A visit by Mining Weekly to the Venetia Underground Project (VUP) on November 14 provided insight into this major diamond development that is scheduled to achieve occupational readiness and first production next year.

“Hopefully, the first part of the year, all going well. We had a setback recently with some of our visa approval processes, which have caused some challenges, but we’ll overcome them, VUP project director Allan Rodel assured.

Venetia, South Africa’s largest diamond producer, is located about 32 km south of the Limpopo River, not far from the borders of Botswana and Zimbabwe, and about 500 km from Johannesburg.

In 2012, Mining Weekly witnessed the first sod turning of the $2-billion underground extension first sod turning, amid vibrant, ongoing opencast operation.

“The mine, as we speak, is 30 years old this year,” said Rodel of the operation, which has been an absolute gem for De Beers ever since the openpit was launched in 1992.

Scheduled to continue to operate until December, the openpit will then transition to underground, which will extend to 2046. “We know, though, that there is definitely opportunity below current levels,” was Rodel’s comment to visiting media.

The ground-handling facilities include manual and automated load-haul dumpers, manual and automated rock breakers, vertical ore passes, an automated truck-loop, underground crushers, ore and waste conveyors and silos.

The trackless fleet will be maintained underground.

Mining Weekly went down the production shaft and the decline and pit ramp, the first production areas.

The production shaft, with a finished internal diameter of 7 m, will be fitted with two rock winders, each having two 24 t payload skips.

The service shaft, which with a finished internal diameter of 7 m, will provide all the services to the underground workings, with both production and service shafts offering downcast air intakes.

The decline and pit ramp will also serve as an additional air intake and logistics management facility.

Vertical shafts, lateral access tunnels, life-of-mine decline and pit ramp, and related surface, underground and offsite infrastructure make up the VUP’s scope, which provides for the continued mining of two kimberlite orebodies – K01 and K02.

The K01 orebody will be mined using sub-level caving mining to produce four-million tonnes a year (4 Mt/y) to 4.5 Mt/y, averaging 3.5-million carats a year.

Sub-level caving will also be used to mine KO2, producing 1.9 Mt/y and averaging 0.9-million carats a year.

This equates to 5.9 Mt/y, which will match the throughput capability of Venetia’s main treatment plant.

The K01 and K02 orebodies will be accessed through two vertical shafts extending to 1 065 m below surface.

ROCKS STRENGTHENING TAILINGS DAMS

As Mining Weekly flew in, visible from the air was the exemplary way Venetia has used waste rock to bolster its fines residue deposits, rock impounding has been implemented in addition to the normal tailings-related checks, balances, and assurances.

Moreover, the first of six water control doors designed to counter water ingress into the underground mine has been completed, with De Beers and the South African Weather Services collaborating to develop a weather radar system that will detect weather activities beyond the borders of South Africa, into Botswana and Zimbabwe where most of the tropical storms arise.

The water control doors will be activated in the event of water inflows into the mine exceeding the capacity of the underground pumping system, which will ultimately have the ability to pump 4 500 m3/h out of the mine. They are designed to seal off the ‘dry’ side of the mine, where the water pumps and other critical infrastructure are located, from the ‘wet’ side, where mining operations on the kimberlite pipe take place.

“Certainly the sheer size of these doors is unusual,” was Murray & Robert Cementation Contracts Manager Jacques Labuschagne’s comment on the water door which has been built into the rough...