Extraction of Metals

This is not mine, it is from this lovely website here:
http://www.a-levelchemistry.co.uk

They are from the AQA section but are useful to anyone that does extraction of metals in their A-level

 These notes go into more detail than is necessary, and I am hoping to upload condensed versions soon :)

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Topic 2.7

EXTRACTION OF METALS

Extraction of Iron
Extraction of Aluminium
Extraction of Titanium
Recycling























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EXTRACTING METALS FROM THEIR ORES

Most metals do not occur native. They exist in compounds, usually oxides or sulphides. These
compounds are known as minerals. A rock which contains this mineral is called an ore.

A number of methods are used to extract metals from their ores.

The best method…

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SULPHIDE ORES

Sulphide ores cannot be converted directly into the metal. Instead they must be converted to the
oxide. This is achieved by roasting them in air:

2ZnS + 3O2(g) 2ZnO(s) + 2SO2(g)
2PbS + 3O2(g) 2PbO(s) + 2SO2(g)

This process causes problems because of the large quantity of sulphur…

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The carbon monoxide is a reducing agent and reduces the haematite to iron:
Fe2O3(s) + 3CO(g) 2Fe(l) + 3CO2(g)
The liquid iron sinks to the base of the furnace and is tapped off.

Some of the haematite is reduced directly by the carbon:
Fe2O3(s) + 3C(s) 2Fe(s) + 3CO(g)

The…

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REDUCTION OF OXIDES BY ELECTROLYSIS

Metals which form ionic oxides can be extracted by electrolysis of the metal oxides. As this is
expensive it is generally used for metals which are too reactive to be reduced by any chemical
means. Aluminium is one such example.

Aluminium is the third most…

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The cell can be drawn as follows:







The cylinders in the middle of the cell are the anodes.
The sides and base of the container are the cathodes.

The molten aluminium sinks to the bottom of the cell and can be tapped off.

The oxygen liberated at the anode reacts…

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REDUCTION OF METAL HALIDES WITH MORE REACTIVE METALS

In many cases, carbon cannot be used to reduce the metal oxide to the metal as the metal reacts
with carbon to form the carbide instead. This is the case with tungsten and titanium:
TiO2(s) + 3C(s) TiC(s) + 2CO(g)
2WO3(s) +…

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2. Advantages and disadvantages of the process

advantages:
it produces very pure titanium

disadvantages:
it is a batch process, which means the titanium is not produced continuously. This adds
to the cost of the process.
the sodium/magnesium are expensive
the energy costs are very high

Due to the high cost…

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REDUCTION OF METAL OXIDES WITH HYDROGEN

Hydrogen can also be used as a reducing agent and is the main method for the extraction of
tungsten from its oxide:

1. Extraction of tungsten

Tungsten is reacted with hydrogen gas at a high temperature:

WO3 + 3H2 W + 3H2O

2. Advantages…

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