A new advanced subsea crawler has been installed on a marine vessel and is recovering diamonds off the coast of Namibia.

The De Beers Group’s Upstream Technology business developed the latest subsea diamond recovery crawler more than two decades after launching its first subsea crawler technology for diamond recovery. With the first unit operational on Debmarine Namibia’s flagship vessel, Benguela Gem, a second crawler is being assembled to ensure continuous operations during scheduled servicing.

Next Generation Crawler (NGC) project manager: Upstream Technology Cape Town Rudi Agostinho says the NGC represents a careful blend of automation, precision engineering and lessons from decades of operational experience. 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 benefit from the throughput capability of its onboard treatment plant.

The next generation crawler is larger than its predecessors, weighing 370 t and measuring 28 m long and 8 m high and wide and features a sweeping mining arm that covers a 21 m arc in 25 seconds. The machine operates between 100 m and 135 m below the surface,  drawing a combination of seawater, sand, gravel and diamond-bearing material through an 800-mm-diameter pipeline.

Mining system specialist: Upstream Technology Sebastian van der Laer explains that the crawler’s new track tensioning system enables the hydraulic tensioning system to automatically adjust as conditions change, which helps to reduce wear, extend the life of the track chain and improve gearbox torque.

Technology development manager Imraan Parker points to the high level of automation embedded 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.

Among the features is a forward-looking sonar system that provides images of the seabed, allowing operators to recover down to the footwall. In addition the 47 t dredge motor has been lifted into the crawler frame with two synchronised overhead cranes.

“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,” asserts Agostinho.