R. Meyer J. Köhler A. Homburg Explosives

Destressing Blasting
2. The explosive is poured into a large volume of water and is mixed
with it. This technique can be applied to materials which are soluble
totally in water (black powder, ANFO).
3. Treatment with chemicals (acids, alkalis, boiling with water): lead
azide is destroyed by treatment with nitric acid in the presence of
sodium nitrite; lead trinitroresorcinate by treatment with nitric acid;
mercury fulminate by prolonged treatment with boiling nitric acid.
4. Exploding the material: blasting operations must be carried out in a
barricaded area licensed for the purpose, located at least 1000ft away
from any bulding which may be endangered by the explosion. A
reinforced shelter is needed for protection of personnel; suitable protection
from flying fragments (e.g. by walls; palisades) must be provided.
Destressing Blasting*)
Entspannungssprengung; sautage de détente
Destressing blasting serves to loosen up the rock mass in order to
distribute high compressive loads more uniformly and to counteract
the hazard of rockbursts. Rockbursts are particulary violent fracture
processes, accompanied by considerable earth tremors. They mainly
consist of a sudden thrust or ejection of the rock involved (coal; salts;
massive rocks) and abrupt closure of the excavation. In coal seams,
the risk manifests itself by abnormally great amounts of debris when
drilling small holes (so-called test drilling). Destressing blasting is
performed by contained detonations.
Detonating Cord, Detonation Cord
detonating fuse; Primacord; Sprengschnur; cordeau détonant; Cordtex
Detonating cords consist of a W PETN core (about 12 g/m) with wound
hemp or jute threads and a plastic coating around it. The cord is
initiated by a cap and its detonation velocity is about 7000 m/s. Special
* The article was made available by Dr. Bräuner, Bergbauverein Essen.
Publications:
Bräuner, G.: Gebirgsdruck und Gebirgsschläge. Verlag Glückauf. Essen
(1981).
Bräuner, G.: Möglichkeiten der Gebirgsschlagbekämpfung im Ruhrbergbau
unter besonderer Berücksichtigung des Entspannungssprengens.
NOBEL-Hefte July – September (1978), p. 91–97.
Bräuner, G.: Gebirgsdruck und Gebirgsschläge, Verlag Glückauf, Essen, 2nd
Edition (1991).
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