The North West Province has produced a large portion of South Africa’s inland alluvial diamonds. Kimberlite intrusions are typically the parent source for the alluvial diamonds. Diamondiferous kimberlite intrusions were eroded over time by surface run-off and streams which transport the diamondiferous sediments downstream to depositional regimes. The diamondiferous alluvial deposits around Schweizer- Reneke were mostly deposited on magmatic rock of the Ventersdorp Supergroup. Formal alluvial mining in the area often requires a considerable amount of overburden material to be removed in order to access the coarser gravel beds which contain the economic grade diamonds. Diamond production from secondary sources in this region totalled approximately 14.4 million carats up to 1984, and small scale production persists today.
The case study focuses on the impacts of alluvial diamond mining operations on surface- and groundwater resources in the North West Province, South Africa. To recover diamonds from the sediments, the industry is currently focussing on using modern processing methods and a more clinical approach to increase the sustainability of mining, therefore minimizing the impact on the environment. Wastewater from the screening and the fines management phase is delivered to the primary water treatment phase where up to 70% of process water is recirculated to the processing plant, minimising the volumes of fresh water required. The settled sludge or waste is deposited on a tailings storage facility. Alluvial diamond mining operations, unlike many other industrial processes and types of mining, have a lower environmental hazardous risk associated with waste material, however, it is a possibility that leachate emanating from tailings often have a high salt content. The process raw water to these operations are supplied from both surface- and groundwater sources from the local area. Supplying processing raw water in a sustainable manner is often a challenge in drought stricken areas with limited surface flow and low aquifer potential.