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Electric arc furnace

Process Description

About 30% of the world's steel is produced in electric arc furnaces. The smelting of scrap and sponge iron, with or without the accompaniment of pig iron takes place in steel works by means of electric arc furnaces. Significant developments have taken place over recent decades in transformers, panels, furnace geometry, foam slag technology, automation, electrode regulation, hydraulics, and the use of oxygen, which have significantly improved the economic efficiency of the process.

An EAF consists of the hearth (refractory bricked lower part of the furnace vessel with tap hole), water-cooled panels, the lid with the electrodes, and the exhaust port. The oven is loaded with baskets from above by swivelling the lid and electrodes to the side. After the lid is closed and the electrodes retracted, the melting process begins. Electrical energy is converted into thermal energy by an electric arc between the electrode and the feedstock. The arc generates temperatures up to 3500°C and heats the molten steel up to 1800°C. Here, the converter is replaced by oxygen for refining.

Example of an electric arc furnace

The use of oxyfuel technology supports the process by replacing electrical energy with chemical combustion energy. At the end of the melting phase, oxygen is injected for refining.

Advantages:

  • Savings in electrical energy
  • Minimises batch times (tap to tap)
  • Shorter power-on times
  • Savings in electrode consumption 
  • Improvements in foam slag technology

Application example:

Operating data

 

Minimum

Maximum

Loading weight

[t]

20

200

Tapping weight

[t]

17,6

162

Output

[%]

78

94

Power on time

[min]

15

160

Power off time

[min]

6

46

Tap to tap time

[min]

35

203

Electrical energy

[kWh/t]

318

525

Oxygen combustion

[Nm³/t]

18

50

Natural gas consumption

[Nm³/t]

0

13

Total carbon consumption

[kg/t]

4

31

FeO in slag

[%]

28

46

Electrode combustion

[kg/t]

1

3,1

Tapping temperature

[°C]

1600

1720

 Energy consumption refers to tapping weight

Gas Application

  • Oxygen lances
  • Coherent jet system

Messer SOlution

In addition to the gases required by the process, with a cooperation partner Messer offers a coherent jet system of a modular design, consisting of an oxyfuel burner system with integrated supersonic oxygen injection and pneumatic coal dust feed and regulation and control of oxygen, fuel and carbon, also including the related automation with software.

Oxyfuel burner system with integrated supersonic oxygen injection

The Messer experts have extensive know-how on the relevant process sequences and are able to adapt the system exactly to your requirements.