Coal - Classification
Classification of coal based on volatile matter and cooking 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 matter1) (weight %) | General description | |
|---|---|---|---|
| 101 | < 6.1 | Anthracite | |
| 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 | Cooking steams coals | |
| 204 | 17.1 - 19.5 | ||
| 206 | 19.1 - 19.5 | Heat altered low volatile steam coals | |
| 301 | 19.6 - 32.0 | Prime cooking 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 | ||
1) 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 Density of Coal
- 1100 - 1800 (kg/m3)
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 %
Related Topics
-
Combustion
Combustion processes and their efficiency. Boiler house and chimney topics. Properties of fuels like oil, gas, coal and wood and more. Safety valves and tanks. -
Densities
Densities of solids, liquids and gases. Definitions and convertion calculators. -
Heating Systems
Design of heating systems - capacities and design of boilers, pipelines, heat exchangers, expansion systems and more.
Related Documents
-
Anthracite Coal
Anthracite coal is available in a number of different grades. -
ASTM Standard - Volume 05.06 Gaseous Fuels, Coal and Coke
An overview of ASTM Section 5 - Petroleum Products, Lubricants, and Fossil Fuels - Volume 05.06 Gaseous Fuels, Coal and Coke. -
Combustion of Fuels - Carbon Dioxide Emission
Environmental emission of carbon dioxide CO2 when combustion fuels like coal, oil, natural gas, LPG and bio energy. -
Dust Explosions - Substances, Critical Temperatures and Concentrations
Critical temperatures and concentration parameters for substances like coal, zinc, uranium and more. -
Fossil vs. Alternative Fuels - Energy Content
Net (low) and gross (high) energy content in fossil and alternative fuels. -
Fuels - Higher and Lower Calorific Values
Higher and lower calorific values (heating values) for fuels like coke, oil, wood, hydrogen and others. -
Fuels and Chemicals - Autoignition Temperatures
Autoignition points for fuels and chemicals like butane, coke, hydrogen, petroleum and more. -
Optimal Combustion Processes - Fuel vs. Excess Air
Stable and efficient combustion requires correct mixture of fuels and oxygen. -
Porosity
Volume not occupied by solid material. -
Standard Grade Coal - Heat Values
Standard grades coal heat values. -
Stoker Classification
Coal stokers classified on basis of coal burning capacities.
