How coal is formed - Practically demonstration!

Summary

This video explores coal, an organic sedimentary rock formed from plant material over millions of years under pressure and heat. It explains the five types of coal—peat, lignite, subbituminous, bituminous, and anthracite—detailing their carbon content, density, color, and uses. The presenter compares subbituminous and bituminous coal through physical characteristics like weight, texture, and visible bands, and demonstrates their burning properties. The video highlights how coal matures from soft, moist peat to dense, hard, high-calorific anthracite, providing a clear understanding of coal formation, identification, and practical applications in energy and industry.

Takeaways

• 🌱 Coal is an organic, sedimentary rock formed from accumulated plant material in swamp or wetland environments over millions of years.
• 🔥 Good quality coal is black and can leave hands dirty when handled due to its carbon content.
• 🪵 Peat is the first stage of coal formation, containing recognizable plant debris like leaves, roots, and stems.
• 🟤 Lignite, or brown coal, is low-rank coal with 62–70% carbon, high moisture content, and disintegrates easily when exposed to air.
• ⚫ Subbituminous coal is darker, brittle, contains 35–45% carbon, and is widely used for steam generation and industrial purposes.
• 🪨 Bituminous coal has 60–80% carbon, is denser and harder than subbituminous coal, and is commonly used as fuel due to its higher heat output.
• 💎 Anthracite is the highest grade of coal, very hard, shiny, with 75–95% carbon, high calorific value, and low pollution.
• 🖐 Coal maturity can be identified by color, weight, and texture: darker and heavier coal indicates higher carbon content.
• ✨ Physical characteristics, like bright and dull bands, indicate preserved woody material versus mineral content in coal.
• 🔥 Burning properties vary: subbituminous coal heats slower and burns with a yellow smoky flame, while bituminous coal heats faster and produces more heat.
• 📊 Overall, coal formation is a progressive process where carbon content, density, hardness, and energy potential increase from peat to anthracite.

Q & A

What is coal and how is it classified?

Coal is an organic, sedimentary rock formed from plant materials over millions of years. It is classified into five types based on carbon content, density, and calorific value: Peat, Lignite, Subbituminous, Bituminous, and Anthracite.

How does coal form in nature?

Coal forms from the accumulation and preservation of plant materials in swampy environments. Over time, plant matter mixed with water undergoes pressure and heat for millions of years, gradually transforming into coal.

What is peat and what are its characteristics?

Peat is the first stage of coal formation. It contains decomposed plant debris like leaves, ferns, and roots. Plant structures are still recognizable, making it the least mature form of coal.

Why is lignite called brown coal and what are its properties?

Lignite, or brown coal, is formed from peat and has a low carbon content (62–70%). It contains high moisture, disintegrates easily when exposed to air, and is not suitable for long-distance transport due to its instability.

What distinguishes subbituminous coal from lignite and bituminous coal?

Subbituminous coal, also called black lignite, has 35–45% carbon content. It is darker than lignite, relatively brittle, contains visible bright and dull bands, and is used for steam power and industrial purposes.

What are the characteristics of bituminous coal?

Bituminous coal has 60–80% carbon content, higher density, and is harder than subbituminous coal. It appears dull black, but bright bands are visible when chipped. It burns efficiently due to its higher calorific value.

Why is anthracite considered the highest quality coal?

Anthracite contains 75–95% carbon, is very hard, dense, and produces high heat with low pollution. Its shiny submetallic luster indicates purity and makes it the most efficient form of coal for burning.

How can you visually distinguish subbituminous coal from bituminous coal?

Subbituminous coal is lighter, woody, and has visible bright and dull horizontal bands, while bituminous coal is heavier, rock-like, mostly dull black, but reveals bright bands when chipped.

How does the density of coal relate to its formation?

Coal density increases with maturity and burial depth. Subbituminous coal is lighter and forms closer to the surface, while bituminous coal is denser and forms deeper, reflecting greater pressure and compaction.

How do subbituminous and bituminous coal behave when burned?

Both burn with a smoky yellow flame. Subbituminous coal takes longer to heat up due to lower calorific value, whereas bituminous coal heats faster and burns more efficiently because it contains more carbon and energy.

What is the general trend in coal properties as it matures from peat to anthracite?

As coal matures from peat to anthracite, carbon content, density, hardness, and calorific value increase, while moisture content decreases. This results in coal that burns hotter, cleaner, and more efficiently.

Why is it important to understand coal types and properties?

Understanding coal types helps in selecting the appropriate coal for energy production, industrial use, and storage. Different types have varying heat content, stability, and environmental impact.