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8/2/2019 39939186 Basics of Steel Making
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Customer Technical SymposiumSteelmaking 101
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Todays Topics
Steelmaking Flowline
Blast Furnace
Basic Oxygen Furnace: BOF
Vacuum Degasser
Continuous Casting
Hot Strip Mill
Pickler
Cold Strip Mill
Box Annealing
Temper Mill
Hot Dip Coating Line
Electrogalvanizing Line
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Iron Ore
Limestone
Coal
Pellets
Sinter
Crushed
Coke Ovens
Blast Furnace
Slag Molten Iron
Scrap
Lime & Flux
Oxygen
Electric
Furnace
Basic Oxygen
Furnace
Steelmaking Flowline
Artwork: American Iron and Steel Institute
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Steelmaking Flowline
Continuous Casting
Ladle
Metallurgy
Temper Rolling
Slab Hot Strip Pickling
Annealing
Cold Strip
Coating
Artwork: American Iron and Steel Institute
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Basic Steelmaking Flow
COKE OVENS
BLAST FURNACE
BASIC OXYGEN
FURNACECONTINUOUS CASTER
HOT STRIP MILLCOLD STRIP MILL PICKLING
TEMPER MILL COATING LINE
SHIPPING
SHIPPING
ANNEALING
SHIPPING SHIPPING
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Recipe
Blast Furnace
IRON ORE +
LIMESTONE +
COKE +
HOT AIR
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Blast Furnace Raw Materials
COKE
CRUSHED
SINTER
PELLETS
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Blast Furnace
Input Iron ore, coke, limestone and heatedair
Output
Molten Iron (Pig Iron) is cast intoTorpedo Cars
Transferred to Basic Oxygen
Furnace (BOF)
Metallurgy
Chemical reactions cause heating,reduction and melting
Impurities separate and float on top ofthe molten iron as slag
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Blast Furnace
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COKE (carbon) + OXYGEN CARBON MONOXIDE + HEAT
C+O2 CO + HEAT
IRON ORE + CARBON MONOXIDE IRON + CARBON DIOXIDE
FeO + CO Fe + CO2
LIMESTONE SLAG - LIQUID BLANKET - FLOATS ON IRON BATH
Blast Furnace
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Basic Oxygen Furnace: BOF
Input Molten iron, scrap, and high purityoxygen
Output
Molten steel is tapped into a ladle Transferred to the ContinuousCaster after chemistryadjustments or vacuum degassing
Metallurgy
Impurities are oxidized and someseparate / float on top of the moltensteel as slag
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OXYGEN + CARBON CO + HEAT
OXYGEN + MANGANESE MnO (SLAG)
OXYGEN + PHOSPHORUS P2O5 (SLAG)
OXYGEN + SILICON SiO2 (SLAG)
Basic Oxygen Furnace: BOF
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Basic Oxygen Furnace: BOF
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Vacuum Degasser
Input Molten steel from basic oxygenfurnace (BOF)
Metallurgy
Vacuum degasser snorkels insertedinto ladle of molten steel
Argon gas siphons molten steelthrough a vacuum chamber
Dissolved gases and carbon are
removed
Output Ultra-low carbon steel
Transferred to the ContinuousCaster
To Vacuum
Pump
Ladle
Inert Gas Inlet
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Continuous Caster
Input
Molten steel from ladle is transferred
into a holding vessel (tundish) on top
of the Continuous Caster
The tundish continuously meters
molten steel into a water-cooled,oscillating mold via a Submerged
Entry Nozzle (SEN)
Output
Solid slabs are torch-cut
Slabs transferred to Hot Strip
Mill for Rolling
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Continuous Caster
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HotStrip Mill
Input
Slabs from the Continuous Casterare reheated and placed on a rollingtable
Six roughing mill stands reduceslabs thickness to 1.25 -
producing a bar The bar is sent through sevenadditional 4-high finishing millstands to further reduce thickness
Output
Hot bands from
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HotStrip Mill
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Pickler
Input
Hot bands of steel are processed
through a chemical bath to remove
surface oxides
Output
Pickled (Oiled) Band - free of
surface rust and scale
Transferred to Cold
Mill orShipped to Customer.
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Cold Strip Mill
Input
Pickled Bands are rolled through fivemill stands (4 or 6-High)
Output
Cold Roll Full Hard coils with proper
thickness and surface finish Transferred to Box Annealing, HotDip Coating Line or shipped toCustomer
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Box Annealing
Input
Cold rolled Full Hard coils are
stacked, covered and a non-oxidizing
atmosphere is introduced
A furnace is lowered over the coverand fired to a prescribed cycle of time
and temperature
Output
Annealed steel with improved
mechanical properties
Transferred to TemperMill
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Temper Mill
Input
Annealed coils
Output
Cold Roll steel with continuous yielding,improved flatness and a uniform surfacetexture
Thickness typically reduced
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Hot Dip Coating Line
Input Coils are welded together forcontinuous processing
Continuous annealing in-line
Continuous coating on both sides
Zinc or Aluminum
Output
Hot Dip Galvanized, Galvannealed orAluminized steel
Shipped to Customer
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Electrogalvanized Line
Input Cold Roll (Box Annealed &Tempered) coils are welded togetherand continuously processed throughthe line
Plating cells use electric current toapply zinc to the steel
Output
Electrogalvanized
steel Shipped to
Customer
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Electrogalvanized Line
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Questions?