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COALCOALITAMITAMINTRODUCTION TO AUSTRALIA'S MINERALS
COALCOALITAMITAM
Q U E E N S L A N DM I N I N G C O U N C I L
Australian
AssociationCOAL NN SS WW
MM ii nn ee rr aa ll ssCC oo uu nn cc ii ll
Coal in a Sustainable Future
Coal OverviewCoal is an organic sedimentary rock made up of thealtered remains of mainly plant material. Coal, oil andgas are called fossil fuels because they are all formedfrom the remains of once-living organisms. These fossilfuels provide most of the energy required for humanactivities. Our present lifestyle depends on abundantand relatively cheap coal, oil and gas.
Most of the coal mined around the world is used forelectricity generation in power stations, for steel making or for other industrial production. Power stations are often built beside their feeder coal mines toreduce transport costs. Most of the world's coal production is used within the country in which it ismined.
Australia is the world’s largest coal exporter. It is one ofthe few countries in the world where more of the coalthat is mined is exported than is used in the country. In2002, coal exports of more than 200 million tonnesearned over $13 billion for Australia. These exports contribute enormously to Australia's balance of payments, offsetting the cost of imports. Taxes and royalties paid to government by mining companies andtheir employees contribute significantly to the welfareof all Australians.
Coal mining and export employs many Australiansdirectly and indirectly. Thousands of workers areemployed in the coal mines, at preparation facilities,on railways and at ports. In recent years large machinesand workplace changes have increased the productivityof Australian coal mines supporting a vibrant exportindustry.
In addition to those employed directly in the coalindustry, many other Australians are employed indirectly, such as in the transport sector. A number ofnew towns have been established in regional areas toservice the mines developed since the 1960s.
Opencut coal mining does disturb large areas on themining lease, but modern rehabilitation techniques nowreturn this land to productive use or native ecosystems.Underground mining can cause subsidence at the surface but careful planning, regulation and monitoringminimises damage and compensation is available tothose affected. Burning of coal, and other fossil fuels,adds greenhouse gases to the atmosphere. On-goingresearch and the adoption of clean coal technologies in all facets of coal mining, preparation and use are continuing to significantly reduce greenhouse emissions.
2 ITAM Coal
COAL
Did you know?
The thickest seam of coalanywhere in the world is the 233 metres of brown coal whichoccurs at Loy Yang in Victoria.
CONTENTS
Coal 2
Formation of Coal 3
Coal Basins 4
Types of Coal 6
Uses of Coal 7
History of Coal 8
Coal Mining 10
Rehabilitation 12
Environment 13
Transport 14
Coal Exports 16
Climate Change 18
Clean Coal Technologies 19
Other Energy Sources 21
Glossary 23
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This publication was made possible by the financial support of the following organisations
Australian Coal AssociationMTAA House, 39 Brisbane AvenueBarton, ACT 2600Phone: 02 6273 6044Fax: 02 6273 6060Web: www.australiancoal.com.au
Queensland Mining CouncilLevel 13, 133 Mary StreetBrisbane, Queensland 4000Ph: 07 3295 9560Fax: 07 3295 9570Web: www.qmc.com.au
New South Wales Minerals CouncilLevel 12, 59 Goulburn StreetSydney, New South Wales 2000Ph: 02 8202 7200Fax: 02 8202 7255Web: www.nswmin.com.au
Front Cover: Mine technicians discussing plans at Bengalla Mine. Photo courtesy of Bengalla Mining Company.
3ITAM Coal
Coal is formed when plant material is buried quicklybefore the processes of decay have changed it verymuch. This happens where sediment is deposited andcovers the plant debris. The sediment excludes oxygenand thus prevents the plant material from decaying.Over millions of years, the weight of overlying sediment squashes the plant debris, squeezes out thewater and converts the plant material to coal. Thelonger the time involved and the greater the pressure, the higher is the energy value of the coalproduced. This process of plant material beingturned into coal is called coalification.
There are modern environments where coal could beproduced in the future. These include deltas of largerivers, for example the Mississippi delta in theU.S.A. River deltas in temperate latitudes havemuch plant material growing at or near the waterlevel and large amounts of sediment being deposited. Floods and changing watercourses in thedelta can cause rapid burial of plant material whichcould form coal.
Coal deposits are usually found in sequences (layers) of sedimentary rocks. The coal bed oftenoccurs between beds of shales, siltstones and finesandstones. The bed of coal may also be referred to as a coal seam. Some coal deposits may consist ofvery thick seams of almost pure coal. Others mayhave many thinner coal seams separated by layersof shale.
Sequences of sedimentary rocks containing coalseams often occur in basins. The basins may be elongated or rounded with their deepest parts nearthe centre. The coal lying at the centre of the basin
has usually been subjected to the greatest pressure fromoverlying sediments and is therefore of higher grade.Nearer the edges of the basin the coal may be of lowergrade, not having been subjected to the same degree ofpressure.
Glossopteris
Leaf
Stem
Florette
Trunk
Glossopteris leaf. Most of the black coal in the Sydneyand Bowen Basins is made up of the remains of thePermian age seed fern Glossopteris.
FORMATION OF COAL
Increase in coal rank
Peat Brown Coal Sub Bituminous Bituminous
4 ITAM Coal
COAL BASINS
Coal forms when plant matter isburied by sediment in structurescalled basins. These basins aredepressions in the Earth's crustformed when the crust buckles asa result of movements of the tectonic plates.
Coal formation could onlybecome possible after plantsmoved onto the land from thesea. This happened at about theend of the Silurian Period, 400million years ago. Therefore coalis only found in rocks depositedsince about 400 million years ago.
