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Transport processes in liquid steel : challenge for chemical engineers Kamil Wichterle VSB – Technical University of Ostrava, Czech Republic

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Title: Transport processes in liquid steel : challenge for chemical engineers Kamil Wichterle VSB – Technical University of Ostrava, Czech Republic


1
Transport processes in liquid steel challenge
for chemical engineers Kamil WichterleVSB
Technical University of Ostrava, Czech Republic
2
Classical image of iron metallurgyReduction of
iron oxides FeO(s) CO(g) ? Fe(?) CO2(g)
  • (?)(s) Direct reduction - smelting
  • (?)(l) Blast furnace reduction

3
Smelting furnace, Tlt1000oC
Iron ore Charcoal Air
CO2 ,N2
Gas - Solid reaction
Iron bloom (solid Fe)
hammering, forging, carburization, quenching
Steel
4
IRONWORKS (Technical museum of Brno)
1st milenium
18th century
http//www.technicalmuseum.cz/pamatky.html
5
Genesis
  • Adam
  • Cain
  • Enoch
  • Irad
  • Mehuajel
  • Methushael
  • Lamech
  • Tubalcain
  • Noah THE GREAT FLOOD

Tubalcain, an instructor of every artificer in
brass and iron Genesis 422
6
English Heritage Archaeology Day 22 June
2002http//www.brad.ac.uk/acad/archsci/depart/res
grp/amrg/Rievaulx02/Rievaulx.htm
IRON BLOOM
7
HAMMERING
http//www.cassovia.sk/stm/v3.php3
8
Blast furnace, Tgt1500oC
Iron ore Coke Hot air
CO, CO2 ,N2
Gas Liquid - Solid reaction
Pig iron (liquid Fe Fe3C)
Molding
Cast iron (high carbon )
9
STEEL CAST IRON
(wrought iron) less than 2 C more
than 2 Cductile, malleable
brittle
10
STEEL - CAST IRON
Prague 1891
Petrín tower
Hannau Pavillon
11
MAIN REASON FOR STEELMAKING
  • Removing of carbon

Steel less than 2 C Special steels 99.9 Fe
liquid steel process
12
Fe C
13
PUDDLING - Henry Cort 1780
  • The Crucible Steel Furnace
  • Melted high carbon iron (pig iron)
  • air flue gas
  • Reaction
  • Fe-C(l) O2 (g) ? Fe(s) Fe-C(l) CO(g)
  • or
  • Fe-C O2 ? ltFegt Fe-C CO
  • Mechanical separation of solid steel lumps from
    the puddle

14
The Crucible Steel Furnace Shop at Abbeydale
http//www.woodberry.org/acad/hist/irwww/Metallurg
y/Biography/Henry_Cort.htm
15
CONVERTER Sir Henry Bessemer 1856
  • The Converter
  • Melted high carbon iron (pig iron)
  • bottom injected air
  • Fast reaction
  • Fe-C O2 ? Fe CO
  • Minor reaction
  • Fe O2 ? (FeO)
  • Liquid steel product
  • SiO2 lining (acidic)

16
Sir Henry Bessemer 1813 - 1898
http//www.history.rochester.edu/ehp-book/shb/illu
s.htm
17
EFFECT OF THE LINING - 1875Sidney Gilchrist
Thomas and Percy Gilchrist
Dephosphorization in the converter MgO, CaO
lining (basic) The lining enters following
reactions Fe-P O2 ltCaOgt ? Fe
(Ca3(PO4)2) metal melt gas
solid non-metal metal melt non-metal melt
(slag) slag gt fertilizer Thomas powder
Other reactions Fe-S O2 ltCaOgt ?
Fe (CaS) Fe-Si O2 ltCaOgt ?Fe
(CaSiO3)
18
CONVERTER 1936
CONVERTER 1936
19
OPEN HEARTH FURNACE - 1863 Sir Charles William
Siemens Émile et Pierre Martin
  • Melted iron (pig iron scrap)
  • hot air
  • flue gas
  • magnesite lining
  • CaO powder

