended product is cooled and then continu-ously filtered and washed. The resulting RDXcontains HMX (1% max.) and some nitric acid,which can be removed by heating with water at135 �C for 3 h in an autoclave. The yield basedon hexamine is 78 – 80%.

The RDX can be recrystallized or used direc-tly, after desensitizing by wax or 10% TNT topermit drying and transportation. Recrystalliza-tion from cyclohexanone or methyl ethyl ketoneremoves traces of acidity (required, for example,for use with aluminum powder) and producescrystals of the desired size.

A process without acetic anhydride was alsodeveloped in Germany in 1940 (KH process). Amodification is the addition of NH4NO3 to reactwith all CH2 groups of hexamine (K process).

The KA process was developed during WorldWar II in Germany, and the Bachman processwas developed and is used in the United States.Both processes use acetic anhydride, and thereactions are very complex.

To a solution of hexamine (1 part) in glacialacetic acid (1.65 parts) are added a solution ofNH4NO3 (1.5 parts) in concentrated HNO3 (2parts) and acetic anhydride (5.2 parts) at ca. 65 –72 �C. The mixture is maintained at that temper-ature for at least 1 h, diluted with water, andheated to hydrolyze impurities. The yield is ca.80 – 85%; nitrous fumes are not evolved.

The product contains ca. 8 – 15% HMX,depending on the reaction conditions. An


adequate source of acetic anhydride must benearby, where acetic wastes can be dealt with.This process is easier to carry out than the processemploying nitric acid alone, but its environmen-tal problems aremore difficult to solve. The sameplant can be adapted to HMX production.

Both RDX and TNT are the basic componentsof almost all modern high explosives. They aremixed together, alone or with wax, or formulatedwith plastic binders. For a powerful and heat-stable explosive, RDX is preferred.

1,3,5,7-Tetranitro-1,3,5,7-tetraazacyclooc-tane [2691-41-0], C4H8O8N8, Mr 296.16 (2, R¼NO2), octahydrotetranitrotetrazocine, cyclote-tramethylenetetranitramine, octogen, HMX, wasdiscovered shortly before World War II as abyproduct of RDX synthesis by a Bachman-typeprocess. It exists in four crystalline forms [4, 67,68]. The b form has the highest density (r ¼1.907 g/cm3) and a shock sensitivity similar tothat of RDX. Large crystals of the a form areshock sensitive, but microcrystals are not.

HMX is now obtained directly by a modifiedBachman process. In this batch process, aceticanhydride and a mixture of NH4NO3 and HNO3

are added simultaneously at 44 � 1 �C to hex-amine dissolved in glacial acetic acid. After15 min, the operation is repeated. The reactionmixture is aged at 45 – 60 �C, diluted with hotwater, and refluxed for up to several hours. Thesuspended HMX is filtered off and washed untilneutral. TheHMX is obtained as small crystals ofthea form, which are transformed into the b formby recrystallization from acetone or DMSO.

HMX can also be obtained via dinitropenta-methylenetetramine (DPT, 3, R ¼ NO2) [69]. Inanother process starting from hexamine, the dia-cetyl intermediates DAPT (3, R ¼ COCH3) [70]andDADN (2, R¼COCH3) are isolated, and thisis followed by nitration with nitric oleum. How-

ever, since demand for HMX is now very low,production by this route has ceased.

The price of HMX is usually 3 – 5 times thatof RDX. It is used when high performance isrequired (e.g., shaped charges). Both RDX andHMX are also used in propellants.

Other High Explosives. Numerous nitra-mine derivatives have been studied. Forexample:

Dinitroglycoluril [55510-04-8] (DINGU orDNGU ; 4, R ¼ H) has a high density (1.99 g/cm3, X-ray) [101] and explosive properties closeto those of TATB [71, 72], but at a much lowerprice. It can replace part of the RDX in mixtureswith TNT and can be introduced as a componentin gunpowder. Some comparative thermodyna-mic properties are studied [73].

It is prepared by continuous nitration of gly-coluril with 98 wt% HNO3 at 30 – 60 �C incascade-type reactors.

Tetranitroglycoluril (sorguyl ; 4, R ¼ NO2)prepared by nitration of DINGU with a mixtureHNO3 – N2O5, has a high density (2.01 g/cm3),and detonation velocity (9300 m/s). Only onecrystalline form is known. It must be coated orplastic bonded because it is sensitive to hydroly-sis [71, 73, 75].

Hexanitrazaisowurtzitane (HNIW, CL-20).One way to obtain explosives of high crystaldensity is the synthesis of cage compounds suchas HNIW, which was discovered in 1986 by A.NIELSEN [99].


It is prepared by the reaction of benzylaminewith glyoxal, followed by debenzylation andnitration. It exists in six crystalline forms [93,94]; the e form has a density of 2.04 g/cm3.Production has begun in pilot plants [89]. It canbe used as a high explosive and in propellantformulations.

Oxynitrotriazole [932-64-9], ONTA, NTO,3-nitro-1,2,4-triazol-5-one, was first reported in1905, but its use as a low-vulnerability explosivewas only discovered in 1979 [97, 74]. It has a highdensity (1.91 g/cm3), good detonation velocity,low sensitivity to impact and friction, and goodthermal stability (> 200 �C) [98].

It is manufactured in two steps: reaction of thesemicarbazide hydrochloride with formic acid togive the triazolone, which is nitrated with nitricacid. TheNTO is recrystallized fromwater. NTOis used in LOVA formulations, some of whichwere tested in a joint LOVA programme of theUSA, UK, Germany, and France.

Ammonium Dinitramide (ADN), NHþ4 NðNO2Þ�2 , r 1.83 g/cm3, mp 92 �C, is a carbon-

free ammonium salt that was discovered anddeveloped in the former Soviet Union in the1960s and has in the mid-1990s been disclosed[100]. ADN is almost as hygroscopic as ammo-nium nitrate and very insensitive. It is of interestas a component of certain explosivemixtures andas a clean propellant.

6. High Explosive Mixtures

Explosives are used for global or directed de-struction (bombs, torpedoes, mines, reactive ar-mors, and warheads) or for pyrotechnics. Amongpure compounds, only TNT and trinitrophenolare sufficiently insensitive to be loaded in largequantities by casting. Small quantities of otherpure compounds are sometimes used for detona-tors or cutting or transmitting cords.

For flexiblewrapped cords (detonating cords),the pure explosive (e.g., PETN) flows continu-

ously through a funnel to form a flowing streamthat is wrapped in a thin plastic band. Thread isimmediately woven on the plastic-enclosed ex-plosive, and this is again encased with plastic bydrawing through a die, which also helps adjustthe loading density.

For metallic cords, the high explosive (PETN,RDX, HMX, or HNS) is introduced into a metal-lic tube (lead, copper, or silver), which is drawnthrough dies until the desired size and crosssection are obtained.

