Meyer R., Koehler J., Homburg A. Explosives. Wiley-VCH, 2002 / Explosives 5th ed by Koehler, Meyer, and Homburg (2002)

Lambrit

Trade name of an ANFO blasting agent distributed in Austria by DYNAMIT NOBEL WIEN.

Large Hole Blasting

Großbohrloch-Sprengverfahren; sautage a` grand trou

In large-scale blasting processes in open pit mining and quarrying, rows of nearly vertical boreholes are drilled parallel to the quarry face; the diameter of each borehole is 3 – 8 in. (in Germany more often 3 – 4 in.), while the borehole length is over 10 m. The holes are filled with explosive and stemmed. W Free-flowing Explosives or pumped W Slurries can be applied.

Lawinit 2

Trade name of a slurry blasting agent for loosening avalanches, distributed in Austria by DYNAMIT NOBEL VIENNA GmbH.

cartridge density: 1,05 g/cm3 detonation velocity (unconfined): 4600 m/s

Lead Acetylsalicylate

Bleiacetylsalicylat; ac´etylsalicylate de plomb

colorless, fine crystals

empirical formula: C18H14O8Pb · H2O molecular weight: 583.5

energy of formation: – 810 kcal/kg = – 3391 kJ/kg enthalpy of formation: – 823 kcal/kg = – 3444 kJ/kg oxygen balance: – 98.7 %

Lead acetylsalicylate is a combustion-modifying additive, especially so in rocket propellants based on double base powder; W Double Base Propellants.

Lead Azide

Bleiazid; azoture de plomb

Pb(N3)2

colorless crystals; microcrystalline granules, if dextrinated

molecular weight: 291.3

energy of formation: +397.5 cal/kg = +1663.3 kJ/kg enthalpy of formation: +391.4 cal/kg = +1637.7 kJ/kg oxygen balance: – 5.5 %

nitrogen content: 28.85 %

volume of explosion gases: 231 l/kg explosion heat: 391 kcal/kg = 1638 kJ/kg density: 4.8 g/cm3

lead block test: 110 cm3/10 g detonation velocity, confined:

4500 m/s = 14 800 ft/s at r = 3.8 g/cm3 5300 m/s = 17 400 ft/s at r = 4.6 g/cm3

deflagration point: 320 – 360 °C = 600 – 680 °F impact sensitivity:

pure product: 0.25 – 0.4 kp m = 2.5 – 4 N m dextrinated: 0.3 – 0.65 kp m = 3 – 6.5 N m

friction sensitivity:

at 0.01 –1 kp = 0.1 –1 N pistil load explosion

Lead azide is insoluble in water, is resistant to heat and moisture, and is not too hygroscopic. It is prepared by reacting aqueous solutions of sodium azide and lead nitrate with each other. During the preparation, the formation of large crystals must be avoided, since the breakup of the crystalline needles may produce an explosion. Accordingly, technical grade product is mostly manufactured which contains 92 – 96 % Pb(N3)2, and is precipitated in the presence of dextrin, polyvinyl alcohol, or other substances which interfere with crystal growth. Lead azide is employed as an initiating explosive in blasting caps. When used as a primary charge, it is effective in smaller quantities than mercury fulminate, has a higher triggering rate, and, unlike mercury fulminate, cannot be dead-pressed by even relatively low pressures. In order to improve its flammability, an easily flammable additive, such as lead trinitroresorcinate, is added. Lead azide is decomposed by atmospheric CO2, with evolution of hydrazoic acid.

Lead azide detonators for use in coal mining have copper capsules; for all other blastings, aluminum caps are used.

Specifications

Lead Block Test

Bleiblockausbauchung; essai au bloc de plomb, coefficient d’utilisation pratique, c. u. p.

The Trauzl lead block test is a comparative method for the determination of the W Strength of an explosive. Ten grams of the test sample, wrapped in tinfoil, are introduced into the central borehole (125 mm deep, 25 mm in diameter) of a massive soft lead cylinder, 200 mm in diameter and 200 mm long. A copper blasting cap No. 8 with an electric primer is introduced into the center of the explosive charge, and the remaining free space is filled with quartz sand of standard grain size. After the explosion, the volume of the resulting bulge is determined by filling it with water. A volume of 61 cm3, which is the original volume of the cavity, is deducted from the result thus obtained.

Fig. 17. Lead block test

In France the lead block performance value is given by the coefficient d’utilisation pratique (c. u. p.): if mx is the mass of the tested explosive, which gives exactly the same excavation as 15 g of picric acid, the ratio

15 · 100 = % c. u. p. mx

is the coefficient d’utilisation pratique. Also, 10 g of picric acid can be applied as a standard comparison explosive. For the relationship with other testing procedures W Strength.

Another modification of the lead block test is recommended by BAM (Bundesanstalt für Materialprüfung, Germany). The test sample is prepared as follows: a special instrument wraps the sample in tinfoil and molds it into a cylinder of 11 ml capacity (24.5 mm in diameter, 25 mm in height, with a coaxial cavity 7 mm in diameter and 20 mm long for the blasting cap), whereby the resulting density should be only slightly higher than the pour (bulk) density. Liquids are filled into thinwalled cylindrical glass ampoules or, in special cases, directly into the cavity of the lead block.

The initiation is effected with an electric copper blasting cap No. 8 containing 0.4 g of high pressed (380 kp/cm2) and 0.2 g of low pressed W PETN as the secondary charge and 0.3 g of lead azide as the initiating charge.

