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:
“New York is the meeting place of the peoples, the only city where you can hardly find a typical American.”
—Djuna Barnes (1892–1982)
“Agnosticism is a perfectly respectable and tenable philosophical position; it is not dogmatic and makes no pronouncements about the ultimate truths of the universe. It remains open to evidence and persuasion; lacking faith, it nevertheless does not deride faith. Atheism, on the other hand, is as unyielding and dogmatic about religious belief as true believers are about heathens. It tries to use reason to demolish a structure that is not built upon reason.”
—Sydney J. Harris (1917–1986)
“I say to myself that I mustn’t let myself be cut off in there, and yet the moment I enter my bag is taken out of my hand, I’m pushed in, shepherded, nursed and above all cut off, alone. Whitehall envelops me.”
—Richard Crossman (1907–1974)
“There are no grades of vanity, there are only grades of ability in concealing it.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)