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