Primary explosives mercury fulminate

Figure A. 109 Mercury fulminate primary high explosive.

According to Romocki [2], in 1630, the Dutchman, van Drebbel was the first chemist to investigate mercury fulminate, and explosive gold . The first description of the laboratory preparation of mercury fulminate is given in Kunkel s book Laboratorium Chymicum published in 1690 [3]. This substance was described again by Howard in 1799-1800 [4]. No further discoveries of other primary explosives were made until the development of modern chemistry. 

Primary explosives differ from secondary explosives in that they undergo a rapid transition from burning to detonation and have the ability to transmit the detonation to less sensitive (but more powerful) secondary explosives. Primary explosives have high degrees of sensitivity to initiation through shock, friction, electric spark, or high temperature, and explode whether confined or unconfined. Some widely used primary explosives include lead azide, silver azide, tetrazene, lead styphnate, mercury fulminate, and diazodinitrophenol. Nuclear weapon applications normally limit the use of primary explosives to lead azide and lead styphnate. 

This primary explosive is created by adding lead acetate to a solution of sodium or ammonium azide. Lead azide has a good shelf life in dry conditions but is unstable in the presence of moisture, oxidizing agents, and ammonia. It is less sensitive to impact than mercury fulminate, but more sensitive to friction. Since lead azide is a nonconductor, it may be mixed with flaked graphite to form a conductive mixture for use in low-energy electronic detonators. 

Tetrazene (C2H8N10O) is a pale yellow crystalline explosive generally used in ignition caps, where a small amount is added to the explosive composition to improve its sensitivity to percussion and friction. Tetrazene is not suitable for filling detonators because its compaction properties make the transition from burning to detonation very difficult. This primary explosive is stable in ambient temperatures. Its ignition temperature is lower and it is slightly more sensitive to impact than mercury fulminate. 

Mercury fulminate (C2N202Hg) is one of the most important primary explosives. It is usually found in the form of a gray powder, is sensitive to impact and friction, and is easily detonated by sparks and flames. It is desensitized by the addition of water, but is very sensitive to sunlight. It reacts with metals in moist environments. It is created by treating a solution of mercuric nitrate with alcohol in nitric acid. Its most important explosive property is that it easily detonates after initiation.10... 

Primary explosives are sensitive to modest stimuli such as heat, spark, or friction application of the correct stimulus will lead to a detonation. The primary explosives used in detonators are typically extremely sensitive but not particularly powerful common examples are mercury fulminate, lead azide, and lead styphnate. In principle, the heavy metals present in most primary explosives should be a good cue for detection however, there are primary explosives that do not contain such elements. 

For the terrorist, TATP and HMTD offer easy sources of primary explosives. Consulting the do-it-yourself literature, it can be seen that there are two other commonly recommended primary explosives—lead azide Pb(N3)2 and mercury fulminate Hg(ONC)2, but these are difficult to prepare cleanly. The synthesis of diazodinitrophenol (DDNP) (Fig. 2.5), common in commercial detonators, is reported in such publications, but apparently is rarely attempted by clandestine chemists. Typically, the brisance of a primary is less than TNT, but the efficacy is the fact that a shock wave can result from a relatively mild insult. 

This distinction is more in kind than in degree. Small quantities of primary or initiating explosives usually detonate when exposed to flames or high temperatures whiie secondary explosives usually burn or deflagrate under these conditions. However under slightly altered conditions primary explosives can be made to deflagrate and secondary explosives can be made to detonate. Examples of primary explosives are Lead Azide, Mercury Fulminate, DDNP, etc Examples of secondary explosives are PETN, RDX, HMX, Tetryl, TNT, as single HE compns and Comp B, Comp C, PBX 9404, Dynamite ANFO (Ammonium Nitrate/Fuel Oil) as HE mixtures... 

Examination of nitration acids 167—191 — Examination of finished products propellants, secondary expls and primary expls 192 — Examination of individual expls solid TNT, liquid TNT, Hexogen (RDX), Hexotol (Cyclotol), Hexotonal (RDX/TNT/A1, Torpex), Penthrite (PETN), Bofors Plastic Explosive (BPE), Bonocord, Tetryl, Lead Azide, Lead Styphnate, Mercury Fulminate, Silver Azide and Tetracene]... 

Thermal decomposition of pure explosives such as primary explosives lead azide, lead styphnate, mercury fulminate etc. [35], monomethylamine nitrate [36] and explosive mixtures RDX + HMX mixtures [37]. 

Group A Primary explosives, for example, mercury fulminate, lead azide, basic lead azide, styphnic acid, lead styphnate etc. 

Fig. 30. Comparison of the rate of decomposition of mercury fulminate and other primary explosives at 75°C, according to Wallbaum [38].

Berchtold and Eggert [50] and Eggert [51] established that mercury fulminate (like silver fulminate and other primary explosives) is exploded when strongly irradiated. To explode mercury fulminate a light with an intensity of 1.65 J/cm2 is required (to explode silver fulminate—2.1 J/cm2). 

