Naturally occurring metals
Copper, silver, gold and platinum are the four most un-reactive metals. This means that they do not form compounds and can exist as simple lumps of the metal in the rock. They can be found native. These are easy to extract since they can be mined. Also, you can even find pieces of gold in streams. More reactive metals are not found in lumps and must be extracted from the rocks in which they occur.
Roasting in oxygen
For all this extraction processes, the rock must ...view middle of the document...
Metals with quite a low reactivity can be extracted by roasting the ore in air. The oxygen in the air reacts with the compound, releasing the metal. Copper and mercury ores can be treated in this way to extract the metal.
Metals with a medium reactivity can be extracted using a process called carbon reduction. This is where the element carbon is used to separate the metal from the ore. Although carbon is not a metal it can act like a metal in a displacement-type reaction. The carbon can come in and take the place of the metal in the ore compound.
This process is used for extracting metals with a high reactivity, e.g. the metals from aluminium upwards in the reactivity series. In this process the ore has to be made into a liquid: this can be done by either melting it or dissolving it in a solvent. In this state there exists a mixture of metal ions and non-metal ions, all of which can move around freely. The metal ions are positive and the non-metal ions negative. An electric current is then passed through the liquid by means of a positive electrode, the anode, and a negative electrode, the cathode. This requires a lot of electricity.