Lithosphere Flashcards
What is an In Situ resource?
a resource that is extracted from where it is made
What happens to an In Situ resource as it is extracted
it is depleted UNLESS they are made rapidly
How long do most geological, resource making processes take?
thousands/millions of years
Give examples of In Situ resources that are:
a) formed slowly
b) formed faster
a) fossil fuels
metal ores
rocks
b) sand
gravel
What are the three main rock types and how can we generally identify them?
Sedimentary - has layers/fossils/clasts
Igneous - crystalline
Metamorphic - changed by heat and/or pressure, also has layering/folding
Give two example metals extracted from the crust, their global annual production in tonnes, and examples of their major uses
- Iron
1700 million tonnes
Buildings: girders
Transport: ships
Appliance casing: fridges - Copper
19 million tonnes
Electric cables, water pipes
Give two examples of minerals/materials extracted from the crust, their global annual production in tonnes, and examples of their major uses
- Limestone
600 million tonnes
Cement
Building blocks - Aggregates (sand/gravel)
40 billion tonnes
Concrete
Building mortar
Glass
What are igneous processes?
the processes by which rocks and minerals are created by the cooling and hardening of magma or molten
What can igneous processes create?
mineral veins
Give an example of an igneous process
Hydrothermal deposition
How does hydrothermal deposition work?
- Igneous intrusion produces pressurised superheated water at high temps
- That water dissolved many minerals from the surrounding rock
- The mineral-rich solutions travel along fissures away from the igneous batholith, and cool
- As they cool, dissolved minerals come out of solution (crystallise) in order of solubility
Why is hydrothermal deposition useful?
Before solution and crystallisation, it is just a mixture of minerals that cannot be exploited
- soon after the batholith forms, minerals separate and deposit, and exploitation becomes possible
Give some examples of metal ores deposited by hydrothermal processes
tin
copper
lead
silver
gold
arseinc
What is an ore?
naturally occurring solid material from which a metal or valuable mineral can be profitably extracted
a rock that contains a significant quantity of ore minerals/rock with a relatively high concentration of a particular metal
Give an example of a valuable mineral in a vein
Gold
Silver
Lead ore
What are metamorphic processes?
give examples
when igneous processes and tectonic movements of crustal plates alter existing igneous/sedimentary rocks with high temp and/or pressure
e.g. limestone to marble, mudstone to shale
What are sedimentary processes?
Where minerals settle and build up to produce layers of sediment
The deposition and cementation at the Earth’s surface and in water bodies creates sedimentary rocks/minerals
What are the four sedimentary deposits?
- Proterozoic Marine Sediments (banded iron deposits)
- Alluvial deposits
- Biological sediments
- Evaporites
What are Proterozoic Marine Sediments?
- Where iron ore deposits form when dissolved iron compounds became oxidised by oxygen released
- due to the abundance of photosynthesising organisms
- between 2.5 and 1.8 million years ago
What are Alluvial deposits?
Give some examples
- ancient ore veins eroded by flowing water (e.g. rivers) and deposited in river sand and gravel
- the ability of the water to carry solids depends on velocity of water and density of solids
- gold, diamonds, tin ore
What are Evaporites?
Give an example
- when ancient seas become isolated, water evaporates leaving crystallised minerals
- also forms in inland seas in desert areas due to river evaporation
- halite (sodium chloride)
What are biological sediments?
- where living organisms form the mineral deposits e.g. shells, guano, plankton, dead plants
- the processes concentrate minerals that are then deposited in sedimentary rocks
What biological material forms:
a) limestone and chalk
b) coal
c) crude oil and natural gas
a) shells of marine organisms
b) terrestrial vegetation
c) marine organisms
What is secondary enrichment?
- if the initial mineral was soluble, it may dissolve from one rock, and move through the groundwater to a new place
- the groundwater leaches and oxidises primary ores, adding O2, OH, CO2
- as oxidation state changes, it gets deposited
- creates ores 10x richer than the original
Give some secondary ores created by secondary enrichment that are prized
Turquoise
Malachite
Azurite
What is weathering?
