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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 to use depends on a number of factors:
1. Will the method successfully extract the metal?
i. This depends on the reactivity of the metal
2. How much do the reactants cost?
i.…read more

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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: For example
Zinc
Zinc sulphide reacts with oxygen to give zinc oxide and sulphur dioxide
Lead
Lead sulphide reacts with oxygen to give lead oxide and sulphur dioxide
This process causes problems because of the large quantity of sulphur dioxide produced.
Sulphur dioxide is one of the principal causes of acid rain.…read more

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The carbon monoxide is a reducing agent and reduces the haematite to iron:
Iron 3 oxide reacts with carbon monoxide to give iron and carbon dioxide
The liquid iron sinks to the base of the furnace and is tapped off.
Some of the haematite is reduced directly by the carbon:
Iron 3 oxide reacts with carbon to give iron and carbon dioxide
2.…read more

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Method two: 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 abundant element in the earth's crust, and the most abundant metal.
It occurs predominantly as bauxite, which is an impure form of aluminium oxide, A L 2 O 3.…read more

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The oxygen liberated at the anode reacts with the graphite electrode, which burns slowly:
Carbon reacts with oxygen to give carbon dioxide gas
The anode must therefore be regularly replaced.
2. Advantages and disadvantages of the process
advantages:
1. it is a continuous process, so is efficient
2. it makes the metal in pure form
disadvantages:
1. the cost of melting the aluminium and supplying the energy for electrolysis is very high
2.…read more

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Method three: 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.…read more

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Advantages and disadvantages of the process
advantages:
it produces very pure titanium
disadvantages:
1. it is a batch process, which means the titanium is not produced continuously. This adds
to the cost of the process.
2. the sodium/magnesium are expensive
3. the energy costs are very high
Due to the high cost of this process, titanium is not widely used, despite is useful
properties. Steel is used instead unless the special properties of titanium are specifically
needed.…read more

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Method four: 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 to give tungsten and water
2. Advantages and disadvantages of the process
advantages:
1. it produces very pure tungsten
2. hydrogen is a cheap reagent
disadvantages
1. the energy cost are high
2.…read more

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