- For the place in California, see Lignite, California.
Lignite, often referred to as
brown
coal, or
Rosebud coal by
Northern Pacific Railroad,is a
soft brown fuel with characteristics that put it somewhere between
coal and
peat.
It is considered the
lowest rank of coal; it is mined in Russia
, the
United
States
, Australia and many
European countries, and it is used almost
exclusively as a fuel for steam-electric power generation.
Up to 50% of Greece's electricity and 11% of Germany's comes from
lignite power plants (German Technical and Economic Agency
2008).
Lignite is brownish-black in color and has a carbon content of
around 25-35%, a high inherent moisture content sometimes as high
as 66%, and an
ash content ranging
from 6% to 19% compared with 6% to 12% for
bituminous coal.
The heat content of lignite ranges from 10 to 20 MJ/kg (9 to 17
million
Btu per
short ton) on a moist, mineral-matter-free basis.
The heat content of lignite consumed in the United States averages
13 million Btu/ton (15 MJ/kg), on the as-received basis (i.e.,
containing both inherent moisture and mineral matter). When reacted
with
quaternary amine,
amine treated lignite (ATL) forms. ATL is used in
drilling mud to reduce fluid loss.
Lignite has a high content of volatile matter which makes it easier
to convert into gas and liquid petroleum products than higher
ranking coals. However, its high moisture content and
susceptibility to
spontaneous
combustion can cause problems in transportation and
storage.
Because of its low energy density, brown coal is inefficient to
transport and is not traded extensively on the world market
compared with higher coal grades.
It is often burned in power stations
constructed very close to any mines, such as in Australia's
Latrobe Valley and Luminant's
Monticello
plant
in Texas. Emissions from brown coal fired plants are
generally much higher than for comparable black coal plants, with
the world's worst polluting being the brown coal fueled Hazelwood Power
Station, Victoria
. The operation of brown coal plants,
particularly in combination with
strip
mining, can be politically contentious due to environmental
concerns.
Lignite is geologically younger than higher-grade coals,
originating mainly in the
Tertiary
period.
Types
Lignite can be separated into two types. The first is xyloid
lignite or fossil wood and the second form is the compact lignite
or perfect lignite.
Although xyloid lignite may sometimes have the tenacity and the
appearance of ordinary wood it can be seen that the combustible
woody tissue has experienced a great modification. It is reducible
to a fine powder by
trituration and if
submitted to the action of a weak solution of
potash it yields a considerable quantity of
ulmic acid.
Production
Lignite mined in millions of metric
tons
| Country |
1970 |
1980 |
1990 |
2000 |
2001 |
|
369.300 |
388.000 |
356.500 |
167.700 |
175.400 |
|
127.000 |
141.000 |
137.300 |
86.400 |
83.200 |
|
5.400 |
42.300 |
82.600 |
83.500 |
80.500 |
|
24.200 |
32.900 |
46.000 |
65.000 |
67.800 |
|
8.100 |
23.200 |
51.700 |
63.300 |
67.000 |
|
24 |
24 |
24 |
24 |
24 |
|
32.800 |
36.900 |
67.600 |
61.300 |
59.500 |
|
4.400 |
15.000 |
43.800 |
63.000 |
57.200 |
|
67.000 |
87.000 |
71.000 |
50.100 |
50.700 |
|
13.000 |
22.000 |
38.000 |
40.000 |
47.000 |
|
26.000 |
43.000 |
60.000 |
- |
- |
|
- |
- |
- |
35.500 |
35.500 |
|
14.100 |
27.100 |
33.500 |
17.900 |
29.800 |
|
5.700 |
10.000 |
10.000 |
26.000 |
26.500 |
| Total |
804.000 |
1,028.000 |
1,214.000 |
877.400 |
894.800 |
See also
References
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