The greatest deposits of coal occur in basins containing rocks of the Carboniferous and PermianPeriods (about 350 to 250 million years ago).
Coal has continued to form in basins all around theworld since the Silurian Period. Younger basins contain coals of lower energy value because the coalforming process has not continued for as long as ithas in the older basins. The coal in the older basinshas been compressed under thick piles of sedimentfor long periods, resulting in higher grades of coal.
Bowen, Sydney Basin coals
Main black coal — formingperiod
Most Brown Coals formed
Period
Quaternary
Cretaceous
Tertiary
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
LatePrecambrian
Events
Tim
e -
mil
lio
ns
of
ye
ars
be
fore
pre
se
nt
Of plants,only Algae presentin oceans
First Land Plants
Lower value black coalsmined locally forelectricity generation
0
100
200
300
400
500
600
(Not to Scale)
Peak Downs Mine
Isaac River Conners River Conners Range
Bruce Highway
EastWest
Approximately 150km
Permian Bowen Basin Sediments Intrusive Rocks, Granites Permian Coal Seams Pre-Permian Basement Rock
Sydney
Gunnedah
Newcastle
WollongongCoal
Sedimentaryrocks
Olderrocks
North
100 km
Typical Cross Section of the Bowen Basin.
Geological Time Scale.
Block diagram of Sydney-GunnedahBasin. The same coal seam is mined in
different parts of the basin.
5ITAM Coal
COAL BASINS
High grade coals exist in basins ina number of areas aroundAustralia. In eastern Australia, coalformed during the Permian Periodin two large basins. These twobasins are the Sydney-GunnedahBasin in NSW and the Bowen Basinin Queensland. They contain mostof the high grade bituminous coaland some anthracite that is extracted for electricity generation,steel making and export. The coalis mined by both opencut andunderground methods.
In the Sydney-Gunnedah Basincoal is mined at each of the edgesof the basin. At the southern edgelies the Illawarra Coal Measures, atthe northern edge, the HunterCoalfield, and the WesternCoalfield lies at the western edge.To the north-west lies theGunnedah Coalfield. Coal at thecentre of the Sydney Basin is mostly too deep to mine economically at present.
The Permian coals in the Sydney-Gunnedah andBowen Basins are mostly formed from the remains ofan extinct seed-fern called Glossopteris. The largeleaves, fronds, roots and trunk of the deciduousGlossopteris trees provided the raw material whichlater became the coal measures.
Coals formed in basins belonging to the Triassic andTertiary Periods are important locally in some Statesof Australia. Most of them are sub-bituminous orbrown coals used for electricity generation. Becausethese younger coals are generally lower in energyvalue, they are not usually suitable for export.
An example of current mining methods.Photo courtesy of BHP Billiton Mitsubishi Alliance
BOWENBASIN
GALILEEBASIN
SYDNEYBASIN
CANNINGBASIN
PERTHBASIN
GIPPSLANDBASIN
OAKLANDSBASIN
OTWAYBASIN
ARCKARINGABASIN
SURATBASIN
BASIN OF THELEIGH CREEK
COALFIELD
FINGALBASIN
Some of the important coal-bearingbasins of Austalia.
6 ITAM Coal
TYPES OF COAL
The process of coalification converts the plantmaterial, which consists essentially of compoundsof carbon, hydrogen and oxygen, to coal. Coal, inits purest form, consists of carbon only. The different grades or types of coal vary between relatively unchanged plant material and pure carbon.
There are a number of ways in which the different types of coal can be classified. Someclassifications rely on the use to which the coal is put, for example coking coal or steaming coal.
One common classification system divides coalsinto various rankings based on a range of properties. The order of rank of the coals fromlowest energy-value to highest energy-value is:� Peat � Lignite� Sub-bituminous � Bituminous � Anthracite.
Another simple classification uses only black coal (alsocalled hard coal) and brown coal (also called soft coal).The higher energy-value black coal includes anthraciteand the bituminous coals. Brown coal includes lowerenergy-value lignite and peat.
Pure carbon has the highest energyvalue when burnt and thereforemakes the most valuable fuel.Anthracites may contain more than90% carbon with only a few percentof volatile materials. Lignite, on theother hand, may need to be dried toremove the over 50% of water itcontains before the 50 to 60% of carbon is able to be burned.
COAL
MOISTURE CONTENT
CARBON/ENERGY CONTENT HIGH
HIGH
LOW RANK COALS48%
HARD COAL52%
LIGNITE20%
SUB-BITUMINOUS28%
BITUMINOUS51%
ANTHRACITE~1%
THERMALSteam coal
METALLURGICALCoking coal
% o
f W
orl
d R
es
erv
es
USES Largely powergeneration
Power generationCement manufacture
Industrial uses
Manufactureof iron and
steel
Domestic/industrialincluding
smokeless fuel
Types of coal and their uses.Image courtesy of World Coal Institute
Did you know?
A walking dragline in an opencut mine may weigh as muchas 2,500 tonnes, is as tall as a four storey block of flats, has a boomas long as a football field and costs as much as $70 million.
????
Dragline operating in an opencut coal mine.
Photo courtesy of BHP BillitonMitsubishi Alliance
7ITAM Coal
USES OF COAL
Coal mined in Australia is mainly used for electricity generation (steaming or thermal coal)and in the production of iron ore and steel (coking or metallurgical coal).
Steaming CoalOf the more than 3.6 billion tonnes of steamingcoal produced annually around the world, over50% is used for electricity generation. In NewSouth Wales and Queensland over 90% of theirelectricity is produced from coal-fuelled powerstations. The coal is burnt in a boiler and thesteam produced drives a turbine, which in turn,drives the generator which produces the electricity.
