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Rock engineering uses a developed understanding of the behaviour of rock to design safe excavations that do not hinder productivity.
Stability pillar removal
Witwatersrand gold mines consist of enormous near-horizontal tabular excavations. In order to support the roof of the excavation, large stabilizing pillars are left behind. It has been suggested that it may be possible to remove the stabilizing pillars, particularly at depth, because the roof has closed to the floor between the pillars, and partially relieved the pillars of the stress of support.
This revolutionary idea would open up substantial reserves of gold. Anglogold Ashanti alone estimates that it has more than ten million ounces locked up in stabilizing pillars in the Witwatersrand, valued today at more than thirty billion rand. To create a viable strategy for mining pillars, a focussed research programme is required on how the stress has changed with time, and how to mitigate the stresses that remain to safely remove the pillars.
Impact: Liberating the thirty billion rand that currently sits locked in stability pillars would extend the life of the key Witwatersrand gold mines by ten to twenty years, securing thousands of jobs.
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