Blasting guns
As Knäppersprengung shortly Knäpper or secondary reduction is called the blowing up of a Knäppers, so a stone chunk, sometimes also called free stone, which is for machining on site too large or unwieldy.
Knäpper are often brought to light in quarries during blasting rock extraction or in civil engineering during earthworks. These knaps are so big or heavy that the processing or removal with the existing machines, eg. B. dump trucks , excavators or wheel loaders , is impossible. The boulder can be crushed by explosives .
species
The explosive ( gelatinous explosives are often used , and more rarely black powder ) can be attached in a number of ways.
Blasted with a charge
The explosive charges are placed flat on the knappers and detonated. This type of detonation is quick and easy, but has the disadvantage of high noise emissions and high explosives consumption and is therefore inefficient.
Blasting gun with applied shaped charge
In this case, the explosive is not placed flat, but rather like a hollow charge with a hollow surface (e.g. supported by a plastic funnel) on the latch. This increases the effectiveness of the explosives when the stone is broken up, but the process is still very noisy.
Knäppersundung with borehole
Since this method only uses around 30% of the explosives required for the loaded charge, the lowest noise emissions occur while at the same time the explosive potential is fully exploited. The explosive is placed in blast holes previously drilled in the knapper, so that the explosive effect unfolds directly in the knapper. The disadvantage of this method is that the blast holes have to be drilled, which can represent a considerable amount of machinery, time and personnel. Furthermore, there is a greater amount of fragments compared to the load placed on it.
application
With the increase in the performance of construction machines, larger and larger boulders can be shredded and removed. Furthermore, by using electronic detonators in quarries, a more homogeneous and smaller-scale pile can be produced. Therefore, the number of blasts continues to decrease. In addition, blasts are problematic from a safety point of view because the fragmentation flight is difficult to control. Today there are knapsack blasts when there is a danger of rockslides. B. on roads to which construction machines have no access or the size of the knappers poses too great a challenge for machine removal.
literature
- Civil protection regulations 250 (KatS-DV 250) . Bonn 1984.
- Explosives Sales Company: The Romperit Blasting Culture Process . 4th edition. Explosives sales company mb H., Berlin 1934.
- Horst Roschlau: Sprengen - theory and practice . German publishing house for basic industry, Leipzig 1993, ISBN 3-342-00492-4 .