Market Survey on Copper - Indian Bureau of Mines

a grade of 0.82% copper, a 25% increase in tonnage from ore reserves of 1.76 bn tons
at 0.89% copper from December 2006.
Environment
As the environment at Collahuasi is harsh and fragile, ecological issues have a
top priority. Collahuasi is a zero-discharge operation, with much of its water being
recycled. An extensive environmental monitoring system is in place along with
research projects in high altitude operations.Collahuasi achieved its ISO 14001
environmental management certification in 2000.
5. El Teniente
Situated 44 km east of Rancagua and 75 km south of the capital, Santiago, El
Teniente claims to be the largest underground copper mine in the world (see below).
The El Teniente orebody has been known and worked on a small scale for many
years.
Work started on establishing a mine in 1905 after Government permission had
been acquired but progress was slow because of difficulty of access and a hard winter
climate. A small gravity plant was soon erected but it was not until 1912 that a
flotation plant was erected at Sewell. Control passed to Kennecott in 1915 and it ran
the mine until nationalisation in 1971.
The Present Mine
The porphyry orebody consists of a stockwork (a network of narrow veins) of
mineralised veinlets, mainly in andesitic lavas and tonalite, superimposed by a
leached zone and a substantial zone of secondary enrichment, both of very variable
thickness. It surrounds a narrow, almost circular ring of tourmaline breccia which in
turn surrounds the Braden Chimney, an inverted cone of breccia which was emplaced
after the main mineralisation. Reserves and resources are substantial. At the end of
2007 reserves and resources in the mining plan totalled 4,204 million tonnes grading
0.91% copper or 38.3 millionn tonnes of contained copper. In addition the mine has
identified additional resources of 15,827 million tonnes grading 0.46% copper or
nearly 73 million tonnes of contained copper though there is no indication how much
of this may prove economic. Production in 2007 was 404,728 tonnes copper and
5,053 tonnes molybdenum.
Mining is gradually moving lower and removing the ore between the barren
country rock and the Braden Chimney. Access is through adits (horizontal tunnels) to
shafts and other services cut in the Braden Chimney. Mining methods include panel
caving, panel caving with pre-undercut, and block caving, which have been adapted to
overcome the serious rockburst problem which stopped mining some years ago on
level 6 and threatened the future of the mine. A new level, Level 8, is now in
operation and another, lower, level is being studied which will give access to 1.5
billion tonnes of ore grading 0.96% copper and extend the life of the mine by many
years.
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