Environmental management IGCSE,chapter 1 ROCKS AND MINERALS AND THEIR EXPLOITATION.

The rock cycle

a representation of the changes between
the three rock types and the processes causing

Types of rocks

Igneous rocks,Sedimentary rocks and Metamorphic rocks

what are Igneous rocks?

Made when liquid magma cools to form solid rock.
▪ Molten rock below the surface is called magma, and
lava when it reaches the surface.

what are the two types of Igneous rocks?

°Extrusive igneous rock
and
°Intrusive igneous rock

How are extrusive Igneous rocks formed?

▪If the rock cools quickly,
small crystals are formed e.g. basalt.

How are intrusive rocks ?

▪ If the rock cools slowly, large
crystals are formed e.g. granite.

What are sedimentary rocks ?

Formed by the weathering of existing rocks at the
Earth's surface.
▪ Fossils may be present.

What are sediments ?

Sediments (small particles of rocks) accumulate into
layers and get pressurised due to the newer deposits
above them.
▪ The sediments are transported by water and wind
(erosion).
▪ Particles like clays, silts, sands, gravels and small
boulders are found in sediments.
▪ Examples: limestone, sandstone and shale.

What are metamorphic rocks ?

Formed from existing rock when heat and/or
pressure causes changes in the rock crystals without
melting it.
▪ The changes can be physical, chemical or both.
▪ Examples: marble and slate.

Extraction of rocks and minerals from
the Earth

Exploring for minerals

What is Prospecting?

This is a process of
searching for minerals by
examining the surface of
the rocks.

What is remote sensing?

a
process in which information is gathered about the
Earth's surface from above.
▪ Photographs of the area are taken from air.
▪ The images are carefully analysed for mineral
presence.
▪ Aerial photography can cover more ground than a
person on the surface.

What is radiation detection

▪ Mineral deposits are weathered at the Earth's
surface, forming mineral oxides.
▪ They can be detected by their unique radiation
pattern (recorded by a satellite and downloaded to a
computer for analysis).

Satellite signals

▪ Some satellites send signals to the Earth's surface
and collect the reflected signals, indicating the
presence of minerals.
▪ The system works in all weather conditions

Satellite images

▪ Computers are used to process the data from a
region of interest to check for mineral presence.
▪ Geologists confirm the presence of the mineral by
visiting the location
(recorded by the
satellite's positioning
system).
▪ Geologists can further
check the availability of
the mineral in nearby areas.
▪ Using satellites saves time and costs less.

What are the ecological impacts of mineral extraction?

▪ Loss of habitat as the vegetation is cleared ؞ plants
do not have a place to grow, so the animals
depending on them for food and shelter are
affected.
▪ After deep mining has been working for several
years, more habitats will be destroyed due to the
increased overburden aboveground.

How does mineral extraction cause pollution?

▪ Noise pollution: due to machinery and explosives ؞
disturbs the behaviour of animal species and causes
hearing problems for people.
▪ Water pollution: water supplies may also be
polluted, making it unsafe for people to drink.
▪ The water may become acidic and dissolve toxic metal ions-this combination kills many aquatic
organisms.
▪ Land pollution: toxic nature of the waste doesn't
allow plant growth even years after the mining is
stopped.
▪ Air pollution: dust particles settle on the vegetation,
not allowing sunlight to reach the leaves and thus,
reducing the rate of photosynthesis.
▪ Breathing in dust that remains in the lungs can cause
serious lung diseases.
▪ Visual pollution: landscape is damaged.

Bioaccumulation

organisms absorb the ions and
retain them in their body, reaching concentration
higher than that in water.

Biomagnification

The concentrations of ions increase
higher up in the food chain and cause the death of
top consumers.

Economic impacts of mineral extraction

o The income earned can be used for buying goods and
services and investing in infrastructure projects.
o Provides employment for people and taxes for the
government.

