Abstract:
South Africa has two main platinum reef deposits, namely the Merensky reef and the UG2 reef.
These reefs are currently mined using traditional drilling and blasting methods. Mechanized
cutting could potentially enable continuous mining, which would offer significant advantages.
This would require thorough understanding of the cutability of the rock. To explore this, a linear
cutting machine was developed to conduct laboratory scale cutting tests. This work describes the
development and commissioning of the cutting machine using sandstone, as well as subsequent
characterization tests on UG2 reef samples.
UG2 reef has large variability in strength on a millimeter scale. This introduces uncertainty
in the test results due to added variance from one cut to the next for the same UG2 reef sample.
Another problem is the variability in rock properties of the UG2 reef, when testing samples from
different mines. The cutting tests led to fine fragmentation, which is known to be a significant
problem for cleaning operations in underground stopes and warrants further research.
A finite element method simulation of the rock cutting was conducted using ANSYS LS-DYNA
and the continuous surface cap model to simulate rock cutting in the UG2 reef. It was found that
it is possible to use LS-DYNA with the continuous surface cap model to model rock cutting of
UG2 reef and get acceptable results, but the user must calibrate the model parameters using the
experimental results. Therefore, the model is only fit for one set of cutting parameters and further
work is required to generalize results.
