In Electric Arc Furnace (EAF) steelmaking, scrap quality directly affects production safety, furnace stability, electrical efficiency, and final steel quality. Moist scrap, refractory-containing scrap, closed containers, and oily scrap are the four most dangerous categories of scrap materials. Each carries serious risks that can lead to explosions, equipment damage, production interruption, and steel quality deterioration.
1. Moist Scrap: The Most Dangerous Material in EAF Steelmaking
Moist scrap or scrap mixed with ice and snow can easily cause steam explosions during charging. When water rapidly vaporizes in contact with high-temperature molten steel, extreme pressure is created.
Main hazards of moist scrap
- Steam explosion during charging, causing scrap to eject violently and damaging water-cooled panels, furnace lining, and nearby equipment.
- Shortened refractory life due to explosive thermal shock.
- Increased power consumption, because moisture absorbs large amounts of heat when evaporating.
- Higher hydrogen content in steel, which negatively affects mechanical properties.
- Severe safety risks, especially when hot metal is added after scrap charging.
Certain regions experience frequent incidents during rainy or snowy seasons when scrap cannot be dried properly. Explosions may interrupt charging, damage water-cooled components, or even shatter control room windows.
Therefore, scrap used for EAF steelmaking must remain dry and free from dripping water, ice, or snow.
2. Scrap Containing Refractory Materials: Non-Conductive and Difficult to Melt
Most refractory materials are extremely poor conductors. When refractory-attached scrap enters the furnace, it becomes a non-conductive inclusion that interferes with arc formation.
Hazards of refractory-containing scrap
- Electrode breakage due to arc instability.
- Difficulty striking the arc, requiring manual intervention.
- Extended melting time, increasing energy consumption.
- Potential blockage of the tap hole due to slow melting behavior.
Typical refractory-attached scrap includes
- Skull iron
- Leftover tundish scrap
- Mould casting runners and pipes
- Trench iron
- Cold steel from accident ladles
- Ladle bottoms and ladle mouth residues
Such scrap must be crushed and cleaned to remove refractory materials before furnace charging.
3. Closed Containers and Explosive-Type Scrap: Strictly Prohibited
Any sealed object heated inside an EAF is an extreme explosion hazard. Pressure rises instantly as temperature increases.
Typical dangerous scrap items
- Liquefied gas tank
- Pressure vessels
- Rusted shell-type objects resembling shells or mines
- Military scrap materials (must be treated professionally)
Example incident
A plant once mixed a severely deformed anti-tank mine into the scrap charge. During subsequent hot-metal addition, the device exploded violently. Scrap pieces shot upward, damaging overhead conductors and causing several hours of production interruption.
All sealed containers must be cut open or professionally treated before use.
4. Oily and Greasy Scrap: Hydrogen Source and Fire Hazard
Scrap contaminated with oil, grease, lubricants, or rubber materials poses major risks.
Main hazards
- Increased hydrogen content in steel, as oils decompose into hydrogen and carbon at high temperatures.
- Large flames during charging, which can damage crane ropes and ladle-charging equipment.
- Severe fire accidents, especially when excessive combustible materials are present.
Common oily scrap includes
- Turning chips
- Automobile fuel tanks
- Shafts or components with lubricants
- Rubber tires
Such scrap must be cleaned or avoided, especially when producing hydrogen-sensitive or high-quality steel grades.
Conclusion
Scrap quality is a fundamental safety requirement in Electric Arc Furnace steelmaking. Moist scrap, refractory-containing scrap, closed containers, and oily scrap are four high-risk materials that must be strictly controlled. Establishing proper inspection, cleaning, drying, and preparation procedures is essential for ensuring stable and safe steelmaking operations.
