Transcript Mineral Resources

1. Mineral Resources
Environmental Studies - Unit 2
Lesson 1
Objectives
• To know the structure of the Earth
• To be able to list minerals that can be
extracted from the Earth’s Crust.
• To recap the rock cycle
The Earth
Resources from the Earth
There are a variety of natural resources taken from the Earth’s Crust including.
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Fossil Fuels
Metals
Non Metal Materials
Rock Cycle
Sedimentary Processes
Alluvial /
Placer Deposit
Evaporites
Biological Deposits
• Chalks and limestone
are formed from the
Calcium carbonate
shells of organims
• Fossil fuels are formed
from the build up of
organic matter,
compressed in anerobic
conditions.
Chemical Precipitation
Manganese Nodule
Formed by the precipitation of the
substance from sea water. This is a
very slow process taking millions of
years.
Metamorphic Rock
Intrusive Igneous - Batholiths
2. Mineral Resources
Environmental Studies – Unit 2
Lesson 2
What do you know about the
following???
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Oil
Iron
Aluminium
Diamond
Gold Prices
Other Metals
BHP Share Price
Resources, reserves and
Exploitation
• Minerals are non-renewable resources because the amounts
that exist are finite although most are very abundant.
• Economically recoverable resources account for a tiny
proportion of the total that exists.
• The main limitations on mineral availability are the locations,
chemical form and purity of the deposits, and the availability
of technologies to exploit them.
• Their exploitation is economically important but can cause
environmental damage.
Lead Ore
Resources and Reserves
– Resources include all the material which is theoretically available for
exploitation.
• This includes deposits that cannot be exploited now. eg too deep, low
grade, unusable chemical form, prohibitive land use conflict
– Reserves include that portion of the resource which can be exploited
now, economically, using existing technology.
The size of a resource is finite but the quantity included in the reserves can
change.
– eg the reserves will increase if there is an increase in market price or if new extraction
technologies are developed. If market prices drop then reserves may decrease.
Sources and Demand
Factors affecting the viability of exploiting mineral deposits
1.
Extraction costs
• Affected by depth, overburden quality, drainage problems, size of deposit.
2.
Processing costs
• The cost of extracting a metal depends upon the other elements with which it is
combined.
– eg aluminium is most abundant in clay but can only be economically extracted
from bauxite
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4.
Purity
The financial cost, energy required and quantity of ore-bearing rock
extracted all increase rapidly as ore purity decreases.
Factors affecting the viability of exploiting
mineral deposits
5.
Land conflicts
Competing land uses may be considered
more important or valuable than mining.
E.g. urban areas, conservation of
landscape or wildlife.
6. Transport costs
These are affected by the distance to
market, the ease of bulk transport and the
presence of a suitable existing transport
infrastructure.
Factors affecting the viability of
exploiting mineral deposits
7. Market economics
The market demand and sale value of the minerals control the
economic viability of exploiting a particular mineral deposit.
The cut-off ore grade is the lowest ore purity that can be
exploited economically.
Mineral Resources
Environmental Studies – Unit 2
Lesson 3
The Environmental Impact of
Mineral Exploitation
Exploration, extraction and processing all cause
significant environmental damage. A range of methods
may be used to reduce these.
www.goodquarry.com
Exploration
• Marine seismic surveys
affects whales.
• Exploration on land
causes vegetation loss.
http://www.smh.com.au/news/whale-watch/blue-whales-faceseismic-upset-when-feeding/2008/01/08/1199554655598.html
Land take
Extraction may
cause conflicts with
existing land uses.
Minerals can only be exploited where they are
found. This makes land use conflicts more likely
as there is a limited choice of locations that can
be exploited.
Habitat loss
• The loss of the species where the mineral is to be extracted is
unavoidable.
• Removing the wildlife by capturing the animals and
transplanting the plants to move them to unthreatened
habitats has been attempted but is rarely completely
successful.
• Habitat restoration when mining has ended is often carried
out.
Loss of Amenity
Mining may cause aesthetic problems for local
communities.
This may be
reduced by
landscaping and
tree planting.
Air Pollution
Dust, reduced by water
sprays.
Noise, reduced by baffle
mounds and restricted
times for blasting.
Water Pollution
• Turbid drainage
water, reduced by
sedimentation
lagoons and filtration.
• Toxic leachate,
reduced by chemical
treatment.
Spoil Disposal
• Spoil instability
can cause
landslides or
erosion.
• It can be
reduced by
drainage,
compaction and
landscaping.
Transport nuisance
• Mineral transportation can produce noise, fumes, dust and
cause traffic accidents.
• These can be reduced by water sprays and careful route
choices.
Flooding can
be caused by
drainage
water
The risk can be
reduced by
containment in
lagoons behind wellconstructed dams with
carefully timed
releases.
Subsidence
• This is caused by poor spoil compaction or
undermining.
• It can be reduced by compaction of spoil and
leaving support pillars in deep mines
Turbid Drainage Water
• Drainage water from mines or ore processing can
smother aquatic plants and silt up rivers.
• This can be reduced by building sedimentation
lagoons.
Toxic Leachate
• Water draining from spoil heaps may contain
toxic metals.
• This may be reduced by collection and
chemical treatment.
The Future of Mineral Supplies
Environmental Studies – Unit 2
Lesson 4
The future of Mineral Supplies
Reserves of exploitable minerals are finite. They are nonrenewable resources. A range of methods may be used to extend
the time period in which they may be exploited.
More exploration
• In previously unexplored areas, e.g. remote areas/areas with
difficult conditions.
eg Antarctic;
Deep ocean floor for manganese nodules
Better Exploratory techniques
Remote sensing
– eg Satellite surveys – allow rapid aerial photography of large areas of
land Geophysical techniques
– seismic surveys – echoes of surface vibrations provide information on
depth, angle, density and thickness of rock strata.
– Gravimetry – the strength of gravity provides information on the
density of rocks. Igneous rocks are usually more dense than
sedimentary rocks.
– Magnetometry – the strength of magnetism helps to detect magnetic
rocks, eg iron ores.
Better Mechanised Mining
Techniques
Better/more mechanised mining techniques
• eg larger excavators which can dig deeper into
the ground
Use of low-grade ores
Electrolysis of spoil heap leachate to remove
copper; bacterial recovery from disused mine
spoil
Recycling
• to make used materials into
a new resource.
– eg melting of scrap metals
and glass;
– crushing of used concrete
Substitution
• The use of alternative more abundant
materials.
• eg plastic pipes instead of copper;
• fibre-optics instead of copper for
telecommunications