JOHANNESBURG (miningweekly.com) – The implementation of an acid mine drainage (AMD) pumping and treatment solution in the Witwatersrand Central basin, has enabled Central Rand Gold (CRG) to reclassify the gold mineralisation found between 450 m and 900 m below surface at its CMR mine as a mineral resource.

The resource had previously been downgraded to an exploration target, owing to the rising water levels in the basin.

CRG said in a statement on Tuesday that the installation by the Trans-Caledon Tunnel Authority of high-capacity AMD pumps in March and the subsequent commissioning of the high-density sludge (HDS) plant on May 23, combined with a simultaneous reduction in the water level at the CMR mine, had demonstrated that the entire Central basin could be dewatered from a single point.

Moreover, economic capital and operating cost studies showed that further dewatering beyond the 450 m level could be done “efficiently and economically” with the installation of additional pumps and piping.

“[As a result], the mineral resource has been reclassified, more than doubling the resource base of the company from 4.51-million ounces to 9.9-million ounces of contained gold,” CRG stated.

Further exploration work, including trial mining and processing of the shallow target to establish grade and orebody continuity, mineability, dilution and throughput characteristics, was ongoing.  

As recently announced, within the company’s mining area in the Central basin, the water level was currently about 165 m below surface and, therefore, the focus was to exploit the resources currently available to CRG above this level.  

“CRG’s focus in the short to mid-term will remain on the exploitation of resources above 450 m, which will be throttled by the success and discharge rate of the pumping and HDS treatment.

“However, reserve studies, mine planning and scheduling below 450 m can now proceed with a view to extending the life of the CMR mine,” the company noted.

This basin-wide increase in mineral resources would also significantly augment reserve scheduling and prefeasibility studies on adjacent mining targets, such as Crown and City Deep.  

Commenting on the reclassification of resources, CEO Johan du Toit said the progress made in dewatering the basin was positive for all stakeholders in the region.

“The lower water table not only increases the life-of-mine of our assets by having higher quality reserves and resources, it also provides job opportunities and a sustainable AMD management system.”