Copper
| Gold | Silver | Copper |
Peru has long been known for its impressive mineral wealth of rare and precious metals dating back thousands of years. Mineral exports account for a significant portion of Peru's export revenue. Currently, Peru ranks third in world copper production besides being a front runner in gold and silver mining.
Since Peru’s government is pro-mining and open to foreign investment, Solid Resources is exploring the region actively for developing Peru's copper deposits along with other precious meals like gold and silver with the help of advanced equipments and mining techniques. This is helping Peru’s mining economy to become full-scale.
Characteristics
Copper occupies the same family of the periodic table as silver and gold, since they each have one s-orbital electron on top of a filled electron shell which forms metallic bonds. Like silver and gold, copper is easily worked, being both ductile and malleable. The ease with which it can be drawn into wire makes it useful for electrical work as does its excellent electrical conductivity. Copper is normally supplied, as with nearly all metals for industrial and commercial use, in a fine grained polycrystalline form. Polycrystalline metals have greater strength than monocrystalline forms, and the difference is greater for smaller grain (crystal) sizes.
Copper just above its melting point keeps its pink luster color when enough light outshines the orange incandescence color.
Comparison between unoxidized copper wire (left) and normal oxidized copper (right).
Copper has a reddish, orangish, or brownish color owing to a thin layer of tarnish (including oxides). Pure copper, is pink- or peach-coloured. Copper, osmium (blueish) and gold (yellow) are the only three elemental metals with a natural color other than gray or silver. Copper's characteristic color results from its band structure: copper is the exception to Madelung's rule, with only one electron in the 4s subshell instead of two. The energy of a photon of blue or violet light is sufficient for a d band electron to absorb it and transition to the half-full s band. Thus, the light reflected by copper is missing some blue/violet components and appears red. This phenomenon is exhibited by gold which has a corresponding 5s/4d structure. Liquid copper appears somewhat greenish, a characteristic shared with gold in the absence of bright ambient light.
Occurrence
Copper can be found as native copper in mineral form (for example, in Michigan's Keweenaw Peninsula). It is a polycrystal, with the largest single crystals measuring 4.4×3.2×3.2 cm. Minerals such as the sulfides: chalcopyrite (CuFeS2), bornite (Cu5FeS4), covellite (CuS), chalcocite (Cu2S) are sources of copper, as are the carbonates: azurite (Cu3(CO3)2(OH)2) and malachite (Cu2CO3(OH)2) and the oxide: cuprite (Cu2O).
Copper is found in a variety of enzymes and proteins, including the cytochrome c oxidase and certain superoxide dismutases. Copper is used for biological electron transport, e.g. the blue copper proteins azurin and plastocyanin. The name "blue copper" comes from their intense blue color arising from a ligand-to-metal charge transfer (LMCT) absorption band around 600 nm. Most molluscs and some arthropods such as the horseshoe crab use the copper-containing pigment hemocyanin rather than iron-containing hemoglobin for oxygen transport, so their blood is blue when oxygenated rather than red.
Production
Most copper ore is mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits that contain 0.4 to 1.0% copper. Examples include: Chuquicamata in Chile, Bingham Canyon Mine in Utah and El Chino Mine in New Mexico, US. The average abundance of copper found within crustal rocks is approximately 68 ppm by mass, and 22 ppm by atoms. In 2005, Chile was the top mine producer of copper with at least one-third world share followed by the USA, Indonesia and Peru, reports the British Geological Survey.
Reserves
Copper has been in use at least 10,000 years, but more than 95% of all copper ever mined and smelted has been extracted since 1900. As with many natural resources, the total amount of copper on Earth is vast (around 1014 tons just in the top kilometer of Earth's crust, or about 5 million years worth at the current rate of extraction). However, only a tiny fraction of these reserves is economically viable, given present-day prices and technologies. Various estimates of existing copper reserves available for mining vary from 25 years to 60 years, depending on core assumptions such as the growth rate.
Recycling is a major source of copper in the modern world.[30] Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of Peak copper, analogue to Peak Oil.
Application
About 98% of all copper is used as the metal, taking advantage of distinctive physical properties – being malleable and ductile, a good conductor of both heat and electricity, and being resistant to corrosion.
The purity of copper is expressed as 4N for 99.99% pure or 7N for 99.99999% pure. The numeral gives the number of nines after the decimal point when expressed as a decimal (e.g. 4N means 0.9999, or 99.99%). Copper is often too soft for its applications, so it is incorporated in numerous alloys. For example, brass is a copper-zinc alloy, and bronze is a copper-tin alloy.
Copper can be machined, although it is usually necessary to use an alloy for intricate parts, such as threaded components, to get good machinability characteristics. Good thermal conduction makes it useful for heatsinks and in heat exchangers.
It is widely used in piping for water supplies, refrigeration and air conditioning.