Coal or Coke

Coal or Coke

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Have you ever wondered whether coal and coke are the same  or what makes coal different from coke? After examining the differences, you’ll appreciate how both types of fuel benefit mankind. 

Coke and coal are the two different forms of fossil fuel. In fact coke is a byproduct of coal and both of these forms are used for a variety of industrial applications and as fuels. These are the conventional sources of energy.

Let’s understand what is the difference between coal and coke?

What is Coal

Coal is a naturally occurring black or brownish-black sedimentary rock that can be burned for fuel and used to generate heat for varied purposes. It is composed mostly of carbon and hydrocarbons, which contain energy that can be released through combustion (burning). It is one of the most common fossil fuels.

Coal or Coke

What is Coke

Coke is a gray, hard, and porous fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air—a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.

Coal or Coke

Process of Making Coke From Coal

Coke is produced by heating coal at high temperatures, for long periods of time. This heating is called “thermal distillation” or “pyrolysis.” In order to produce coke that will be used in blast furnaces, coal is usually thermally distilled for 15 to 18 hours, but the process can take up to 36 hours. The temperature of the ovens ranges between 900 and 1100 degrees Celsius (1,650 and 2,000 degrees Fahrenheit).

Difference Between Coal and Coke

Following are the main differences between coal and coke:

Coal is a fossil fuel which appears to be a stone and is extracted directly from coal mines. Thus, coal is naturally available (though exhaustible in nature) and does not require any chemical or physical treatment.Coke on the other hand is obtained with the help of a rigorous treatment of coal that involves distillation of bituminous coal.
Coal contains a lot of impurities.Coke is obtained as a residue and is far more refined. Impurities like carbureted hydrogen, naptha and ammonia are removed from coal in the gaseous form and therefore coke is mainly a pure form of carbon.
Coal is raw and can be obtained in large amounts.The industrial process and refining of coal reduces its volume and almost one-third of the volume of coal is obtained as coke.
Coal produces a lot of soot and smoke on combustion.Since coke is devoid of all the gaseous impurities and contaminants, it is a cleaner fuel as compared to coal which produces a lot of soot on combustion.
Coal is a solid mass with high density and specific gravity.Coke is more porous and has relatively low specific gravity.

Which is Better – Coal or Coke

Coke is a better fuel because coke produces more heat on burning as compared to coal. Coke has a higher calorific value than coal. When equal masses of coke and coal are burnt, coke produces more heat.

There’s a reason, actually quite a few of them, why blacksmiths prefer to forge with coke. Let’s take a look at the advantages provided by coke fuel.

  • Higher Forging Temperatures: When coal turns to coke in a forge, its temperature can reach 2,912 degrees Fahrenheit. This extreme heat is hot enough to melt iron and is ideal for blacksmiths.
  • Smokeless Fuel: Before coal becomes coke, it emits a harsh, dark smoke. On the other hand, when coke combusts, it burns clean. That’s a significant advantage if you plan on spending several hours in front of the forge.
  • Fewer Emissions: Many of the impurities and volatiles, including methane, sulfur, and carbon dioxide, burn off in the conversion from coal to coke. 
  • High Carbon Content: Since coke contains a higher level of carbon than bituminous coal, it’s more efficient to burn. Higher carbon levels mean that coke retains more energy from its plant debris origins. 
  • Center Glare Reduction: When a forge nears 3,000 degrees, it produces an intense, white light. The light will damage your eyes if they’re unprotected.

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Image Credit: Coal photo created by dashu83 –

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