Monday, April 21, 2008

Classification of coal based on volatile matter and coking power of clean material

Classification of coal based on volatile matter and coking power of clean material

Coal is a readily combustible rock containing more than 50 percent by weight of carbonaceous material, formed from compaction and indurations of variously altered plant remains similar to those in peat.

After a considerable amount of time, heat, and burial pressure, it is metamorphosed from peat to lignite. Lignite is considered to be "immature" coal at this stage of development because it is still somewhat light in color and it remains soft.

Lignite increases in maturity by becoming darker and harder and is then classified as sub-bituminous coal. After a continuous process of burial and alteration, chemical and physical changes occur until the coal is classified as bituminous - dark and hard coal.

Bituminous coal ignites easily and burns long with a relatively long flame. If improperly fired bituminous coal is characterized with excess smoke and soot.

Anthracite coal is the last classification, the ultimate maturation. Anthracite coal is very hard and shiny.

Class

Volatile matter
(weight %)

General description

101

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Anthracites

102

3.1 - 9.0

201

9.1 - 13.5

Dry steam coals

Low volatile steam coals

202

13.6 - 15.0

203

15.1 - 17.0

Coking steams coals

204

17.1 - 19.5

206

19.1 - 19.5

Heat altered low volatile steam coals

301

19.6 - 32.0

Prime coking coals

Medium volatile coals

305

19.6 - 32.0

Mainly heat altered coals

306

19.6 - 32.0

401

32.1 - 36.0

Very strongly coking coals

High volatile coals

402

> 36.0

501

32.1 - 36.0

Strongly coking coals

502

> 36.0

601

32.1 - 36.0

Medium coking coals

602

> 36.0

701

32.1

Weakly coking coals

702

> 36.0

801

32.1 - 36.0

Very weakly coking coals

802

> 36.0

901

32.1 - 36.0

Non-coking coals

902

> 36.0

Volatile matter - dry mineral matter free basis. In coal, those products, exclusive of moisture, given off as gas and vapor determined analytically.

Anthracite coal creates a steady and clean flame and is preferred for domestic heating. Furthermore it burn longer with more heat than the other types.

Typical Sulfur Content in Coal

Anthracite Coal : 0.6 - 0.77 weight %

Bituminous Coal : 0.7 - 4.0 weight %

Lignite Coal : 0.4 weight %

Typical Moisture Content in Coal

Anthracite Coal : 2.8 - 16.3 weight %

Bituminous Coal : 2.2 - 15.9 weight %

Lignite Coal : 39 weight %

Typical Fixed Carbon Content in Coal

Anthracite Coal : 80.5 - 85.7 weight %

Bituminous Coal : 44.9-78.2 weight %

Lignite Coal : 31.4 weight %

Typical Bulk Density of Coal

Anthracite Coal : 50 - 58 (lb/ft3), 800 - 929 (kg/m3)

Bituminous Coal : 42 - 57 (lb/ft3), 673 - 913 (kg/m3)

Lignite Coal : 40 - 54 (lb/ft3), 641 - 865 (kg/m3)

Typical Ash Content in Coal

Anthracite Coal : 9.7 - 20.2 weight %

Bituminous Coal : 3.3-11.7 weight %

Lignite Coal : 4.2 weight %

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