What is Bituminous Coal?
Bituminous coal is actually the most copious rank of coal found in the United States, and it accounted for approximately 48% of U.S total coal production in 2019. In the United States, it is aged between 100 million and 300 million years old. Bituminous coal is used for producing electricity and is a significant fuel and raw material for generating coking coal. It is also used as a raw agent in the iron and steel industry.
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Percentage of Carbon in Bituminous Coal
The Bituminous coal comprises 45%–86% of carbon. Coal rock is actually composed of almost pure carbon. The coal in different deposits consists of different configurations, thus, coal is divided in different categories. After Anthracite, Bituminous coal is the second highest quality of coal and the most copious type. Generally, it is derived from fairly old coal deposits (about 300 million years) and exposes a carbon content which varies from 76-86%. The energy density of this coal is comparatively high (27 MJ/kg), thus, disperse a substantial amount of energy when burned.
Heating Value of Bituminous Coal
Bituminous coal renders about 10,500 to 15,000 BTU per pound when mined.
Prosperities of Bituminous Coal
Bituminous coal has moisture content up to 17%.
Approximately 0.5 to 2% of the weight of bituminous coal is nitrogen.
Its fixed carbon content ranges up to 85%, with ash content up to 12% in weight.
The calorific value of bituminous coal A is 8 - 10% about 6,300 - 7,000 kcal/kg while that of medium volatile bituminous has 7,000 - 8,000 kcal/kg.
Bituminous coal can be further divided by the level of volatile matter it consists of, like high-volatile A, B, and C, medium-volatile, and low-volatile.
Volatile matter takes into account any material that is free from the coal at high temperatures.
In the context of coal, the volatile matter may include sulfur and hydrocarbons.
What is Sub Bituminous Coal?
Subbituminous coal essentially comprises 35%–45% carbon, and comparatively has a lower heating value than bituminous coal. Most sub bituminous coal in the U.S are at least 100 million years old. Around 44% of the total coal production of the United States in 2019 was subbituminous while the remainder was yielded in Alaska, Colorado and New Mexico.
Bituminous Coal Uses
High carbon content and low moisture of this specific coal type makes it ideal in the production use of steel and cement, as well as in coke production and electricity generation and coke production.
Types and Uses of Bituminous Coal Uses
Bituminous Coal is divided into 2 type’s i.e.
Thermal Coal
Metallurgical Coal
Thermal Coal: also referred to as steaming coal, it is deployed to power plants which produce steam for electricity and industrial uses. Trains that operate on steam engines often are fueled with "bituminous coal,".
Metallurgical Coal: also sometimes called coking coal, is used in the making of coke. This type of coke is a source of carbon necessary for making steel and iron.
Environmental Concerns Associated With Bituminous Coal
Bituminous coal ignites fire easily and can thus yield immoderate smoke and soot – if burned improperly.
The high sulfur of bituminous contributes to acid rain.
Consisting of the mineral pyrite, which caters as a host for impurities such as arsenic and mercury, it releases pollution in the air.
When burned, bituminous coal releases hazardous emissions like hydrogen fluoride (HF), hydrogen chloride (HCl), and polycyclic aromatic hydrocarbons (PAHs).
Partial combustion results in higher levels of PAHs that are carcinogenic.
Bituminous Coal Facts
Bituminous coal ranks 2nd in carbon and heat content in comparison to other types of coal
Earlier in the 20th century, bituminous coal mining was a tremendously dangerous task, taking away the lives of an average of 1,700 coal miners' annually. About 2,500 workers per year were left permanently disabled as an outcome of coal mining mishap.
Little particles of bituminous coal waste left over after preparation of commercial-grade coal is known as "coal fines."
Coal Fines are very light weighted, dusty, and difficult to manage, and traditionally were stored with water in alluvium impoundments to prevent them from blowing away.
Breakthrough technologies have been developed to recoup coal fines. One technique employs a centrifuge to isolate the coal particles from the alluvium water. Other techniques bind the fines into briquettes which contain low moisture content, making them apt for fuel use.
Bituminous coal has been generated in at least 19 states in 2019, but five states reckoned around 75% of total bituminous production: West Virginia accounted for 27.5%, Pennsylvania (14.0%), Illinois (13.5%), Kentucky (10.6%), and Indiana (9.3%).
