“The ocean is where future resources exist.” These words were pronounced by Rahul Sharma, an Indian oceanographer, at the South Africa’s Council for Geoscience Annual Conference 2017. The exploitation of submarine mining deposits is in its initial phases, but they estimate that in the near future millions of tonnes of such metals like, copper, nickel, cobalt, manganese and iron. However, it was diamonds that indicated the route already fifty years ago when they noticed that the belt of drifts that, in Namibia, follows the track of the river Orange continues well beyond the coast of what is now the ocean bed. A lot of kimberlitic chimneys in the South African region have been gradually eroded and their diamonds were lost, slipping into drifts. If we calculate that, for example, in the Kimberley area, about 1400 meters of historically exploited chimneys were previously eroded over millennia and that in this region there are more than 3,000, we can estimate that a billion and a half carats can be recovered in the secondary basins, many of them off-shore. After some little productive attempts, in 2002 the big enterprise starts an equal joint venture with Debmarine between the Namibian government and the De Beers Group that, in 2016, procured diamonds worth 1.2 million carats, 13% of the total product. This production level is thought to stabilize until 2035, the year when the concession will expire. At the moment there are no other extraction activities of submarine diamonds, mainly due to the fact that a reference technology does not exist. De Beers had to draw inspiration from the oil rig engineering to organise specific units where they could design and test the phases connected to entrainment, fluidization of the drilling equipment, gravel pumping or gravel water and material reconciliation. The working phases include a crawler that can slip on the seabed and pump, digging around 5 meters on the sea bottom, tonnes of sediments every hour. On board the material is selected based on size and geologic composition. On 16th June Debmarine built and launched at Walvis Bay Nujoma, the biggest ship in the world for this type of operation. 113 of length, worth 157 million US$, 12,000 tonnes, a helicopter and a crew including 80 people. The ship added to a fleet aiming to monitor and exploit the remaining 97% of the 3,000 square miles whose concession started in 1991. Nujoma will operate without interruptions over a three year period with working shifts of 12 hours and 28 day cycles for worker.
Gem News by Trasparenze News, published on Rivista Italiana di Gemmologia #2, September 2017.
