De Beers Consolidated Mines (DBCM) launched its first marine diamond vessel in april 2007.
The vessel is currently mining off the South African coast. De Beers has been testing the viability of marine diamond mining for years. Off the Namibian coast, De Beers has already held trials with the raw power of conventional trailer-dredgers to prove their point.
The "Peace in Africa" is the ex "Dock Express 20", retrofitted to mine diamonds offshore. The whole project took two years to finish. The Dock Express was built 1983, and latest used as a cable-layer.
The ship carries a 240-ton remotely controlled seabed crawler, which undertakes the mining, or dredging, and is connected to the ship by a 650 mm internal diameter rubber hose through which the seabed material is pumped to the plant, using a 2.4MW IHC centrifugal dredgepump. The ship and crawler are able to work to waterdepths of max 150 metres.
The dredged material is pumped into a screening and sieving installation onboard. The raw material is treated untill a diamond rich residue remains. This residue is airlifted with a helicopter to the shore, for further processing.
The treatment installation was designed by Bateman Engineering (see: http://www.batemanengineering.com/TECHNOLOGY/Peace%20in%20Africa%20PP%20lo.pdf).
The whole ship incorporates almost all processes found in a land-based diamond mine.
The vessel is mining sediment at up to 400 m3/h, which is double the rate that other mining ships can achieve.
The vessel will attempt to remain at sea continuously for 2 ½ years before returning to port for repairs. The crew works on board for 28 days (12 hours on, 12 hours off) followed by 28 days leave and is flown in and out by helicopter, similar to offshore oil rigs.
If the vessel manages to uncover the right materials continually, De Beers will consider expanding its fleet of diamond mining vessels to exploit a greater part of the resource at a greater pace.
Marc Van de Velde