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1. Mineral Resources
Environmental Studies - Unit 2Lesson 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 EarthThere are a variety of natural resources taken from the Earth’s Crust including.
•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 PrecipitationManganese 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 2Lesson 2
What do you know about the following???
• 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 DemandFactors 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
3. Purity4. 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 conflictsCompeting land uses may be considered more important or valuable than mining. E.g. urban areas, conservation of landscape or wildlife.
6.Transport costsThese 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 economicsThe 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 2Lesson 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-face-seismic-upset-when-feeding/2008/01/08/1199554655598.html
Land take
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.
Extraction may cause conflicts with existing land uses.
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 AmenityMining 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 well-constructed 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 2Lesson 4
The future of Mineral Supplies
Reserves of exploitable minerals are finite. They are non-renewable 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 techniquesRemote 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
