Metal extraction

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  • Created by: Jack
  • Created on: 11-05-14 15:55
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Metals can be extracted using 4 main methods:
Reduction with carbon
Reduction with a more reactive metal
Reacting with hydrogen
Metals are naturally found as ores. Ores are rocks with enough of a metal content to make
them economical to extract. Many ores are metal oxides or metal sulfides.
Metal sulfides are roasted to turn them into metal oxides. We do this because it is more difficult
to extract from a sulfide than an oxide.
The ore is crushed to increase the surface area, then is heated strongly in a stream of air.
The products of this reaction are the metal oxide and sulfur dioxide. Sulfur dioxide causes acid
rain, so it has to be removed somehow. It is converted into sulfuric acid by the contact
process (SO2 is oxidised with oxygen and a vanadium (V) oxide catalyst to make SO3, which is
then added to water to make H2SO4). This also increases the atom economy of the metal
extraction process.
This is used for the most reactive metals (such as aluminium) that can be extracted by no other
method. Electrolysis is expensive because of the high electricity cost, so this makes the metal
expensive too.
Reduction with carbon:
This is used for the less reactive metals (the main one is iron, but manganese and copper too).
Iron is extracted from its ore in a
blast furnace. The raw materials
needed are iron ore (Fe2O3),
coke (C) and limestone
C + O2 CO2
CO2 + C 2CO
Fe2O3 + 3CO 3CO2 + 2Fe
CaCO3 + SiO2 CaSiO3
(calcium silicate CaSiO3 is slag)
Some metals can't be reacted
with carbon because they just
form compounds with it.
TiO2 + 3C TiC + 2CO

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Tungsten carbide is deliberately manufactured sometimes because it is extremely hard,
but you can't extract pure tungsten from it.
Aluminium is too reactive to be extracted with carbon.
Aluminium is extracted from its main ore bauxite (Al2O3) by electrolysis. Bauxite is
purified to make aluminium oxide.…read more

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It can be expensive to produce (electrolysis of salt solutions byproducts can be sold to
other industries)
Environmental and economical advantages and disadvantages of recycling scrap metals
instead of extract more:
There are a finite amount of ores, so recycling means that already processed ores can
be reused.
Saves energy (e.g. electrolysis requires huge amount of energy).
Reduces waste at landfill sites
Reduces land spoilage due to mining and waste
Recycling plants are noisy and can contaminate the local environment (e.g.…read more


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