Charging methods for DRI

In small furnaces (lower than 5T) batch charging is preferred.
Continuous charging brings advantages like

• Less power off-time.
• Heat losses resulting from delays are eliminated.
• Lower electrical losses.
• Reaction between carbon and  of DRI produces strong carbon boil during charging which improves heat transfer and slag/metal mixing.
• Charging and refining take place simultaneously which reduces tap to tap time.

Continuous charging is preferred when the sponge iron or DRI is around 60%; the limitation is due to the small furnace capacity. However, ultra high powered furnaces can operate with 100% sponge iron.

References:

A.   Chakrabarti:  Steelmaking
G.L.Dressel: Use of DRI in EAFs: Iron and steelmaker, October 1988, P 121
Electric Furnace Steel production, E. Plocking and O. Eltrich (Eds), Joohn Wiley and Sons, Chichester, U.K., 1989, p286]