iv) Carbon injection 

Injection of carbon brings following benefits:

1. For 100 percent scrap practice or when carbon content of the bath is insufficient to produce CO for slag foaming, carbon injection is beneficial.
   
   
2. Carbon oxidation produces CO which on post combustion generates thermal energy.

It is to be noted that carbon injection requires oxygen injection to onset carbon oxidation.

Requirements for chemical energy usage

The chemical energy usage requires to develop a device to inject oxygen in different modes:

1. Hold mode (to prevent plugging)
2. Burner mode (to heat and melt scrap)
3. Soft lancing mode (for post combustion)
4. Supersonic lancing mode (for decarburization and slag foaming)
5. Carbon injection mode (when slag foaming is required)

Injectors are either fixed type or moveable type. Submercible hand lances arc used through the slag door. Large opening in EAF shell is required. Slag and metal splashing restricts the device movement. Excessive repairs and down- time are associated with this technology.

An innovative design is CO-jet injectors which are fixed type and can be mounted on the furnace shell. CO-jet injectors are highly flexible in usage. The reader may see the references given in this lecture.

The next lecture deals with charge mix in EAF steelmaking.