Apart from mercury fulminate, lead azide is the most important primary explosive. 

Fig. 56. Blasting caps (a)—charged with a single explosive (mercury fulminate or lead azide) (6)—charged with a primary explosive and a high explosive (c)—charged with three layers a primary explosive and two high explosives.

Primary explosives have a high degree of sensitivity to initiation through shock, friction, electric spark or high temperatures and explode whether they are confined or unconfined. Typical primary explosives which are widely used are lead azide, lead styphnate (trinitroresorci-nate), lead mononitroresorcinate (LMNR), potassium dinitrobenzo-furozan (KDNBF) and barium styphnate. Other primary explosive materials which are not frequently used today are mercury azide and mercury fulminate. 

Curtius added lead acetate to a solution of sodium or ammonium azide resulting in the formation of lead azide. In 1893, the Prussian Government carried out an investigation into using lead azide as an explosive in detonators, when a fatal accident occurred and stopped all experimental work in this area. No further work was carried out on lead azide until 1907 when Wohler suggested that lead azide could replace mercury fulminate as a detonator. The manufacture of lead azide for military and commercial primary explosives did not commence until 1920 because of the hazardous nature of the pure crystalline material. 

Lead and silver azides are widely used as initiating, or primary explosives because they can be readily detonated by heat, impact, or friction. As such, these materials, particularly lead azide, arc used in blasting caps, percussion caps, and delay initiating devices. The function of the azides is similar to that of mercury fulminate or silver fulminate. 

Nitrosoguanidine is a cool and flashless primary explosive, very much more gentle in its behavior than mercury fulminate and lead azide. It is a pale yellow crystalline powder which explodes on contact with concentrated sulfuric acid or on being heated in a melting point tube at 165°. It explodes from the blow of a car-... 

Explosives are generally categorized as either primary or secondary, depending on their sensitivity to shock. Primary explosives are the most sensitive to heat and shock. They are generally used in detonators, blasting caps, and military fuses to initiate the explosion of the less-sensitive secondary explosives. Mercury(II) fulminate, Hg(ONC)2, was the first initiator to be used commercially, but it has been largely replaced by lead(II) azide, Pb(N3)2, which is more stable when stored under hot conditions. 

Primary explosives include mercury fulminate [Hg(ONC)2, melting point 160°C with explosion, density 4.2], lead azide [Pb(N3)2, density 4.0], basic lead styphnate (lead trinitroresorcinate), diazodinitrophenol, and tetrazine (a complex conjugated nitrogen compound, melting point 140 to 160°C with explosion). Most priming compositions consist of mixtures of primary explosives, fuels, and oxidants. 

Add S parts primary explosive (mercury fulminate, lead azide, etc.) and stir until well mixed. A 1-quart bottle holds about 800 grams of this mixture. If you have access to plastic explosives, an excellent ratio is 40 parts gasoline and 40 parts C-4. Stir until a smooth mix is obtained, then pop in two nonelectric blasting caps. The polyiso-butylcnc in the C-4 helps to gel the fuel. 

Primary Explosives Mercury fulminate Lead azide Silver azide Lead styphnate Mannitol hexanitrate (Nitromannite) Diazodinitrophenol Tetrazene... 

In early days Alfred Nobel already replaced mercury fulminate (MF, see above), which he had introduced into blasting caps, with the safer to handle primary explosives lead azide (LA) and lead styphnate (LS) (Fig. 1.17). However, the long-term use of LA and LS has caused considerable lead contamination in military training grounds which has stimulated world-wide activities in the search for replacements that are heavy-metal free. In 2006 Huynh und Hiskey published a paper proposing iron and copper complexes of the type [cat]2[Mn(NT)4(H20)2] ([cat]+ = NH4, Na+ M = Fe, Cu NT = 5-nitrotetrazolate) as environmentally friendly, green primary explosives (Fig. 1.17) [3]. 

Typical primary explosives are lead azide and lead styphnate (see Fig. 1.17). The latter one is less powerful than LA but easier to initiate. Tetrazene (Fig. 2.2) is often added to the latter in order to enhance the response (sensitizer). (N.B. mercury fulminate used to be used as a sensitizer). Tetrazene is an effective primer which decomposes without leaving any residue behind. It has been introduced as an additive to erosion-free primers based on lead trinitroresorcinate. Unfortunately, tetrazene is hydrolytically not entirely stable and in long term studies decomposes at temperatures above 90 °C. Diazodinitrophenol (Fig. 2.2) is also a primary explosive and is primarily used in the USA. However, the compound quickly darkens in sun-... 

CDNTA form a white to bluish white powder, crystals, or granules. The crystals are sensitive to shock, friction, and percussion. CDNTA is a powerful primary explosive that demonstrates outstanding potential as a future replacement for mercury fulminate, lead styphnate, lead azide, and diazodinitrophenol for use in blasting caps and detonators. It should not be stored dry, and should be desensitized with dextrose, sulfur, starch, wood pulp, dextrin, or gum Arabic after preparation... 

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