one of the most abundant elements on give rise to
TRANSCRIPT
One of the most abundant elements on
Earth.
Give rise to civilizations.
Key ingredient in Steel.
Said to have originated from explosion of
stars.
Formation – most violent process
Star – Red Giant – Turn helium in C and
O2 atoms
C and O2 atoms – turn into Iron atoms
Star becomes Supernova.
Supernova explodes – showering space
with Fe, C and O2 atoms.
Earth’s core – molten iron
Earth’s crust – 10% Iron
Life on Earth also contains iron (from
plants to humans)
Asteroids – entered Earth’s atmosphere
Meteorite fragments – did not burn in
atmosphere – more iron to Earth’s
surface.
Key metal until 1850s
Innovators learnt –
More C + Fe = Durable Metal STEEL
1870s – Steel took over – Mass production
Chemical Properties
Very active metal
Combines with O2 in moist air
Reacts with hot water, produces H2 gas
Dissolves in acid
Other reactions
What is a Blast Furnace?
•The purpose of a blast furnace
is to reduce and convert iron
oxides into liquid iron called "hot
metal".
•The blast furnace is a huge,
steel stack lined with refractory
brick.
•Iron ore, coke and limestone
are put into the top, and
preheated air is blown into the
bottom.
Why does Iron have to be extracted in
a Blast Furnace???
•Iron can be extracted by the blast furnace
because it can be displaced by carbon.
•This is more efficient method than electrolysis
because it is more cost effective
Three substances are needed to enable to extraction of iron from its ore.
The combined mixture is called the charge:
Iron ore, haematite - often contains sand with iron oxide, Fe2O3.
Limestone (calcium carbonate).
Coke - mainly carbon
The charge is placed a giant chimney called a blast furnace. The blast
furnace is around 30 metres high and lined with fireproof bricks. Hot air is
blasted through the bottom.
The Method
•Oxygen in the air reacts with coke to give carbon dioxide:
C(s) + O 2(g) CO2(g)
•The limestone breaks down to form carbon dioxide:
CaCO3(s) CO2 (g) + CaO(s)
•Carbon dioxide produced in 1 + 2 react with more coke to
produce carbon monoxide:
CO2(g) + C(s) 2CO(g)
Several reactions take place before the
iron is finally produced...
• The carbon monoxide reduces the iron in the ore to give molten
iron:
3CO(g) + Fe2O3(s) 2Fe(l) + 3CO2(g)
• The limestone from 2, reacts with the sand to form slag (calcium
silicate):
CaO(s) + SiO(s) CaSiO3(l)
•Both the slag and iron are drained from the bottom of the furnace.
•The slag is mainly used to build roads.
•The iron whilst molten is poured into moulds and left to solidify - this is
called cast iron and is used to make railings and storage tanks.
•The rest of the iron is used to make steel.
GREY CAST IRON
C -2.5 TO 4.0% Si – 1 – 3% Mn – 0.5 – 0.8% P – 0.2% S – 0.1%
WHITE CAST IRON C – 2.5 – 4.0% Si – 0.2 – 0.6% Mn – 0.5 – 0.8% P – 0.2%
S – 0.1% MALLEABLE IRON C – 0.08 – 0.5% Si – 1 – 3% Mn – 0.5 – 0.8%
P – 0.2% S – 0.1%
Magnetite- 72.4% Fe,magnetic,black
Carbonate-<30% Fe+C+P
Hemetite-40-65%Fe,reddish
Limonite-20-55%
Pyrite-50% Fe and 50% S
Taconite-25-30% Fe,reddish or blackish
Sulphate-50% S,golden
Silicate-50%Si
Siderite-30% Fe,yellow brownish
C – 3.3 – 3.4%
Si – 2.2 – 2.8%
Mn – 0.1 – 0.5%
Mg – 0.03 – 0.05%
P – 0.005 – 0.04%
S – 0.005 – 0.02%
For minor structural and decorative
elements in 18th century.
Until mid-19th,used as tie rods,straps,etc.
Decorative ironwork in
balconies,fencings,etc.
Structural use became more widespread
around 1850.
Iron mills began to roll rails,bulb-tees and
eventually I-beams.
Ornamental balconies or hardware.
Brittle, but strong in compression.
Structural Purposes:Columns,domes,building
fronts,etc.
Decorative Purposes:
Stairs,elevators,lintels,railing,balconies,et
c.
Commissioner’s house at Bermuda,
designed by Edward Holl and built in
1820s is considered to be the first
residence that used cast iron in its
structural framework.
It was the standard support structure in
greenhouses and led to crystal palace in
London, built in 1851.
Glass and cast iron structure was much
imitated around the world.
Nowadays used for plumbing fixtures
and piping.
Structural and decorative use is used
occasionally through historic
preservation practices.
Can be subjected to rapid corrosion
Pressed decorative sheet iron used for
ceilings,called a ‘tin ceiling’.
Generally not used indoors
Development of structural steel in mid-
19th century gave rise to tall buildings.
Stronger than cast iron in compression
and wrought iron in tension.
Bridges, railroads, skyscrapers
All structural steel must be fireproofed.
Cladding of terra-cotta can be
utilized,tile,plaster-
poured,concrete,sprayed concrete or
insulation.
Steel wire+concrete=reinforced
concrete[ferro concrete]
Stainless steel
18%chromium and 8-12%nickel
Corrosion free
Expensive
Used primarily as non-structural
component or where probability of
corrosion is very high
15-25% copper.
Develops increased resistance to
atmospheric corrosion.
Forms an uniform deep brown coloured
oxide coating
Eero Saarinen experimented with the
material in the Deere and
Company building in 1964