The Lithosphere Flashcards
(16 cards)
Survey techniques for mineral exploration
Seismic surveys- sound waves send to the area, tells us into about depth density and shape of rock strata
Trail drilling-expensive but you get samples of rock
Chemical analysis-chemicals to confirm purity
IR spectroscopy-diffrent minerals emit IR at diffrent wavelengths
How does COOG change when
Market value increases
Market value decreases
Improved extraction tech
Higher energy costs
1) decreases
2) increases
3) decreases
4) increases
Environmental impacts of mineral exploration
Land take
Habitat loss
Loss of amenity(aesthetics)
Dust
Noise (baffle mounds to reduce this)
Exploration of low grade deposits
Bioleaching-living organisms extract the metals, acidophillic bacteria extract copper, zinc and lead and gold. The bacteria produce a leachate containing the ions
Photomining:plants absorb metal ions and concentrate them in the leaves, plant is then burnt and metals dissolved by acids and separated by electrolysis
Iron displacement: iron is more reactive than copper so iron will replace the copper in a solution and copper will be collected
Leachate collection: rainwater runs through spoil heaps dissolving metal ions - extracted via electrolysis
What are magneese nodules?
Metal rich module found on earths seabeds - most are 5-10cm in diameter
Contains 30% magnese with small amounts of other ions which as iron and copper
Hydrothermal deposition
Igneous intrusions are rock formed from magma that cools and solidifies witching earths crust.
They produces superheat water at high temp that dissolves many minerals. They travel and cool forming crystals
This is called fractional crystallisation
Metamorphic processes
Igneous processes and tectonic movements of crustal plates can alter existing rock is with high temp and pressure. High temp and pressure can change limestone to marble
Sedimentary processes
Minerals settle and build up to produce layers of deposited sediment. This creates sedimentary rocks
How to get
1) igneous from sediments
2) sediments from metamorphic/igneous
1) sediments compact and cement to form sediment rocks
Under heat and peruse they turn into metamorphic rocks and melt into magma, once cooled this is igneous
2) igneous/metamorphic is weathered and turns into regolith, via erosion and deposition they turn into sediments. Under compaction and cementation turns into sedimentary rocks.
What is laskys principle
In general- as purity of mineral decreased the amount of mineral increases.
Define Stock, resource and reserve
Stock: all of the materials that exists within the lithosphere
Resource: all materials that is theoretically available for exploration and materials available now
Reserve: amount of resources that can be exploited now
Factors affecting mining viability
Chemical form- will affect the ease of extraction of the metal
Overburden and hydrology-overburden is rock that lies above mineral deposits, hard overburden may require blasting increasing the costs. Loose overburden may cause landslides so the sides of the mine have to be a gentle gradient
Depth- costs rise as depth increases
COOG
Transports costs
Problems caused by soil disposal
Aesthetic - spoil heaps can damage the scenic beauty of an area, can landscape to reduce this
Stability-lack of surface compaction can reduce surface stability and lead to erosion, can be reduced by landscaping
Leachate - rainwater percolating through spoil can dissolve toxic metals and sulphides that produce acidic leachate solutions. Many toxic metals are more soluble under acidic conditions- to stop this mine drainage water can be passed though a filter bed of crushed limestone to immobilise the metal and prevent it being carried into rivers.
Improvements in exploration methods
Deep mining- using machines to mine where to hot/dangerous for people. Ex-deep gold in South Africa which is 3.8km deep
Open cast mining-larger machinery in open cast mines allows overburden and minerals to be extracted more quickly and cost effectively
Problems with recycling schemes
Transports - recycling involves the collection and transport of smaller quantities which is expensive and bulk transport isnt available
Labour costs-processing smaller quantities of materials increases labour costs, however recycling dosent usually require training
Public coordination
Identification- labour intensive and slow
What is the cradle to cradle design
Design of products so that the materials used are able to be reused at the end of their useful lives
Separation of components and easy identification of materials