Many power stations are built beside the coal minewhich is the source of the fuel. The reason for this positioning is that electricity is much easier and cheaperto transport than coal.
The energy transformations involved in a power stationare from chemical (coal), to heat (boiler), to kinetic (turbine) to electric (generator). Each transformationinvolves energy losses, with the result that only about35 to 42% of the original energy is converted to electrical energy. Improvements in technology areincreasing the efficiency of these changes all the time.
Electricity is vital to the efficient functioning of our society. In general, the higher the standard of living ofthe country, the more electricity per head of populationthat country uses.
Coking CoalAnother major use for coal is in the production of ironand steel. Coal is converted to coke before being fedinto the blast furnace. Coke is produced by heating coalin a coke oven which excludes air. The water and gasesare driven off and collected for the production of arange of useful chemicals. Left behind is a sponge-likelump of almost pure carbon, which is coke.
In a blast furnace, carbon in the coke combines withoxygen to release the heat needed to change the ironminerals to pure iron. The result is a pool of molten iron at the bottom of the furnace with a layer of slag, containing the impurities, floating on top of the iron.
Most industrial processes involve the use of steel inmachinery and a great deal of steel is used for motorvehicle production and in the construction industry.
Other UsesCoal and its products are used in the production of avariety of chemicals important to a range of industries.
The manufacture of cement also involves the use ofcoal as a fuel. Coal and coke are also used in
making some common materials like baking powder and soda water.
Other2%
Non-metallic industry,including cement
5%
Steel industry16%
Domestic5%
Commerce, pubilc services,transport, agricultureand other industry10%
Power and heat stations,including electricity generationand district heating62%
Uses of coal around the world.
1,23
6
936
303
223
219
149
117
74 67 61 45 41 38 34 24
Ch
ina
US
A
Ind
ia
S A
fric
a
Au
stra
lia
Ru
ssia
Po
lan
d
Ukr
ain
e
Ind
on
esia
Ger
man
y
UK
Can
ada
Co
lom
bia
N K
ore
a
Mill
ions
of t
onne
s (M
t)
0
300
600
900
1200
1500
Kaz
akh
stan
Total world hardcoal production
3600 Mt
World hard coal production for 2002, (top 15 producers).
8
HISTORY OF COAL
New South WalesIn the early days of the colony of New SouthWales coal was discovered both to the north andsouth of Sydney. Explorer George Bass, of Bassand Flinders fame, found outcrops of coal atwhat is today the village of Coalcliff, nearWollongong in 1797. The outcropping beds werepart of what is now called the Illawarra CoalMeasures in the southern part of the SydneyBasin. Although coal had been exported fromNew South Wales since 1799, the most importantcoal mine in the area, at Mt Keira, began commercial production in 1857. This mine operated for over one hundred and thirty years,finally closing in 1991. Most of the coal mined inthe Illawarra area was originally produced forthe Port Kembla steelworks. In recent years largetonnages have been exported.
Aboriginal inhabitants of the Hunter Valley may haveused and traded coal outcropping on the banks of theHunter River at the site of what is now the city ofNewcastle. European explorers noted this occurrence in1797, not long after the first settlement was establishedat Sydney Cove. Newcastle is now the major port forexport of black coal from the Hunter Valley mines.
QueenslandIn Queensland the first coal discovery was made byMajor Edmond Lockyer in 1825 when he collected coal
from a seam outcropping on the banks of the BrisbaneRiver. The first coal mine in the State opened in 1843 atRedbank near Ipswich. This area remains an importantcoal mining and electricity generating centre for thestate. Explorer Ludwig Leichhardt discovered coal inthe Bowen Basin in 1845 and water well diggers discovered coal instead of water at Blair Athol in 1864.It was not until 1936 that Blair Athol became the State'sfirst continuous opencut coal mine. Much later, in the1960s, Queensland took the lead in Australia's greatexport boom with coal from this basin.
VictoriaBrown coal was discovered in the Gippsland area in theearly days of the colony of Victoria. The first attempts tomine the coal were unsuccessful. When overseas experience and technology was applied in the 1940sVictoria was able to build a massive electricity generating industry based on the plentiful brown coal.
Western AustraliaCoal was first mined in the Collie area in the southwestof the State in the 1890s to provide fuel for steamshipsand trains. Since 1916, coal mined in this area has provided a resource for Western Australia’s electricitygeneration.
ITAM Coal
Davey Lamp.Photo courtesy of W. G. 'Haggis' Shackleton
Abandoned mines may become tourist attractions. A Pit Ponyshows how coal was moved underground in earlier times.Photo courtesy of W. G. 'Haggis' Shackleton
South AustraliaIn South Australia, brown coals were discovered in anumber of the sedimentary basins in the 1880s, both inoutcrops and in bores drilled for water. The only large,present day mining occurs at Leigh Creek, in the northof the State. Here, Triassic sub-bituminous coal hasbeen mined by opencut methods since 1944. The coal israiled to Port Augusta for use in two power stationswhich provide the majority of electricity for the State.Large deposits of higher energy value coals occur inSouth Australia's sedimentary basins, however they aredeeply buried and relatively far from the coast.
TasmaniaCoal was discovered on the Tasman Peninsula near thepenal establisment of Port Arthur in 1833. Today bitumous coal is still mined in the Fingal Valley on theeast coast of Tasmania. Total production is limited toproviding the local market, with the main user beingthe cement industry at Railton in Tasmania’s centralnorth. It is also used to produce steam in the confectionery, brewing and paper industries in theState.