Loading Processes. In casting processes, theexplosive is employed as a solution or a liquidsuspension; it is cast into the shell or in the mold,where it crystallizes on cooling (physical pro-cess) or solidifies by the cross-linking of a poly-mer (chemical process). In pressing processes,the explosive is introduced in granular form intoa mold or shell and pressed with a piston at apressure of 10 – 300 MPa; conditions depend onthe munitions size, the binder, and the requiredmechanical properties. Special shapes are pre-pared by laminating or calendering.

Flexibility is increased by the use of blends,which can enhance explosive performanceswhile preserving safety and reducing cost. Spe-cial effects, such as delayed detonation, arepossible with improved safety and high-temper-ature stability.

6.2. Desensitized Explosives

Because of their sensitivity and high meltingpoints, RDX, PETN, and HMX must be desen-sitized before casting or pressing. This isachieved by coating the particles with wax,sometimes with addition of graphite as a lubri-cating and antistatic agent. The beeswax used inthe past has been replaced by paraffin or syntheticwaxes, which give more reproducible results.The wax content in the explosive mixture isusually 2 – 10 wt%.

In the simplest process, the particles are coat-ed in hot water. The explosive (RDX, for exam-ple) is vigorously stirred in water and heatedslightly above the melting point of the wax,which is introduced and dispersed on the parti-cles. The mixture is cooled by the rapid intro-duction of coldwater,without formation of crustson the vessel walls. The suspension is filtered and


dried. Coating agents melting above 100 �C areapplied in a solvent (e.g., butyl acetate), which isremoved by steam distillation. If the explosive issensitive to hot water, the solvent is removed byfiltration, possibly preceded by evaporation un-der vacuum. These processes are also used toprepare ternary mixtures of explosive aluminumand wax.

Detonation velocities can be obtained close tothose of the pure explosives; e.g., for amixture of94.5% RDX, 5% wax, and 0.5% graphite, D ¼8600 m/s at r ¼ 1.76 g/cm3 (D ¼ 8850 m/s atr ¼ 1.82 g/cm3 for pure RDX). However, largeloadings are difficult to carry out becauseof problems with homogeneity, brittleness,porosity, and cost. The process is very usefulfor automatic filling of press-loaded smallmunitions.

6.3. TNT Mixtures

Molten TNT (mp 80 �C) is compatible withmany explosives and other products, providinga castablemelt above 80 �C.Among the productsmost frequently added are ammonium nitrate, toobtain very cheap munition loadings (amatols),and nitramines (RDX or HMX) or other highexplosives (PETN, NTO), to improve perfor-mance. Mixtures containing 50 – 75 wt% RDXare used in bombs and warheads such as shapedcharges. Some castable blends contain aluminumpowder (tritonals, ammonals, Torpex, andHBX 1 and 3).

Wet and dry processes are employed. Theformer, the same as that used for desensitizingwith low-melting wax, has cost and safety ad-vantages. Almost the entire process is carried outunder water. In France, RDX coated with10 wt% TNT is produced in this manner, be-cause its transportation as a dry product is al-lowed. However, air bubbles on theRDXcrystalscan create difficulties in loading.

In the dry process, the components are addeddry to molten TNT with stirring, and the mixtureis cast in shells.Wet RDX can be added to TNT atca. 95 – 100 �C; the water is removed by decan-tation and evaporation.

Blends of TNT are used in the large-scaleproduction of munitions. Shaped charges can beobtained by controlled sedimentation of the mol-ten mixture. Crack formation in TNT during

cooling can be controlled by the addition of1% HNS.

Explosive performance is restricted by thecondition that the mixture must be pourable; forexample, for a blend of RDX:TNT of 70: 30(wt%), D ¼ 8060 m/s at r ¼ 1.73. (Since rtheor1.765, the porosity is ca. 2%.)For blends with higher RDX or HMX content,

a special apparatus such as a porous piston isused. Because of the danger of detonation by fire,mixtures of RDXwith TNT are now forbidden onships by some countries.

6.4. Plastic-Bonded Explosives (PBX)

Two different procedures are followed whichimprove the performance of new munitions.

Desensitized Explosives. Some new war-heads require improved mechanical propertiesand stability at high temperature. Waxes arereplaced by thermoplastics or by other plasti-cized polymers (nitrocellulose).

The manufacture of these plastic-bonded ex-plosives resembles the use of waxes dissolved ina solvent immiscible with water. The moldingpowder is pressed, often in a heated and evacu-ated mold; for large charges, machining is nec-essary to obtain homogeneous charges of com-plex shapes with good mechanical properties athigh temperature.

Examples include RDX or HMX boostersbonded with polyamide and mixtures of HMXand TATB containing 10 wt% fluorinated poly-mer [96]. Use is limited by the high cost of thepressing machines and the length of the proces-sing cycle, especially for large charges.

Castable Explosives [76, 77]. For largercharges, mixtures are used of an explosive witha liquid binder, which is then cross-linked (com-posite explosives). A similar process is used forcomposite propellants. Composite explosives arebeing developed for uses requiring high accuracyand low vulnerability (LOVA explosives).

The liquid binder is introduced first into amixer equipped with S-blades. A mixture of adiisocyanate and a diol (hydroxy-terminatedpolyether or polybutadiene) is usually employedin a precise ratio, with a precise quantity of across-linking agent such as a triol. The dry solid


explosive (RDX, HMX, or PETN) is then addedand mixed under vacuum with additives (e.g.,surfactants) and a catalyst providing a pot life, i.e., the mixture remains pourable, of a few hours.During this time the mixture is cast, sometimesunder pressure or by injection, in vibrating andevacuatedmolds or shells. Themolds are cured inan oven for a few days. Two different composi-tions may be cast, one over the other (bicomposi-tions), to produce special detonation waves.

The main advantage of these formulations istheir low sensitivity, especially against bullets,impact, and friction, and the difficulty of thetransition from combustion to detonation. Themechanical properties can be excellent, and ther-mal stability is fair.

Among the drawbacks are the slow curing andhigh cost when a multimodal particle-size distri-bution is used to increase the explosive content.The detonation velocity is diminished by the inertcharacter of the binder; it can be estimated by theUrizar formula [7, pp. 8 – 10], [78]. Energeticbinders improve the detonation velocity, butincrease sensitivity. A review of energetic bin-ders is given in [15, 80]. The use of thermoplasticelastomers as binders is of interest for environ-mental reasons since they facilitate the disman-tling of ammunition.

7. Industrial Explosives

For more than 350 years explosives have beenemployed to mine ores and minerals, as well asfor quarrying, construction, dam building,tunneling, seismic exploration, metal formingand cladding, and demolition. The annual con-sumption of commercial explosives in Europe(EU 27 þ Norway and Switzerland) in 2008amounted to 550 000 t (which were initiated by65 � 106 detonators). Each of the largest West-ern European countries used between 40 000 tand 60 000 t. World annual consumption ofindustrial explosives is at least 5 � 106 t, 75%of which is ammonium nitrate–fuel oil (ANFO).

