Contributed on behalf of the Tech Edge Group by Allycats PR
The Stilfontein mine tragedy, where at least 78 people lost their lives, underscores the complexities of illegal mining in South Africa. The rescue of 246 individuals from the perilous shaft in less than three days is a testament to South African engineering prowess.
All images supplied by Tech Edge Group
The remarkable Stilfontein mine rescue was enabled by a locally designed and manufactured mobile rescue winder, equipped with world-first capabilities – including the ability to operate to a depth of 3km.
Tech Edge offers hope amid horror
“The Mobile Mines Rescue Winder (MMRW) performed flawlessly and offered a glimmer of hope amid the devastating loss,” said Russell Moore, executive chairperson of Gauteng-based Tech Edge Group, which was responsible for the winder’s conception, design and manufacture.
“The loss of life at Stilfontein is a profound tragedy that left us deeply saddened,” he said.
“However, our MMRW demonstrated South Africa’s capacity to develop world-class solutions and contribute to a safer global mining future.”
The rescue
On Friday, 10 January 2025, the Gauteng High Court ordered the rescue of miners who had been trapped for over three months in shafts 10 and 11 of the former Buffelsfontein Gold Mine at Stilfontein. The mine had been closed since 2013 when its operations were no longer financially viable.
Mines Rescue Services (MRS) South Africa, the owner and operator of a Tech Edge MMRW, led the rescue operation.
Tech Edge MD, Bannister Erasmus’s phone rang just before 20:00 on Sunday, 12 January. On the line was MRS’ CEO Mannas Fourie. Erasmus was asked to have a team on-site at Stilfontein early the next morning.
Erasmus described the ground around the shaft as having been somewhat cleared over the weekend and that after on-site tests of the MMRW, the first cage of people was brought to the surface at about midday from a depth of 1.4km.
The MMRW’s live camera feeds, from below the cage, inside the cage and on top of the cage, gave the surface team three different views of the interior of the shaft, while the communication system allowed messages to be relayed between the miners and the rescue team.
Although the cage’s recommended passenger load is six, Erasmus said that most of the miners were so emaciated that around 11 people could be accommodated per trip.
“The relief on the faces of the miners brought to the surface was humbling,” he said.
Emergency workers were on-site to treat the rescued miners. Those healthy enough were arrested, while the frail were sent to hospital under police guard.
Both Moore and Erasmus said that had it not been for the MMRW, which was designed to travel on both national roads and extremely rough terrain, the rescue would not have been possible.
Even though site preparation had been done over the weekend, the area remained rugged. “For any other machine to have operated on the site, a concrete foundation would first have had to be laid,” said Moore.
Tech Edge support staff – including a mechanical and an electrical engineer – were on site 24/7 to monitor the rescue system.
“The immense time spent on research and development in bringing the MMRW to fruition has paid off – it worked seamlessly,” said Erasmus.
The rescue operation ended late on Wednesday, 15 January.
Conception of the MMRW
The MMRW’s development was inspired by the 2010 Chilean mining disaster, where a lengthy rescue operation highlighted the need for more efficient and mobile rescue equipment.
When Moore became involved in Tech Edge in 1992, it had been manufacturing custom-made winders for the mining industry for more than 60 years. In 1993, the company’s focus shifted to pioneering solutions for the mining industry.
When 33 miners were trapped in Chile’s San Jose mine after a massive rockfall, a standard Tech Edge winder was airlifted to the disaster site as part of Murray & Roberts’ response to the Chilean government’s call for assistance.
“Despite several countries with expert mining skills being involved in the rescue operation, it took 69 days to eventually retrieve the miners, who initially survived on emergency rations and water from a spring and radiators.
“The incident got me thinking about how a comparable situation would be handled in South Africa. I realised we needed to develop better equipment and that this equipment would need the capabilities to go anywhere – and to do so quickly,” said Moore. “The idea for the MMRW germinated.”
Once Moore’s ideas were fleshed out by Tech Edge’s team, he took the design to MRS and MRS commissioned Tech Edge to complete the MMRW project.
Years were invested in perfecting the unit, prioritising unwavering reliability. Moore emphasised that the winder operates under extreme conditions, and human lives depend on its flawless performance. “To mitigate any risk, every component is designed with redundant systems.”
The winder was tested and commissioned at one of the world’s deepest mines – Gold Fields’ South Deep Twin Shafts near Johannesburg – in January 2021. It was then licensed by the Department of Mineral Resources and Energy (DMRE).
Subsequently, Tech Edge developed another winder for shallower mines with 1km depth capabilities, which MRS also acquired. “A similar machine was delivered to a company sinking a diamond mine in Botswana,” said Moore.
Moore and Erasmus believe South Africa needs more licensed mobile rescue units.
Design challenges
To ensure rapid deployment, the rescue winder needed to be easily transportable, capable of navigating diverse terrains, and road-legal without requiring special permits. In addition, it needed to be a self-contained system, with a power supply and sheave wheel deployment.
The winder drive and control systems are considerably more complex and sophisticated because of the significantly increased depth of wind. Rope dynamics (the movement, tension and material properties) at extreme depths necessitate sophisticated control and feedback systems.
The end result – the MMRW – made news headlines because no mobile rescue winder in the world is able to operate at a depth of 3 000m.
Because it is a mobile winder, getting it licensed by the DMRE was challenging. It had to comply with the Mine Health and Safety Act Chapter 16, with some exemptions that were approved by the department.
Monitoring of the rope dynamics is crucial during the hoisting of personnel and is safety-critical in terms of mining regulations.
Engineering prowess
Elaborating on the specific engineering solutions implemented in the MMRW to address the challenges of rope dynamics at extreme depths and ensure safe and controlled operation, Erasmus explained, “Monitoring of the rope dynamics is crucial during the hoisting of personnel and is safety-critical in terms of mining regulations. Our MMRW has gone through numerous design risk assessments, which include the modelling and Failure Mode and Effect Analysis (FMEA) of all safety-critical components. This ensures the safety of personnel being transported inside the rescue capsule.
“The MMRW is fitted with a ‘slack/tight rope’ detection device which continuously monitors dynamic rope conditions. The device in essence checks that the steel wire rope tension is within a pre-determined window while in operation.
“This ‘tension window’ is a calculated value which takes into consideration the weight of the steel wire rope (hanging in the shaft) and the mass of the personnel within the rescue capsule, plus the capsule. The load is continuously monitored by a sophisticated load cell. This ‘window’ allows a 15% variation on either side from the theoretically calculated value of the rope tension at differing depths in the mine shaft.
“Any dynamic condition which falls outside this ‘tension window’ will feed back into the winder safety circuit and will trigger an emergency trip-out instruction to the safety-rated Programmable Logic Controller (PLC) of the winder. During the trip-out process, the winder braking system will be applied in a controlled manner, in order to decelerate the rescue capsule at a predetermined rate to a clamped/stopped position.
“The Safety Integral Level (SIL) rating of the MMRW braking system (which includes the PLC, hydraulic power pack and highly specialised brake units) is in line with IEC 61508 specifications (international safety requirements).”
Erasmus, who himself developed another South African first – the Tech Edge mobile rope reeling system – concluded, “We are extremely proud that our equipment played a huge role in the success of the Stilfontein rescue operation and are honoured to work closely with MRS, which is a top-notch organisation.
“The MMRW stands as a testament to South Africa’s capacity to develop world-class solutions and contribute to a safer future for miners worldwide.”
Interesting facts and figures
For further information contact Bannister Erasmus on +27 (0)11 976 3063 or visit https://www.techedge.co.za/ |
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