Open-pit Mining - Typical Open Cut Grades

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

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