Environmental Engineering Reference
In-Depth Information
Science: Finding Substitutes for Scarce
Mineral Resources
Scientists and engineers are developing new types
of materials that can serve as substitutes for many
metals.
Some analysts believe that even if supplies of key min-
erals become too expensive or scarce, human ingenu-
ity will find substitutes. They point to the current
mate-
rials revolution
in which silicon and new materials, par-
ticularly ceramics and plastics, are being developed
and used as replacements for metals.
Ceramics offer many advantages over conven-
tional metals. They are harder, stronger, lighter, and
longer lasting than many metals, and they can with-
stand intense heat and do not corrode. Within a few
decades, scientists may develop high-temperature
ceramic superconductors in which electricity flows
without resistance. The result: faster computers, more
efficient power transmission, and affordable electro-
magnets for propelling high-speed magnetic levitation
trains.
High-strength plastics and composite materials
strengthened by lightweight carbon and glass fibers
are beginning to transform the automobile and aero-
space industries. They cost less to produce than metals
because they take less energy, do not need painting,
and can be molded into any shape. New plastics and
gels are also being developed to provide superinsula-
tion without taking up much space. Nanotechnology
may also lead to the development of materials that can
serve as substitutes for various minerals.
Substitutes exist for many scarce mineral re-
sources. Unfortunately, finding substitutes for some
key materials may prove difficult or impossible. Exam-
ples include helium, phosphorus for phosphate fertil-
izers, manganese for making steel, and copper for
wiring motors and generators.
In addition, some substitutes are inferior to the
minerals they replace. For example, aluminum could
replace copper in electrical wiring. But producing alu-
minum takes much more energy than producing cop-
per, and aluminum wiring is a greater fire hazard than
copper wiring.
Clearly, there are a number of exciting possibilities
and a number of environmental hazards involved in
extracting and using the nonrenewable mineral re-
sources that support our economies and provide us
with many useful materials and products.
Black
smoker
White
smoker
Sulfide
deposits
Magma
White clam
White
crab
Tube
worms
Figure 12-15
Natural capital:
hydrothermal ore deposits
form when mineral-rich superheated water shoots out of vents
in solidified magma on the ocean floor. After mixing with cold
seawater, black particles of metal ore precipitate out and build
up as chimneylike ore deposits around the vents. A variety of
organisms, supported by bacteria that produce food by
chemosynthesis, exist in the dark ocean around these black
smokers.
ocean floor and around black smokers (Figure 12-15).
Currently, it costs too much to extract these minerals,
even though some deposits contain large concentra-
tions of important metals.
Manganese-rich nodules found on the deep-ocean
floor may be a future source of manganese and other
key metals. They might be sucked up from the ocean
floor by giant vacuum pipes or scooped up by buckets
on a continuous cable operated by a mining ship.
So far these nodules and resource-rich mineral
beds in international waters have not been developed
because of high costs and squabbles over who owns
them and how any profits from extracting them
should be distributed among the world's nations.
Some environmental scientists believe seabed min-
ing probably would cause less environmental harm
than mining on land. They remain concerned that re-
moving seabed mineral deposits and dumping back
unwanted material will stir up ocean sediments, de-
stroy seafloor organisms, and have potentially harmful
effects on poorly understood ocean food webs and ma-
rine biodiversity. They call for more research to help
evaluate such possible effects.
Mineral resources are the building blocks on which modern
society depends. Knowledge of their physical nature and
origins, the web they weave between all aspects of human
society and the physical earth, can lay the foundations for a
sustainable society.
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