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Lignite (derived from Latin lignum meaning 'wood'), often referred to as brown coal, [1] is a soft, brown, combustible sedimentary rock formed from naturally compressed peat.It has a carbon content around 25–35% [1] [2] and is considered the lowest rank of coal due to its relatively low heat content.
5.56 × 45 mm NATO bullet muzzle energy density [clarification needed] 0.4: 3.2: battery, Nickel–metal hydride (NiMH), low power design as used in consumer batteries [29] 0.4: 1.55: Liquid Nitrogen: 0.349: Water – Enthalpy of Fusion: 0.334: 0.334: battery, Zinc–Bromine flow (ZnBr) [30] 0.27: battery, Nickel–metal hydride (NiMH), High ...
Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a submetallic lustre.It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coals.
The rank of coal is correlated with its geologic history, as described in Hilt's law. In the ASTM system, any coal with more than 69% fixed carbon is classified by its content of carbon and volatiles. Coal with less than 69% fixed carbon is classified by its heating value. Volatiles and carbon are on a dry mineral free base; heating value is ...
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Its bank density (the density of a coal seam prior to breaking up during mining) is about 1346 kg/m 3 (84 lb/ft 3) while the bulk density of extracted coal is up to 833 kg/m 3 (52 lb/ft 3). [12] Bituminous coal characteristically burns with a smoky flame and softens and swells during combustion. [13]
Renewable resources are available each year, unlike non-renewable resources, which are eventually depleted. A simple comparison is a coal mine and a forest. While the forest could be depleted, if it is managed it represents a continuous supply of energy, vs. the coal mine, which once has been exhausted is gone.
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