Mining_Methods_UnderGround_Mining - Mining and Blasting

anTOFagaSTa, CHile
Modernization at Sierra Miranda
Computerized
systems
The Sierra Miranda copper mine
in Chile has undergone a complete
transformation over the last year,
as a result of which it is now rated
as one of the most modern mines
in Latin America. Along the way,
the mine has acquired a purposematched
fleet of new generation
Atlas Copco equipment, capable of
high output without the availability
of a high tension underground
electricity supply. To support this
process of modernization, proactive
and preventive service and
maintenance is essential, and the
management at Sierra Miranda
know that good aftermarket support
for this type of advanced eq-
uipment is vital in order to achieve
their production goals. It was for
this reason that the mine entrusted
Atlas Copco as a true partner, having
confidence in their reputation
as a serious company with a lot of
experience.
large operation
The Sierra Miranda Mine, located about
60 km northeast of the city of Antofa-
gasta, is one of Chile’s largest underground
mining operations and has a history
of using the most modern mining
techniques and equipment available.
Sierra Miranda lacks a substantial
power facility, with the exception of
electricity for lighting and ventilation,
and has no water or air supply lines.
As a result, to mechanize effectively,
all of its underground equipment has
to be self-sufficient. The drill rigs, for
example, are all diesel-hydraulic with
independent water-mist flushing systems.
The mine’s total production is 3.3
million t/y, 1.1 million t of which is
waste rock from development work, and
the remaining 2.2 million t is copper
ore with an average grade of 0.75%.
The host rock is volcanic andesite
and the mineral deposit is principally
copper malachite, a combination of
At the controls of a Rocket Boomer L1 C drill rig. Operators at the Sierra
Miranda mine appreciate the benefits of the computerized systems.
copper pitch ore and chryssocholla, with
sporadic atacamite.
Three years ago, the mine owner star-
ted the first stage of modernizing the
mine’s operations. This required the
latest generation of equipment in order
to improve the systems for extraction
and the mining processes.
atlas Copco fleet
Sierra Miranda is one of the few, and
possibly the only mine of its size in the
world, that is equipped with dieselhydraulic
machines.
Currently, the mine production drilling
fleet is all Atlas Copco, including
a Simba M6 C, four Rocket Boomer
L1 C drill rigs equipped with the RCS
computerized rig control system, and a
Scaletec scaling rig, which is the first of
its kind in Latin America.
In addition, the mine has five Atlas
Copco ROC 460 PC drill rigs, and
Diamec U6 and CT14 exploration rigs,
as well as various mobile compressors.
The production fleet of mobile equipment
comprises four Scooptram
ST1020 remote controlled loaders. A
Scooptram ST2G loader and an additional
Simba are also expected to join
the fleet this year.
The owner is investing in the latest
generation of equipment in order to
grow the mine as quicly as possible, and
the selection of Atlas Copco machines
has provided the exact match for this
requirement.
efficient production
Sierra Miranda has a workforce of about
300, including contractors’ personnel.
The mining method is sub-level stoping,
without backfill. As the orebody is
relatively narrow at 4-10 m-wide it is
necessary to use an extraction method
that is both precise and focused.
The deposit is situated near the
surface, which from a geo-mechanical
point of view is favourable, as the support
pillars in the mine are not subjected
to excessive pressure.
Until recently, Atlas Copco ROC 460
truck-mounted drill rigs with short
feeds and DTH hammers were used
underground mining methods 97