Undergroungd trial testing of NRE Support Rig
Narrow Reef Mining (NRM) is a modern method developed to extract valuable minerals, such as platinum group metals (PGMs) and gold, from narrow ore bodies. The two main drivers for adopting new mining technologies in PGM mining are improved safety and economic sustainability. Mechanised methods, including advanced drilling, rock bolting, and ore transport systems, are seen as necessary to prolong the viability of platinum mines. The Narrow Reef Equipment (NRE) fleet is a unique, innovative, electric robotic solution for underground mining, aiming to increase safety and productivity while reducing both capital and operating costs. The fleet consists of three main machines, each designed for a specific stage of the mining cycle: a drill rig, a dozer, and a support rig.
The NRE Fleet represents a new class of ultra-low-profile equipment tailored for stope widths below 1.7 m. Its ability to operate in confined reef conditions minimizes ore dilution, improves production efficiency, and reduces costs, while remote-controlled functionality enhances worker safety. Operating within mining heights of 0.9–1.7 m, the NRE machines are fully electric, remotely operated, and highly automated, making them the only mechanized option for reefs thinner than 1.7 m or with dips lesser than 25°. Among the fleet, the support rig plays a key role in roof safety. It is specifically designed for narrow-reef mining, enabling the automated installation of self-drilling resin bolts (SDRs) while allowing the operator to remain at a safe remote location.
Four NRE support rigs (SR0003, SR004, SR008 and SR009) were tested at two underground platinum mines in South Africa: the Tumela 15 shaft, which forms part of the Amandelbult mining complex, and Bokoni Platinum Mine. All field trials were conducted under breast mining conditions.
At Tumela, the first-generation support rigs (SR003 and SR004) showed modest drilling productivity, high numbers of breakdowns, long repair times, and frequent component failures resulted in very low availability. In contrast, the second-generation rigs (SR008 and SR009), tested at Bokoni, delivered much better results. Productivity nearly doubled, the number of breakdowns was significantly reduced, and repairs were completed more quickly. Consequently, machine availability increased considerably, while utilization improved to 40.22% and 49.48%.
Feedback from the sites indicates that improved performance depends not only on technical upgrades of the machines but also on the experience of the personnel operating them. In addition, the quality of mine infrastructure, such as water supply, access to compressed air and a workshop, plays a major role in the support rig performance. Insufficient infrastructure complicates maintenance activities, increases downtime, and ultimately limits the achievable operational performance of the equipment.