Depending on their severity, potholes present several significant challenges from a safety, quality, cost, logistical and mine design perspective that can disrupt mining operations.
This has resulted in drilling technology solutions provider Rosond of Midrand researching the potential development of a smaller, lightweight portable diamond drill rig that can be deployed conveniently on the reef horizon.
A comparative study between the traditional drill unit available for this application and the latest innovation by Rosond is currently underway to assess its performance efficiency and safety aspects for the mining industry, reveals Director Carlos Da Silva. The business case for the new drill rig is that it allows for informed decision-making to eliminate costly, unnecessary prospecting with re-development and a reduction in the creation of abandoned ends.
In addition to using less compressed air to power the new drill units, drilling ahead of faces in high-risk gas pocket areas can confirm potential gas-associated structures, notes Da Silva. “Our equipment is significantly lighter, portable and easily moved onto the reef horizon, meaning a reduced chance of injuries and less delays and dependency on mine personnel for transport. This is critical, because a quicker set-up means more face drilling time.”
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The new unit allows for smaller drill sites to be deployed, which reduces the costs associated with larger drill crews. In terms of efficiency performance, the benefits are more meters drilled per shift and more core transported daily to the surface due to the reduced weight.
Potholes are slump structures characterised by hanging wall rock units and reef horizons occurring at a lower elevation than normal. Roughly circular in shape and varying in size and depth, potholes tend to occur randomly. “It is suggested that potholes originated from density-unstable conditions combined with disequilibrium and vortex or strong eddying currents and the scouring action of pyroxene crystals eroding floor rocks,” explains Da Silva.
Potholes can obliterate highly mineralised economic reef horizon, leading to a potential loss in mineral reserves. In addition, stope and development faces tend to go off-reef with potholes. Thus, additional costly development is required to re-establish faces back on reef in order to resume mining operations.
Structured main grid on/off reef development is also negatively impacted, which could lead to sterilisation of the mineral resource. Lastly, from a safety perspective, the intensity of joints and fractures increases around pothole edges. Natural potential parting planes in deep hanging wall rocks may be exposed, resulting in fall of ground incidents.
The beauty of the new Rosond drill units is that no additional training is required because the drilling practice remains the same, so it falls under the same standard operating procedure. While the concept is still in the testing phase, this purpose-built technology is aimed squarely at the entire platinum-mining industry, concludes Da Silva.