Diamonds can be found in volcanic pipes filled with a blue rock called kimberlite.
Venetia Mine is currently the largest producer of diamonds in South Africa.
When mining a kimberlite pipe the ore material is removed with large hydraulic shovels and ore trucks. Hard rock is drilled and blasted with explosives so the broken material can be removed.
Open-pit mining is used when diamond deposits appear on or near the surface. The overburden, or surface material covering the diamond deposit (or orebody), is relatively thin and unsuitable for tunnelling (as would be the case for sand, cinder, and gravel).
Open-pit mining generally:
- generates revenue quite early
- results in a flexible mining rate and sequence
- has a lower initial capital and operating cost per tonne mined
- allows larger machinery to be used
- leads to better blending capabilities
The size, shape and value of the deposit, as well as the stability of the host rock, determine the layout and ultimate depth of the open-pit mine.
This method uses GPS and dispatch type control systems, and integrates this with on-line drilling systems and blast design, to make the mining operations as efficient as possible.
When the open pit is deep enough, mining goes underground with vertical shafts that descend into horizontal drifts, or passageways, that enter the pipe.
De Beers’ open-pit mines are:
- Damtshaa (Botswana)
- Jwaneng (Botswana)
- Letlhakane (Botswana)
- Orapa (Botswana)
- The Oaks (South Africa)
- Venetia (South Africa)
- Williamson (Tanzania)
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