A host of diamond placers of variable age have been deposited on the Namaqualand coastal plain. The source of the diamond populations in these placers were primary diamondiferous kimberlite pipes located on the South African Kaapvaal Craton. Extensive erosion of these kimberlites released the diamonds into fluvial systems that transported them vast distances to the Atlantic coast. A portion of the diamonds were deposited in fluvial deposits of different ages on the coastal plain, however the majority were carried into the marine environment and deposited and reconcentrated in beach terraces. The abrasive fluvial and marine transport mechanisms have, effectively, removed a high percentage of the poorer quality diamonds from the secondary placer deposits, thus providing a diamond population that is 95% gem quality. The active nature of the tectonic framework of the Namaqualand region during the Cretaceous and Tertiary resulted in a complex structural setting that played a major role in the continuously evolving rift-flank drainage pattern adjacent to this area. As a result, the diamond placers on the Namaqualand coastal plain are complex due to continuous reworking of deposited diamondiferous fluvial sediments which resulted in a highly variable suite of placer deposits in terms of mineralisation style and diamond grade (stone density and stone size).

Most of the earliest placer and associated sedimentary deposits have been reworked completely, thus making it difficult to trace a complete stratigraphic history for the diamond placers. However, DBCM has undertaken extensive exploration work on the coastal plain and has identified a substantial range of ages of the deposits from the older Koingnaas fluvial channels (Cretaceous) in the south to the Megalodon type channels (Oligocene) and proto Buffels River sediments (Miocene) and finally the marine terraces of the Buffels Marine Complex (Plio-Pleistocene) in the north.

Open pit mining methods are used to expose the diamond-bearing ore which lies beneath varying depths of sandy overburden. Before the initial cut is opened, topsoil is removed and stockpiled for use in reclamation.

Current mining methods include truck-and-shovel operations. After stripping, the majority of exposed ore is dozed into windrows and loaded into trucks for transportation to the treatment plants. Teams of bedrock workers using either mechanised or manual methods collect the remaining ore. The ore is routed via road by trucks to beneficiation plants. Reclamation or rehabilitation is conducted concurrent to mining activities.

The Somiluana Mine and WCR operations all have modular plants that can be moved as the production centres change.

Of the treatment plants previously in operation at WCR, only the Michell’s Bay dense media separation (DMS) plant and the Kleinsee Final Recovery (KFR) will be used in the new overall treatment process. The other old plants were not included in the WCR NM purchase agreement.

Trans Hex commissioned a new 200 tph scrubbing and screening plant at Koingnaas/Michell’s Bay in FY2016. An additional 200 tph plant will be commissioned at the Dikgat / Mannelsvley deposits in FY2018. In FY2019 an additional 450 tph jig plant will be brought on-line when treatment of the Langhoogte TMR commences. Once processing of the Langhoogte TMR is completed this plant will move to the KNC TMR.