Coal Flashcards
Describe the origins of coal.
1) Warm, humid conditions lead to vast accumulations of plant debris.
2) In anaerobic conditions, bacteria cause biochemical changes, transforming plant matter into peat.
3) Peat buried under layers of sand and silt, commences slow physical/chemical changes.
4) Peat subjected to rising temperatures and pressures. Compression reduces volume by removing water and volatiles. Over time, this peat will become coal.
What is coalification?
The loss of water and volatile compounds from peat.
Rank the 4 types of coal in order.
1) Anthracites
2) Bituminous Coals
3) Sub-Bituminous Coals
4) Lignites
Describe the two stage transformation process.
1) Decomposition of water soluble constituents and cellulose.
2) Accumulation of resistant components, resins, waxes and lignin.
What is peat?
Spongy decomposed plant material with a very high water content.
What are lignites/brown coal?
Early stages of coal formation. Lignites still contain visible woody material. High water content, high volatiles.
What is bituminous coal?
Coal that burns with a smoky flame. Generally used for steam raising, gasification and general combustion.
Describe anthracites.
Less than 5% volatiles. banding is absent, metallic aspect, very hard.
Describe banding.
Bright bands are mainly from wood or bark material.
Dull bands are formed from degraded plant debris, including plant spores and pollen.
What is the main constituent of ash?
Inorganic material.
Describe the sulphur content of coals.
Under anaerobic conditions, sulphur is reduced to sulphides, namely FeS2 and H2S. Content is usually 0.5-3.0%
What are the main costs associated with coal, what do they depend on?
Extraction, treatment and transport.
Depends on the form and location of coal seams.
Describe the coal economic landscape.
Coal is mind commercially in 50 countries and used in 70 countries. Most coal is used in the country that it is mined.
Define resources and reserves.
Resources: Quantities that are likely to exist but not exploitable at this time.
Reserves: Quantities that can be exploited.
Who are the biggest exporters/importers of coal?
Exporters: Australia
Importers: Japan