During the first 250 years of this period, onlyblack powders were known and used, but funda-mental changes occurred in the 1860s (inventionof dynamite and blasting caps by NOBEL), 1950s(ANFO), 1980s (emulsion explosives) and 1990swith the introduction of mobile emulsionmanufacturing units (MEMUs) for the on-site

mixing of explosives from non-explosive com-ponents and the commercialization of electronicinitiation systems. The search continues for lessexpensive products and safer techniques for pro-duction and field use inmines, quarries, and road,tunnel, and dam construction. At the same time,the introduction of new products is restrained bythe cost of existing investments and by safety,security, and environmental regulations.

7.1. Dynamites

Gelatine dynamites are powerful explosiveswhose main ingredients are nitroglycerin and/ornitroglycol, ammonium nitrate, and nitrocellu-lose. They were invented opportunely to replaceblack powder in the construction of railroad andtunnels and gave great impetus to the use ofexplosives. Although diminished in importancesince the 1950s and progressively replacedby new types of explosive, dynamites are stillwidely used because of their excellent qualitiesand high performance. In 2007 dynamites ac-counted for 11% of total European explosivesconsumption.

A detonation velocity range from 4300 to7500 m/s provides high brisance. Sensitivity toinitiation by cap or detonating cord is very good,as is the flashover coefficient. Density (ca. 1.4 g/cm3), water resistance, and detonation pressureare high.

The composition of dynamites has changedonly slightly since their origin. Nitroglycerin,gelatinized by nitrocellulose, has been totally orpartially replaced by nitroglycol to reduce costsand permit lower operating temperatures. How-ever, nitroglycol ismore toxic than nitroglycerin,and its use is limited in some countries. Oxidizerssuch as ammoniumnitrate reduce the cost of low-energy formulas. Combustible components(wood meal, peat, silicon, and aluminum) andother additives (sodium nitrate, ammonium chlo-ride, and sodium chloride), provide formulationswith specialized properties.

The consistency of such mixtures varies ac-cording to the nitroglycerin – nitroglycol con-tent. Gelatin dynamites containing 20 – 40 wt%of nitroglycerin – nitroglycol form a plasticpaste that may be made into paper-wrapped(Rollex process, small calibers up to 50 mm) orplastic film (large caliber, over 50 mm)


cartridges after cutting or extrusion. Dynamitescontaining 10 – 20 wt% nitroglycerin – nitro-glycol are powdery, and tampers are required tomake cartridges. They have been largely re-placed by the new explosives, except for use incoal mines, where the potential presence of dan-gerous dust and gas means that only very safeexplosives with the lowest possible detonationtemperature should be used. Permissible explo-sives for these applications usually contain alarge amount of ammonium nitrate and sodiumchloride as cooling salts, the endothermic melt-ing of which absorbsmuch of the energy releasedby the detonation. Historically, there are noharmonized standards for permitted explosivesin Europe. Degrees of safety in coal mines aredefined by national regulations. In Germanythere are three safety classes. Class three is thesafest group with reduced detonation tempera-ture and energy and which is safe against coaldust and methane mixtures. In France the classesare rocher, couche, and couche am�elior�ee. Thefirst refers to less safe explosives, permitted forunderground use only. In Great Britain, anexplosive is approved by the Minister of Powerand placed on the Permitted List after it haspassed the official gallery tests prescribed forthe particular class of explosives to which itbelongs. These tests are carried out at the SafetyinMines Research Establishment Testing Stationat Buxton. The safety classes are P1 to P5with P5or P4/P5 being the safest class which is used incoal mines to reduce the hazard of firedamp orcoal-dust ignitions which might occur in gassy ordusty mines.

Dynamites are marketed in cylindrical paper,cardboard, or plastic cartridges. The character-istics of a standard composition are given inTable 4.

7.2. Ammonium Nitrate Explosives(Ammonites)

Ammonium nitrate (AN) explosives were devel-oped in European countries to replace explosivesmade with chlorates. They appeared later in theUnited States (Nitramon, DuPont, in 1935).

AN explosives are made with ammoniumnitrate (ca. 80 wt%) sensitized with a nitro com-pound (TNT, PETN, or their mixtures, calledPentolite). Formulas can include aluminum pow-der and other additives. These products are char-acterized by their good production safety and lowproduction cost. They show good sensitivitywhen initiated by detonators and detonatingcords. However, they are sensitive to humidity.Properties of a typical Ammonite are as follows:

Composition, wt%

Ammonium nitrate 81.5

High explosive 16

Aluminum 0

Mass energy, kJ/g 3.51

Detonation velocity, m/s 4800

Flashover coefficient, cm 2

Detonating pressure 6.34

Density, g/cm3 1.10

Ammonium nitrate explosives made in theUnited States may contain dinitrotoluene (DNT)but no nitro high explosive. They are produced byblending and as a result are not cap sensitive. TheU.S. Government, followed by other govern-ments, has established a category with relaxedrules for the transport and storage of these ex-plosives. This category was first called NCN(nitrocarbonitrate) and is now known as blastingagents. They have been progressively replacedby water gels and emulsion explosives.

Table 4. Properties of dynamites

Property F16 F19 GDC 16

Nitroglycerin/nitroglycol, wt% 32 40 12

Classification gelatin gelatin powder

Application general and underground general and underground permissible

Mass energy, kJ/g 3.97 4.15 1.78

Detonation velocity, m/s 6000 6500 2200

Flashover coefficient*, cm 8 10 10

Cartridging density, g/cm3 1.45 1.45 1.10

Detonation pressure** 13.05 15.32 13.31

*Maximum distance at which a cartridge of diameter 30 mm and weight 50 g has a 50% probability of initiating another cartridge.**Calculated with the formula 1/4 AD

2.


7.3. Ammonium Nitrate/Fuel OilExplosives (ANFO/ANC Explosives)

Ammonium nitrate/fuel oil (ANFO/ANC) explo-sives have been developed since 1955. They aremanufactured from porous prills of ammoniumnitrate (ca. 94 wt%) soaked in mineral oil, usu-ally domestic fuel oil (ca. 6 wt%) or native oilslike rapeseed oil methyl ester. In some cases,aluminum powder is added to increase the ex-plosive strength. ANFO accounted for 41 % oftotal European explosives consumption in 2007.

Ammonium nitrate/fuel oil explosives areusually delivered in packaged or bulk form. Theycan be made on-site in a mobile mixing unit,oftenmounted on a truck (ANFO truck). Relativeto their lower inherent energy they are inexpen-sive and safe to handle, but lower in strength,performance, detonation velocity, and detonat-ing pressure in comparison to dynamites oremulsion explosives. In addition, they cannot beused in the presence of water. Because of theirvery low sensitivity, they require powerful prim-er charges, powerful detonating cords, dynamiterelay cartridges, and boosters. The densities arelow. Properties are listed in Table 5.

