Engineering company Mincon South Africa has achieved a milestone development in exploration drilling with one of its clients, drilling company Torque Africa Exploration.

Mincon supported Torque at a greenfield mineral exploration drill site in the Northern Cape, where a new Mincon reverse circulation (RC) system was used to successfully drill to 1 019 m in nine days. 

This represents a new record, Torque Africa director and owner Nardus Bezuidenhout told Mining Weekly, as, to the best of the company’s knowledge, the previous known record depth for an RC hole using air-powered tools is 886 m.

Therefore, he highlighted that for a small South African company, this is a considerable milestone.

“We believe this is a great leap forward for air-powered drilling solutions. We now have a system that can drill to depths previously only reached by far more expensive and complex systems.

"Additionally, this approach is far faster, thus saving time and money,” Mincon South Africa operations manager Gerhard Scott enthused.

Between February 10 and 15, work began on setting up a site for exploration drilling at the remote greenfield site.

Bezuidenhout moved in on site with one of his company’s Thor 8000 RC truck-mount drill rigs. Joining the main rig on site were a fleet of support vehicles, including rod carrier trucks, compressors, water and fuel tankers, and medical service vehicles, as well as a full team of staff to support the operation.

In undertaking the project, Bezuidenhout noted that there was no data or manual for drilling at that depth, so the company relied on previous experience and feel. “Practice makes perfect,” he states.

Airflow changes to Mincon’s evolved RC hammers in the MR range enable more successful dry sampling even after encountering groundwater.

Additionally, Torque Africa used Mincon’s range of drill bits that use polycrystalline diamond- (PCD-) impregnated buttons which offer greatly enhanced wear resistance when drilling in abrasive ground conditions.

Bezuidenhout said this system enabled the company to save time, because it did not have to extract drill string and equipment as often, which is usually the case with other machinery as a result of wear and tear.

When Torque reached the target depth, the drill string was retrieved for its final inspection, which showed only expected wear and no failures.

“Mincon’s air-powered RC drilling tools offer a more affordable approach than diamond coring systems because no expensive muds are needed to stabilise the hole, and it’s also a faster approach. For geologists the most important part of an RC hole is sample quality and there is no compromise in sample quality when using our air-powered system,” added Scott.

Once retrieved, a post-drilling survey was conducted to verify the depth and straightness of the shaft, with the survey report indicating a hole deviation of only 0.83°.

Mincon said this exceeds the performance of competing technologies and proves yet another benefit of air RC systems.

Mincon emphasised that a record-depth hole drilled in record time would be a pointless achievement if sample cuttings were unusable. However, the air RC approach has yet another advantage in this regard, by consistently returning uncontaminated sample cuttings to the surface, the company acclaimed.

It explained that this is owing to cuttings being flushed up through a sample tube rather than being exposed to the drilled hole.

Bezuidenhout noted that samples continued to be collected even after encountering extensive groundwater at 886 m. For every metre drilled, a sample was collected, bagged and tagged, allowing geologists to analyse the ground conditions and mineral content.

Torque is the first customer in South Africa to use Mincon's new system.

Scott said Torque selected the system based on Mincon’s performance claims. “Mincon works closely with customers, engaging in pioneering projects and in this instance that also included on-site assistance,” he noted.

LOOKING AHEAD

With the achievement recorded with Torque, Mincon believes the air RC systems are now a strong alternative to coring-based exploration solutions.

“The hole drilled by Torque Africa Exploration proves that it’s possible for air RC systems to drill past 1 000 m while collecting samples, using significantly less time, resources and money,” Mincon said.

Scott said the new system provides a faster and more affordable approach for drilling to depths of 1 km for exploration drilling.