Rock Breaking Cartridges
Nxburst™ Safety Cartridges
Environmental restrictions for concrete and rock fragmentation
The main environmental constraints that normally apply to concrete and rock fragmentation in environmentally sensitive areas are overpressure, noise, ground vibrations and flying concrete and rock fragments
Controlling these elements in ecologically sensitive areas is critical to prevent or minimize potential damage to people and infrastructure.
Overpressure
Overpressure (pressure above atmosphere) is caused by vibrations or compressive waves transmitted through the air, produced by the rapid expansion of explosive gases and the rapid movement of the concrete or rock, resulting in the sudden displacement of air around the payload .
The overpressure levels produced by Nxburst™ cartridges are low compared to conventional explosions, are of shorter duration and much less likely to cause damage. This gives our cartridges an important advantage over explosives in environmentally sensitive areas.
Noise
Noise is part of the overpressure wave that falls within the audible frequency region of the human ear, causing nuisance rather than damage, the high-frequency part of the air pressure part is not audible, but structures, such as windows, can react to it and produce secondary noise, such as rattling. A properly matched Nxburst™ cartridge in concrete or granite generally produces a noise level of 80 – 85 dB at 50 meters from the explosion, well within the 128 dB safety level set by the US Bureau of Mines. The noise level can be reduced by using a conveyor belt, other mats or ground cover to cover the holes where the cartridges are fired.
Vibration of the ground
Ground vibrations as a result of explosions can cause damage to buildings and infrastructure in the vicinity of the explosion. The amount of damage caused by vibrations after an explosion depends on the size, frequency and duration of the vibrations.
Nxburst™ cartridges have a vibration signature produced by the combination of high frequency vibration waves of short duration and small size, enabling them to be used close to vibration prone locations where conventional explosions are prohibited or impractical.
A specific vibration equation of Nxburst™ cartridges has been developed from data tracked and collected from various rock cavities fragmented in sensitive civil applications. This data was collected by an independent group to produce a practical graph relating vibration levels (PPV) to the weight of the payload and the distance from the explosion where the vibrations were measured. Ground vibration from our cartridges is well within the maximum levels set by the US Bureau of Mines.
Flying concrete or rock fragments
Flying rock can be a particularly dangerous side effect of blasts. An Nxco cartridge produces optimum pressure regulation of the cartridge in the orifice, for a given load and given type of concrete or rock. The speed and distance traveled by the concrete or rock fragments are limited when using our cartridges due to the pressure pulse characteristics of Nxburst™ cartridges.
Controlled gas released from Nxburst™ cartridges at relatively low pressure creates a minimal amount of low-velocity flying rock, generally remaining within 20 – 30 meters of the explosion.
Flying rock is 100% controllable by covering the concrete or rock with sand or rubber mats.
Blocking of crushing machine
Removing blockages from a crusher caused by oversized boulders in the crusher jaws or opening requires a minimum of energy and a maximum of flexibility.
Using Nxburst™'s 13mm Rockpoppers to break up rocks caught in a crusher's jaws prevents damage to the crusher or any part of the mine's infrastructure. Our 13mm Rockpopper splits the rock without flying rock, shock effects or a lot of noise.
Extraction of natural stone
Nxburst™ cartridges are used to split granite for natural stone in the extractive industry. The advantages of using Nxburst™ cartridges instead of black powder or equivalent are that our cartridges are water resistant, do not fire sparks and are not shock sensitive.
This makes Nxburst™ cartridges easier and safer to use, store and transport. In general, the 28mm series of Nxburst™ cartridges are used in a 32mm aperture.
13mm Rock Poppers
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