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copper

 
(kŏp'ər) pronunciation
n.
  1. (Symbol Cu) A ductile, malleable, reddish-brown metallic element that is an excellent conductor of heat and electricity and is widely used for electrical wiring, water piping, and corrosion-resistant parts, either pure or in alloys such as brass and bronze. Atomic number 29; atomic weight 63.54; melting point 1,083°C; boiling point 2,595°C; specific gravity 8.96; valence 1, 2.
  2. A coin, usually of small denomination, made of copper or a copper alloy.
  3. Chiefly British. A large cooking pot made of copper or often of iron.
  4. Any of various small butterflies of the subfamily Lycaeninae, having predominantly copper-colored wings.
  5. A reddish brown.
tr.v., -pered, -per·ing, -pers.
  1. To coat or finish with a layer of copper.
  2. Slang. To bet against, as in faro.

[Middle English coper, from Old English, from Late Latin cuprum, from Latin Cyprium (aes), Cyprian (metal), from Cyprius, of Cyprus, from Greek Kuprios, from Kupros, Cyprus.]

coppery cop'per·y adj.

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Crystalline copper from Michigan
(click to enlarge)
Crystalline copper from Michigan (credit: Courtesy of Ted Boente Collection; photograph, John H. Gerard)
Metallic chemical element, one of the transition elements, chemical symbol Cu, atomic number 29. Sometimes found in the free state in nature, it is a reddish metal, very ductile and an unusually good conductor of electricity and heat. Most of the world's copper production is used by the electrical industries; the remainder is combined with other metals (e.g., zinc, tin, nickel) to form alloys such as brass, bronze, nickel silver, and Monel. Copper is part of nearly all coinage metals. In compounds copper usually has valence 1 (cuprous) or 2 (cupric). Cuprous compounds include cuprous oxide, a red pigment and a fungicide; cuprous chloride, a catalyst for certain organic reactions; and cuprous sulfide, with a variety of uses. Cupric compounds include cupric oxide, a pigment, decolorizing agent, and catalyst; cupric chloride, a catalyst, wood preservative, mordant, disinfectant, feed additive, and pigment; and cupric sulfate, a pesticide, germicide, feed additive, and soil additive. Copper is a necessary trace element in the human diet and essential to plant growth; in blue-blooded mollusks and crustaceans it plays the same role in hemocyanin as iron does in hemoglobin.

For more information on copper, visit Britannica.com.

Gale's How Products Are Made:

How is copper made?

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Background

Copper is one of the basic chemical elements. In its nearly pure state, copper is a reddish-orange metal known for its high thermal and electrical conductivity. It is commonly used to produce a wide variety of products, including electrical wire, cooking pots and pans, pipes and tubes, automobile radiators, and many others. Copper is also used as a pigment and preservative for paper, paint, textiles, and wood. It is combined with zinc to produce brass and with tin to produce bronze.

Copper was first used as early as 10,000 years ago. A copper pendant from about 8700 B.C. was found in what is now northern Iraq. There is evidence that by about 6400 B.C. copper was being melted and cast into objects in the area now known as Turkey. By 4500 B.C., this technology was being practiced in Egypt as well. Most of the copper used before 4000 B.C. came from the random discovery of isolated outcroppings of native copper or from meteorites that had impacted Earth. The first mention of the systematic extraction of copper ore comes from about 3800 B.C. when an Egyptian reference describes mining operations on the Sinai Peninsula.

In about 3000 B.C., large deposits of copper ore were found on the island of Cyprus in the Mediterranean Sea. When the Romans conquered Cyprus, they gave the metal the Latin name aes cyprium, which was often shortened to cyprium. Later this was corrupted to cuprum, from which the English word copper and the chemical symbol Cu are derived.

In South America, copper objects were being produced along the northern coast of Peru as early as 500 B.C., and the development of copper metallurgy was well advanced by the time the Inca empire fell to the conquering Spanish soldiers in the 1500s.

In the United States, the first copper mine was opened in Branby, Connecticut, in 1705, followed by one in Lancaster, Pennsylvania, in 1732. Despite this early production, most copper used in the United States was imported from Chile until 1844, when mining of large deposits of high-grade copper ore around Lake Superior began. The development of more efficient processing techniques in the late-1800s allowed the mining of lower-grade copper ores from huge open-pit mines in the western United States.

Today, the United States and Chile are the world's top two copper producing countries, followed by Russia, Canada, and China.