The export boomUntil the 1960s, Australia's coal production was primarily for domestic electricity generation and steelmaking. As Japan's steel industry expanded in the1960s it sought to import large quantities of coal fromreliable, long term suppliers. Australia moved quicklyto increase its exports of coking coal to meet thisdemand. Expansion followed as other Asian countriesincreased their steel production and sought high gradecoking coals from Australia.
During the 1970s oil producers significantly increasedthe price of oil. As a result, countries looked to othersources of energy for electricity generation. Many
turned to Australian producers of steaming coal forsupplies to allow them to continue to produce electricity at reasonable prices. Australia's steamingcoal export boom had begun.
The new markets for Australian coal resulted in extensive expansion and modernisation of coal minesand ports on the east coast of Australia. Major opencut
mines were developed in theBowen Basin of Queensland usingvery large equipment. New railway lines were constructed andold lines upgraded to allow thelarge tonnages to be moved efficiently to the coastal ports. InNSW, existing underground minesbecame highly mechanised andproductivity increased markedly.
9ITAM Coal
Did you know?
Each Australian will use the energy from 200 tonnes of coal in a lifetime. Mostly this will be usedas electricity and in the production ofmaterials such as steel, aluminiumand plastics.
????Large ships being loaded at a coal export port.Photo courtesy of BHP Billiton Mitsubishi Alliance
HISTORY OF COAL
Night time operations at a coal mine.Photo courtesy of NSW Minerals Council
Early methodsCoal beds outcropping at the Earth's surface wereexploited very early in human history. As the beds werefollowed underground, so began the earliest under-ground mining. Fuel to power the machines of theindustrial revolution led to rapid growth in the demandfor coal during the late 19th century. The invention ofthe steam engine led to huge demand for coal.
Towns sprang up around the coal mines of Europe asmany men were required to dig out the coal with picksand shovels. The coal 'pit' or 'colliery' was a source ofmany jobs, and as a result of the dangerous nature ofthe work, became the focus of very strong unionism.
Coal miners often faced a long, dark underground tripto get to the 'face' where they dug out the coal, initiallyby lamplight. They were paid on the basis of theamount of coal that they produced and usually workedin small teams. Some men dug out the coal while othersloaded it into horse-drawn wagons running on woodenrails.
Working in dark, cramped conditions the miners had tocope with breathing fine dust particles, the constant fearof gas explosions and the possibility of collapse of themine roof. Canaries in cages were taken undergroundbecause they were quickly affected by the release ofdangerous gases, giving miners early warning thatgases were building up. Despite these precautions therewere many coal mining disasters leading to large loss of life.
Gradually, mining methods improved, leading to a saferworking environment and greater productivity. Oneearly innovation was the Davey Lamp, used to detectthe explosive gas methane in coal mines. Over time,hand tools were replaced with electric drills and hammers and electric trains replaced horses. However,coal mining remained a labour intensive activity.
10 ITAM Coal
Did you know?
A one metre thick coal seammay have started out as a pile of plant material 120 metres thick and taken over 200 million years to form.
????
Topsoil and subsoilstripped by motor scrapers
and carefully stored
Graded embankmentto act as baffle against
noise and dust
Overburden from benchesdug by shovels and hauled
by dump trucks
Overburden being excavatedby dragline
Spoil pile
Dragline bucketunloads burdenDragline
excavationOverburdenCoal seams
Overburden
Preparing to mine Mining
COAL MINING
Cross-section through a dragline opencut coal mine.Image courtesy of World Coal Institute
Modern methodsSince the 1960s large machines haveincreased the productivity of coal minesand miners. Large machines allow a smallernumber of miners to produce greatlyincreased tonnages of coal.
In underground mines, 'longwall' miningmachines are used. They have large cuttingblades which shear coal from the seam andcollect it onto a conveyer belt. Hydraulicjacks support the roof over the machine. Asthe machine moves forward through thecoal seam, the roof is allowed to collapsebehind it. Moveable conveyor belts carrythe coal through the mine and ultimately tothe surface. The underground atmosphereis closely monitored for dangerous gas and to ensure adequate ventilation for the miners.
The use of large 'walking draglines', huge mobile bucket excavators, has allowed opencut mining toexpand dramatically. Following blasting the excavatorscan strip off large depths of overburden (the rocks layers overlying the coal seam) efficiently, exposing thecoal seam. The coal can then be mined with loaders andlarge capacity dump trucks. Water sprays are used tocontrol dust.
After the coal has been recovered, the overburden isreplaced and shaped to resemble the original landforms. The topsoil, which was originally strippedoff and stored separately, is spread over the surface andthe area is replanted with vegetation.
Coal preparationWhen the raw coal reaches the surface it is processed toprovide a pure product. These surface processes arecalled 'preparation'. The coal is first crushed to a specified size and passed over a sieve to remove fineparticles. The main process involves washing the coal toremove as much of the non-coal material, usually shale,as possible. The coal is allowed to dry out and then isstored in stockpiles and fed into giant bins before loading into railway trains.
11ITAM Coal
Longwall mining machine in operation.Photo courtesy of NSW Minerals Council
Draglinebackfill
levelled bybulldozers
Tippingoverburden
from benchesto backfill
Subsoil andtopsoil being
replacedand shaped
Grass andtrees
Overburden being excavatedby dragline
After the soils are replaced in their proper sequence,they are ripped to relieve compaction and
then cultivated, limed and fertilised
Spoil pile
Dragline bucketunloads burden
Draglineexcavation
Mining Rehabilitation
Cross-section through a dragline opencut coal mine.Image courtesy of World Coal Institute
COAL MINING
12
REHABILITATION
The environmental performance ofmining operations in Australia is central to the industry’s continuedviability. Coal mining represents only temporary use of the land underwhich the coal lies. Mining aims forsustainable development where theland, after mining is completed, isstill able to be productive for futuregenerations. Modern opencut minesare planned in such a way that theland surface may be returned tomuch the same appearance beforemining took place. The land can becontoured, then sown to pasture,planted as forest native ecosystem orused in some other productive orrecreational use. The cost of rehabilitation is built into the overallcost of the mining and the rehabilitation process is subject to government regulation.
