Mini Mills
Electric Arc Furnace Steelmaking
Mini mills, the result of innovative technology and market competition, are smaller, cheaper, and more flexible than traditional integrated mills. Instead of creating steel from iron ore and coke, as integrated mills do, mini mills melt steel scrap. They are less dependent on natural resources and require less space, so there is more freedom to build mini mills closer to customers.
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Because they are much smaller and therefore have less capacity, mini mills produce significantly less annual tons than integrated mills, but their operations can be slowed and even stopped to reflect market demand. The disadvantage of mini mills is their dependency on scrap: they are constrained by elements already in the steel scrap that cannot be removed, along with fluctuating scrap prices.
1. Melting scrap in the EAF
An electric arc furnace melts scrap by arcing electricity between three large electrodes. This takes about 30 minutes from start to finish. Once melted, the furnace is tapped and the molten steel empties into a ladle.
2. The steel is refined at the ladle metallurgy station
Alloys are added to the heat and final chemistry checks are taken.
Electric Arc Furnace
3. The steel is transferred to the tundish for continuous casting
The steel is poured into a mold similar to the molds used at integrated mills, except the molds produce much thinner slabs (about 3" thick as opposed to 8" - 10" at an integrated mill). Once the steel slab has been cut, it goes into a tunnel furnace that charges directly into the hot strip mill.
Continuous Casting