Zinc: The Extraction of Metals and Its Impact on the Environment (PART ONE)

Metals

Metals are normally found as compounds or as crusts of the uncombined metal. These metals are mainly found in the earth’s crusts as ores.
Ores are rocks that contain a certain type of metal.
The ore is usually a compound of the metal which is mixed with other impurities in it.
Extraction of metals refers to the separation of metals from its pure or relatively pure state in which it occurs as naturally, or the method in which is used to separate the metal from the rests of the impure ore to obtain the pure metal.
The method of extraction is highly dependable on how reactive the metal is. For example, highly reactive metals, such as aluminium, is extracted by electrolysis.
A moderately reactive metal is extracted by redox reactions-reduction or oxidation.
Metals with low reactivity are either found uncombined or extracted solely by heating.
In conclusion, the more reactive the metal is, the more difficult it is to extract the metal from its compound.

http://www.s-cool.co.uk/gcse/chemistry/extraction-of-metals/types-of-extraction.html

Different methods of extraction of metals

Pyrometallurgy
Pyrometallurgy processes are generally grouped into one or more of the following categories

Drying
Calcining
Roasting
Smelting
Refining

http://en.wikipedia.org/wiki/Pyrometallurgy
http://kerrigan.co.za/~mintekci/Pyromet/SlagTap.gif

Electrolysis
Electrolysis is the most powerful extraction method. But it takes a lot of electricity and that makes it expensive. Hence, electrolysis is only used for the most reactive metals.

Mining