Rock-breaking technology supplier Nxco Mining Technologies offers nondetonating cartridges that use a pyrotechnic composition to break rock based on its tensile strength, rather than on its compressive strength, as is the case with traditional explosives.
Nxco’s Nonex cartridges contain a nondetonating chemical compound enclosed in a cartridge that reacts quickly when ignited to produce high volumes of harmless gas.
When the cartridge is sealed by means of stemming in a drill hole, the gas generated by the ignition of the mix enters into the microfractures created from the percussion drilling process and into natural fractures and planes of weakness in the rock to produce a shearing of the rock, called splitting.
Using expanding gas, compared with explosive materials, improves workplace safety, recovery, reduces costs and also reduces the impact of the mining process on the environment.
Nxco MD Michael Durie tells Mining Weekly that the cartridges do not release any noxious gases, allowing for immediate re-entry into the mine and, therefore, opening the door for continuous mining.
“It does the same work as explosives, without damaging the hanging and side walls. “The cartridges also offer better fragmentation, owing to the reduced pulverisation of rock, which is beneficial, as it decreases the collection and separation of rock underground.”
Subsequently, Nxco’s cartridges offer minimal fines and a 90% dust reduction, which also reduces mineworkers’ risk of developing emphysema.
Durie points out that gold contained within the crush zone also gets blasted away when using traditional explosives; however, Nxco’s cartridges do not produce a crushed zone and, in addition, can offer up to 30% improvement in gold recovery, compared with using traditional explosives.
The company further offers a stemming device for use with traditional explosives, which it says, is easy to insert and remove in underground holes, has no side effects and adheres to the Department of Mineral Resources’ recommendation for stemming devices to improve safety on mines.
The stemming device has undergone 1 200 tests, states Durie, and offers a minimum of 10% improvement in face advance, with no silica residue, which is often contained inside the cheaper clay-based stemming sachets, and presents an imminent risk to mineworkers’ health.