Metals

Metallurgy

• the extraction of metals from oresby reduction (less reactive metals)by electrolysis of melt (reactive metals)

• the preparation of metals for use

• the study of the relationship between structures and properties of metals

Metal extraction

• Pre-treatment of Ore

• Concentration

• Roasting

Pre-treatment of ore

• crude ore is crushed

Concentration

• floatation

Roasting

• converting sulphide ore to oxide

2ZnS(s) + 3O2(g) -----> 2ZnO(s) + 2SO2(g)

2CuS(s) + 3O2(g) -----> 2CuO(s) + 2SO2(g)

3FeS2(s) + 8O2(g) -----> Fe3O4(s) + 6SO2(g)

Manufacture of Iron and Steel

• Chemistry of blast furnace

• Chemistry of basic oxygen furnace

Chemistry of blast furnace

iron reduction

raw materials

Several Blast Furnaces

Liquid Iron Pour

Iron(l) & Slag(l) Pours

Chemistry of blast furnace

raw materials:

iron ore – several kinds

limestone – calcium carbonate

coke – heated coal

air – to provide the blast

Chemistry of blast furnace – raw materials

iron ore => source of iron

Could be any of the following:

Fe2O3, Fe3O4, FeO,

Ore names: haematite, magnetite, ferrite

Sand impurity - SiO2

Chemistry of blast furnace – raw materials

Limestone (calcium carbonate) is used to remove impurities – it reacts with the sand which is usually found mixed with the iron ore. In the heat of the furnace it decomposes to calcium oxide (lime) and this then reacts with the silicon dioxide to produce calcium silicate (slag)

CaCO3 CaO + CO2

CaO + SiO2 CaSiO3

Chemistry of blast furnace

coke => reducing agent

C

Chemistry of blast furnace

C(s) + O2(g) -----> CO2(g)

coke air

Chemistry of blast furnace

CO2 + C ---> 2 CO

coke

Chemistry of blast furnace

3 Fe2O3(s) + CO(g) -----> 2Fe3O4(s) + CO2(g)

iron ore

Chemistry of blast furnace

Fe3O4(s) + CO(g) -----> 3FeO(s) + CO2(g)

iron ore

Chemistry of blast furnace

FeO(s) + CO(g) -----> Fe(l) + CO2(g)

iron ore pig iron

Chemistry of blast furnace

CaCO3(s) + heat -----> CaO(s) + CO2(g)

limestone lime

Chemistry of blast furnace

CaO(s) + SiO2(s) -----> CaSiO3(l)

lime sand slag

Purification of Metals

• Electrolysis

• Chemical Reactions

Production of Copper

Cu2S(l) + O2(g) -----> 2 Cu(l) + SO2(g)

Cu(s) -----> Cu(s)

impure electrolysis pure

Chemistry of Basic Oxygen Furnace

iron purification

steel making

raw materials

Chemistry of Basic Oxygen Furnace

raw materials

pig iron from blast furnace

fluxing agent to remove impurities

alloying agents

Chemistry of Basic Oxygen Furnace

Removal of excess of carbon

C(s) + O2(g) -----> CO2(g)

impurity air

in pig iron

Magnetism

• 2 main types– diamagnetism => all electrons are paired– paramagnetism => one or more unpaired

electron, parallel spins on electrons