The break down of rocks in situ by ice, water, temperature and organisms
What are the types of weathering?
Physical/Mechanical
Biological
Chemical
What is physical/mechanical weathering?
the disintegration of rocks into smaller pieces by mechanical processes without any change in the chemical composition
What are the types of physical weathering?
Frost shattering (FTA) in cold environments
Exfoliation in environments with temperature extremes
What is biological weathering?
the disintegration of a rock due to biological action
Give examples of biological weathering
- biota (e.g. rabbits, earthworms, birds) burrow into the soil which exposes a larger surface area of the rock - leaves vulnerable for more weathering
- large roots penetrate and force their way through - forces cracks in the rocks to get bigger and increases surface area for water to enter - breaks up the edge of a cliff
What is chemical weathering?
the disintegration of a rock via chemical reactions as a result of either the input of water or humic acid
What influences chemical weathering?
climate - extreme temp/high levels of rainfall can increase chemical weathering
Outline an example of chemical weathering
- Rainwater contains dissolved CO2 - makes carbonic acid (H2CO3)
- Weak acid reacts with rocks composed of calcium carbonate (limestone)
- Limestone dissolves
- Calcium carbonate is removed in solution
What are the two types of igneous rock?
Intrusive
Extrusive
How do intrusive rocks form?
Give an example
magma cools slowly underground, there is more time for crystals to grow
e.g. granite
How do extrusive rocks form?
Give an example
magma cools quickly on the surface of the Earth’s crust (in a lave flow), then there is no time for crystals to grow so the crystals are very small
e.g. Basalt
How is sedimentary rock formed?
- previous rock is weathered and eroded and the particles are transported and deposited
- as the loose sediment is buried, the layers are under a huge pressure and this binds them together to form a rock
physical pressure fusing grains together = compaction
if minerals are precipitated into spaces = cementation
How do metamorphic rocks form?
- sedimentary rock = buried
- intense heat/pressure exerted
- rock recrystallises to form a new metamorphic rock
How do rocks recrystallise?
What differences will there be?
Give examples
They become semi molten, then the minerals recrystallise and interlock
They will be much stronger than they were before
e.g. marble = metamorphosed limestone
e.g. slate = metamorphose clay/mudstone
What is a resource?
All of the material theoretically available for exploitation
Includes reserves plus those that cannot yet be exploited
- FINITE
What is a stock/resource base?
All of the material in the lithosphere - including the minerals that can be exploited now/may be exploited in the future/never be economically exploitable
What is a reserve?
The amount of resource that can be economically exploited now using existing technology
- frequently changes
Give three examples of reasons why reserves may fluctuate
Market price - increase=increase
Extraction tech - economically viable = increase
COOG - increase=decrease
How can reserves be categorised?
Inferred reserves
Probable reserves
Proven reserves
What is an inferred reserve?
Where the presence of the mineral can be predicted from knowledge of present geological structures but you don’t know enough to estimate the economically extractable amount
What is a probable reserve?
Where sufficient information about the deposit is known so you can sufficiently accurately estimate the amount that can be economically extracted, justifying further exploitation
What is a proven resource?
Where you have already carried sufficient exploration (including trial drilling) to accurately estimate the amount of mineral to be economically extracted
What factors influence the viability of exploitation? (3)
absence of tech to exploit it
financial cost = too much
env. impact = unacceptable
What is Lasky’s principle?
As the purity of a mineral decreases, the amount of the mineral present increases exponentially
What is the problem for future reserves?
We need to develop better tech/exploitation methods, the quantity of the ore is not the issue
Why do we use arbitrary units?
Whatever the units, the trend will be the same
Allows comparison
What are the two types of mineral exploitation graphs?
linear-linear
logarithmic-linear
Which graph is more accurate, lin-lin or log-lin?
Log-lin
We can read more accurate data points, and be more specific (accurate)
What are the mineral exploitation methods?