In opencut mining, rehabilitation involves firstly removing and stockpiling the topsoil for later replacement. The rocky material overlying the coal(overburden) is then removed by giant draglines orshovels and trucks to expose the coal seam. The seam ismined and then the overburden is replaced. Large bulldozers then reshape the overburden until it closelyresembles the original contours of the land. The stockpiled topsoil is then returned to the shaped landand pasture or other plants are sown. Careful attentionis paid to ensure that erosion does not affect the new landscape.
Dams may be built to control runoff and to assist retention of water. Rehabilitation progresses behind thesurface mining. This means that only a relatively smallarea of land is affected at any time.
In the case of underground mines the land surfaceremains largely unaffected, although sometimes subsidence of the surface may occur over mined outareas. The coal mining industry uses a range of engineering techniques to design the layout and dimensions of underground mine workings so that surface subsidence can be anticipated and controlled.
ITAM Coal
Vickery coal mine, near Gunnedah, NSW, during mining operations.Photo courtesy of Coal and Allied
Vickery coal mine after rehabilitation.Photo courtesy of Coal and Allied
The environmental effects of mining need to be controlled by good mine planning. Mine owners wishto be good neighbours to the landowners surroundingthem. As part of the mining approvals process, a majorenvironmental impact assessment must be undertakenso that the public, local community and governmentauthorities are properly informed when considering amining proposal.
Land ManagementOne way of being a good neighbour involves buildingearth wall barriers to keep noise, dust and pollutiononsite. The walls prevent noise from spreading acrossthe countryside. Dust is minimised by spraying waterover roads, stockpiles and dumping areas. Sometimesan area surrounding the mine is set up to act as a bufferzone protecting the neighbours. Native animals andstock animals can live happily quite close to the mine.The mine plan involves a succession of rehabilitationafter mining in an area is completed.
Management of the animals and plants in the local areais important to miners. At the Blair Athol coal mine inthe Bowen Basin a unique koala breeding and management program is conducted by the mine’s environmental officers.
Air Quality and Emissions ControlCareful measurement and monitoring of noise, dustand water and air quality is undertaken around eachmine. This monitoring is undertaken by environmentalscientists employed by the mining company. Findingsfrom the monitoring sites are continuously fed back tothe mine management team to enable better planningand operations. Government regulators receive the monitoring results and assess whether standards arebeing met. Local communities are also advised.
Water qualityThe quality of water is critical at mine sites and is continuously monitored. Salts and sediment are takenup in the water draining from the disturbed area of the
minesite. This water is collected in settling ponds toallow the sediment to settle. Chemicals are added toneutralise any acidic water and to precipitate salts. Thetreated water is reused to prevent dust and is also usedin the coal preparation plant. Coal mines are major re-users and recyclers of water. All water leaving minesites must meet stringent environmental regulatorystandards.
Waste materialFine coal sediments (or tailings), left over from coalpreparation are retained in dams so that they can dryout and be covered with overburden and revegetated.In some cases tailings can also be used in some powerstations to generate electricity. Coarser waste (non-coalmaterial) of gravel size is buried under the overburdenduring rehabilitation of the site.
EnergyEnergy is conserved in some underground coal minesby draining methane from the mine and burning it toproduce electricity to run the mine. Burning coal-seammethane instead of releasing it into the atmosphere alsodramatically reduces greenhouse gas emissions associated with coal mining. Computer modelling ofdragline operations has led to improvements whichsave energy.
13
ENVIRONMENT
ITAM Coal
A rehabilitated mining site.Courtesy of BHP Billiton Mitsubishi Alliance
An environmental scientist monitors vegetation ata rehabilitated mining site.Photo courtesy of BHP Billiton Mitsubishi Alliance
14 ITAM Coal
Coal TransportMost of the coal produced throughoutthe world is used within the country inwhich it is mined. Coal for export makesup only approximately 15% of the totalworld production. Australia is the largestcoal exporting country.
In many countries most of the coalmined is used for the production of electricity and it therefore makes sense toproduce that electricity near the sourceof the coal. This is because electricity canbe transported through wires much morecheaply than coal can be transported bymeans of railways or roads. Electricity generating stations are therefore oftensited very near to coal mines.
If a mine and electricity generating station arequite close, the coal may be transported on aconveyor system between them. Conveyor systems are more efficient to operate than mostalternative transport methods over short distances.
Railways provide the most efficient transport system for moving large quantities of coal over medium distances. Efficient railways are vital toAustralia's coal export success. Trains may carryover 8,000 tonnes of coal, be up to two kilometresin length and consist of six locomotives and 100rail trucks. The aluminium rail trucks are specially designed to allow them to be emptiedquickly for rapid turnaround.
Coal from the mine is washed and sized in the preparationplant before being loaded for transport by rail.Photo courtesy of MIM Holdings Limited
Coal is transported by conveyor directly to the power station.Photo courtesy of Barry Cook
TRANSPORT
One train may carry up to 8,000 tonnes of coal fromthe mine to port.Photo courtesy of Barry Cook
15ITAM Coal
Coal terminals are located at deepwater ports and contain a stockpile of coal of sufficient size to allowships to be loaded quickly and efficiently. Large stackermachines stockpile the coal delivered by the rail system. Reclaimer machines take coal from the stockpile for transport to the loading conveyors on the dock.