The empty space above the test sample is filled with dried, screened quartz sand (grain size 0.5 mm), as in the original method.

The volume of the excavation is determined by filling it with water; after 61 ml have been deducted from the result, the net bulge corresponding to the weight of the compressed sample is obtained. In accordance

with the international convention, this magnitude is recalculated to a 10-g sample.

The European Commission for the Standardization of Testing of Explosive Materials*) recalculated the results for a 10-ml test sample, using a calibration curve established by Kurbalinga and Kondrikov, as modified by Ahrens; the reported value refers to the mixture of PETN

*Now: International Study Group for the Standardization of the Methods of Testing Explosives. Secretary: Dr. Per-Anders Persson, Swedish Detonic Research Foundation, Box 32058, S 12611 Stockholm, Sweden.

with potassium chloride which gives the same result as the test sample under identical experimental conditions.

Since this regulation is still recent, the values given in the following table, as well as the values given under the appropriate headings of the individual explosive materials, are still based on the older method, in which a 10-g sample is employed. Other conventional methods for the determination of the explosive strength are the ballistic mortar test and the sand test.

For further details, including descriptions of other tests, W Strength.

Lead Dioxide

Bleidioxid; dioxide de plomb

O =Pb = O

dark brown powder empirical formula: PbO2 molecular weight: 239.2

energy of formation: – 274.7 kcal/kg = –1149.4 kJ/kg enthalpy of formation: – 277.2 kcal/kg = –1159.8 kJ/kg oxygen balance: +6.7 %

density: 9.38 g/cm3

Lead dioxide serves as an oxidizer in primer compositions.

Lead Ethylhexoate

Bleiäthylhexoat: ethylhexoate´ de plomb

technical product: brownish, nearly amorphous empirical formula: C16H30O4Pb

molecular weight: 493.6

energy of formation: – 703 kcal/kg = – 2940 kJ/kg enthalpy of formation: – 724 kcal/kg = – 3027 kJ/kg oxygen balance: –142.6 %

Lead ethylhexoate is a combustion-modifying additive, especially in

W Double Base Propellants for rockets.

Lead-free Priming Compositions

Air contamination with health-impairing pollutants gave rise to the demand for sport ammunition free from lead, barium and mercury.

W SINTOX Primer Composition.

Lead Nitrate

Bleinitrat; nitrate de plomb

Pb(NO3)2

colorless crystals molecular weight: 331.2

energy of formation: – 318.9 kcal/kg = –1334.4 kJ/kg enthalpy of formation: – 326.1 kcal/kg = –1364.3 kJ/kg oxygen balance: +24.2 %

nitrogen content: 8.46 % density: 4.53 g/cm3

beginning of decomposition: 200 °C = 390 °F

Lead nitrate is employed as an oxidizer in initiating mixtures in which a particularly high density is required.

Lead Picrate

Bleipikrat; picrate de plomb

yellow crystals

empirical formula: C12H4N6O14Pb molecular weight: 663.3

oxygen balance: – 31.4 % nitrogen content: 12.7 %

Lead picrate is insoluble in water, ether, chloroform, benzene and toluene, and sparingly soluble in acetone and alcohol. It is prepared by precipitation with a solution of lead nitrate in a solution of sodium picrate and picric acid.

It can be used as an active component in initiating mixtures, e.g. for electrical squibs in bridgewire detonators. It is more powerful and more sensitive than W Lead Styphnate reaction.

The unintentional formation of picrates by reaction of picric acid with the surrounding metals must be strictly avoided.

Lead Styphnate

lead trinitroresorcinate; Bleitrizinat; trinifroresorcinate de plomb

orange-yellow to dark brown crystals empirical formula: C6H3N3O9Pb molecular weight: 468.3

energy of formation: – 417.6 kcal/kg = –1747.2 kJ/kg enthalpy of formation:

– 427.1 kcal/kg = –1786.9 kJ/kg oxygen balance: –18.8 % nitrogen content: 8.97 % density: 3.0 g/cm3

lead block test: 130 cm3/10 g detonation velocity, confined:

5200 m/s = 17 000 ft/s at r = 2.9 g/cm3 heat of explosion: 347 kcal/kg = 1453 kJ/kg deflagration point: 275 – 280 °C = 527– 535 °F

impact sensitivity: 0.25 – 0.5 kp m = 2.5 – 5 N m

Lead trinitroresorcinate is practically insoluble in water (0.04 %), and is sparingly soluble in acetone and ethanol; it is insoluble in ether, chloroform, benzene and toluene. It is prepared by precipitation with a solution of lead nitrate from a solution of magnesium trinitroresorcinate, while maintaining certain concentration relationships and working in a given temperature and pH range, with stirring, in a reaction vessel which can be heated or cooled. The magnesium trinitroresorcinate solution required for the precipitation of lead trinitroresorcinate is obtained as a brown-to-black solution in a dissolving vessel by reacting an aqueous suspension of trinitroresorcinol with magnesium oxide powder while stirring.

Lead trinitroresorcinate is mostly employed as an initiating explosive in the form of a mixture with lead azide forming the detonator charge; it is particularly suited for this purpose, since it has a high ignition sensitivity, and its hygroscopicity is low. It is also employed as the main component of “sinoxide” charges in non-eroding percussion caps; these charges also contain the usual additives and a low percentage of tetrazene.