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Steelmaking Basics

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					EDSGN Kick Off Meeting – 2/27/2012
Steelmaking Basics and Project Overview


R. Zellers
Steelmaking Process Map - Iron
Steelmaking Process Map - Refining
Basic Oxygen Furnace – Raw Materials
                              Fluxes
                              Coolant
                              Fuel
BOF - Reactions
• Decarburization
2C + O2  2CO (reaction occurs in bath, CO to off gas)
2CO + O2  2CO2 (reaction occurs above bath, CO2 to off gas)

• Silicon Oxidation
Si + O2  SiO2 (reaction occurs in bath, SiO2 to slag)

• Manganese Oxidation
Mn + O2  MnO

• Aluminum Oxidation
4Al + 3O2  2Al2O3 + HEAT!
Chemistry of “Open” Steel

•   C 0.04%
•   Mn 0.1%
•   Cr 0.01%
•   Cb 0.00%
•   Al 0.00%
BOF – Order of Reactions – Ellingham Diagram


                                              Cr: 1/2

                               C + O2  CO2
                                               Mn: 1/3
Energy




                                               Si: All

                                               Al: All



                                               Ca: All




                 Temperature
Alloying – Why & Where?

•   Aluminum – Deox, aluminum-nitride grain refining
•   Carbon – Strengthener
•   Calcium – Inclusion modification, castability
•   Chrome – Hardening, corrosion resistance
•   Columbium (Niobium) – Grain refining
•   Manganese – Strengthener, heat treatment hardening

BOF during tap – Good mixing, allows for “settling”
Ladle met facility – Greater control
Alloy Calculation
Example: LCAK Mn addition


•   Aim: 0.5%
•   Already in steel from BOF: 0.1%
•   Needed from alloy: 0.4%
•   Heat Size: 440,000 lb
•   HC Mn: 78% Mn, 90% Recovery (note: “pure alloy” in project)

Calculation: (0.4% Mn/steel) * (440,000 lb steel) = 1760 lb Mn
(1760lb Mn) / (78% Mn/HC Mn * 90% Recovery) = 2500 lb HC Mn
Project

Part 1 – No Off Chemistries
• Separate advanced high strength steel (AHSS) from scrap autos
• Use mix of AHSS and low carbon aluminum-killed (LCAK) scrap
  to make LCAK heat

Part 2 – Cost Savings
• Utilize AHSS scrap to make line pipe heat
• Calculate addition alloys needed

				
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posted:8/19/2012
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