Ores contain enough metal to make their extraction (from rocks) worthwhile.
As technology improves, metals which would have previously been too expensive to extract are now able to be extracted and sold for a profitable price.
Metals can be extracted from their ores (chemically) by reduction or electrolysis. Electrolysis is also used to purfiy metals.
Reduction with carbon is when oxygen is removed to extract the metal.
Metals higher than carbon in the reactivity series need to be extracted using electrolysis: which is more expensive.
Metals below carbon in the reactivity series can be extracted by reduction with carbon; as carbon can only take oxygen away from metals less reactive than itself.
Example: Iron oxide is reduced using blast furnaces to make iron
Metals which are more reactive than carbon need to be extracted via the electrolysis of molten compounds.
Electrolysis is more expensive than reduction as more energy is used.
Coppper is purified by electrolysis after it has been smelted since by removing its impurities it can conduct electricity better.
Electolysis is the breaking down of a substance using electricity. An electrolyte is a liquid which conducts electricity; which are are often metal salt solutions or molten metal oxides.
Electrons are taken away from the anode (positive) and given away by the cathode (negative)
Since more reactive metals react more vigorously than less reactive metals, when you put a very reactive metal in a dissolved metal compound that metal will replace the less reactive metal in the compound; due to the formation of stronger bonds.
A common example is scrap iron being used to displace copper from a solution - as iron is cheaper than copper. This can occour since copper is more reactive than iron. Copper sulfate + iron -> iron sulfate + copper
Copper-rich ores are limited so copper is often recycled due its demand: by bioleaching and phytomining.
BIOLEACHING: bacteria seperates copper from copper sulfide by getting energy from the bond between copper and sulfur. The leachate (solution produced) contains copper which can be filtered.
PHYTOMINING: growing plants in soil containing copper, so the copper builds up in the plant's leaves. The plant can be harvested and then burned to collect copper from its ash.
Impacts of Extracting Metals
PROS AND CONS
Whilst mining ores is useful due to its products and it provides jobs that bring money into areas so that services can be improved, it is harmful to the environment, noisy, scars the landscape and ruins habitats. Abandoned shafts can also be dangerous.
The extraction of metals fron ores uses many fossil fuels to provide the energy required. However burning fossil fuels reduces the amount of fossil fuels there are left, and contributes to acid rain, global dimming and climate change.
Therefore recycling metals not only helps reduce the negative environmental impacts but also saves money. There is also less landfill due to more metal being recycled: which reduces the pollution landfill causes and saves space.
An alloy is mixture of two or more metals.
A common example is Steel:
Pure iron (cast iron contains impurities such as carbon) is brittle - hard but easy to break. It has a regular arrangement of identical atoms; these layers can slide over each other thus pure iron is too bendy for many uses.
Steel is formed by adding small amounts of carbon and other metals to iron.
Alloys are harder than pure metals since they contain different sized atoms thus their arrangement means that they cannot slide over each other - so they're less bendy.
Example: Brass = Copper + Tin
Brass is harder than pure copper; so it's useful for making statues and medals.