Getting Metal From Rocks: Copper

More reactive metals react more vigorously than less reactive metals. This is important because if you put a reactive metal into a solution of a dissolved metal compound then the more reactive metal will replace the less reactive metal.

Basically what happens is the more reactive metal bonds to the non-metal bit of the original compound and this causes the less reactive metal to be pushed out.

A really important implication of this is using scrap iron to displace copper from a solution. Scrap iron is cheap, copper is expensive – so generally you really want to get at the copper!

If iron is put into a solution of copper sulfate then it will react more vigorously than the copper and caused it to be displaced from the solution:

copper sulfate + iron ?  iron sulfate + copper

This only works because iron is more reactive than copper. If gold were put into the solution nothing would happen because gold is less reactive than copper.

NOTE: Remember copper can also be extracted using displacement and then made more pure using electrolysis – this is expensive as it requires lots of energy and has many steps to the process though.

Other Notes On Copper

Copper ores are in short supply – so, as with every metal, it’s important to recycle as much as possible! Your examiner will expect you to know that we should recycle metals because they are expensive to extract and in limited supply.

There may be shortages of copper soon as demand is growing – so scientists are working on ways to extract copper from low-grade ores or from the waste that is currently left over when copper is extracted. Two methods they have come up with are:

  • Bioleaching

Bacteria is used to separate copper from copper sulfide. The leachate (the solution that is produced by this process) contains copper which can then be extracted.

  • Phytomining

Plants are grown in soil that contains copper. The copper then gradually builds up in the plants. Eventually the plants are dried and burned. Copper can then be collected from the ash left over.

Both these methods are much kinder to the environment than traditional methods – but they are very slow!