Coke (fuel)

For other uses, see Coke.

Coke is a form of processed coal. Coal is cooked in airtight retorts, at high temperature, separating it into a flammable gas, and solid almost pure Carbon -- the coke. The coke enables higher temperatures to be reached than is possible with even the highest grade coal.

In a traditional blast furnace coke iron ore, limestone, are mixed together, and burned with a supply or Oxygen or high pressure air. Burning coke which almost pure carbon doesn't leave impurities in the finished steel.

In the 19th century, prior to widespread electrification, the flammable gas driven off from the coal was used for lighting and cooking.