Extraction of Metals

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SULPHIDE ORES ARE USUALLY CONVERTED TO
OXIDES FIRST
An ore is a natural substance that a metal can be economically extracted from.
Metals are often found in ores as sulphides (such as lead sulphide and zinc sulphide)
or oxides (like titanium dioxide and iron(III) oxide). The metal element needs to be
removed from these compounds.
The first step to extract a metal from a sulphide ore is to turn it into an oxide. This is
done by roasting the sulphide in air.
E.g. zinc sulphide + oxygen zinc oxide + sulphur dioxide
ZnS(s) + 3O2(g) 2ZnO(s) + SO2(g)
Sulphur dioxide causes acid rain. Acid rain can cause harm to plants and aquatic life
and damage limestone buildings, so the sulphur dioxide can't be released into the
atmosphere.
By converting the sulphur dioxide into sulphuric acid a pollutant is avoided, and a
valuable product is made ­ sulphuric acid is in demand because it is used in many
chemical and manufacturing processes.
OXIDES ARE REDUCED TO THE METAL
The method for reducing the oxide depends on the metal you are trying to extract.
Carbon (as coke ­ a solid fuel made from coal) and carbon monoxide are used as
reducing agents for many metals ­ usually the ones that are less reactive than
carbon.
REDUCTION OF IRON(III) OXIDE
Iron(III) oxide (haematite) is reduced by carbon or carbon monoxide to iron and carbon
dioxide.
2Fe2O3 + 3C 4Fe + 3CO2
Fe2O3 + 3CO 2Fe 3CO2
This happens in a blast furnace at temperatures greater than 700°C. Coke and haematite are
added continuously to the top of the blast furnace. The coke reacts with oxygen at the base
of the furnace to produce carbon dioxide, as this is an exothermic reaction, it heats the
furnace.
C(s) + O2(g) CO2(g)
To make the reducing agent, the carbon dioxide rises up the furnace and reacts with more
coke to produce carbon monoxide (endothermic).
C(s) + CO2(g) 2CO(g)
REDUCTION OF MANGANESE(IV) OXIDE
(MANGANESE DIOXIDE)
Manganese(IV) oxide is reduced with carbon (as coke) or carbon monoxide in a blast
furnace)
MnO2 + C Mn + CO2

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MnO2 + 2CO Mn 2CO2
This needs higher temperatures than iron(III) oxide ­ about 1200°C.
REDUCTION OF COPPER CARBONATE
Copper can be extracted using carbon. One ore of copper is malachite, containing CuCO3.
This can be heated directly with carbon:
2CuCO3 + C 2Cu + 3CO2
Another method involves heating the carbonate until it decomposes, then reducing the oxide
with carbon.
CuCO3 CuO + CO2
2CuO + C 2Cu CO2
Carbon and carbon monoxide are the first choice for extracting metals because they are
cheap.…read more

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The cost of melting the aluminium and
It is a continuous process, so is efficient supplying the energy for electrolysis is very
high
It makes the metal in a pure form It only works for ionic oxides
TITANIUM
Titanium is an abundant metal in the Earth's crust. In its pure form, titanium is a
strong, light metal that is highly resistant to corrosion. It is very difficult and
expensive to produce. Titanium is used in the bodies of modern planes.…read more

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Advantages of Recycling Metals Disadvantages of Recycling Metals
Saves raw materials ­ ores are a finite Collecting and sorting metals from other
resource waste can be difficult and expensive
Saves energy ­ recycling metals takes less
The purity of recycled metal varies ­ there is
energy than extracting metal. This saves
usually other metals and impurities mixed in
money too
Recycling metals may not produce a
Reduces waste sent to landfill
consistent supply to meet demand
Mining damages the landscape. Recycling
metals reduces this.…read more

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