FREQUENTLY ASKED QUESTIONS
The Technology is based on a non-detonating propellant compound enclosed in a cartridge, which reacts very quickly when ignited to produce high volumes of gas, mainly consisting of nitrogen, carbon dioxide and steam. When the cartridge is sealed in a drill hole, the high pressure gas generated by the ignition of the propellant enters into the micro-fractures created from the percussive drilling process and into the natural fractures and planes of weakness of the rock, expanding the fractures and propagating cracks towards the nearest free face of the rock. The number of cracks propagated is related to the maximum pressure and peak pressure rate achieved by the expanding gasses within the drill hole. The gas pressure within the drill hole and propagated cracks then causes the fractured rocks to heave apart, producing a shearing of the rock often called splitting.
1) Nxco RBC’s offer the following features:
1.1 Minimal fly rock
1.2 Minimal vibration
1.3 Lower noise and no overpressure levels
1.4 Negligible noxious gases
2) Only local clearance of personnel is required with Nxco RBC’s.
3) Limited downtime of loading and hauling equipment.
4) Safe transport, storage and usage requirements.
5) Nxco’s RBC’s are quick and easy to use with low capital and lightweight equipment.
6) Low cost and starter training requirements.
No, one of the most salient features distinguishing Nxco RBC’s from high explosives are that it deflagrates.
Yes, they are considered a pyrotechnic . The Nxco cartridge is classified as a 1.4 S product under the United Nations hazardous substances classification, in the same category as small arms ammunition. This classification is given to products that do not explode when ignited in their original packaged state and as such the classification defines Nxco RBC’s as a pyrotechnic product for transport and storage purposes.
When an in situ rock splits / breaks up on tensile, the movement of rock causes minimal vibrations to its environment.
Should the rock which breaks be attached to a wall (without a foundation for example), the movements created by breaking are likely to impact upon the wall, which will probably crack. However these are mechanically induced vibrations, not vibrations induced by a shock wave initiated by detonation.
Noise measurements should not be confused with overpressure measurements. Noise measurements are made with standard sound level meters, which record air vibrations falling in the audible frequency region only. There are times when relatively high overpressures are not audible because their frequency is outside the audible frequency region.
Self-stemming cartridges are louder than the stemmed cartridge range.
1) Pool excavation
2) Rock removal in gardens
6) Underground work
– Hanging wall
7) Mass rock removal
8) Opencast mining
9) Prototeam rescue use
10) Rockfall management
The Nxco RBC’s breakage process drastically reduces the potential for fly rock due to the controlled manner in which the rock is broken. Fly rock is 100% controllable by using correct practices for design and covering.
Drill size is critical to the functioning of the cartridge.
2. Breaking Cycle
It is important that the burden and spacings used are appropriate for the cartridge charge weight.
With RBC’s the rock will always move to the free face with no overbreak.
Nxco rock breaking produces low vibration resulting in significantly reduced damage to surrounding rock and infrastructure: Minimal fly rock resulting in minimal scatter of blasted rock: Low overpressures resulting in minimal concussion effects: Minimal fumes and dust allowing operations to be carried out continuously without the need to evacuate the mine as is the case with conventional explosives blasting.
Yes, divers only need to withdraw about 20 metres, because no shock wave is produced; as a result there is minimal damage done under the water, fish are safe and the surrounding environment preserved.
Due to its tensile breakage mechanism, Nxco RBC’s produces less fires and dust.