Metals and their Uses

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  • Created by: Curlot
  • Created on: 02-07-13 17:09

Ores

The Earth's crust contains many naturally occuring elements and compounds called minerals.

A metal ore is a mineral that contains enough metal to make it economically viable to extract it. Over time it may become more ot less economic to extract a metal from an ore as technology develops.

Ores are mined and impurities may be removed before the metal is extracted and purified. This mining can involve the digging up and processing of large amounts of rock.

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Extracting Metals from their Ores

The method of metal extraction depends on how reactive the metal is.

Unreactive metals, like gold, exsist naturally in the Earth and can be obtained through panning. But most metals are found as metal oxides, or as compounds that can easily be changd into a metal oxide.

Metals that are less reactive than carbon can be removed from their oxide by heating with carbon. e.g Iron and Lead

Metals that are more reactive than carbon are extracted by electrolysis of molten compounds. e.g aluminium.

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Extraction of Copper

Copper is a good conductor of electricity and heat therefore is a useful metal. It is easily bent into another shape yet is rigid enough to make water pipes and tanks. It doesn't react with water.

Copper can be extracted from copper-rich ores by heating these ores in a furnace. This is known as smelting next the copper is purified by electroysis. Copper can also be gotten from solutions of copper salts by electrolysis or by displacement from scaro iron.

During the process of electrolysis the positive copper ions move towards the negative electrode and form pure copper metal.

However the mining of so much copper means that we are running out of copper-rcih ores. So, new methods have been found to extract less copper-rich ores.

Copper can be extrcated from:

  • Low grade ores (ores that contain small amounts of copper)
  • Contaminated land by phytoming or by bleaching.
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Phytoming and Bleaching

These two methods are more environmentally friendly than the traditional mining methods.

Phytoming

Is a method that uses plants to absorb copper. As the plants grow they absorb (and store) copper. the plants are then burnt and the ash produced contains copper in relativley high quantities. This copper is then made pure by electrolysis.

Bleaching

Uses Bacteria to extract metals from low grade ores. A solution containing bacteria is mixed with a low-grade ore. The bacteria convert the copper into solution (known as lechate solution) where is can be easily extracted.

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Exploiting Metal Ores

  • Metal Ores are often mined from the Earths Crust.
  • Open cast minig is udes to get copper ore.
  • Water in an area that mines becomes acidic because it drains through **** heaps.
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Recycling Metals

  • Each person uses 8kg of aluminium per year
  • Compared with aluminium extrcated straight from the ore, using recycled aluminium saves 95% of energy.
  • Recycling also prevents polluion probelms
  • It also makes sure all of our natural resources arent used up.
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