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Copper's chain is a purification story. The ore is under one percent metal; the finished product is 99.99%. Between them sit flotation, smelting, converting and electrorefining — and a smelter fleet that sits mostly on a different continent from the mines.
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Porphyry copper system
A cooling granite intrusion cracks the rock above it and copper-bearing fluids precipitate sulfides through a huge, low-grade volume.
Escondida or Bingham Canyon
Hundreds of thousands of tonnes of rock are moved per day. Sulfide ore is crushed, ground and floated to about 30% copper.
Catatan: Around 99.7% of the mined rock becomes waste or tailings.
Smelter
Concentrate is melted with oxygen. Iron and sulfur burn off; the sulfur is captured as sulfuric acid rather than released.
Catatan: Blister copper is about 98% pure.
Electrorefining
Impure anodes dissolve and pure copper plates onto cathodes over about two weeks. Gold, silver, selenium, tellurium and platinum-group metals settle out as anode slime.
Catatan: This single step is where a large share of world tellurium and selenium supply originates.
Rod, wire and cable
Cathode is melted and drawn into rod, then wire, then insulated cable.