7.4. Slurries and Water Gels

A new class of industrial explosives, known aswater explosives has been developed since 1956;they contain no nitroglycerin and are based on asolution of nitrates, thus containing considerablewater (10 – 15 wt%). During the 1970s and1980s, water explosives have taken over muchof the market, at the expense of dynamites andAN powders, because of their lower productionand raw material costs and improved safetyduring production and handling.

Water gel explosives are supplied in car-tridges or in bulk form. The bulk explosives arepoured or pumped into the blast holes. Cartridgesare formedwith a continuous through-circulationdevice (CHUBPACK) in cylindrical plastic car-tridges closed by metal clips.

Slurries and water gels are made of aqueoussolutions of ammonium nitrate and sodium orcalcium nitrate gelled by the addition of guargum or cross-linking agents. They are sensitizedby nitro explosives, organic amine nitrates, or byaluminum powder. Combustible materials, suchas aluminum, urea, sugar, or glycol, are mixedwith these solutions either continuously ordiscontinuously.

The presence of reactive aluminum, water,and ammonium nitrate requires careful control toavoid chemical side reactions. The typical prop-erties of water gel explosives and slurries arelisted in Table 6.

7.5. Emulsion Explosives

Since the cost of sensitizer for slurry explosives ishigh, other formulas based on nitrate solutionscontaining cheaper raw materials have been in-vestigated. This led in 1962 to the developmentof ‘‘water-in-oil’’ and ‘‘oil-in-water’’ emulsionexplosives, whose sensitivity is due to the pres-ence of air bubbles; these are most efficientlyintroduced by means of hollow glass bubbles(microspheres) or chemical gassing techniques.

Emulsion explosives are produced, similar towater gels, by a continuous or a batch process.They can be supplied in cartridges of variousdiameters (25 to 120 mm), lengths, and weights,

Table 5. Properties of ANFO explosives for general applications

Property N 135 D7 fuel

Composition, wt%

Ammonium nitrate 91 94.3

Fuel oil 4 5.7

Aluminum 5 0.0

Mass energy, kJ/g 3.43 2.74

Detonation velocity, m/s 3900 3700

Detonating pressure 3.42 2.84

Density, g/cm3 0.9 0.83

Table 6. Properties of water gel and slurry explosives for general

applications

Property Hydrolite AP, Gelsurite 3000,

in bulk in cartridges

Composition, wt%

Nitrates 46 61.6

Water 15 13

Aluminum 0 15

High explosive 27 0

Mass energy, kJ/g 2.70 3.87

Detonation velocity, m/s 5100 4000

Flashover coefficient, cm 0 5

Detonating pressure 9.75 4.80

Density, g/cm3 1.50 1.20


or in bulk form. Bulk emulsion explosives aremanufactured from nonexplosive components(emulsionmatrix plus gassing agents and/or glassmicrospheres plus optionally ammonium nitrateprills or ANFO) on the quarry bench by mobilemanufacturing units (MMU) and are pumpeddirectly into blast holes on demand. Once insidethe blast hole they start the sensitizing reactiondue to the specific weight decreasing from about1.4 to 1.1 g/cm3 due to the development of gasbubbles (chemical gassing process). Although theemulsions are neither gelled nor reticulated, theirstorage life has been considerably improved byusing sophisticated emulsifiers.

Emulsions differ from nitrate/fuel oil, nitrate,andwater gels in their higher detonation velocity.The properties of typical emulsion-type productsare listed in Table 7. The emulsions are sensi-tized by a chemical gassing process, apart fromIremite 2500s, the formulation of which includesmicrospherical glass bubbles. Since the emulsionbulk explosives are usually sensitized just beforefilling the components into the blast holes theunsensitized substances are not classified as anexplosive (class 1) and are not entirely subject tothe regulations for producing, handling, trans-porting, and storing dangerous materials.

About 70% of the EMS consumed in Europecomes in bulk form. In 2007 emulsion explosivesaccounted for 48% of the total European explo-sives consumption.

7.6. Uses

The energy provided by explosives is used in anumber of ways, including explosive cladding(see Section 3.3), metal working (forming, weld-ing, and cutting), and shearing by pyrotechnicssystems. However, the principal nonmilitary useof explosives is in mining, quarrying, tunneling,dam building, demolition, and construction.

These applications are governed by extensivesafety and security regulations and is subject tocompetition from increasingly powerful me-chanical means of extraction, such as miningmachines, rippers, and tunnel-boring machines.Although the use of explosives entails such draw-backs as noise, vibration, dust, and smoke, thetechnique is flexible, effective, easy to use, andlow in capital and material cost.

When using bulk explosives, production costsare reduced because the process of loading intocartridges and the labor-intensive filling of theblast holes become unnecessary. In addition,since the entire blast hole is completely filled,the filling grade is much better compared tocartridged explosives, allowing the possibilityof enlarging the drilling pipe. The bulk explo-sives (ANFO and EMS) make up 70% of thoseused inEurope, and over 80%of those used in theUnited States. They can be produced on-site inmobile emulsion manufacturing units (MEMUs,ANFO trucks, pump trucks).

The introduction of improved blasting sys-tems nowadays allows for a relatively exactforecast of the blasting results by evaluating allrelevant blasting parameters, such as bench andwall dimensions, type of rock, required fragmen-tation, avoidance of fines, reduction of noise andvibrations, and the avoidance of fly rock. Thesesystems use specific software, computerized la-sers, vibration-measuring equipment, electronicdevices for measuring the inclination of the boreholes, and computer programs to calculate theideal placement of the drill holes and the correctcombination of delay times of the detonators forthe initiation of the explosive charges. Electronicdetonators can be incorporated into such systemsby selecting the optimal delay time by the milli-second, whereas conventional initiation systemssuch as electric or nonelectric detonators havefixed delay intervals such as 25 ms (short period)or 250/500 ms (long period).

Table 7. Properties of explosive emulsions used for general and underground applications

Property Iremite 1000 in

cartridges

Iremite 4000 in

cartridges

Iremite 2500s in

cartridges

Gemulsite 100 for

pumping

Mass energy, kJ/g 3.34 3.92 3.51 3.49

Detonation velocity m/s 5300 5300 5500 5100

Flashover coefficient, cm > 5 > 5 5

Detonating pressure 8.43 8.43 9.08 7.80

Density, g/cm3 1.20 1.20 1.20 1.20


8. Test Methods

Tests of secondary explosives are designed tostudy detonation phenomena, to approve a prod-uct, and to verify that manufactured lots meet therequirements (i.e., quality control).

Detonation phenomena (10�9 to 10�12 s) areobserved by laser interferometry, streak cameras,and X-ray flashes, all electromagnetic methods.The very high instantaneous pressures (10 –40 MPa) aremeasured, e.g., with low-impedancepiezoresistive manganin gauges (Cu–Mn–Ni al-loy) [79] or with fluorinated piezo polymers asshock sensors [102]. Phenomena are modeled onthe basis of the Becker – Kistiakowsky – Wil-son (BKW) [32] or Jones – Wilkins – Lee(JWL) [33] equations developed in the UnitedStates at the Los Alamos Scientific Laboratories(LASL) and the Lawrence Livermore NationalLaboratory (LLNL).

