Coke is the residue, mainly amorphouscarbon, left on heating bituminous coal and thus driving off its volatile constituents, or on heating hydrocarbons to a point at which they decompose with deposition of carbon (cracking).
The simplest method of producing coke is based on the preparation of wood charcoal, the coal being arranged in heaps which are smothered with clay or coal-dust, and then set on fire, sufficient air being admitted to keep the mass at the proper temperature for decomposition without wasting the coke. After the volatile portions are got rid of, the heap is allowed to cool, or is extinguished with water, and the coke is then ready. Methods of heating the coal in close or open ovens until the gaseous and fluid products are driven off are also commonly used. Gas-coke is that which remains in the retorts after the gas has been given off.
Good oven-coke has an iron-grey colour, sub-metallic lustre, is hard, and somewhat vesicular; but gas-coke has rather a slagged and cindery look, and is more porous. Coke contains about 90 percent of carbon, and is used where a strong heat is wanted without smoke and flame, and it is accordingly largely consumed in drying malt and similar purposes. It used to be burned regularly in locomotive-engines, but after about 1900 raw coal was commonly substituted. The largest quantities of coke used to be consumed in smelting operations. Research Coke
Abbreviations
SciTech
Research Coke