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Useful metals come from rocks and
minerals in the Earth’s crust.
Metals-1-1
Mining of metal-bearing rocks also
requires removing less valuable rocks waste rocks.
Metals-1-2
Separating metal-bearing
minerals from others produces
waste called “tailings”.
Metals-1-3
Environmentally sound disposal of
waste rock and tailings is needed to
protect soil and water resources.
Before
After
Metals-1-4
Environmentally sound disposal of
waste rock and tailings commonly uses
soil covers that prevent erosion and
development of acidic waters (acid
rock drainage).
Revegetated Pile Surface
Soil Growth Medium
Uncompacted Lime - amended wasterock
12”
12”
Compacted consolidated wasterock
Metals-1-5
In some cases, covering tailings with
water prevents acid rock drainage
and creates valuable habitat.
Before
After
Metals-1-6
Historically, mineral processing to recover
metals from minerals emitted large amounts
of harmful gases and particles to the
atmosphere.
Metals-1-7
Modern facilities to recover
metals from minerals use new
technology that reduces
Discharges at Kennecott
emissions below those
smelter in Utah.
Comparison units in metric tonnes.
permitted by regulatory
Acid Mist – 151
Acid Mist – 48
agencies.
Particulates – 728
Particulates – 400
SO2 - 20,050
SO2 – 982
1992
Modernized
(Permitted) Smelter
Metals-1-8
Metals we need can be provided
in environmentally sound ways.
Metals-1-9