DOP200 in diamond mining operation

Diamonds can be found along the shores of the western coast of South Africa and Namibia. These diamond deposits have been covered by sand through the course of time. Before the diamonds can be extracted, a layer of up to 8 m of sand must be removed. A DOP200 with sand mining head is up for the job.

Customised vessel

To handle and accommodate the DOP200, a special vessel has been commissioned. The “Lady Liya” is a 14.5 m long vessel, fitted out with a moon pool with an A-frame above and plenty of deck space. The DOP pump is lowered to the seabed through this moon pool. The dredge pump’s hydraulic drive is arranged by a power pack on board, and a jet water pump has been installed to deliver pressurised water to the mining head.

Dredging operation

The diamond rich deposits can be found up to a depth of -20m to -25m. According to surveys, the layer of sand to be removed varies between 1 m and 8 m. The DOP dredge pump is lowered to the sea bed and discharges the sand through a flexible pipeline. Due to the restricted mining concession – only 60 m in diameter – the discharge pipe is of minimal length to avoid the spill of sand in neighboring concessions. A splash plate at the end of the floating pipeline disperses the sand and reduces the mixture velocity.

Mining diamonds

Once the sand sediment covering the diamondiferous gravel is dredged away, opening up an area approximately 60 m², the DOP is used to keep the sand from filling in this area. Then the diamond mining vessel is moved into place, the divers go down and begin to pump the gravel with an eight inch (200 mm) gravel suction pump. This gravel goes up to the deck of the mining vessel where it passes through a rotating classifier. This classifier has sized screening to capture any gravel between 2mm and 24mm, which is then placed in one ton bags. Once in to harbour these bags are offloaded and will be processed through a dense medium separation plant at the mine, where the diamonds will be sorted out from the plants concentrate.