Tests to approve a product measure detona-tion velocity and pressure, energy released,ability to initiate or transmit detonation, andcritical diameter. They also determine thesafety characteristics in use, storage, andtransportation.

The verification of a lot is usually based on thedetermination of physical properties (meltingpoint, particle size, specific area) and chemicalanalysis. Safety and storage characteristics mustmatch those of the approved product.

Codified tests for military use are published inthe United States as military specifications(MIL), in France as Manuel des modesop�eratoires, in the Federal Republic of Germanyas VTL, in the United Kingdom as DEF. STAN,and at NATO as STANAG. Japan issues Japa-nese Industrial Standards [81]. Unified and stan-dardized European explosives tests (EXTEST)are published in Explosifs (Belgium, 1960 –1970), in Explosivstoffe (FRG, 1971 – 1973), inPropellants andExplosives (FRG, 1977 to 1981),and in Propellants, Explosives, Pyrotechnics(1982 to date) (see also [7, 10]).

8.1. Performance Tests

Detonation Velocity. The Dautriche me-thod is based on a comparison of the velocity intwo parts of a circuit, composed in one section ofa known detonating cord and in the other of a

cartridge made with the test sample. The detona-tion wave fronts run in opposite directions in thetwo segments and collide at a precise point[82].

More sophisticated electrical or opticalmethods are also available. For example, elec-trical wires (switches), inserted into a cylindri-cal cartridge at precise locations, are short-circuited by the passage of the detonation wave,giving a signal that is recorded on a chrono-graph. Other methods use streak cameras. Thedetonation wave is built up at a distance fromthe initiation point, and this occurs only if thecartridge diameter is large enough. Therefore,this test requires an adequate quantity ofexplosive.

Energy Output [5, 82]. In the lead blocktest, strength or CUP (coefficient d’utilisationpratique) is measured by the expansion of acavity in a lead block caused by the detonationof a sample of explosive, in comparison with astandard (PETN, picric acid, or TNT).

In the ballistic mortar test, the energy releasedby detonation gases is measured in a steel mortarconsisting of two cavities: the first contains theexplosive, and is connected to the second, whichcontains a projectile. The assembly is suspendedby a pendulum, and when the projectile is drivenout by the detonation, the recoilmoves themortarto an angle that is compared to that given by astandard explosive.

TheKast method is used to evaluate explosivebrisance, a value related to the product r D2

wherer ¼ density andD ¼ detonation velocity.The crushing of a copper cylinder by the detona-tion is compared to that obtained with a standardexplosive.

The cylinder test has been studied at theLawrence National Laboratory, Livermore,California, [83]. The velocity transmitted by acylindrical rod of explosive to a tightly fittingcopper tube is measured by a streak camera.

For more routine measurements, theD�efourneaux test can be used (push-plate test).A metal plate lies on an explosive plate, which isdetonated by a linear wave generator. During thedetonation, the metal plate is continuously bentto an angle, which is observed, for example, byX-ray flash [84]. Among other tests is underwaterexplosion, with measurements of the bubbleproduced.


Other Performance Tests. In one of thecritical-diameter tests, the detonation propaga-tion of metal cords (copper or silver) filled withan explosive of known density is observed as afunction of the inner diameter. In another meth-od, a conical charge is used.

Other tests include the determination of thecoefficient of transmission of detonation, thesensitivity to initiation, the self-excitation coef-ficient (maximum distance between two car-tridges loaded with the same explosive, allowingthe initiation of one by the other), and the plate-dent test.

8.2. Safety

Stability. Aging effects are frequently de-termined by the vacuum stability test, in additionto the usual chemical methods. It can be used tostudy the compatibility between explosives andother materials.

The sample is placed in a test tube fittedwith a manometric capillary glass tube; theother end of the tube dips into a cup ofmercury. The tube is evacuated and the sampleis heated, usually between 80 and 130 �C. Thevariation of the inner pressure in the tube isshown by the mercury level. Pressure usuallyincreases during the first few hours with therelease of traces of moisture and volatile sub-stances. Afterward, during a period of 100 h, therise in pressure can be linear (constant decom-position rate) or more rapid (autocatalyticdecomposition).

Sensitivity. The impact sensitivity of an ex-plosive is the minimum energy that causes quickdecomposition [5, 13, 85]. The test conditionsstrongly influence the results, which (given inJoules) are only orders of magnitude. The clas-sification of explosives depends on the apparatusand the test conditions.

In the Bruceton test for impact sensitivity, thestimulus after a positive result is lowered by oneunit and raised after a negative result. The valueof the sensitivity is obtained as the mean of 30 –50 trials. Probabilistic values are also deter-mined.

The procedures differ in the size and place-ment of the sample and the use of tools exposedor covered with sandpaper. The reaction may be

followed visually, aurally, audiometrically, or byexamination of gas evolution.

Tests are prescribed by the U.S. Bureau ofMines, Picatinny Arsenal (United States), Ex-plosives Research Laboratory (United States),BAM (Federal Republic of Germany), JuliusPeters (Federal Republic of Germany, France),Rotter (United Kingdom, Canada), and Auber-tein (France). Another test is the Susan projectile-impact test, where a projectile containing ca.450 g of explosive is directed against a hardtarget at selected velocities.

The friction sensitivity test is even more diffi-cult to reproduce than the impact sensitivity test.A thin layer of sieved explosive on a fixed surfaceis rubbed by a hard or abrasive surface moved bytranslation (Julius Peters apparatus) or by rota-tion (U.S. Bureau of Mines) under adjustablepressure.

Impact and friction are combined in the skidtest (Pantex) and the Popolato test; an explosivesphere is projected against a sand-coated targetplate at defined impact angles.

In the electrostatic sensitivity test, a smallquantity of explosive is placed between twoelectrodes. A capacitor discharge causes a sparkto pass between the electrodes through the ex-plosive. The sensitivity is expressed by the mini-mum energy required to decompose the sample.

In addition to differential thermal analysis(DTA) and thermogravimetric analysis (TGA),the following heat sensitivity tests are employed:

1. The sample is subjected to a constant increaseof temperature and the decomposition or ig-nition temperature is noted; the result dependson the quantity of explosive and the rate ofheating.

2. The sample placed in a small bulb is dippedinto aWood’smetal bathmaintained at a fixedtemperature. The time to decomposition isnoted, or the temperature at which a decom-position occurs after 5 s.

3. The sample is ignited in a gutter and theburning rate measured.

4. The sample is externally heated in a closed orhalf-closed vessel. The tendency to burn or todetonate is observed (steel-sleeve test).

