If you are thinking of investing in copper, this article explains copper mining and the copper extraction process: how copper is extracted from the earth’s ores.
It also summarises where the main copper mining regions are located and identifies who the major producers are.
Copper mining
While copper does occur as a native metal, most of the copper used today is mined as ores. The ores occur as both sedimentary and igneous rocks, and mining methods include traditional underground and open pit mining.
Although copper is widely distributed in the earth’s crust, for it to be mined as commercially exploitable deposits, it needs to contain at least 0.5% copper and preferably 2% or more.
The known reserves of high-grade ore would produce around 1 billion tons of copper, which at current consumption levels represents a 65–year supply.
However, there are likely to be many more reserves as yet undiscovered, even though they may be less convenient and more expensive to mine. In addition, copper can be readily recycled.
Copper ores contain a mixture of minerals, the most common of which are sulphides. Common copper minerals include:
| Copper ore | Chemical formula |
| Chalcopyrite | CuFeS2 |
| Chalcocite | Cu2S |
| Covellite | CuS |
| Bornite | 2Cu2S·CuS·FeS |
| Tetrahedrite | Cu3SbS3 + x(Fe,Zn)6Sb2S9 |
| Malachite | CuCO3 – Cu(OH)2 |
| Azurite | 2CuCO3·Cu(OH)2 |
| Cuprite | Cu2O |
| Chrysocolla | CuO·SiO2·2H2O |
| Tennantite | Cu12As4S13 |
How does the copper extraction process work?
Most copper is refined from sulphide ores. The process includes the following stages:
The copper ores are mechanically crushed and ground. The resulting mixture is treated using flotation with air injection and agitation to leave concentrates containing around 30% copper.
The concentrates are fed to a smelter to remove most of the iron and sulphur and then to a converter which is used to refine the material further. Most of the sulphur is recovered as sulphuric acid which can be used for leaching copper from oxidised ores.
The resultant copper, known as blister copper, is around 98% pure. It is then “fire refined” which increases the purity to that of de-oxidised copper, making it suitable for most applications other than electrical.
When the impurities include commercial quantities of precious metals, the copper is further refined electrolytically to produce between 99.94 %and 99.96% pure copper.
Copper is also extracted from oxidised ores including copper silicates, carbonates and sulphates. Here, the copper ores are crushed and ground as above, but they are then leached with sulphuric acid to produce an impure copper sulphate solution. The solution is purified using solvent extraction and electrode twinning.
Can copper be recycled?
Over a third of copper used industrially is recycled, and some is recycled several times over. It is far more efficient to recover copper than it is to mine and refine new copper.
Reasonable quality, high conductivity copper can be recycled by melting, though copper that has been brazed needs refining or can be used to make copper alloys.
Where are the most important copper regions and producers?
The largest copper mining country in the world is Chile, which produces 5.5 million tonnes per year.
Peru produces 2.3 million tonnes, China 1.7 million tonnes, the US 1.41 million tonnes, and Australia 0.9 million tonnes. Other significant players are Democratic Republic of Congo, Zambia, Canada, Russia and Mexico.
Some of the bigger copper producing companies include Freeport-McMoRan Inc, the largest copper miner in the world; BHP Billiton Plc which owns BH Copper; Anglo American Plc which mines for many different metals; and Rio Tinto Plc.
The world’s largest copper mine is the Escondida mine in Chile which is owned by Rio Tinto and BHP Billiton. In 2017 it produced 772 kilo tonnes of copper concentrate; and since opening 25 years ago, it has processed more than 2 billion tonnes of ore.
Investing in copper and uses of copper
If you want to learn more about investing in copper or the most common uses of copper, then please click on the links.
