The
Australia's largest open cut gold mine
Location: Kalgoorlie,
Western Australia.
Products: Gold.
Owner: Kalgoorlie
Consolidated Gold Mines Pty Ltd.
Overview: The
Super Pit is located off the Goldfields Highway on the south-east edge of
Kalgoorlie, Western Australia. The pit is oblong in shape and is approximately
3.5 kilometres long, 1.5 kilometres wide and 570 metres deep. At these
dimensions, it is large enough to be seen from space.
The Super Pit is owned by Kalgoorlie
Consolidated Gold Mines Pty Ltd, a company owned 50/50 by Barrick Gold Corporation
and Newmont Mining Corporation. The mine produces 850,000 ounces (28 tonnes) of
gold per year, and employs around 550 employees directly on site.
Originally consisting of a number of small
underground mines, consolidation into a single open pit mine was attempted by
Alan Bond, but he was unable to complete the takeover. The Super Pit was
eventually created in 1989 by Kalgoorlie Consolidated Gold Mines Pty Ltd.
Barrick Gold acquired its share of the mine in
December 2001, when it took over Homestake Mining Company. Newmont became
part-owner of the mine three months later, when it acquired Normandy Mining in
February 2002.
Geological Setting: Most of the good gold mined in the
Super Pit occurs within ore lodes formed by ancient shears in a rock unit
called the Golden Mile Dolerite. The gold mining area of
Kalgoorlie-Boulder-Fimiston has long been called the Golden Mile because of the
geographical concentration of rich mines in that area, even though the lodes
occur in an area over 2 km in width and 1 km in depth.
Kalgoorlie Terrane.
1. Pre- to syn-D, granitoids were emplaced as
broadly conformable sheet-like bodies at the base of, or within, the greenstone
succession, probably during
2. Post-D, to syn-D, granitoids were
diapirically emplaced, and are concentrated in a zone along the western side of
the Kalgoorlie Terrane.
3. Late-tectonic to post-tectonic granitoids
were emplaced late in the history of the Terrane. Limited geochronological data
suggest the granitoids were emplaced at 2690-2680 Ma (group I), 2665-2660 Ma
(group 2) and 2650-2600 Ma (group 3) (Hill ef al.,
1992). Small porphyry intrusions, including
lamprophyres
(Rock et aL, 1989), are widespread and petrologically
diverse; they may be genetically related to some of the I-type granitoid suites
(Witt, 1992). They are common in and near regional deformation zones, and are
associated with many gold deposits (Perring et al., 1988,1989).
GOLD MINERALIZATION:
All rock types in the Kalgoorlie Terrane host
gold mineralization, but most production has come from fractionated quartz-dolerite
zones of mafic-ultramafic sills and from tholeiitic basalt.
The dominance of quartz-dolerite and
tholeiitic basalt remains even if bias introduced by the "giant"
Kalgoorlie deposits (Golden
Mile, Mount Charlotte) is eliminated. A
similar picture emerges when host rocks to gold mineralization throughout the
Yilgarn Craton are considered (.1B; Groves & Barley, 1988). Quartz-dolerite
and tholeiitic basalt host rocks are characterized by high FeO* contents and
FeO*/(FeO*+MgO) (Tables II.1,11.2), where FeO* is total iron expressed as FeO.
Although mafic rocks are the dominant hosts, other rock types (e.g.,
granitoids, porphyry, ultramafic rocks) host important deposits, and can even
be the dominant host rock on a camp scale (e.g., porphyries at New
Celebration). All rock types in the Kalgoorlie Terrane host gold mineralization,
but most production has come from fractionated quartz-dolerite zones of
mafic-ultramafic sills and from tholeiitic basalt .
Production:
Mining is via conventional drill and blast
mining via face shovels and dump trucks. Around 15 million tonnes of rock is
moved in any given year, consisting primarily of waste rock.
Gold within the Golden Mile lode system is
unusual in that it is present as telluride minerals within pyrite. In order to
recover the gold, the ore must be crushed, passed through a gravity circuit to
recover the free gold present in some of the higher-grade lodes, and then
subjected to flotation to produce an auriferous pyrite concentrate. This is
then roasted at a small smelter outside Kalgoorlie-Boulder to liberate the gold
from the tellurides, with doré bars poured.
More information and resources
0 التعليقات:
Post a Comment