Typical Open Cut Grades
Gold is generally extracted in open-pit mines at 1 to 2 ppm (grams per tonne) but in certain cases, 0.75ppm gold is economical. This was achieved by bulk heap leaching at Alkane Minerals Ltd. Peak Hill mine in western New South Wales, near Dubbo, Australia.
Nickel, generally as laterite, is extracted via open-pit down to 0.2%. Copper is extracted at grades as low as 0.15% to 0.2%, generally in massive open-pit mines in Chile, where the size of the resources and favorable metallurgy allows economies of scale.
Materials typically extracted from open-pit mines include:
- Clay
- Coal
- Copper
- Coquina
- Diamonds
- Gravel and stone (stone refers to bedrock, while gravel is unconsolidated material, as found in glacial or fluvial deposits)
- Granite
- Gritstone
- Gypsum
- Limestone
- Marble
- Metal ores, such as Copper, Iron, Gold, Silver and Molybdenum
- Uranium
Read more about this topic: Open-pit Mining
Famous quotes containing the words typical, open, cut and/or grades:
“A building is akin to dogma; it is insolent, like dogma. Whether or no it is permanent, it claims permanence, like a dogma. People ask why we have no typical architecture of the modern world, like impressionism in painting. Surely it is obviously because we have not enough dogmas; we cannot bear to see anything in the sky that is solid and enduring, anything in the sky that does not change like the clouds of the sky.”
—Gilbert Keith Chesterton (1874–1936)
“I count him a great man who inhabits a higher sphere of thought, into which other men rise with labor and difficulty; he has but to open his eyes to see things in a true light, and in large relations; whilst they must make painful corrections, and keep a vigilant eye on many sources of error.”
—Ralph Waldo Emerson (1803–1882)
“The bite of existence did not cut into one in Hollywood ....”
—Mae West (1892–1980)
“He suggested that there might be men of genius in the lowest grades of life, however permanently humble and illiterate, who take their own view always, or do not pretend to see at all; who are as bottomless even as Walden Pond was thought to be, though they may be dark and muddy.”
—Henry David Thoreau (1817–1862)