Electric Arc furnace

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1. Electric Arc Furnace (EAF)M FACTS
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2. Electric Arc Furnace (EAF)M FACTS
EAF is direct arc furnace.
Steelmaking temp is maintained by an electric arc struck between the
graphite electrodes &the metallic charge.
The arc temperature is above 4000°C and is used to heat the bath by radiative
heat transfer.
Only process wherein either oxidizing or reducing condition can be
maintained as desired.
Different slag types can be carried out.
High cost of electrical energy makes this process costly.

3. Electric Arc Furnace (EAF)
Parts of EAF
Furnace body consisting of the shell,
the hearth, the walls, the spout, doors,
etc.
Gears for furnace body movement
Arrangements for moving the roof
Electrodes with their holders and
supports
Electrode lifting and lowering
mechanism
Electrical equipment
M FACTS

4. Electric Arc Furnace (EAF)M FACTS
Charging materials
Steelscrapistheprinciplerawmaterial.Itmayconstitute60to80%ofthecharge.
Insomepracticesspongeironandorpigironisalsousedforchemicalbalance.
Inbasicfurnacesslagformerslikelimestone,fluorspar,sand,andquartziteareused
toformaslagtorefinethemetal.
Oxygenlancingisusedfordecarburization
ForthepurposeofdeoxidationFerro-manganese,ferrosiliconoraluminumisused.
Alloyingelementsareaddedfortheproductionofalloysteels.

5. Electric Arc Furnace (EAF)M FACTS
EAF Operations
BasicallyEAFoperationsconsistsofthreesteps
Charging
Meltdownperiod
Refining
CHARGING
Heavy and light scrap are preheated through the exit gas. Burnt lime and spar are
added to help early slag formation.
Iron ore may also be added if refining is required during melt-down period.
The furnace is charged from the top (Hot metal is also charged as per the
requirement).
Some furnaces are equipped with continuous charging

6. Electric Arc Furnace (EAF)M FACTS
MELTDOWNPERIOD
Electrodesareloweredandboredintothescrap.
Toprotecttheroofandwallsfromexcessiveheatanddamagefromthearcs,Lower
voltagesareselected.
Whenthearcisshieldedbyscrap,voltageisincreasedtoformmoltenmetalpoolto
reducethemeltdownperiod.
Duringmeltdownperiod,silicon,manganeseandcarbonoxidizes.
Oxidizingandlimyslagisproduceswhichpromotesdephosphorizationaswell.
Meltdownperioddependson(ArcconditionsandDeep/shallowbath)
Largerarcrequireslowercurrentandlowerheatlosses.
Deepbathshortensthemeltdownperiod.

7. Electric Arc Furnace (EAF)M FACTS
REFINING
Refiningcontinuesevenduringmelting.
Removalofphosphorusmustbecompletebeforetheriseintemperatureandcarbon
boil.
Whenremovalofsulphurisnotrequiredsingleoxidizingslagpracticeisused.
WhenbothPhosphorousandSulphurisnotrequireddoubleslagpracticeisused.
Indoubleslagpractice,oxidizingslagisremovedandreducingslagisformedafter
deoxidation.
Reducingslaghelpstoavoidlossofalloyingelements.
Oncethebathchemistryanditstemperatureareattained,heatisdeoxidizedand
finishedfortapping

8. Electric Arc Furnace (EAF)M FACTS
Advantages of EAF Steelmaking
The use of EAFs allows steel to be made from a 100% scrap metal feedstock.
The large reduction in specific energy (energy per unit weight) required to produce
the steel.
EAFs can be rapidly started and stopped, allowing the steel mill to vary production
according to demand.
Hot metal from Blast furnace can be directly used.
Flexibility to produce a variety of grades.

9. Electric Arc Furnace (EAF)M FACTS
Limitations of EAF Steelmaking
Running cost is high because of electrical energy consumptions and other attached
equipments.
When EAF repairs are necessary they are often quite expensive.
Scrap availability as Scrap is principle charge material in EAF.
When and how to use different grades of scraps.

10. Electric Arc Furnace (EAF)M FACTS
Modern Developments in EAF Steelmaking
Ultra high power supply (UHP)
Oxygen lancing
Foamy slag practice
Use of DRI/Hot briquetted iron
Pre-heating of scrap and DRI
Bath stirring by argon
Eccentric bottom tapping
Emission and noise control
Process automation and control

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