Export coal terminals are located at Abbot Point, HayPoint-Dalrymple Bay, Gladstone and Brisbane to servicethe Queensland mining centres. The Sydney-GunnedahBasin mining areas of NSW are serviced by the coal terminals at Port Waratah-Newcastle and Port Kembla.Over 200 million tonnes of coal were exported fromAustralia through these terminals in the 2001 calendar year.
The ships that carry export coal are large and speciallydesigned for rapid loading and unloading. The largestcarry over 200,000 tonnes and usually travel on a specific route.
One innovative method of transporting coal which hasbeen tried experimentally involves a slurry pipeline.Crushed coal is mixed with water to form the slurryand is then pumped along the pipeline before beingdried at the end point. Such systems have been used totransport coal over short distances but are not yetproven to be economically viable.
Did you know?
Coal is transported aroundthe world in large bulk ships,the largest of which may carryover 200,000 tonnes at a time.
????
A coal loading operation.Photo courtesy of BHP Billiton Mitsubishi Alliance
Loading ships at the Hay Point and Dalrymple Baycoal terminals.Photo courtesy of BHP Coal Pty Ltd
TRANSPORT
GALILEEBASIN
SYDNEYBASIN
ARCKARINGABASIN
Coal Terminals
A - Abbot Point
D - Dalrymple Bay
H - Hay Point
G - Gladstone
B - Brisbane(Fisherman Islands)
N - Newcastle(Port Waratah andKooragang)
W - Wollongong(Port Kembla)
GIPPSLANDBASIN
OTWAYBASIN
OAKLANDSBASIN
GUNNEDAHBASIN
W
N
NSW
Victoria
Queensland
B
G
H
A
D
SURATBASIN
BOWENBASIN
Australia is the world's largest coal exporter, exportingnearly 200 million tonnes of steaming and coking coalin 2001. Other major exporters include South Africa,Colombia, Indonesia and China.
The export market involves only about 15% of the totalworld coal production of more than 3,600 milliontonnes per year. Most of the coal produced in the majority of countries is used in their domestic markets.Coal production in many Western countries is very highcost and is slowly being replaced by imports.
Australia has a successful coal export industry becauseit has:
� large quantities of accessible coal� high quality, high energy-content coal� mines located close to the coast� highly mechanised and efficient mines� efficient transport links to the ports� efficient terminals/bulk loading facilities� deepwater access for large ships� low sulfur, low ash content coal� skilled workforce and management� low cost electricity supplies� excellent environmental credentials.
16
COAL EXPORTS
6
2
3
4
7
1
8
1 Australia2 South Africa3 Indonesia4 China5 Colombia & Venezuala6 Poland & Russia (Westbound)7 USA & Canada8 Russia (Eastbound)
GLOBAL COAL TRADE ROUTES
5
Global Coal Trade Routes indicating volumes exported for 2001.
Major Coal Producing and Exporting Nations in 2001.
ITAM Coal
66
ChinaS AfricaUSAAustralia
Mill
ions
of t
onne
s (M
t)
916922
5
1250
1500
1000
750
500
250
0
44
1,29
4
945
ExportProduction
19325
7
Indonesia
93
Most of the export mines occur in the Sydney-Gunnedah Basin of New South Wales and theBowen Basin in Queensland. These basins contain large deposits of near-surface, bituminous coals and are relatively near deepwater ports. High capacity rail lines connect each mining area to a port.
A stockpile of coal is maintained at the coalterminal to ensure rapid ship loading. As well,different types of coal may be blended to meetspecific customer requirements.
Coal was Australia's most important exportcommodity in 2002. The value of the coalexported was over $13 billion. Coal is thus animportant contributor to the lifestyle enjoyedby all Australians, and coal will remain a vitalexport earner for many decades to follow!
17ITAM Coal
Ship loading facilities.Photo courtesy of BHP Billiton Mitsubishi Alliance
COAL EXPORTS
Mining operations showing bucket wheel excavator. Photo Courtesy of NSW Minerals Council
Fossil fuels and climate changeThe ‘greenhouse effect’ is a natural process in whichgases that make up the atmosphere help to regulate theEarth’s climate by trapping some solar radiation thatwould otherwise be radiated back out into space. Theprocess is very similar to the effect of a glassed-ingreenhouse, which traps heat to help plants to grow.Without this effect, the Earth’s temperature would besome 30 degrees centigrade cooler than the currentaverage of 15 degrees.
Atmospheric concentration of carbon dioxide, the major'greenhouse gas', and the Earth’s temperature areknown to have varied throughout geological history.The decay of plants and animal material is one of thenatural processes which releases carbon dioxide to theatmosphere, while photosynthesis by plants removes it.
The burning of fossil fuels, including coal, oil and natural gas, releases additional greenhouse gases intothe atmosphere. This has resulted in a build up ofatmospheric concentrations of these gases, in particularcarbon dioxide and methane. Many scientists believethat this unnatural build-up is enhancing the naturalgreenhouse effect, causing global warming and changesto the Earth’s climate.
The use of low-cost coal for electricity generation hasbrought with it many economic and social benefits. Ithas underpinned economic development since theindustrial revolution of the 19th century and is nowbringing social progress and raised living standards todeveloping countries where nearly two billion peoplestill have no access to electricity.
The challenge is to maintain the many benefits societyderives from access to low cost coal-based electricity,while at the same time reducing or eliminating greenhouse gas emissions. As the result of a major global research and development effort over the pastdecade, new and emerging clean coal technologies arepromising to revolutionise the way coal is used and aresignificantly reducing greenhouse gas emissions.