Raw Materials

Pure copper is rarely found in nature, but is usually combined with other chemicals in the form of copper ores. There are about 15 copper ores mined commercially in 40 countries around the world. The most common are known as sulfide ores in which the copper is chemically bonded with sulfur. Others are known as oxide ores, carbonate ores, or mixed ores depending on the chemicals present. Many copper ores also contain significant quantities of gold, silver, nickel, and other valuable metals, as well as large quantities of commercially useless material. Most of the copper ores mined in the United States contain only about 1.2-1.6% copper by weight.

The most common sulfide ore is chalcopyrite, CuFeS2, also known as copper pyrite or yellow copper ore. Chalcocite, Cu2S, is another sulfide ore.

Cuprite, or red copper ore, Cu2O, is an oxide ore. Malachite, or green copper ore, Cu(OH)2•CuCO3, is an important carbonate ore, as is azurite, or blue copper carbonate, Cu(OH)2•2CuCO3.

Other ores include tennantite, boronite, chrysocolla, and atacamite.

In addition to the ores themselves, several other chemicals are often used to process and refine copper. These include sulfuric acid, oxygen, iron, silica, and various organic compounds, depending on the process used.

The Manufacturing
Process

The process of extracting copper from copper ore varies according to the type of ore and the desired purity of the final product. Each process consists of several steps in which unwanted materials are physically or chemically removed, and the concentration of copper is progressively increased. Some of these steps are conducted at the mine site itself, while others may be conducted at separate facilities.

Here are the steps used to process the sulfide ores commonly found in the western United States.

Mining

  • Most sulfide ores are taken from huge open-pit mines by drilling and blasting with explosives. In this type of mining, the material located above the ore, called the overburden, is first removed to expose the buried ore deposit. This produces an open pit that may grow to be a mile or more across. A road to allow access for equipment spirals down the interior slopes of the pit.
  • The exposed ore is scooped up by large power shovels capable of loading 500-900 cubic feet (15-25 cubic meters) in a single bite. The ore is loaded into giant dump trucks, called haul trucks, and is transported up and out of the pit.

Concentrating

The copper ore usually contains a large amount of dirt, clay, and a variety of non-copper bearing minerals. The first step is to remove some of this waste material. This process is called concentrating and is usually done by the flotation method.

  • The ore is crushed in a series of cone crushers. A cone crusher consists of an interior grinding cone that rotates on an eccentric vertical axis inside a fixed outer cone. As the ore is fed into the top of the crusher, it is squeezed between the two cones and broken into smaller pieces.
  • The crushed ore is then ground even smaller by a series of mills. First, it is mixed with water and placed in a rod mill, which consists of a large cylindrical container filled with numerous short lengths of steel rod. As the cylinder rotates on its horizontal axis, the steel rods tumble and break up the ore into pieces about 0.13 in (3 mm) in diameter. The mixture of ore and water is further broken up in two ball mills, which are like a rod mill except steel balls are used instead of rods. The slurry of finely ground ore that emerges from the final ball mill contains particles about 0.01 in (0.25 mm) in diameter.
  • The slurry is mixed with various chemical reagents, which coat the copper particles. A liquid, called a frother, is also added. Pine oil or long-chain alcohol are often used as frothers. This mixture is pumped into rectangular tanks, called flotation cells, where air is injected into the slurry through the bottom of the tanks. The chemical reagents make the copper particles cling to the bubbles as they rise to the surface. The frother forms a thick layer of bubbles, which overflows the tanks and is collected in troughs. The bubbles are allowed to condense and the water is drained off. The resulting mixture, called a copper concentrate, contains about 25-35% copper along with various sulfides of copper and iron, plus smaller concentrations of gold, silver, and other materials. The remaining materials in the tank are called the gangue or tailings. They are pumped into settling ponds and allowed to dry.

Smelting

Once the waste materials have been physically removed from the ore, the remaining copper concentrate must undergo several chemical reactions to remove the iron and sulfur. This process is called smelting and traditionally involves two furnaces as described below. Some modern plants utilize a single furnace, which combines both operations.