5. The sample is heated at a given rate in a closedvessel. The time of detonation or the temper-ature at which the sample detonates after agiven time is noted (cook-off test).


To test the sensitivity to initiation through aspacer (card-gap test), a sample in a steel tube issubjected to the detonation of a standard boosterexplosive separated from the sample by a barrierof cellulose acetate cards of 0.19 mm thickness[8]. The minimum number of cards that preventtransmission of detonation fixes the legal class ofthe explosive for transportation and otherregulations.

To obtain a LOVA agreement (MURAT inFrance), the following tests must be carried outon ammunitions: bullet and fragment impact,slow and fast cook-off tests, reaction towards ashaped-charge jet, and sympathetic reactions.The results depend on storage of the ammuni-tions, their design, and on the properties of thepropellants and explosives they contain [95, 20].These investigations are supported by the NATOInsensitive Munitions Information Center (NI-MIC, Brussels).

9. Legal Aspects and Production

European Directives and national legislationstrictly regulate the possession, production, stor-age, packaging, shipping, handling, use, export,import, transfer, and trading of explosives. Peri-odic inspections and labeling prevent theft. Tag-ging the explosive permits tracing its origin. Incases where unauthorized explosives are found,there is an absolute necessity to identify the lastofficial owner of these explosives as quickly aspossible. For this reason an EC Directive on theidentification and traceability of explosives forcivil use was passed in 2008. Under the Directiveall explosives articles would be marked with aunique identification both in human-readable andin bar-code or matrix-code format. Implementa-tion of the scheme should be taken forward by theECmember states in 2012 at the latest. The ADRregulations regulate the transport, packaging,and labeling of hazardous goods such as explo-sives on the road. Other organizations like theIMO and ICAO regulate transport by sea and airaccordingly.

9.1. Safety Regulations

Originally, each country established its ownregulations; the standardization recommended

by the UN was first published in 1984 in theso-called Orange Book (Recommendations onthe Transport of Dangerous Goods – ModelRegulations and Manual of Tests and Criteria)[86]. Substances are classified according to thetype of risk involved, unless they are too danger-ous to ship. Explosives are in Class 1, whichcontains six subdivisions [86]:

Division 1.1: Substances and articles which havea mass explosion hazard

Division 1.2: Substances and articles which havea projection hazard but not a mass explosionhazard

Division 1.3: Substances and articles which havea fire hazard and either a minor blast hazard ora minor projection hazard or both, but not amass explosion hazard

Division 1.4: Substances and articles which pres-ent no significant hazard

Division 1.5: Very insensitive substances whichhave a mass explosion hazard

Division 1.6: Extremely insensitive articleswhich do not have a mass explosion hazard

Class 1 is restricted, containing only regis-tered substances; for new substances, test resultsmust be presented. Simultaneous transport andstorage are permitted for ‘‘compatibilitygroups’’.

The transportation regulations specifypackaging and labeling instructions, an identify-ing insignia on vehicles, compatibilities, andmaximum load and safety devices on vehicles.

Manufacture and storage are governed by theTNT equivalency, which is defined as the quan-tity of TNT producing the same effects as 100 kgof the explosive [87].

The expression d ¼ k Q1/3 gives the safedistance from a load Q of explosive (expressedas TNT equivalent), where the constant k de-pends on the presence of walls or otherprotection.

9.2. Production of Military Explosives

High explosives are manufactured by privatecompanies in many countries, e.g., Russia,United States, China, India, United Kingdom,Germany, Norway, Sweden, Switzerland, andJapan.


In the United States, research and develop-ment involving high explosives are often under-taken in military laboratories. Production is con-ducted by arsenals or by private companies underthe GOCO system (Government owned – con-tractor operated), in which investments and fac-tories are owned by the government. The productis government property and cannot be sold by theoperating company.

Since 1990 the production and consumptionvolumes in the EU of explosives for defensepurposes have reduced to a few thousand tonnesannually.

10. Toxicology and OccupationalHealth

Raw Materials. Both acids (HNO3 andH2SO4) and benzene derivatives (toluene andchlorobenzene) are of concern [4]. The usualsafetymeasuresmust be followed to protect eyes,skin, and respiratory tract. Red fumes of nitrogenoxides, formed normally or by accident, caninduce lung edema two days after exposure; theuse of a gas mask is recommended.

Explosives. Some primary explosives aretoxic (mercury fulminate and certain lead salts),but the toxic hazards are far below those arisingfrom high sensitivities to detonation. Among thesecondary explosives, nitroglycerin and otherliquid nitrates exhibit hypotensive action accom-panied by headaches and, in chronic cases, bymethemoglobinemia. A tolerance to nitroglycer-in can be developed. These substances are usu-ally absorbed through the skin rather than byinhalation. For nitroglycerin and glycol dinitrate,TLV ¼ 1.5 mg/m3. PETN, which like nitroglyc-erin is prescribed for heart diseases, has a verylow vapor pressure and is not readily absorbed bythe skin.

The toxic effects of TNT include bloodchanges, cyanosis, methemoglobinemia, andtoxic hepatitis. It is introduced by inhalation,ingestion, and skin absorption; at inhalationlevel, TLV ¼ ca. 1 mg/m3. Dust in the plant isto be avoided.

Tetryl can induce an allergic dermatitis, there-fore its use is practically abandoned.

Both RDX and HMX have negligible vaporpressures. They do not penetrate the skin and

their toxicity is very low. However, there havebeen reports of epileptiform convulsions, with-out liver involvement, or carcinogenic or muta-genic effects. Dust formation should be avoidedand masks should be worn.

References

General References1 Ullmann’s Encyklop€adie der TechnischenChemie, 4th ed.,

21, 637 – 697, Verlag Chemie, Weinheim 1972–1984.

2 T. Urbanski: Chemistry and Technology of Explosives,

Pergamon Press, Oxford 1983 – 1985.

3 A. Marshall: Explosives, 2nd ed., P. Blakiston’s Son and

Co., Philadelphia 1917.

4 B. T. Fedoroff et al.: Encyclopedia of Explosives and

Related Items, U.S. Army and National Technical Infor-

mation Service, Springfield, Va., 1960 – 1983.

5 R. Meyer: Explosives, 2nd ed., Verlag Chemie, Wein-

heim-New York 1981.

6 Kirk-Othmer, 9, 561 – 620, and 15, 841 – 853.

7 B. M. Dobratz: LLNL Explosives Handbook, UCRL

Report 52 997, Livermore, Calif., 1981. B. M. Dobratz:

LLNL Explosives Handbook, UCRL Report 52 997,

Change 2, Livermore, CA 1985.

8 J. Quinchon et al.: Les explosifs, 2nd ed., Technique et

Documentation, Paris 1987.

9 J.Quinchon,R.Amiable, P.Chereau:S�ecurit�e et hygi�ene

du travail dans l’industrie des substances explosives,

2nd ed., Technique et Documentation, Paris 1985.

