Coke split

Is used for melting metal charge and flux. It is also used to maintain the required coke bed level in the cupola furnace.

Coke split burns in the combustion zone and is replaced with each charge. The amount of coke split depends on the furnace design, the iron charge to be molten, the type of furnace control, coke quality, the blast rate and temperature. The amount e.g. in case of the same composition and channel temperature of the iron is lower for hot blast cupola furnaces than for cold blast cupola furnaces, for high steel contents in the composition higher than for no or low steel contents, for oxidizing furnace processes lower than for reducing furnace processes.

Additional references:
Bed coke
Cupola furnace network diagram
Buffer coke charge