Steyn says the target is to blast two
panels per shift, clean two panels per
shift, support two panels per shift, and
prepare two panels per shift. “That is
our typical cycle,” says Steyn.
Steyn showed Mining Mirror the big
rocks in the worked-out areas to which
Van Aswegen alluded to before. This
is part of the strategy to reduce waste.
“We have a vibrating feeder grizzly
on our tip with an aperture of about
30cm. The LHD will dump its load
after the blast, and the fines (referred
to as ‘stof ’), which is normally the reef,
will fall through the grizzly onto the
pan, while the big rocks (the waste)
will remain on the grizzly. We then just
push these rocks off the grizzly and
pack it in the worked-out areas again.
About 7% of all the waste that we
create is repacked,” says Steyn.
Underground extraction
The pillars in Bathopele’s East Shaft
constitute about 19% of the mine
infrastructure, while the mining losses
equate to about 16%. East Shaft’s
extraction ratio is approximately 65%.
“Mining losses are caused by potholes,
dykes, and geological features. In
these areas we have to increase the
size of the pillars to ensure stability,”
explains Van Aswegen.
Section 10E of Bathopele is
about halfway between the top and
bottom boundaries of East Shaft, and
between 280m and 300m vertically
underground. One has to travel about
1.2km in the back of a personnel
carrier to reach Steyn’s section. The
bottom of the shaft is another 300m
beneath Steyn’s section.
For support, the crew uses
1.6m-long roof bolts as primary
support, and 3m coupling bolts are
installed as secondary support in
areas deemed necessary by the rock
engineer modelling.
“Before a blast, we drill a 3.2m hole
with an Atlas Copco Jumbo rig. In
this section, a six-ton Atlas Copco
LHD and another Atlas Copco with a
seven-ton bucket are used to clean the
panels. We tip onto a strike belt and
from there onto a dip belt. Before it
r