  • The copper concentrate is fed into a furnace along with a silica material, called a flux. Most copper smelters utilize oxygen-enriched flash furnaces in which preheated, oxygen-enriched air is forced into the furnace to combust with fuel oil. The copper concentrate and flux melt, and collect in the bottom of the furnace. Much of the iron in the concentrate chemically combines with the flux to form a slag, which is skimmed off the surface of the molten material. Much of the sulfur in the concentrate combines with the oxygen to form sulfur dioxide, which is exhausted from the furnace as a gas and is further treated in an acid plant to produce sulfuric acid. The remaining molten material in the bottom of the furnace is called the matte. It is a mixture of copper sulfides and iron sulfides and contains about 60% copper by weight.
  • The molten matte is drawn from the furnace and poured into a second furnace called a converter. Additional silica flux is added and oxygen is blown through the molten material. The chemical reactions in the converter are similar to those in the flash furnace. The silica flux reacts with the remaining iron to form a slag, and the oxygen reacts with the remaining sulfur to form sulfur dioxide. The slag may be fed back into the flash furnace to act as a flux, and the sulfur dioxide is processed through the acid plant. After the slag is removed, a final injection of oxygen removes all but a trace of sulfur. The resulting molten material is called the blister and contains about 99% copper by weight.

Refining

Even though copper blister is 99% pure copper, it still contains high enough levels of sulfur, oxygen, and other impurities to hamper further refining. To remove or adjust the levels of these materials, the blister copper is first fire refined before it is sent to the final electrorefining process.

  • The blister copper is heated in a refining furnace, which is similar to a converter described above. Air is blown into the molten blister to oxidize some impurities. A sodium carbonate flux may be added to remove traces of arsenic and antimony. A sample of the molten material is drawn and an experienced operator determines when the impurities have reached an acceptable level. The molten copper, which is about 99.5% pure, is then poured into molds to form large electrical anodes, which act as the positive terminals for the electrorefining process.
  • Each copper anode is placed in an individual tank, or cell, made of polymer-concrete. There may be as many as 1,250 tanks in operation at one time. A sheet of copper is placed on the opposite end of the tank to act as the cathode, or negative terminal. The tanks are filled with an acidic copper sulfate solution, which acts as an electrical conductor between the anode and cathode. When an electrical current is passed through each tank, the copper is stripped off the anode and is deposited on the cathode. Most of the remaining impurities fall out of the copper sulfate solution and form a slime at the bottom of the tank. After about 9-15 days, the current is turned off and the cathodes are removed. The cathodes now weigh about 300 lb (136 kg) and are 99.95-99.99% pure copper.
  • The slime that collects at the bottom of the tank contains gold, silver, selenium, and tellurium. It is collected and processed to recover these precious metals.

Casting

  • After refining, the copper cathodes are melted and cast into ingots, cakes, billets, or rods depending on the final application. Ingots are rectangular or trapezoidal bricks, which are remelted along with other metals to make brass and bronze products. Cakes are rectangular slabs about 8 in (20 cm) thick and up to 28 ft (8.5 m) long. They are rolled to make copper plate, strip, sheet, and foil products. Billets are cylindrical logs about 8 in (20 cm) in diameter and several feet (meters) long. They are extruded or drawn to make copper tubing and pipe. Rods have a round cross-section about 0.5 in (1.3 cm) in diameter. They are usually cast into very long lengths, which are coiled. This coiled material is then drawn down further to make copper wire.

Quality Control

Because electrical applications require a very low level of impurities, copper is one of the few common metals that are refined to almost 100% purity. The process described above has been proven to produce copper of very high purity. To ensure this purity, samples are analyzed at various steps to determine whether any adjustment to the process is required.

Byproducts/Waste

The recovery of sulfuric acid from the copper smelting process not only provides a profitable byproduct, but also significantly reduces the air pollution caused by the furnace exhaust. Gold, silver, and other precious metals are also important byproducts.

Waste products include the overburden from the mining operation, the tailings from the concentrating operation, and the slag from the smelting operation. This waste may contain significant concentrations of arsenic, lead, and other chemicals, which pose a potential health hazard to the surrounding area. In the United States, the Environmental Protection Agency (EPA) regulates the storage of such wastes and the remediation of the area once mining and processing operations have ceased. The sheer volume of the material involved—in some cases, billions of tons of waste—makes this a formidable task, but it also presents some potentially profitable opportunities to recover the useable materials contained in this waste.

The Future

Demand for copper is expected to remain high, especially in the electrical and electronics industries. The current trends in copper processing are towards methods and equipment that use less energy and produce less air pollution and solid waste. In the United States, this is a difficult assignment because of the stringent environmental controls and the very low-concentration copper ores that are available. In some cases, the production costs may increase significantly.

One encouraging trend is the increased use of recycled copper. Currently over half the copper being produced in the United States comes from recycled copper. Fifty-five percent of the recycled copper comes from copper machining operations, such as screw forming, and 45% comes from the recovery of used copper products, such as electrical wire and automobile radiators. The percentage of recycled copper is expected to grow as the costs of new copper processing increase.

