what is a blast furnace? the purpose of a blast furnace is to reduce and convert iron oxides into...

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.

Stainless steel

• Stainless steel (inox steel) is a steel alloy with a minimum of 10.5 or 11% chromium content by mass.

• It does not corrode, rust, or stain with water as ordinary steel does.

Wrought iron has better tensile strength than cast iron and is more ductile.Wrought iron has better properties than cast iron for structural use. Because of its low carbon content wrought iron is ductile, 'tough' and has good resistance to corrosion. It is more fibrous in texture, highly ductile, and is strong in both tension and compression

ApplicationsThe following are the list of applications of wrought iron:Decorative items such as railings, outdoor stairs, fences and gatesNuts and boltsHandrails.

Shape-Memory Alloy• Two main metal phases are shown below:

The Atomium is a building in Brussels originally constructed for Expo 58, the 1958 Brussels World's Fair. Designed by the engineer André Waterkeyn and architects André and Jean Polak,[1] it stands 102 m (335 ft) tall. Its nine 18 m (59 ft) diameter stainless steel clad spheres are connected so that the whole forms the shape of a unit cell of an iron crystal magnified 165 billion times. It is a museum. Tubes of 3 m (9.8 ft) diameter connect the spheres along the 12 edges of the cube and all eight vertices to the centre. They enclose stairs, escalators and a lift (in the central, vertical tube) to allow access to the five habitable spheres which contain exhibit halls and other public spaces

Steel Products

• Key: carbon content:– Steel – alloy consisting mostly of iron with a little

carbon (0.05% - 2.04% by weight)– Also have:

• Iron = iron-carbon alloy with less than 0.005% carbon.• Cast iron = carbon content between 2.1% - 4.0%• Wrought iron – contains 1 – 3% by weight of slag in the form of

particles elongated in one direction – more rust resistant than steel and welds better

Metals

Ferrous metals Non-ferrous metals

Steels Cast Irons

Plain carbon steels

Low alloy steels

High alloy steelsStainless & Tool steels

Grey Iron

White Iron

Malleable & Ductile Irons

Low carbon steels

Medium carbon steels

High carbon steels