More than two decades after innovating its first sub-sea crawler technology for diamond recovery, De Beers Group’s Upstream Technology business has developed a next generation of advanced subsea diamond recovery crawlers.
The unit, developed for Debmarine Namibia’s flagship vessel Benguela Gem, marks a significant leap in marine diamond recovery capability, according to Rudi Agostinho, Next Generation Crawler (NGC) Project Manager at Upstream Technology in Cape Town. After almost four years of development, the crawler has been installed on the vessel and is recovering diamonds off the coast of Namibia.
A second identical unit is already being assembled ready to take over operations during scheduled servicing of the first, ensuring minimal downtime. Agostinho says the next generation crawler represents a careful blend of cutting-edge automation, precision engineering and lessons from decades of operational experience.
“We have taken everything we have learned from earlier models and engineered a crawler that can operate with significantly enhanced efficiency, with greater reliability,” he says. He says the upgrade allows the Benguela Gem to boost its effective rates by approximately 20% with minimal increase to operating cost. This extra capacity means the vessel can now fully benefit from the throughput capability of its onboard treatment plant.
The new crawler is larger than its predecessors, weighing 370 tonnes and measuring 28 metres long and 8 metres high and wide. With a sweeping mining arm that covers a 21 metre arc in just 25 seconds, it includes several powerful systems.
The crawler operates between 100 and 135 metres below the surface, drawing a combination of seawater, sand, gravel and diamond-bearing material through an 800 mm diameter pipeline.
Sebastian “Bas” van der Laer, Mining System Specialist at Upstream Technology, says the goal was to push engineering availability from 82% to 87%, supporting the drive for extra production.
He points to the crawler’s new track tensioning system as a key innovation, where a hydraulic tensioning system automatically adjusts as conditions change. This reduces wear, extends the life of the track chain and improves gearbox torque.
Technology Development Manager Imraan Parker says automation has been central to embedding consistent best-practice operation into the crawler.
“Automation enables more predictable performance and better control over the stresses on the machine which in turn extends its structural life,” he explains. The high level of automation also extends to deployment of the crawler from the vessel.
Among the features is a forward-looking sonar system that provides clear images of the seabed allowing operators to recover right down to the footwall.
At Upstream Technology’s Cape Town facility, the building of the larger crawler led to other innovations. Senior Workshop Engineering Officer Abdul-Gameed Davids points to the lifting of the 47 tonne dredge motor into the crawler frame with two synchronised overhead cranes – a method now formalised for future builds.
Getting the completed crawler to the harbour took careful planning, according to Senior Project Engineer Steven Smith. Once at the dock, a 750-tonne crane hoisted the crawler onto the quay.
Before going to sea, the crawler underwent full-scale land-based simulations to test all systems under realistic loads. The machine contains over 2,2 km of cabling and more than 10,000 connections, each of which was verified before departure. Close collaboration with Debmarine Namibia’s operational team during assembly meant feedback from the vessel’s own operating crew could be incorporated.
Agostinho highlights that the next generation crawler provides a robust platform for the future of marine diamond recovery.
“By combining advanced tools, adaptive systems, automation and predictive maintenance, we have delivered a crawler that will recover more material, more consistently, with less downtime – even in tougher conditions,” he says.
