In 2008, Primetals Technologies received an order to build a new stainless steel works with steelmaking and casting facilities in Calvert, Alabama. The plant was designed to produce one million tons of AISI 200, 300, and 400 grades per year. The final acceptance certificate was received in April 2013.
Challenge
The production route is based on melting up to 100% stainless steel scrap in the electric arc furnace (EAF). The premelt is processed in the AOD converter using a top lance for the highest productivity. The secondary metallurgy is performed in two ladle treatment stands, from which the liquid metal is transported to the one-strand continuous casting machine. The material charged to the EAF is mostly stainless steel scrap, but depending on the steel grade, carbon steel scrap, ferrochromium, or ferronickel may also be charged. Slag is removed from the premelt after tapping at a deslagging stand.
Outokumpu Alabama Steelmaking Shop
Solution
In the AOD converter, not only decarburization but also mass build-up is performed. Blowing time is about 30 minutes. The vessel is designed for flat bath operation; the lower metal bath depth reduces the ferrostatic pressure and improves decarburization. Final alloying for all grades is performed at the ladle treatment stand, and cooling is possible with shredded scrap. The installed bow-type caster with a straight mold is designed to cast ferritic as well as austenitic stainless steels. Slab thickness ranges from 180 mm to 240 mm.
AOD converter at Outokumpu Alabama
AOD converter tapping
Benefits
- Fastest ramp-up of the plant
- Proven performance from the first heat on
- 55 min charge-to-tap time
- Modern electrics and automation technology
- Environmental protection at the highest possible standard
Conclusion
- Most modern integrated plant for stainless steel in the USA
- All time and cost targets achieved during project execution
- Competitive cost position for the production of flat stainless steel products
