Lignite

For the place in California, see Lignite, California.

Lignite briquette

Strip mining lignite at Tagebau Garzweiler near Grevenbroich, Germany

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.^[1]

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.^[2] The operation of brown coal plants, particularly in combination with strip mining, can be politically contentious due to environmental concerns.^[3][4]

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.^[5]

Production

Lignite mined in millions of metric tons

Country	1970	1980	1990	2000	2001
Germany	369.300	388.000	356.500	167.700	175.400
Russia	127.000	141.000	137.300	86.400	83.200
United States	5.400	42.300	82.600	83.500	80.500
Australia	24.200	32.900	46.000	65.000	67.800
Greece	8.100	23.200	51.700	63.300	67.000
India	24	24	24	24	24
Poland	32.800	36.900	67.600	61.300	59.500
Turkey	4.400	15.000	43.800	63.000	57.200
Czech Republic	67.000	87.000	71.000	50.100	50.700
People's Republic of China	13.000	22.000	38.000	40.000	47.000
SFR Yugoslavia	26.000	43.000	60.000	-	-
FR Yugoslavia	-	-	-	35.500	35.500
Romania	14.100	27.100	33.500	17.900	29.800
North Korea	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

Energy portal

• Bergius process
• Coal assay
• Energy value of coal
• Fischer-Tropsch process
• Karrick process
• Leonardite
• List of CO2 emitted per million Btu of energy from various fuels

References

External links

• Geographyinaction - an Irish case study
• Photograph of lignite
• Environmental Clean Technologies - What is brown coal?
• Why Brown Coal Should Stay in the Ground