18 ITAM Coal
Absorbed into atmosphereby greenhouse gases
Infra-red radiationfrom surface
Radiated outto space
Atmosphere
Incoming solarradiation
CLIMATE CHANGE
The Greenhouse Effect - without this natural phenomenon the surface temperature of the earth would be some 30 degrees cooler and life would be impossible. The Greenhouse effect is caused by gases in the atmosphere trappingsolar heat radiated by the Earth. Courtesy of Australian Coal Association
19ITAM Coal
Clean coal technologies improve the performance ofcoal as an energy source and reduce its impact on theenvironment. They are being developed for all facets ofcoal production and use – from the extraction, preparation, storage and transportation, through to usein power stations, steel mills and other industrial applications. Examples of how clean coal technologiescan be employed include:
In coal production…� Reducing greenhouse gas emissions during mining
by capturing methane gas and using it to providepower for the mine, for local communities, and forinput to the electricity grid. Not only does this provide an additional source of energy but alsohelps to reduce the safety risks associated withpotentially explosive methane build-up in mines.
� Using advanced preparation and cleaning techniques to eliminate impurities from coal, so thatit burns more cleanly and efficiently and helps toreduce emissions to the atmosphere.
In coal use…� Employing new combustion processes to improve
thermal efficiency (the amount of useful energy thatcan be obtained from a given quantity of fuel).Increasing thermal efficiency reduces greenhousegas emissions and other pollutants.
� Incorporating pollution control devices in powerstations to capture gases such as oxides of sulfurand nitrogen, which are produced when coal isburned.
� Converting coal to gas (gasification), mainlyhydrogen, and using this as the primary fuel sourcein power stations, instead of burning coal directly.
� Capturing the carbon dioxide (a greenhouse gas)that results from the burning of coal or coal gas,and storing it permanently underground (known ascarbon sequestration).
Methane extraction system at Central Colliery coal mine,German Creek. Photo courtesy of NSW Minerals Council
30000
25000
20000
15000
10000
5000
TW
h
TWh = terrawatt - hour
1971 19800
1990 2000 2010 2020
Coal Oil Gas Nuclear
Hydro Other Renewables
World Electricity Generation, 1971-2020
Source: International Energy Agency
CLEAN COAL TECHNOLOGIES
20
A zero emission future for coal?
A number of advanced coal technologies for electricity generation are already being trialled throughout the world. Several of these have the potential to achieve electricity production from coalwithout emissions to the atmosphere.
One that shows great promise in terms of its high efficiency and environmental performance is theIntegrated Gasification Combined Cycle (IGCC) system.In IGCC, coal is initially converted to gas, mainly carbon monoxide and hydrogen. Electricity is producedwhen the gas is burned in a gas turbine with the excessheat used to drive a steam turbine resulting in evengreater efficiency.
Another advantage of IGCC is that a concentratedstream of carbon dioxide, a major greenhouse gas, canbe produced. This can be readily captured and thenstored in underground formations, resulting in zeroemissions to the atmosphere.
This system also has the potential to produce chemicalsand liquid fuels from the coal gas, in addition to electricity. In the future, hydrogen from coal gasificationmay also be used to generate clean power in fuel cellsor to run hydrogen-powered vehicles.
ITAM Coal
CLEAN COAL TECHNOLOGIES
Photo Courtesy of Los Alamos National Laboratory, USA
Did you know?
Coal forms the most significant fossil fuel resourceon Earth, much more plentifulthan oil and gas and will therefore bethe most significant source of energyfor many years to come.
????
A zero emission coal plant of the future
21
More than 90 per cent of the world’senergy demands are met by fossil fuels,including coal, oil and gas. As the mostabundant, widely distributed and lowestcost fuel, coal is used to generate morethan a third of the world’s electricity.
Greenhouse gas emissions and otherenvironmental impacts associated withthe use of fossil fuels have led to interestin the potential of alternative or 'renewable' energy sources. Theseinclude sources such as solar, wind,hydro, geothermal, tidal and biomass.
While the use of these alternatives isgrowing, none are yet capable of economically meeting society’s enormous and rapidly growing demandfor energy. World demand for energy ofall types is expected to increase by 60 percent over the next 20 years. Demand forelectricity is expected to almost double.Renewable energy is expected to meet anincreasing share of this demand. However, high costs and practical limitations mean their overall contribution will remain relatively small for the foreseeable future.
In many parts of the world nuclear power providesanother alternative to fossil fuels for electricity generation. However, higher costs and community concerns over the safety of nuclear reactors andradioactive waste have seen the uptake of nuclearpower much reduced in the past few years. Australiahas no nuclear power plants.
ITAM Coal
Energy trapped by plants may be converted to fuel which can supplementfossil fuels.Photo courtesy of Bundaberg Sugar Ltd
OTHER ENERGY SOURCES
Photo-electric cells mounted on the roofs of buildings.Photo courtesy of Pacific Energy
Wind powered electricity generators.Photo courtesy of Bluewind
22 ITAM Coal
Source
Conventional Coal
Clean Coalincluding IntegratedCoal GasificationCombined Cycle(IGCC) and carbondioxide capture andstorage.
Natural Gas
Nuclear
Solar
Wind
Hydro
Geothermal
Tidal/wave
Biomass
Application
Coal is burned in a furnaceto raise steam which drivesa turbine.
Coal is reacted with oxygenand water to produce ahydrogen-rich gas which isthen combusted in a turbine.Carbon dioxide is capturedand permanently storedunderground.
Gas is burned directly in aturbine.
Uranium is used in a nuclearfission reaction to produceheat.
The energy of the sun istrapped by solar cells to heatwater (solar thermal) or produce electricity directly(photovoltaics).
Wind striking propellerblades is used to drive turbines.
Water stored in reservoirsfalls through pipes via gravity and turns a turbine.