10 L. M�edard: Les explosifs occasionnels, Technique et

Documentation Paris 1979, (engl. Transl.: Accidental

Explosives), Ellis Horward Ltd (Distrib. J. Wiley &

Sons) 1987.

11 J. Calzia: Les substances explosives et leurs nuisances,

Dunod, Paris 1969.

12 S. Fordham: High Explosives and Propellants, 2nd ed.,

Pergamon Press, Oxford 1980.

13 H. D. Fair, R. F.Walker:EnergeticMaterials. Inorganic

Azides, Plenum Press, New York 1977.

14 Houben-Weyl, XI and XI2, 99 – 116.

15 Structure and Properties of Energetic Materials, Symp.

Proceedings, vol. 296,Materials Research Society 1992.

Composition, Combustion and Detonation Chemistry of

Energetic Materials, Symp. Proceedings, vol. 418, Ma-

terials Research Society, Pittsburgh, USA, 1995.

16 J. E. Field, P. Gray, Energetic Materials, The Royal

Society, London 1992.

17 Approches microscopique et macroscopique des deto-

nations, Journ. de Physique, Suppl., 1er atelier int. (31.

May — 07. June 1987). Approches microscopique et

macroscopique des detonations, Journ. de Physique,

Suppl., 2e atelier int. (02. — 07. October 1994).

18 Proc. Int. Symp. Energetic Materials, Paris, May 1994;

International D�efense et Technologie, Sept. 1994.


19 Europyro, 5e Congres Int. de Pyrotechnie, 1993. Euro-

pyro, 6eCongres Int. dePyrotechnie, 1995. Europyro, 7e

Congres Int. de Pyrotechnie, 1999.

20 Insensitive Munitions Technology Symposium, ADPA

(American Defense Preparedness Association) 1996.

21 Life Cycle of Energetic Materials, Conferences Pro-

ceedings (1993, 1994, 1996), Los Alamos Lab.

22 G. A. Olah et al., Nitration. Methods and Mechanisms,

VCH Publishers 1989. Useful periodicals treating

explosives include ICT Intern. Jahrestg. (1970 to date);

Propellants and Explosives (1976 – 1981), continued as

Propellants, Explosives, Pyrotechnics (1982 to date);

Symposia on Detonation (United States); and Explosion

andExplosives (translation ofKogyoKayaku (published

by the Industrial Explosives Society of Japan) that is

published by the NSF, Washington).

Specific References23 D. L. Chapman, Phil. Mag. 47 (1899) 90.

24 E. Jouguet, J. Math. Pures. Appl. Paris 60 (1905)

347.

25 I. B. Zeldovich, NACA Techn. Memo. no. 1261 (1950).

26 V. von Neumann, OSRD Report 549 (1942).

27 W. D€oring, G. Burkhardt, Air Material Command Tech-

nical Report F-TS-1227-IA (GDAMA9 – T46) (1949).

28 F. Bauer, MRS Fall Meeting Boston 2001. Session

‘‘Electroactive Polymers’’.

29 D�etonique Th�eorique, Edition de l’Ecole Nationale Sup.des Techniques Avanc�ees, Paris 1981.

30 J. O. Hirschfelder et al.:Molecular Theory of Gases and

Liquids, J. Wiley & Sons, New York 1954.

31 M. Cowperthwaite, W. H. Zwisler, Symposium (Inter-

national) on Detonation, 6th, Office of Naval Research

Report ACR-221 (1976).

32 C. L. Mader, Los Alamos Laboratory Report CA-2900

(1963).

33 E. L. Lee, H. C. Hornig, J. W. Kury, UCRL Report

50 422.

34 M. J. Kamlet, S. J. Jacobs, J. Chem. Phys. 48 (1968) 23.

35 L. R. Rothstein, Propellants Explos. 4 (1979) 56 – 60;

Propellants Explos. 6 (1981) 91.

36 C. H. Johansson, P. A. Persson: Detonics of High Ex-

plosives, Academic Press, London-New York 1970.

37 A. F. Belyaev: Combustion, Detonation and Explosive

Work of Condensed System, USSRAcademy of Science,

Moscow 1968.

38 A.K. Parfenov, A.Y.Apin,ATDPress 4 (1965) no. 113.

39 R. R. Bernecker et al., Symposium (International) on

Detonation, 7th, Office of Naval Research Report

NSWC MP 82 – 334 (1981).

40 M. Samirant, Symposium (International) on Detonation,

7th, Office of Naval Research Report NSWC MP 82 –

334 (1981).

41 C. Fauquignon, H. Moulard, Sciences et Techniques de

l’Armement 1 (1984) 27.

42 F. P. Bowden, A. D. Yoffe: Initiation and Growth of

Explosives in Liquids and Solids, Cambridge University

Press, 1952.

43 C.M. Tarver, J. O. Hallquist, Symposium (International)

on Detonation, 7th, Office of Naval Research Report

NSWC MP 82 – 334 (1981).

44 F. E. Walker, R. J. Wasley, Explosivstoffe 17 (1969) 9.

45 Y. de Longueville, C. Fauquignon, H. Moulard, Sympo-

sium (International) on Detonation, 6th, Office of Naval

Research Report ACR-221 (1976).

46 D. Price, Symp. (Int.) Combust. 11th (1967) 963.

47 S. J. Jacobs, Naval Ordnance Laboratory Technical

Report 74 – 86.

48 M. L. Wilkins, UCRL Report 90 142 (1983).

49 V. D. Linse, H. E. Otto, P. Pocaliko: ‘‘Explosion Weld-

ing’’, Welding Handbook, vol. 3, Am. Welding Soc.,

Miami 1980.

50 M.D�efourneaux, Sciences et Techniques de l’Armement,

Paris 2 (1970) 293.

51 J. Dubar, J. Calzia, C.R. Seances Acad. Sci. S�er. C 266

(1968) 1114 – 1116.

52 T. Urbanski: Chemistry and Technology of Explosives,

vol. 1, Pergamon Press, Oxford 1983, pp. 139 – 151.

53 P. Aubertein, M�em. Poudres 30 (1948) 7 – 42.

54 M. J. Barbiere, M�em. Poudres 26 (1935) 294 – 302.

55 E. E. Gilbert et al., Propellants Explos. Pyrotech. 7

(1982) 150 – 154.

56 J. P. Konrat, FR 1 258 323, 1961; Chem. Abstr. 57

(1962) P 3358 h.

57 M. L. Kastens, J. F. Koplan, Ind. Eng. Chem. 42 (1950)

402 – 413.

58 K. G. Shipp, J. Org. Chem. 29 (1964) 2620 – 2623.

59 SNPE, FR 2 256 144, 1973 (J. M. Emeury, L. Leroux).

60 E. E. Gilbert, Propellants Explos. 5 (1980) 168 – 172.

61 S. E. Klassen [Sandia ABQ] 32th Int. Ann. Conf. ICT

(2001) 24 (1 – 12).

