It is general knowledge that metals are mined from the ground, but in what form? Does copper come out of the ground shiny and ready to use? Many metals, before they are shiny and malleable, come from a special type of rock called metal ore; but what is metal ore?
Metal ore is a type of rock from which metal can be extracted. Metal ores are normally oxides; for example, aluminium is the most common metal in the Earth's crust, but in order to get as pure aluminium as possible, it needs to be extracted from an ore. The best ore for aluminium is called bauxite; it contains almost 70 per cent aluminium oxide. Aluminium can be further extracted to its pure form. Different ores contain different metals; for example, hematite and magnetite are types of iron ores. They contain particles of iron, which can be extracted.
There are many forms of extraction. Ore concentration is one of the methods used. Ore concentration occurs when as much of the useless rocky material as possible is separated. Bauxite (aluminium ore) can soak in sodium hydroxide solution; a chemical reaction leaves aluminium oxide. This process can be used for copper as well. In some copper ores, the rock can be converted into a copper sulphate solution, after soaking in a diluted solution of sulphuric acid. After this process, copper can be easily extracted.
Froth flotation is commonly used to separate many types of metals from their ores. In this process, ore is crushed, then soaked in a solution that makes the metal in the ore hydrophobic. Hydrophobic literally means afraid of water. After this occurs, the ore is put in a large vat with soap/detergent and air is flowed through the ore. Because of the hydrophobic quality, the pure pieces of metal begin to float to the surface of the vat, and are then collected.
Reduction is simple in theory; it occurs when the metal oxide is extracted from the ore. After, the oxygen is removed and a pure metal is left.