Electric Arc Furnace

1. EAF Introduction
2. Developments in EAF Technology
3. Basic Equipment and Operation
4. Furnace Layout
5. Electrical Equipment
6. Melting
7. Burners
8. Raw Materials
9. Raw Materials Preparation
10. Alloy Yield
11. Electrode Breakage
12. Slag Foaming
13. Slag Foamability
14. Slag Reduction
15. Deslagging
16. Tapping
17. Exercise: EAF Operation
18. EAF Simulation

The basic set-up of an electric arc furnace consists of a furnace shell with a roof on top. The furnace shell is lined with ceramic bricks (usually carbon bonded magnesia bricks) insulating the furnace from the liquid steel. On the upper side walls and on the inside of the roof, water cooled elements are used instead of ceramic insulation. These water cooled panels are positioned so there will be no direct contact with the liquid steel.

Before the melting and heating operations start, the furnace is charged with recycled steel scrap using a scrap basket that has been carefully loaded at the scrap yard. After scrap charging, the roof is closed and three graphite electrodes are lowered towards the scrap. The electrical power is switched on and on contact electrical power is transformed into heat as arcing takes place between the electrodes and the solid feedstock. As the scrap melts, a liquid steel pool starts to form at the bottom of the furnace.

The electrodes are moved downwards as the scrap is melted and caves into the scrap. The vertical movement of the electrodes is obtained by adjusting the electrode arms positions, which are controlled by the feedback from the electrical system, constantly supervising the electrical performance and aiming for an optimum power input at a predefined set-point.

As the scrap is melted, more volume is made available inside the furnace and at a certain point power is switched off, the furnace roof is opened, and another scrap basket will be loaded into the furnace. The power is again switched on and melting of the second basket starts.

When all scrap baskets (usually 2 or 3) have been melted, the heating continues for some time in order to superheat the steel to the target temperature at tapping. During this period - usually referred to as the refining period - some metallurgical operations such as desulfurization, dephosphorization and decarburization, may be performed.

When the steel has obtained the correct composition and temperature, the furnace power is switched off and the furnace is tapped.