62 T. M. Benziger, ICT Intern. Jahrestg. 1981, 491 – 503.

63 U. S. Energy R. and D. Adm., US 4 032 377, 1977 (T.

M. Benziger).

64 DE 104 280, 1898 (G. F. Henning).

65 G. Desseigne, M�em. Poudres 28 (1938) 156 – 170.

66 J. Issoire, G. Burlet, M�em. Poudres 39 (1957) 65 – 95;

40 (1958) 47 – 76.

67 H. H. Cady, A. C. Larson, D. T. Cromer, Acta Crystal-

logr. 16 (1963) 617 – 623.

68 H. H. Cady, ICT Intern. Jahrestg. 1986, 17, 1 – 12.

69 J. A. Bell, I. Dunstan, J. Chem. Soc. C 1969, 1556 –

1562.

70 V. I. Siele et al., Propellants Explos. 6 (1981) 67 – 73.

71 J. P. Kehren, ICT Intern. Jahrestg. 1976, 47 – 58. J.

Boileau, J. M. Emeury, Y. de Longueville, P. Montea-

gudo, ICT Intern. Jahrestg. 1981, 505 – 526.

72 M. Stinecipher, L.A. Sketg, 8th Int. Symposium on

Detonation (1985) 351 – 360.

73 V. P. Sinditskii, V Y. Egorshev, M. V. Berezin, 32th

Int. Ann. Conf. ICT (2001) 59 (1 – 13).

74 M. D. Coburn, B. W. Harris, K. Y. Lee, M. M. Stine-

cipher, H. H. Hayden, Ind. Eng. Chem. Prod. Res. Dev.

25 (1986) 68 – 72.

75 E. Wimmer: ‘‘D�eriv�es nitr�es du glycolurile’’, Th�ese,

Universit�e d’Aix-Marseille, 1985.


76 G. Roche, ICT Intern. Jahrestg. 1978, 235 – 242.

77 L. R. Rothstein, ICT Intern. Jahrestg. 1982, 245 – 256.

78 C. Gaudin, ICT Intern. Jahrestg. 1978, 243 – 254;

1981, 541 – 551.

79 M. J. Ginsberg, A.R.Anderson, J.Wackerle,Symposium

sur les jauges et mat�eriaux piezoresistifs, 1st, Arcachon,

France, 1981. L. M. Erickson et al., ibid.

80 J. Boileau, MRS Symposium Proceedings 418 (1996)

91 – 102.

81 I. Fukiyama, Propellants Explos. 5 (1980) 94 – 95.

82 H. Ahrens, Propellants Explos. 2 (1977) 7 – 20.

83 J. W. Kury et al., Symposium on Detonation, 4th (1965)

3.

84 M. D�efourneaux, Sciences et Techniques de l’Armement47 (1973) 723 – 814, 847 – 930.

85 K. N. Bascombe, R. M. H. Wyatt, ICT Intern. Jahrestg.

1976, 211 – 231.

86 United Nations Organization: Transport of Dangerous

Goods, 14th ed., 2005.

87 D. M. Koger, ICT Intern. Jahrestg. 1980, 549 – 560.

88 J. Ding, The discovery of gunpowder and shockwaves in

China — CETR rep. A 12–89, New Mexico Tech.,

Soccoro, 1989.

89 A. B. Sheremetev, T. S. Pivina, ICT Int. Jahrestg. 1996,

30, 1 – 11.

90 FR 1060425, 1952 (C. Frejacques). J. P. Passarello,

Thesis (ENSTA-Paris), 1996.

91 R. W. Millar et al., ICT Int. Jahrestg. 1996, 26, 1 – 14.

92 R. B. Wardle, et al., ICT Int. Jahrestg. 1996, 27, 1 – 10.

93 M. F. Foltz, Prop. Exp. Pyro. 19, 1994 63–69 and 133–

144.

94 N. V. Chugehov, F. Volk, ICT Intern. Jahrestg. 2001,

101, 1–9.

95 A. Sanderoon (NIMIC-NATO), ICT Int. Jahrestg. 1996,

18, 1 – 8, and references given in this paper.

96 B. M. Dobratz, TATB, Development and Characteriza-

tion 1888 to 1994, LA 13014 H, Aug. 1995, UC 741, Los

Alamos Nat. Lab. (NM 87545).

97 K. Y. Lee et al., J. Energ. Mat. 5 (1987) no. 1, 27 – 33.

A. Becuwe, A. Delclos, ITC Int. Jahrestg. 1987, 27, 1 –

14. M. Piteau, A. Becuwe, B. Finck, ADPA, Compati-

bility of Plastics with Explosives, Proceedings, San

Diego 1991, 69 – 79.

98 A. Becuwe, A. Delclos, Prof. Exp. Pyro. 18, 1993, 1–10.

99 A. Nielsen, J. Org. Chem. 55 (1990) 1459 – 1466.

100 V. A. Tartakowsky, O. A. Lukyanov, ICT Int. Jahrestg.

1994, 13, 1 – 9. A. Davenas, [18], 69 – 71. H. Hatano,

et al. Europyro (AFP), 6e Congres Int. Pyrotechnie

Tours, 1995, 23 – 26.

101 J. Boileau et al., Acta Cryst. Sect. C 44 (1988) 696.

102 F. Bauer, H. Moulard, 4e Symposium Hautes Pressions

Dynamiques (AFP), 1995 333 – 340. R. A. Graham, L.

M. Lee, F. Bauer, Proceedings of Shock Waves in

Condensed Matter, Elsevier SC Publ. 1988, 619.

103 B. Blaive et al., Europyro (AFP), 6e Congres Int. Pyro-

technic Tours, 1995, 413 – 419.

104 H. Moulard, 9th Int. Symposium on Detonation (OCNR

113291–7), 1989, 18 – 24.

105 L. Borne, 10th Int. Symposium on Detonation (ONR

33395–12), 1993, 286 – 293.

Further Reading

J. Akhavan: Explosives and Propellants, ‘‘Kirk Othmer En-

cyclopedia ofChemical Technology’’, 5th edition, vol. 10,

p. 719–744, John Wiley & Sons, Hoboken, 2005, online:.

J. Fraissard, O. Lapina: Explosives Detection using Magnetic

and Nuclear Resonance Techniques, Springer, Dordrecht

2009.

N. Kubota:Propellants and Explosives, 2nd ed.,Wiley-VCH,

Weinheim 2007.

C. L. Mader: Numerical Modeling of Explosives and Pro-

pellants, 3rd ed., CRC Press, Boca Raton 2008.

M. Marshall, J. C. Oxley: Aspects of Explosives Detection,

Elsevier Science, Amsterdam, 2008.

R. L.Woodfin: TraceChemical Sensing of Explosives,Wiley,

NJ 2007.

J. Yinon: Counterterrorist Detection Techniques of Explo-

sives, Elsevier Science, Amsterdam, 2007.


explosives,' in: ullmann's encyclopedia of industrial...

Documents