FAQs on Bituminous Coal
1. What is bituminous coal and where does it rank among the four main types of coal?
Bituminous coal is a dense, black sedimentary rock formed from ancient plant matter subjected to intense heat and pressure over millions of years. It is the most abundant type of coal. In the ranking of coal types by carbon content and heat energy, it sits between lignite and anthracite. The four main types, from lowest to highest rank, are:
- Peat: The precursor to coal.
- Lignite: Also known as brown coal, with low carbon content.
- Bituminous Coal: A middle-rank coal used widely for electricity and steel production.
- Anthracite: The highest rank of coal, also known as hard coal.
2. What are the key characteristics and properties of bituminous coal?
Bituminous coal is identified by several key properties:
- Appearance: It is typically black, sometimes with a shiny lustre, and often shows distinct layers or bands.
- Carbon Content: It has a carbon content ranging from about 60% to 80%.
- Heating Value: It possesses a high calorific (heating) value, making it an efficient fuel for generating steam and electricity.
- Bitumen Content: It contains a tar-like substance called bitumen, which contributes to its high volatile matter content and makes it smoke when burned.
3. What are the primary industrial uses of bituminous coal in India?
Bituminous coal is a cornerstone of India's industrial sector due to its versatility. Its primary uses include:
- Electricity Generation: It is the main fuel used in thermal power plants to produce steam that drives turbines for generating electricity.
- Iron and Steel Industry: Specific grades of bituminous coal, known as coking coal, are used to produce coke, which is essential for smelting iron ore in blast furnaces.
- Cement Manufacturing: It is burned in kilns to provide the high temperatures needed to produce cement clinker.
- Other Industries: It is also used as a fuel source in chemical manufacturing, paper production, and other industrial heating processes.
4. Where are the major bituminous coalfields located in India?
In India, the vast majority of bituminous coal reserves are found in the Gondwana coalfields, which are over 200 million years old. The most significant locations include:
- Damodar Valley: This region in West Bengal and Jharkhand contains some of India's largest coalfields, such as Jharia, Raniganj, and Bokaro.
- Godavari Valley: Located in Telangana and Andhra Pradesh.
- Mahanadi Valley: Found in Chhattisgarh and Odisha.
- Son Valley: Located in Madhya Pradesh.
5. What is the main difference between bituminous coal and anthracite?
The main difference lies in their rank, carbon content, and burning properties. Anthracite is the highest-ranking coal; it is harder, has a higher carbon content (over 86%), and contains very little volatile matter. It burns slowly with a hot, clean, blue flame. In contrast, bituminous coal is a middle-ranking coal with a lower carbon content (60-80%) and higher volatile matter. This causes it to burn with a smokier, yellow flame and makes it ideal for producing coke.
6. Why is some bituminous coal specifically called 'coking coal'?
Not all bituminous coal is coking coal. 'Coking coal', also known as metallurgical coal, is a special high-grade type of bituminous coal with a low content of ash, sulphur, and phosphorus. Its most important property is its 'caking ability'—the capacity to soften, swell, and resolidify into a hard, porous mass called coke when heated in an oxygen-free environment. This coke is strong enough to be used in a blast furnace to reduce iron ore to iron, making coking coal indispensable for the steel industry.
7. How do the environmental impacts of burning bituminous coal compare to other fossil fuels?
Burning bituminous coal has significant environmental impacts. Due to its relatively high sulphur and volatile matter content, its combustion releases large quantities of pollutants, including:
- Sulphur Dioxide (SO₂): A primary cause of acid rain.
- Particulate Matter (PM2.5): Fine soot particles that can cause respiratory health problems.
- Nitrogen Oxides (NOx): Contributors to smog and acid rain.
- Carbon Dioxide (CO₂): It releases more CO₂ per unit of energy than oil or natural gas, making it a major contributor to global warming.
8. Why is bituminous coal often referred to as 'soft coal' if it is a hard rock?
The term 'soft coal' is a practical, industrial classification rather than a geological one. Geologically, bituminous coal is a hard sedimentary rock. It is called 'soft coal' in comparison to 'hard coal' (anthracite) for two main reasons:
- Physical Structure: It breaks and fractures more easily than the harder, more brittle anthracite.
- Volatile Content: It has a much higher percentage of volatile compounds. When burned, these volatiles are released, making the coal 'softer' in its burning characteristics compared to the dense, slow-burning anthracite.
