Childrens Illustrated Encyclopedia

(Marvins-Underground-K-12) #1

127


PEOPLE HAVE used coal
for cooking and heating
for thousands of years.
During the 19th century,
coal was the world’s most
important fuel. It powered
the steam engines that
made the Industrial

Revolution possible. Today, coal is still


used in vast amounts. Most coal is burned


at power stations to produce electricity, and


burning coal meets much of the world’s


energy needs. Coal is also an essential raw


material for making many products, the most


important of which are iron and steel. Coal is


often called a fossil fuel because it is formed


from the fossilized remains of plants that are


millions of years old. Sometimes a piece of coal


bears the imprint of a prehistoric plant or insect.


Earth contains reserves of coal which, with


careful use, may last for hundreds of years. But


many people are concerned that coal burning


adds to global pollution.


COAL MINERS


For centuries, miners had to
cut coal by hand. Now there


are drills and computer-
controlled cutting


machines to help them.


2


PEAT
The plant remains slowly dried out
under the mud, forming layers of peat,
a fuel that can be dug from the ground.

3


LIGNITE
Layers of peat became
buried. Heat and pressure
turned the peat into lignite,
or brown coal. Lignite
is dug from shallow pits
called strip mines.

Skip (shuttle
car) lifts coal
to surface.

Miners use cutting machine
to dig out coal at coal face.

Miners have lamps on their helmets
that light up everything in front of
them in the dark depths of a mine.

Conveyor belts take
coal to shaft.

MINING
Mine shafts are dug down
to seams (layers) of coal far
below the surface. Miners
dig a network of tunnels to
remove coal from the seams.
In addition to coal, many
other useful minerals, such
as copper, are mined. The
deepest mine is a gold mine
in South Africa
nearly 2.5 miles
(4 km) deep.

Air shaft

Supports hold roof and sides
of tunnels in place.

Railroad takes
miners to the
coal faces.

USES OF COAL
A few steam-powered
trains still burn coal, and some
homes have open fires or coal-fired heating
systems. The main use for
coal is in the production of
electricity. Heating coal without
air produces coke, which is used
to make steel, and coal gas, which
may be burned as a fuel. Another
product is coal-tar pitch, which is
used in making roads. Coal is also
treated to make chemicals that
are used to produce drugs, plastics,
dyes, and many other products.

A lump of
anthracite, a type
of hard black coal


Coal

Miners’ cage
carries miners up
and down mine.

4


BLACK
COAL
Intense heat
and pressure
turned deeper
layers of peat into
a soft black coal,
called bituminous
coal, and anthracite.

1


PREHISTORIC SWAMP
Coal began to form in swamps as long ago as
300 million years. Dying trees and other plants
fell into the water, and their remains became
covered in mud.

FORMATION OF COAL


Pumps circulate
fresh air through
the mine.

Find out more
Electricity
Industrial revolution
Iron and steel
Oil
Prehistoric life
Trains

A large coal-fired power
station in Berlin, Germany
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