Mining_Methods_UnderGround_Mining - Mining and Blasting

on site. Later stopes, which are not cri-
tical in geotechnical terms, can be restored
more economically with unconsolidated
rock fill, or a combination of
both.
Other factors determining the use of
CAF include planned future development
within the stope, and/or a need for
a tight fill to the crown of the stope.
Since CAF forms a substantial proportion
of the mining costs, mine development
plans usually try to minimize
the size of primary stopes in favour
of larger secondary stopes, which use
unconsolidated fill.
This is particularly important in
areas where the orebody is relatively
narrow. If the primary stope is not
filled with CAF, and adjacent stopes
are then required, a pillar, generally
10 m-wide, is left between the two.
Additional support of the stope crown
may be required, and this is carried out
by cable bolting. This is also used to
reinforce drawpoints.
Careful sequencing of the stope extraction
programme is an important
feature of mining at Olympic Dam, for
economical mining and minimal ore di-
lution. The sequence is determined by
several factors, including ventilation
capacity to remove radon gas and other
contaminants, the grade and tonnage
requirements of the mill, and the proximity
of any unfilled stopes. The XPAC
Autoscheduler computer software package
has been introduced to improve the
efficiency of the sequencing process.
Pride of Simba rigs
Atlas Copco has had a fleet of Simba
4356S machines at Olympic Dam since
1992, and has had a service contract
on site supporting and maintaining the
fleet since 1994. The machines consistently
achieve high levels of productivity
and availability at a minimal cost. The
Simba rigs are predominantly used to
drill downhole production blast holes
for the stopes. Their average mechanical
availability is 88-92%, and they drill
between 8,629 m and 9,359 m/month.
Drill-and-blast methods are also used
for main drive developments, and for
roof bolting as necessary, or in the
rehabilitation of old mining areas reentered.
Simba 4356S longhole drill rig with COP 4050 tophammer rock drill.
wOOMera, SOuTH auSTralia
Olympic Dam mining and production statistics
Description Amount
Underground development drives (2000) 1,100 m/month
Producing stopes each month (2000) 24
Average stope size (2000) 300,000 tonne
Average stope production rate (2000) 30,000 tonne/month
Average stope production time Ten months
Average stope filling time One month
Average stope fill curing time Three months
Copper production (2002) 178,523 tonne
Uranium Oxide production (2002) 2,890 tonne
Gold production (2002) 64,289 oz
Silver production (2002) 643,975 oz
underground mining methods 113