How is employment created

▪ Jobs are created directly to extract the mineral;
▪ Further jobs are created to supply transport and
mining equipment;
▪ More jobs are created when the mineral is refined
to make products;
▪ If all these activities occur in the same country, it will
generate the most income;
▪ Earn foreign exchange.

How should the impact of rock and mineral extraction be managed ?

• Safe disposal of mining waste
• Land restoration
• Bioremediation
• Making lakes and natural reserves
• Using as landfill sites

How can mine waste be safely disposed

o Mine waste must be stored to prevent collapse.
o Site of the mine must prevent the chances of water
pollution.
o The waste must be monitored to detect any
movement or further pollution.

How can land be restored

• Land restoration:
o Soil improvement:
▪ After (sanitary) landfilling, mine waste can be
covered by a
layer of soil,
that can be
enriched with
fertilisers.
o Tree planting:
▪ After improving the soil fertility, plants and trees can
be grown in that area, helping an ecosystem to be
reborn.

What is Bioremediation ?

This is a process of removing pollutants from
waste using living organisms.

What is in situ treatment

o In situ treatment: treatment of contaminated waste
where it's left.

What is ex situ

o Ex situ treatment: removal of contaminated waste from a site to a treatment plant.
o Often happens
slowly (can be sped
up by providing
oxygen and
nitrogen).
o Microorganisms, like bacteria, can absorb pollutants
and metabolise them into less harmful substances.
o Some plants have the ability to bioaccumulate toxic
metals.
o After these plants grows for a while, the parts of the
plants aboveground are removed so the waste in the
ground becomes less toxic.

How are lakes and natural reserves made after mineral extraction?

o Several tree and herb species are introduced.
o As their populations grow, they create habitats for
many species.
o These nature reserves become valuable green spaces
for human recreation and help in maintaining
biodiversity.
o If the rock lining the hole (created by the extraction) is
non-toxic and impervious to water, it can be filled with
water to form a reservoir or lake.
o It is used for irrigating farmland or processed to
provide clean, safe drinking water for humans.

How are landfilled sites created after mineral extraction?

o Landfilling: the waste is tipped into a hole; from time
to time it is levelled off and compacted.
o Sanitary landfilling: As in landfilling, the waste is used
to fill the hole, but alternating layers of waste and sand
are used.

Sustainable use of rocks and minerals

continuously replenishment of rocks

What is geochemical analysis

This is analysing the chemical
properties of rocks (by taking samples).
▪ The samples can be taken from stream sediments,soil or rocks (using shallow drilling).
▪ The location of the sample points can be accurately
found using the Global Positioning System (GPS).

What is Geophysics?

The method to identify mineral ores present
in rocks using their physical properties.
▪ A series of vibrations (seismic waves) are sent
through the Earth's surface.
▪ Several sensors are
placed at different
distances from the
source of
vibrations on the
surface.
▪ The vibrations create shock waves that travel down
into the rock layers.
▪ They are reflected back to the sensors on the
surface.
▪ The shock waves record different patterns
depending on the mineral present in the rock layers.

Methods of extraction

ways in which rocks are extracted from the Earth's surface

Surface mining

includes open-cast (open-pit, open-
cut) and strip mining.

What is open-pit mining

Open-pit mining is used
when a valuable
deposit is located near
the surface.
▪ The vegetation is
cleared and topsoil removed.
▪ The rocks are broken
up and loosened with
explosives.
▪ The loose rock is
removed using
diggers.
▪ The rock or mineral is
tipped into trucks or
railway wagons.
▪ Building materials
such as sand, gravel
and stone are removed from open pits called
quarries.
▪ Strip mining is used to mine a seam of mineral.
▪ The overburden
(overlying rock and
soil) is removed as a
thin strip.
▪ It is mainly used to
mine coal.

How does open-pit mining work?

▪ The vegetation is
cleared and topsoil removed.
▪ The rocks are broken
up and loosened with
explosives.
▪ The loose rock is
removed using
diggers.
▪ The rock or mineral is
tipped into trucks or railway wagons.
▪ Building materials
such as sand, gravel
and stone are removed from open pits called
quarries.