Water is pumped deepunderground where it passes through hot geologicalformations. The resultingsteam returns to the surfaceto drive a turbine.
The natural movement oftides and waves is used todrive turbines.
Biomass (plant material suchas agricultural or forestwastes) is burned to raisesteam to drive a turbine.
Current Status
Provides 85 per cent ofAustralia’s and 38 per centof the world’s electricity.
Both IGCC and carbon dioxide capture and storagehave been demonstrated.Further research and development is required toreduce costs.
Provides 17 per cent of theworld’s electricity.
Provides 16 per cent of theworld’s electricity.
Provides less than 0.1 percent of the world’s electricity.
Provides less than 0.5 percent of the world’s electricity.
Provides 17 per cent of theworld’s electricity.
Provides less than 0.5 percent of the world’s electricity.
Provides less than 0.1 percent of the world’s electricity.
Provides less than 1 percent of the world’s electricity.
Advantages
The most abundant andwidely distributed fossilfuel and the lowest costform of electric powergeneration.
Maintains access to abundant, low cost energy from coal withlower or zero greenhousegas emissions.
Proven technology andlower cost than alterna-tives apart from coal.
No greenhouse gas emissions.
Renewable and lowgreenhouse gas emissions.
Low greenhouse gasemissions.
Relatively low greenhousegas emissions (but maybe significant while floodedvegetation in new damsdecomposes).
Uses the natural heat ofthe Earth’s core to produce theoretically limitless energy with nogreenhouse gas emissions or other pollutants.
Renewable energy free ofgreenhouse gas emissions and other pollutants.
Renewable and greenhouse gas neutralprovided the crops usedare regrown each year.
Disadvantages
High greenhouse gasemissions.
Higher cost than conventional coal, butpotentially less costlythan most alternatives.
High greenhouse gasemissions. Less abundant and highercost than coal.
The safety of reactorsand the difficulty of dealing with resultingradioactive waste.
High cost. Intermittent - only workswhen the sun is shining.
Lower cost than solarbut higher than coal andgas. Intermittent - onlyworks when sufficientwind is present.
Large scale applicationrequires major interruption to naturalwatercourses and largeareas of land. Suitablesites limited.
High cost and technological barriersstill to be overcome forlarge scale applications.
High cost and suitablesites are limited.
Requires very largeareas of land to producesufficient plant material.
OTHER ENERGY SOURCES
23ITAM Coal
GLOSSARY
Back Cover: Mining operations at dusk. Photo Courtesy of BHP Billiton
Web addresses
Australian Coal Association:
World Coal Institute:
There is a virtual tour of a coal mine at the NSW Minerals Council:
Queensland Mining Council:
www.australiancoal.com.au
www.wci-coal.com.au
www.nswmin.com.au
www.qmc.com.au
Anthracite
Basin
Biomass
Bituminous
Bord and pillar
Blast furnace
Bulk commodities
Carbon dioxide
Coal
Coalification
Coal preparation
Coal terminal
Colliery
Coke
Coking coal
a hard, black high energyvalue coal
a depression in the Earth’s crustfilled with sediment
living material which can be converted to energy
a rank of black coal of mediumenergy value
underground mining method thatleaves spaces (bords) and pillars(blocks of coal) supporting theroof
a tall furnace in which cokereacts with iron ore to reduce itto pure iron
low value materials, such as ironore and coal, which must be handled efficiently in large quantities if a profit is to be madefrom their sale
colourless, odourless gas formedwhen carbon combines with oxygen - CO 2. A major
greenhouse gas
an organic sedimentary rockformed from partly decayed plantmaterial
the process where heat andpressure turn decomposing plantmaterial to coal
process to convert mined coal toprovide a pure product
stockpile of coal kept at a port
an underground coal mine
solid lump of almost pure carbon formed when coal is heated in the absence of air
coal used for making coke tofeed a blast furnace for makingsteel. Also known as metallurgical coal
Dragline
Generator
Glossopteris
Kinetic energy
Longwall mining
Methane
Opencut
Outcrop
Overburden
Permian
Rank
Rehabilitation
Seam
Sediment
Thermal coal
Topsoil
Turbine
a large bucket excavator used inopen cut mines
machine which, when the magnetaround its shaft is turned, generateselectricity in the surrounding coils ofwire
an extinct seed-fern which makes upmost Permian coal deposits
energy possessed by a moving orrotating object
mining technique where a mechanicalshearer cuts along a coal facebeneath a roof supported by hydraulicjacks
a gas comprising one atom of carbonbound to four hydrogen atoms - CH 4.
A major greenhouse gas
a surface mining method where coalis exposed by removing the overlyingrock
rock or mineral material exposed onthe Earth’s surface
waste rock material overlying a coalseam - also called spoil
a major coal forming geological period, about 250 million years ago
a method of classifying coal based onthe amounts of carbon and volatilematter it contains
the process of returning a mined landsurface into productive use
layer of coal - also called a bed
rock particles, such as sand and clay,produced by weathering
coal used in boilers for generatingsteam. Also known as steaming coal
surface layer of soil
machine in which blades are turnedby gas or steam, usually connected toa generator
Written and edited: Barry Cook. Research: Mary-Anne Binnie, W. G. 'Haggis' Shackleton.With contributions from Simon Andrews, Mark O’Neill, Frank Nizynski and Robert Wilson.
Design and Production: David Brittan, Chris Matthews.2003, Osmond Earth Sciences.
Printed by Lane Print Group, Adelaide. ISSN No. 1322-8218
ITAM stands for 'Introduction to Australia's Minerals'and is the acronym for a series of booklets writtento provide information for teachers and students.
Published: September, 2003
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