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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anTOFagaSTa, CHile<br />
Schematic of sublevel stoping in a narrow vein using the Simba M6 C to drill down holes.<br />
for drilling the blast holes, <strong>and</strong> also for<br />
developing 40 m-deep raises between<br />
the levels.<br />
In order to minimize dilution in the<br />
narrowest veins, it was decided to em-<br />
ploy a Simba M6 C drill rig equipped<br />
with a COP 2550 rock drill on production<br />
drilling of downholes in this<br />
narrow vein/sub-level stoping operation.<br />
At the same time, the distance<br />
between levels was reduced to 25 m <strong>and</strong><br />
the hole diameter was reduced from 4<br />
in to 3.5 in.<br />
The Rocket Boomer L1 C rigs are used<br />
both for development <strong>and</strong> production.<br />
Each rig, equipped with a single COP<br />
1838HF rock drill, advances at a rate<br />
of 800 m/month in galleries that are 5<br />
m-wide x 5 m-high. Scooptram ST1020<br />
loaders are used for hauling <strong>and</strong> transport<br />
during the development of galleries<br />
<strong>and</strong> ramps.<br />
The Scaletec is used throughout the<br />
mine for preparing faces for loading <strong>and</strong><br />
for general roof scaling, mechanizing an<br />
operation that was previously time-consuming<br />
<strong>and</strong> sometimes dangerous.<br />
The ore is transported to the surface<br />
by conventional 40 t-capacity trucks.<br />
Change for good<br />
The technological changes at Sierra<br />
Mir<strong>and</strong>a have been rapid. In less than<br />
Scaletec in action at Sierra Mir<strong>and</strong>a. Close-up of the Scaletec at work.<br />
a year, the entire mine fleet has been<br />
upgraded to modern equipment. In ad-<br />
dition, the operators have acquired new<br />
skills <strong>and</strong> the whole team is now focused<br />
on increasing the planned production<br />
levels <strong>and</strong> on improving risk <strong>and</strong> security<br />
st<strong>and</strong>ards.<br />
Furthermore, productivity has in-<br />
creased beyond all expectations. While<br />
the improvements continue, the mine is<br />
also making every effort to achieve ISO<br />
9000 certification.<br />
At Sierra Mir<strong>and</strong>a Atlas Copco works<br />
in a very proactive way. The fleet is<br />
checked daily for the number of hours<br />
each machine has worked, <strong>and</strong> the<br />
causes of any breakdowns. It is then<br />
decided which machines will be required<br />
for work over the following few<br />
days, <strong>and</strong> Atlas Copco makes sure that<br />
they are available. This entails a very<br />
flexible programme of maintenance<br />
<strong>and</strong> follow-up procedures, which can<br />
change from one day to the next.<br />
At the start of the contract, the mine<br />
stipulated that it required 90% equipment<br />
availability. This took a little time<br />
to achieve while training was underway.<br />
However, once all systems were up <strong>and</strong><br />
running, availability increased to its<br />
present level of more than 95%.<br />
acknowledgements<br />
Atlas Copco is grateful to the owner<br />
<strong>and</strong> management at Sierra Mir<strong>and</strong>a<br />
mine for their assistance with the pre-<br />
paration of this article which first<br />
appeared in <strong>Mining</strong> & Construction<br />
1-2007.<br />
98 underground mining methods