Copper (Cu) is a reddish-brown non-ferrous base metal that occurs naturally in the Earth’s crust in a variety of forms (Source: British Geological Survey).
Copper is often found in the following types of deposits:
- Sulphide deposits (chalcopyrite, bornite, chalcocite, covellite),
- Carbonate deposits (azurite and malachite),
- Silicate deposits (chrysycolla and dioptase), and
- Pure “native” copper.
The porphyry deposits and sediment-hosted deposits are the two most important deposits where economic concentrations of copper is commonly found (Source: British Geological Survey).
Porphyry deposits are currently the world’s main source of copper accounting for approximately 80% of world production. Porphyry deposits occur in plate boundary collision areas such as the Canadian Cordillera, the Andes Mountains and around the western margin of the Pacific Basin in the Philippines, Indonesia and Papua New Guinea.
The mineralisation is fracture-controlled, typically consisting of stockwork of quartz veins and breccias containing copper sulphides with gold and/or molybdenum. Mineralisation can develop in both the intrusive and host rock, typically associated with a core of intense alteration passing outwards into distinct zones characterised by other secondary alteration minerals. Mineralisation may occupy several cubic kilometres and deposits typically contain hundreds of millions of tonnes of ore, although they can range in size from tens of millions to billions of tonnes. For Porphyry deposits copper grades generally range from 0.2 per cent to more than 1 per cent.
Sediment-hosted deposits are the world’s second most important source of copper accounting for approximately 20% of world production. They are also important sources of lead, zinc and silver and the world’s primary source of cobalt, especially from the Central African Copperbelt.
Sediment-hosted deposits consist of disseminations of fine-grained sulphides in a variety of continental sedimentary rocks including black shale, sandstone and limestone. These sequences are typically associated with red-bed sandstones and evaporites. Sediment-hosted deposits tonnages vary, with the average being 22 million tonnes grading 2.1% Cu and 23 g/t Ag but can be as much as several hundred million tonnes. Boundaries between different base-metal deposit types in sedimentary/volcanic sequences are sometimes unclear and depend heavily on the selection criteria employed.
Other types of copper deposits
- Volcanogenic massive sulphide deposits (VMS),
- Sedimentary exhalative deposits (SEDEX),
- Magmatic sulphide deposits,
- Epithermal deposits,
- Red-bed deposits,
- Skarn deposits,
- Vein deposits,
- Supergene deposits,
Map of Copper Occurrences
Market for Copper
Once the copper ore is extracted using open pit or underground extraction techniques, the ore is then processed and concentrated. After the concentration it is then converted into pure copper metal by either:
- pyro-metallurgical process (smelting and electrolytic refining), or
- hydro-metallurgical process (leaching, solvent extraction and electro-winning)
The copper cathodes produced from electrolytic refining and electrowinning are shipped to mills and foundries where they are cast into wire rod (for wires), billets (to make tubes, rods and bars stock), cakes (to make plate, sheets and foil) or ingots (for alloying or casting). These copper and alloyed products are then shipped for final manufacturing, or distribution, to meet consumers needs. Scrap (including excess material discarded during manufacturing and copper-bearing products sent for disposal) can be recycled back into the system (Source: British Geological Survey).
According to the United States Geological Survey in 2015 the world reserves of copper exceeded 720 million tonnes of copper with the major endowed countries as Chile (29%), Australia (12%) and Peru (11%).
Copper and copper alloy products are used in a variety of applications that are necessary for a reasonable standard of living. It can be further transformed by downstream industries for use in end use products such as automobiles, appliances, electronics, and a whole range of other copper-dependent products in order to meet society’s needs (Source: British Geological Survey).
Demand for Copper
According to the International Copper Study Group (ICSG) The demand for copper will continue to be met by the discovery of new deposits, technological improvements, efficient design, and by taking advantage of the renewable nature of copper through reuse and recycling. As well, competition between materials, and supply and demand principles, contribute to ensuring that materials are used efficiently and effectively (Source: ICSG).
Copper is an important contributor to the national economies of mature, newly developed and developing countries. Mining, processing, recycling and the transformation of metal into a multitude of products creates jobs and generates wealth. These activities contribute to building and maintaining a country’s infrastructure, and create trade and investment opportunities. The demand will continue to contribute to society’s development well into the future.
The global demand continues to grow: world refined usage has more than tripled in the last 50 years thanks to expanding sectors such as electrical and electronic products, building construction, industrial machinery and equipment, transportation equipment, and consumer and general products (Source: ICSG).
World Copper Consumption
According to the United States Geological Survey the global copper mine production in 2015 reached over 18.7 million tonnes. The largest producers of mined copper was Chile (5.7 million tonnes), China (1.7 million tonnes) and Peru (1.6 million tonnes).
The price for copper was steady for most of the early 2000’s then escalated dramatically through to 2011 as a result of the urbanisation and industrialisation of China, an increase in demand for copper in China lead to record prices, peaking at US$10,000 per tonne in late 2011. It was not until the peak of 2011 that the industry began contracting due a slowdown in economic growth from China. However since the slowdown of economic growth in China the price of copper has bottomed out at US$4,200 per tonne.
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