Slower process than this in the
converters However higher quality of the product
20
1950
  • Iron- and steelworking - fully matured industry,
    using proven processes
  • Limited demand for a scientific approach to the
    technology

21
Revolution in steelworkingsince 1960
  • Basic oxygen process
  • Continuous casting
  • Environmental issues

22
Revolution in steelworkingCONTINUOUS CASTING
23
Revolution in steelworkingOXYGEN PROCESS
FURNACES
OXYGEN
ELECTRIC ARC
OPEN HEARTH
24
Oxygen in steelmaking
  • Prof. Robert Durrer (pilot-plant experiments
    Gerlafingen, Switzerland 1948)
  • The first industrial oxygen converter (VOEST
    Linz-Donawitz 1952)

25
Advantage of pure Oxygen Absence of inert
nitrogen
  • Faster reaction than with air
  • More efficient employment of heat
  • Higher temperature
  • Suppressed formation of nitrides

26
BOS - Basic Oxygen SteelmakingBOP - Basic Oxygen
Process BOF - Basic Oxygen Furnace
Fe-C O2 ? Fe CO Fe-P-S-Si O2
ltCaOgt ? Fe (P,S,Si in slag)
27
Source of iron for steelworking
  • Liquid pig iron from blast furnace (higher
    content of C, Si, P, S,)
  • Steel scrap (variable composition - also
    Cu, Zn, Pb, Cd,)
  • Iron from direct reduction process (bloom,
    sponge, briquettes quite pure Fe)

30-40 60-70 lt 10
28
BOSSteel batch 200 000 kg O2 500 normal
m3/min 20 min Superficial velocity 1.5 m/s250
vvm Gas power input 60 kW/m3 (or 8 W/kg) Mixing
time 10-100 sWhole cycle 50 min
http//www.bhpsteel.com.au/bhp/steel/steelenv/stee
lpath/steelbos.cfm
29
OXYGEN INTRODUCTION
  • Tuyere above the liquid bath (L-D)
  • Tuyere under the liquid level (Quiet)
  • Bottom blown ladles (converters)
  • Introduction of CaO powder in the oxygen stream
  • Water cooled lance
  • Hydrocarbon gas cooled lance

30
Production of Oxygen cryogenic process and liquid
air distillationLargest facilities in steelworks
  • consumption 50-60 normal m3 per ton of steel
  • delivery rates 500-800 normal m3/min
  • pressure of 1.5 MPa
  • 99.5 O2 the major impurity is Argon
  • byproducts Argon and Nitrogen
  • energy consumption 0.45 kWh per normal m3

31
OTHER AIMS OF STEELMAKING
  • Removing of P, S, Si
  • Removing of metals Zn, Cu, Pb, Cd, Al,
  • Removing of diluted gases N, CO, H, O
  • Removing of solid non-metal particles
  • Addition of alloying metals (e.g. Ni, Cr, Co, Mo,
    Mn, Si, V, )

32
REFRACTORY LINING
  • Up to 1 m thickness
  • Errosion, abrasion, thermal cycling
  • Losses 0.5-1 mm per run
  • Laser controlled thickness
  • Slower wall dissolution when CaO added
  • Life more than 1000 runs (classical
    converters 100 runs)
  • Regeneration of walls by slag spray (up to 10
    000 runs)

33
LIQUID IRON FOR STEELMAKING
  • BLAST FURNACE
  • TORPEDO LADLE
  • ELECTRIC ARC
  • GAS - OXYGEN COMBUSTION
  • HEAT OF OXIDATION C, Si, (Fe)

34
BLAST FURNACE
35
TORPEDO LADLE (up to 100 km from the blast
furnace)
36
ELECTRIC ARC FURNACE
ALSO WITH OXYGEN
37
GAS COMBUSTION WITH OXYGEN
  • less expensive (40) than the electric arc
  • lower temperature than with the electric arc -
    limited heavy metal emissions
  • can be combined with the electric heating

