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Copper in health
 The main stages
Copper minerals and ore are found throughout the Earth's crust. They occur in both sedimentary and igneous rocks. The outer 10km of the crust contains 33g of copper for every tonne of rock. This is not enough to make it commercially viable to extract the rock. Copper mines are only set up where there is more than 5kg of copper per tonne of rock (0.5% by mass). Ideally, the figure should be closer to 2%.

Roll over diagram of sequence The flow chart shows you how copper is extracted from its ore and converted into pure metal. Roll over each stage to get a summary and click to find out more.
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Question 1
Imagine a copper ore that contains 1% copper by mass. After concentration, this rises to 25%.
1 tonne of crude ore will produce kg of copper.
1 tonne of crude ore will reduce to kg of concentrated ore. This will leave kg of gangue.
To produce 1 tonne of copper, we need tonnes of crude ore, which will produce tonnes of gangue .

1 tonne = 1000 kg

Copper mining
There are a number of steps to get nearly pure copper from copper ore. Roll your cursor over the steps in the diagram to see a summary of each one. Click to find out more.

Mining

The ore is removed from the ground in either open pit or underground mines.

The ore

An ore is a rock that contains enough metal to make it worthwhile extracting.

The main copper ores are:

  • chalcopyrite
  • bornite
  • malachite.
Grinding

The ore is crushed then ground into powder

Concentrating

The ore is enriched using a process called froth flotation.

Unwanted material (called gangue) sinks to the bottom and is removed.

Roasting

This is where the chemical reactions start. The powdered, enriched ore is heated in air between 500 °C and 700 °C to remove some sulphur and dry the ore, which is still a solid called calcine.

Smelting with fluxes

The solid calcine is heated to 1200 °C and melts. Some impurities are removed as slag, leaving a matte (copper and iron sulphide liquid).

Conversion of matte

Air is blown into the liquid matte forming blister copper.

Anode casting

The blister is cast into anodes for electro-refining.

Electrolytic refining

The copper is purified to 99.99% by electrolysis. It is like a giant version of a school laboratory experiment.