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From
Ores to Products
Geologists
look for signs and/or anomalies that would indicate the presence of a
mineral deposit. Under the right geological, economic, environmental,
and legal conditions, mining can proceed.
Copper-bearing
ores are extracted from the ground, crushed, and then processed into powder
to form concentrate (containing 18-45% Cu). Alternatively, copper can
be leached out of the rock or ore.
Minerals
can be processed into metal by two methods: leaching and electrowinning,
or by smelting and refining.
· Leaching
& Electrowinning:
Ores (primarily oxide, but occasionally sulfide minerals), and in some
instances tailings, are leached to produce a weak copper solution. The
weak solution is concentrated, using solvent-extraction techniques, and
an electrical current is applied to it. Copper is transferred from the
solution to starter sheets (cathodes) to produce refined copper. In some
processes, copper can be precipitated out of the weak solution to form
"cement copper", which must then be smelted and refined to remove
impurities.
· Smelting & Refining:
Copper ores and concentrates (and in some plants, scrap) are charged into
smelting furnaces (flash, reverberatory, electric, or blast), to separate
the copper from other materials, either in a single continuous process,
or in stages, to form blister (97-99%) copper. Blister copper is finally
transformed into refined copper by electrolytic means or by fire-refining.
Copper is shipped to fabricators mainly as cathode, wire rod, billet,
cake (slab), or ingot. Through extrusion, drawing, rolling, forging, melting,
electrolysis, or atomization, fabricators form wire, rod, tube, sheet,
plate, strip, castings, powder, and other shapes. These copper and copper-alloyed
products are then shipped for final manufacturing, or distribution, to
meet society's needs.
Scrap (including
excess material produced during manufacturing and copper-bearing products
sent for disposal) can be recycled back into the system.
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