38
SECONDARY METALLURGY
ARGON VACUUM LADLE
  • Desorption of diluted gases N, CO, H, O
  • Sedimentation - floating of slag particles
  • Addition of alloying metals
  • De-oxidation
  • Homogenization

TUNDISH
  • Removing of solid non-metal particles
  • Homogenization of temperature and composition

39
ARGON VACUUM TREATMENT
  • Argon gas-lift for agitation (10-300 W/m3)
  • Vacuum for desorption of soluble gases
    (CO, O2, H2, N2)

Superficial gas velocity 0.001 m/s bottom gt 1
m/s level
Atmospheric pressure 1420 mm Fe
RH Ruhrstaal - Heraeus
DH Dortmund-Hoerde
40
ENVIRONMENTAL
  • Gas emissions (CO)
  • Airborn particles (Fe,Zn,Pb,Cd,Cu, )
  • Slag

41
TUNDISH
  • Batch input ? continuous output
  • Turbulence suppression
  • Argon agitation
  • Argon inert atmosphere
  • Last slag separation ? particles lt 50µm
  • Tundish refractories ? steel quality

42
HYDRODYNAMICSMULTIPHASE FLOWHEAT
TRANSFERCFD
43
Transformation of Metallurgy
  • Material engineering merging with polymer
    science, ceramics, electronics materials
  • Process engineering adoption of chemical
    engineering method (chemical reactors
    gas-liquid-solid, non-isothermal processes,
    mechanical separation, transport phenomena,
    scale-up methods, modelling, simulation, CFD, )

44
Our contributionDepartment of Chemistry
Faculty of Metallurgy and Material
EngineeringTechnical University of Ostrava
45
BUBBLE BEHAVIOR IN LIQUID STEEL
  • From the viewpoint of two-phase hydrodynamics
    (density, viscosity and surface tension),
  • water and liquid steel are quite similar !

density dynamic kinematic surface Laplace
Laplace viscosity viscosity tension
length velocity Liquid ? µ ?
s (s/(?g))1/2 (sg/?)1/4
oC kg/m3 Pas m2/s N/m m m/s molten steel 1500
7200 510-3 0.710-6 1.4 4.510-3 0.21 water
25 1000 1.010-3 1.010-6 0.073 2.710-3 0.1
6 mercury 25 13500 1.510-3 1.110-6 0.46
1.810-3 0.14 Wood metal
80 10600 310-3 0.310-6 0.4 1.910-3 0.14 hexane
25 650 0.3510-3 0.510-6 0.018 1.61
0-3 0.13
46
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47
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48
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49
Experimental
50
History of Metallurgical Engineering
51
Georgius Agricola (Georg Bauer)(1494-1555)
DE RE METALLICA LIBRI XII
Chemnitz
Glauchau
Leipzig
Jáchymov (Joachimsthal)
Dukedom Saxony
Czech Kingdom
Basel
Padova
Georgius Agricola (Georg Bauer) (1494-1555)
Bologna
52
Agricola1556Cascade of CSTRImpeller
manufacture
53
Metallurgy ? ? Chemical Engineering
  • Transformation of one journal
  • 1902 Electrochemical Industry
  • 1905 Electrochemical and Metallurgical
    Engineering
  • 1910 Metallurgical and Chemical Engineering
  • 1913 Chemical and Metallurgical Engineering
  • 1946 Chemical Engineering

54
CONCLUSIONS
  • At the end of 20th century steelmaking became a
    fast developing chemical technology
  • Chemical engineering education should also turn
    its attention to the processes in liquid steel
  • In metallurgy, there are challenging jobs for
    chemical engineers

55
Thank you for the attention
Financial support by the Grant Agency of the
Czech Republic (grants No.106/98/0050 and No.
104/01/0547) is greatly appreciated  
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