It is used in electric arc furnaces. Such furnaces are widely used to produce steel from all-metal raw material (scrap, DRI, HBI, etc.).
The charge materials added to the furnace include metal, a source of calcium oxide, a source of magnesium oxide, and a source of carbon. The carbon introduced together with the charge is commonly anthracite or a mixture that ranges from 3″ to 1/4″ and has a percentage of fixed carbon greater than 75%.
Charge coal is important to electric arc furnace operation:
- It prevents over-oxidation of metal filler and flux material prior to melting.
- It accelerates the formation of slag.
- It provides a considerable amount of energy required for steelmaking operations from its reaction with oxygen to produce carbon monoxide. This has led to substantial reductions in energy consumption in the electric arc furnace.
For its part, carbon monoxide is key to achieving low concentrations of dissolved gases in steel, which are evacuated along with carbon monoxide. Furthermore, the oxide inclusions present in the steel flow into the slag.
Carbon recovery from charge coal in electric arc furnaces is not always constant. It has been shown that the size and quality of the charge coal is very important to achieve good and constant recoveries of carbon in steel.