Infrared spectroscopy
Gravimetry
Magnetometry
Seismic surveys
Resistivity
X-ray fluorescence
Trial drilling
Chemical analysis
How does IR spectroscopy work?
Images taken by satellite/plane in the IR spectrum can give info about surface geology, as different minerals emit different wavelengths of IR
Pros and cons of IR spectroscopy?
- Fast
- Non-destructive
- Limited - cannot provide full structural info
- Water skews it
How does gravimetry work?
measures small changes in gravity caused by changes in density in the rock
carried out by hand/plane
ign rocks more dense than sed rocks
Pros and cons of gravimetry
- Allows specific identification of geological features
- Determines purity
- Time consuming/difficult to master
- Expensive
How does magnetometry work?
measures changes in the ambient magnetic field caused by contrasts in magnetic susceptibility
sensitive to more magnetic rocks/ferrous metals like ones containing magnetite, tungsten, cobalt
carried out by hand/plane
What is magnetic susceptibility?
the ability of a substance to take on an induced magnetism caused by it’s immersion in Earth’s magnetic field
directly proportional to iron content e.g. haematite/magnetite
Why is magnetometry a staple in mining exploration?
Iron is often present in accumulations of non-ferrous ores (because it’s risen from the core etc)
Pros and cons of magnetometry?
- Equipment easy to use/transport
- Not impacted by interference that other
geophysical methods are - Difficult to estimate depth
- Skilled people are needed to use the data and configure results etc
How do seismic surveys work? (general)
reliant on sound waves produced by controlled explosions or a seismic vibrator on the surface
uses the echos to give info on depth, density, shape of rock strata
Describe the process of seismic surveys
- Loud noise/vibration produced by striking the surface/explosives
- Vibration passes through the rock and is reflected by changes in density
- Returning vibrations are detected by geophones
- converted into voltage which is then recorded at a recording station
Can also be done under the sea by survey ships/hydrophones
Pros and cons of seismic surveys
- Gives many useful data in just one survey
- gives superior results where large velocity contrasts exist
- cannot image a low-velocity layer e.g. sand below clay
- cannot image thin, high-velocity layers
How does resistivity measuring work? (general)
It measures the resistance of the rocks or ground beneath electrodes to show changes in the rock strata
some rocks are less resistant to electrical current e.g. if they contain water or iron
sed rocks have a lower resistance than ig rocks because they have higher water contents
Describe the process of resistivity measuring
electrodes are placed in a transect and a current is passed between each electrode and the resistance is recorded for each one
What is resistivity?
the measurement of the difficulty with which electricity passes through material
Pros and cons of resistivity measuring
- low cost due to speed and efficiency
- minimal ground disturbance/non invasive
- condition dependent: space, cables etc
- can be easily complicated by external factors e.g. noise
How does X-ray fluorescence work?
an X-ray is emitted towards a rock sample, causing the atoms in the rock to become excited and release an X-ray back
by measuring the returning X-rays you can calculate the composition of the rock
Pros and cons of X-ray fluorescence
- high resolution means it can analyse complex samples
- fast and non destructive
- limitations on measuring lighter elements
- high accuracy requires a similar and suitable reference standard to be compared to
How does trial drilling work?
Where a core sample of he rock is taken and the purity of the ore found can be removed and measured in a laboratory
Pros and cons of trial drilling
- only way to confirm exactly how big and rich a deposit is
- work can be carried out relatively quickly
- high level of surface disturbance and potential for wall collapse
- most expensive form of mineral deposit detection
How does chemical analysis work?
Laboratory tests confirm the chemical composition and purity of the mineral in rock samples
Pros and cons of chemical analysis
- ID of minerals
- quite accurate
- cost
- need for specific expertise and a lab, so time consuming in that way`
What factors affect mining viability?
Mining costs: depth, overburden, hydrology
Processing costs
Transport costs
Land costs
Chemical form
Purity
COOG
Market economics
How do mining costs affect mining viability?
