Scrap is the primary raw material for EAF steelmaking. Its quality directly affects the final steel properties, production cost, and furnace productivity. Therefore, scrap must meet the following requirements before being charged into the furnace:
- The surface of scrap steel should be clean, with minimal rust. Sand, rust, and other impurities can reduce electrical conductivity, extend melting time, hinder phosphorus removal during the oxidation stage, and accelerate lining erosion. Heavy rust or oil stains may also increase the hydrogen content in steel.
- Non-ferrous metals such as lead, tin, arsenic, zinc, and copper must not be present in the scrap. Lead has high density and a low melting point, and it is insoluble in molten steel. Tin, arsenic, and copper tend to cause hot brittleness in steel.
- Sealed containers, as well as flammable, explosive, or toxic materials, must not be included in the scrap to ensure safe operation.
- The chemical composition of the scrap should be known, with sulfur and phosphorus contents kept at low levels.
- The physical dimensions of scrap pieces should not be too large (generally not exceeding 150 mm × 150 mm, with a maximum length of less than 350 mm). In EAF steelmaking, pig iron is often added to increase the carbon content of the charge. However, the proportion of pig iron typically does not exceed 30% of the total charge.
