Post on 08-Sep-2018
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Dr LJ Erasmus
June 2013
History of Iron
Part of the unrecorded history of man
Known as “Metal from heaven”Assyrians – parzilla
Babylonians – barza
Sumerians – barzel
Prehistoric implementsMain source - meteorites
2 – 26% nickel
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Largest meteorite
Hoba
Meteorite
66 tons
Grootfontein
Namibia
84% Fe; 16% Ni
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Willamette Meteorite in Oregon
15 ton,
6th largest
in the world
91% Fe; 9% Ni
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History
First evidence of man made iron (low Ni)
Ur of the Chaldeans (Iraq) 3100 BC – an iron dagger
Egypt 2900 BC– an iron tool between two pyramid stones
Egypt 2600 BC – in a grave in Abydos
Crete 1800 BC – in a grave in Knossos
Greece 1550 BC – an iron finger ring
First known iron working furnaces
Gerar (Palestine) 1200 BC
Hittites are credited with commercialising iron smelting
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The Hittite Empire
Also known as
Chaldeans/Babylonians / Syrians
Bronze Age people
North-central Anatolia
18th century BC
Commercialising iron smelting
Iron artefacts from 14 BC
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Iron
Chalybes tribe in the Hittite Empire
Iron known as Chalybs
Modern city Aleppo
Hittite empire destroyed by the Sea People were
responsible for spreading the knowledge
Ending the bronze age, starting the early iron age
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Primitive furnaces did not
reach temperature
sufficient to melt iron
(1535°C).
Hittites learned that
“carburizing” the iron
substantially reduced its
melting point.
This was done by running
the furnace with a 6-fold
excess of charcoal.
Today, we can understand
this effect from the iron-
carbon phase diagram.
The Empirical Discovery of
the Effect of Carbon
Cast Iron
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The First Recorded Energy Crisis
Carbon-rich iron can be melted and poured at 1130°C
Cast iron or pig iron. But…
It takes about five tons of wood to make one ton of charcoal.
Rapid deforestation.
The availability of wood resulted in an energy crisis.
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Evolution of Iron Know-how
Wrought iron - Oldest iron product
A pure form of iron
First produced ≈ 4000 years ago
– Fibrous structure
– Can be shaped by hammering / rolling
Cast Iron
Alloy of iron and carbon (up to 5% carbon)
First produced commercially ≈14 BC
– Cannot be shaped, is casted in molds
– Grey of white
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Iron alloys
Steel – alloy with various alloying elements
Small quantities in the ore - made accidently
Hardenable upon quenching
Commercialised in the Bessemer process – 1856
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Carbon
This mystery was only solved around 1800 AD
Sven Rinman (Swedish metallurgist)
– The history of iron (1782)
– Special character of steel
• Phlogiston ≡ “anI-oxygen”
We now know that iron exhibits Allotropy
Several temperature dependent crystal structures
with various degrees of carbon solubility
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Iron making in Ancient China
Chinese iron making also initially relied on wood. (Technology transmitted from Hittites)
Some Chinese iron making sites began to use anthracite.
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Iron-making in 14th Century Europe
Carbon saturated metal was produced in a
blast furnace with charcoal
Cast in sand
Solid state re-heat and refined – Wrought iron
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Iron-making in 17th-Century England
English iron-makers used charcoal from oak as the fuel of choice in smelting.
As in the past, the increased demand for iron led to extensive cutting of oak forests.
In this case, there was also a competing application for oak: naval vessels.
War is more important
Introduction of coal Hot shortness making the iron brittleAn advantage if you produce cannon balls
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Oak
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Hot Shortness
With the switch to coal, iron pieces would tear or break apart when being worked at high temperature.
This problem was called hot shortness, or sometimes “hot shorts.”
This is due to precipitation of FeS as the molten Iron solidifies.
FeS segregates in grain boundaries and causes sites of weakness.
Heat treatment of coking coal into cokeCoke became the dominant fuel for iron smelting.
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A short history of Iron production
Iron makingBloomery – sponge iron;
Blast furnace – pig iron
Steelmaking Crucible steel
Tatara furnace
Bessemer converter – to 1868
Basic oxygen processVoest-Alpine in 1952
Mini-millElectric arc furnace
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Bloomery
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Bloomery
Modern replica
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Evolution of The Blast Furnace
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Bessemer converter
1855
Sheffield
Air blown
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Iron Ores
Iron-Carbon-Oxygen equilibrium
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Iron ore reduction with CO is exothermic and
therefore the reaction temperature is relatively
easy to sustain.
Fe2O3 + 3CO → 2Fe + 3CO;
∆H298K = -49.9 kcal/kg Fe
Iron ore reduction
The Blast Furnace
The Blast Furnace Process
500-600°C
600-900°C
900-1100°C
>1100°C
1100°C
1150°C
1450°C
1500 oC
Fe2O3
Fe3O4
FeO
Fe (+ C)
Fe
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Direct Reduced Iron - DRI
Midrex
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Corex
HYL process
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Direct Iron Ore Smelting (DIOS)
Cyclone Converter furnace (CCF)
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High Intensity Smelting (HISMELT)
American Iron and Steel Institute
(AISA)
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Alloystream
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Ess
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