Depth:
- depth doubles, cost more than doubles
- mine sides cannot be vertical due to collapse
- depth increases = water runoff increases = pumping costs increases
Overburden:
- Hard = needs blasting
- Loose = landslide risk = gentle gradient mine = larger area
- ALL INCREASE COST
Hydrology:
- drainage costs increase if high precipitation or impermeable rock below the mine
Is the deposit concentrated or disseminated? That will affect the cost due to area
How do processing costs affect mining viability?
Removal of:
- waste rock
- overburden
increases costs depending on volume
How does chemical form affect mining viability?
- affects ease of abstraction
e.g. Aluminium from bauxite = easy
Aluminium from clay = hard but more abundant - crushing requirements
- electrolysis requirements
How does purity affect mining viability?
- affects extraction cost and environmental impacts
- greater purity = comparatively low processing costs
- low purity:
more rock needed
more waste/spoil generated
more energy required for mining/processing
more pollution generated
How do land costs affect mining viability?
State: derelict will be cheaper than prime agricultural land
Buying: whos land is it?
How do transport costs affect mining viability?
- distance
- bulk/weight, has it been reduced by processing
- presence of existing infrastructure
- ease of bulk transport
(both ore and waste rock)
How does COOG affect mining viability?
MINING MUST BE PROFITABLE
- has to be a balance between production cost and income
- COOG changes as technology improves/becomes available and prices fluctuate
Higher market price: COOG decreases
Lower market price: COOG increases
Improved extraction technology: COOG decreases
Higher energy cost: COOG increases
What is COOG?
Cut-Off Ore Grade
The lowest ore purity that can be mined economically, using existing technology
Mineral reserves include deposits above the COOG
How does market economics affect mining viability?
- controls specific exploitation viability
- controlled by demand, volume produced, cost of extraction/processing
- demand rises/falls quickly
- supply increases slowly
- no match = wild price fluctuation = difficult to predict future markets
- exploiting places is beneficial is they already have:
infrastructure
tech
transport
energy
equip supplies
a trained workforce
What are the environmental impacts of mineral exploitation?
land take
noise
dust
water pollution/turbid drainage water
habitat loss
loss of amenity
spoil disposal
mine site restoration
How much of the Earth’s land surface has ever been mined?
1%
Why do we need to develop new technologies/exploratory techniques that allow us to access future mineral supplies?
Future supplies will be more difficult to exploit as we have previously exploited the large, easy to access, shallow, high grade deposits first.
Rising prices due to demand will reduce the COOG so it will be economically viable to exploit lower grade ores.
What do we need to do to ensure we can maintain future mineral supplies?
Improve exploratory techniques
Improve exploitation methods
Exploit low grade deposits
Exploit previously inaccessible deposits
Recycling
What improvements can be made in exploratory techniques?
- Better remote sensing image resolution
- Portable field equipment
What is better remote sensing image resolution?
Give an example
Where newer satelites carry improved sensors which generate bigger numbers of image pixels
e.g. The Landsat 8 satellite carries 2 sensors that collect visible light and infrared images of the Earth’s surface every 16 days
How is having better remote sensing image resolution beneficial?
Multi-spectral sensors detect a greater range of wavelengths of visible and infrared light, giving more detailed info on Earth’s surface mineral composition
What is portable field equipment?
Give an example
Where lab equipment has become smaller and more movable due to:
- lighter electronic components
- more powerful batteries
- reduced energy consumption
e.g. IR spectroscopy, X-ray fluorescence, radiation detection
Why is having portable field equipment beneficial?
- convenient
- saves time (results are available immediately and do not have to wait for lab results to be received)
What improvements can be made in exploitation methods?
Mechanisation
- deep mining
- open cast mining
Exploitation of low grade deposits
What is deep-(shaft) mining also known as?
underground mining
audit mining
How can mechanisation of deep mining be beneficial?
Give an example
machines can go into dangerous/hot spaces underground where humans cannot, so more mineral can be mined
e.g. Gold mines in S. Africa, 3.8km
How can the mechanisation of open cast mining be beneficial?