Strip mining

Strip mining is used to mine a seam of mineral.
▪ The overburden
(overlying rock and
soil) is removed as a
thin strip.
▪ It is mainly used to
mine coal

What is Sub-surface mining?

This is a mining method which includes deep and shaft mining.
▪ A vertical shaft is sunk down to the rock layer containing minerals.
▪ A horizontal tunnel is
made, following the
mineral layer.
▪ The minerals are
extracted by digging
(by machines and
miners).
▪ The loose rock is brought from the mine and piled
up on waste heaps on the surface.
▪ The minerals are brought to the surface and
transported in trucks or trains.

What are the factors that affect the decision to extract rocks and
minerals?

The costs of exploration and extraction,
Geology,Accessibility,supply and demand,Environmental impact assessment.

The costs of exploration and extraction

Probable cost of extracting one tonne is calculated.
▪ There are fewer technical difficulties of mining on a
large scale using open-pit mining as there'd be low
extraction costs per tonne.
▪ Shaft mining is costlier to set up and maintain as the
cost per tonne will be higher. So, only deposits of
higher value can be mined in this way.

Geology

High-grade ores yield more of the required chemical
elements than low-grade ores.
▪ Small deposits of high-grade ore are worth mining.
▪ Small deposits of low-grade ore that cannot be
mined at a profit are left as reserves.

Accessibility

Transporting the ore from the mine to processing
plants can be difficult and expensive.
▪ The cost of building road or rail links to the
processing plant or to the nearest port for export
has to be considered.
▪ Carrying out some processing at the mine reduces
transport costs.
▪ The mining company must be given a licence before
extracting a deposit.
▪ A long-term agreement between the government
and mining company must be reached to avoid rapid
rises in the tax, which makes the mining
unprofitable.

Supply and demand

the relation between how much
of a commodity is available and how much is needed or
wanted by the consumers.
▪ Increase in world demand for any mineral ore will
elevate the prices.
▪ The profit from a working mine depends on changes
in supply and demand.
▪ If the demand is too high, mines that were not
profitable before become worth mining.
▪ If the demand falls, working mines may get into a
loss due to the transport and extraction expenses.

Environmental impact assessment

▪ For a licence application to be approved, the
company must have a plan to keep the loss of
habitat minimal, followed by the restoration of land
proceeding the completion of mining.
▪ The choice of site for mine waste should also be
considered.

Impact of rock and mineral extraction

after math of mining

Environmental impacts of mineral extraction

o Ecological impacts
o Pollution
o Bioaccumulation
o Biomagnification

What is a sustainable resource?

• Sustainable resource: a resource that can be
continuously replenished e.g. agriculture, forestry, etc.

What is sustainable development?

• Sustainable development:development that meets the
needs of the present, without compromising the ability
of future generations to meet their own needs.

What are the strategies for the sustainable use of rocks and minerals?

o Increasing the efficiency of the extraction of rocks
and minerals
o The need to recycle rocks and minerals
o Legislation

How can the efficiency of the extraction of rocks be increased?

▪ Mine wastes must be processed for the second time.
▪ This allows the valuable minerals to be recovered
and reduces the risk of pollution due to mine waste.
▪ Chemical treatment of the waste and biological
treatment (using
microorganisms) extracts much of
the valuable mineral still within it.
▪ Improvements in the performance of the machines
used in mining and processing.
▪ Greater use of data analysis by computers (to
predict geological conditions).

How can the efficiency of the use of rocks and minerals be increased?

▪ Engineering solutions e.g. design steel beams with
same strength but using less steel.

How can recycling rocks and minerals be sustainable?

▪ Recycling uses less energy than processing the ores.
▪ Recycling also produces less waste and thus, reduces
the risk of pollution.

How can legislation improve sustainability

▪ The governments pass laws that require
manufacturers to become responsible for recycling
and reuse.