Give some machine stats
MACHINES:
Excavators can weigh over 13,000t
Trucks can carry up to 300t
- large machinery means overburden and minerals can be extracted quicker and more cost effectively
- large machinery means deeper open cast mines and be developed, with mines over 600m being possible for more valuable minerals
Why do we need to be able to exploit low-grade deposits?
- smelting (by chemical reduction) is very energy consuming and expensive
- as demand increases, purity of ore deposits declines
- cost of smelting increases as ore purity declines
- we need new methods that are not as energy consuming or require such high temps
What methods have been developed to extract low-grade ores?
Bioleaching
Phytomining
Iron Displacement
Leachate collection
Rare Earth Metal exploitation
Polymer adsorption
What resource could we exploit that was previously inaccessible?
Polymetallic nodules
What is recycling?
the process of converting waste materials into new materials and objects instead of using new resources/materials for manufacturing
What are the two categories of waste material that are recycled?
Pre consumer wastes
Post consumer wastes
What are pre consumer wastes?
What are they also known as?
Give an example
Materials that are recycled before they reach the consumer or are used in the manufacturing process
Also known as post industrial wastes
e.g. waste cuttings/trimmings from cutting/stamping machines
What are post consumer wastes?
Give an example
a waste type produced by consumers in the end of the product life cycle
e.g. any discarded consumer products, like plastic packaging
What has to happen before wastes can be recycled?
Give an example
They have to be separated, preventing quality reduction
e.g. plastic vs paper
What are the two types of recycling methods?
Roadside collection
e.g. paper+card
plastic
glass
garden waste
Local Recycling Centres
e.g. batteries
textiles
vehicle engine oil
building rubble
Does industry use recycling?
Give an example
Yes, but it is complex cost wise and effort wise
e.g. recycled vs raw aluminium for bikes
Give an example of when recycling is effective
Large urban areas:
consumers separate waste and large quantities of recyclable waste aluminium is produced .
Advs far outweigh disadvs
What is cradle to cradle design?
the design of products so the materials used are able to be reused at the end of their working life/useful life, encouraging a circular economy, extending the life cycle of products
What are the principles of cradle to cradle design?
- Nature system based: ‘nutrients’ in cycles
- efficiency
- lifespan of products
- essentially waste free - close loop system
What are the ‘nutrients’ in C2C design?
technical
biological
What are technical nutrients in C2C design?
non-toxic synthetic materials having no negative natural effects and can be used in the same continuous cycles without losing integrity/quality
- William McDonough and Michael Braungart
What are biological nutrients in C2C design?
organic materials that can be disposed of and decomposes with no negative effects on the natural environment
Give two examples of companies using C2C design
Method Home Care Products:
- eco-friendly cleaning products
- C2C in product formulations and packaging
- biodegradable, non toxic ingredients
- 100% recyclable/recycled plastic packaging
Park 20|20
- W.McD
- sustainable business park in Netherlands
- modular components for easy disassembly and reuse
- energy efficient systems
- green roofs
- water management strategies
- shows C2C in an urban scale, promoting healthy, resilient communities
What are the benefits of C2C design?
- reduced waste/pollution
- preserves nat resources
- reduces GGE though sust energy
- disposal vs raw cost savings
- new business opportunities
- increased comp increases brand drive
- improved health/QoL/wellbeing
- job creation
- community resilience and enhancement
What are the cons of C2C design?
- coordination for infra, edu, and policy
- gov and business collaborations
- needs mindset shifts
- overconsumption - ‘guilt-free’ sust or recyclability
- complex global supply chains - are things actually being recycled? lack of transparency and collaboration
What is the biological cycle of C2C?
consumption of products and materials
- product
- usage
- compost (after abrasion/wear debris)
- biological nutrient
- organic agriculture or forestry
- manufacturing
- product…
What is the technical cycle of C2C?
use of products and materials
- product
- usage
- collection
- disassembly and separation
- technical nutrient (can skip this step by direct reuse)
- manufacturing
- product…