Where to Learn More

Books

Brady, George S., Henry R. Clauser, and John A. Vaccari. Materials Handbook. McGraw-Hill, 1997.

Heiserman, David L. Exploring Chemical Elements and Their Compounds. TAB Books, 1992.

Hombostel, Caleb. Construction Materials. John Wiley and Sons, Inc., 1991.

Kroschwitz, Jacqueline I. and Mary Howe-Grant, ed. Encyclopedia of Chemical Technology. John Wiley and Sons, Inc., 1993.

Stwertka, Albert. A Guide to the Elements. Oxford University Press, 1996.

Periodicals

Baum, Dan and Margaret L. Knox. "We want people who have a problem with mine wastes to think of Butte." Smithsonian (November 1992): 46-52, 54-57.

Shimada, Izumi and John F. Merkel. "Copper-Alloy Metallurgy in Ancient Peru." Scientific American (July 1991): 80-86.

Other

http://www.copper.org.

http://www.intercorr.com/periodic/29.htm.

http://innovations.copper.org/innovations.html.

[Article by: Chris Cavette]


A chemical element, Cu, atomic number 29, atomic weight 63.546. Copper, a nonferrous metal, is the twentieth most abundant element present in the Earth's crust, at an average level of 68 parts per million (0.22 lb/ton or 0.11 kg/metric ton). Copper metal and copper alloys have considerable technological importance due to their combined electrical, mechanical, and physical properties. The discoveries that mixed-valence Cu(II)/Cu(III) oxides exhibit superconductivity (zero electrical resistance) at temperatures as high as 125 K (−234°F; liquid nitrogen, a cheap coolant, boils at 90 K or −297°F) have generated intense international competition to understand these new materials and to develop technological applications. Although some pure copper metal is present in nature, commercial copper is obtained by reduction of the copper compounds in ores followed by electrolytic refining. The rich chemistry of copper is restricted mostly to the valence states Cu(I) and Cu(II); compounds containing Cu(0), Cu(III), and Cu(IV) are uncommon. Soluble copper salts are potent bacteriocides and algicides at low levels and toxic to humans in large doses. Yet copper is an essential trace element that is present in various metalloproteins required for the survival of plants and animals.

Copper is located in the periodic table between nickel and zinc in the first row of transition elements and in the same subgroup as the other so-called coinage metals, silver and gold. The electronic configuration of elemental copper is [1s22s22p63s2] 3d104s1 or [argon]3d104s1. At first glance, the sole 4s electron might suggest chemical similarity to potassium, which has the [argon]4s1 configuration. However, metallic copper, in sharp contrast to metallic potassium, is relatively unreactive. The higher nuclear charge of copper relative to that of potassium is not fully shielded by the 10 additional d electrons, with the result that the copper 4s electron has a higher ionization potential than that of potassium (745.5 versus 418.9 kilojoules/mole, respectively). Moreover, the second and third ionization potentials of copper (1958.1 and 3554 J/mole, respectively) are considerably lower than those of potassium, and account for the higher valence-state accessibility associated with transition-metal chemistry as opposed to alkali-metal chemistry. See also Electron configuration; Periodic table; Transition elements; Valence.

Copper is a comparatively heavy metal. The density of the pure solid is 8.96 g/cm3 (5.18 oz/in.3) at 20°C (68°F). The density of commercial copper varies with method of manufacture, averaging 8.90–8.92 g/cm3 (5.14–5.16 oz/in.3) in cast refinery shapes, 8.93 g/cm3 (5.16 oz/in.3) for annealed tough-pitch copper, and 8.94 g/cm3 (517 oz/in.3) for oxygen-free copper. The density of liquid copper is 8.22 g/cm3 (4.75 oz/in.3) near the freezing point.

The melting point of copper is 1083.0 ∓ 0.1°C (1981.4 ∓ 0.2°F). Its normal boiling point is 2595°C (4703°F).

The coefficient of linear expansion of copper is 1.65 × 10−5/°C at 20°C.

The specific heat of the solid is 0.092 cal/g at 20°C (68°F). The specific heat of liquid copper is 0.112 cal/g, and of copper in the vapor state about 0.08 cal/g.

The electrical resistivity of copper in the usual volumetric unit, that of a cube measuring 1 cm in each direction, is 1.6730 × 10−6 ohm · cm at 20°C (68°F). Only silver has a greater volumetric conductivity than copper. On a relative basis in which silver is rated 100, copper is 94, aluminum 57, and iron 16.

The mass resistivity of pure copper for a length of 1 m weighing 1 g at 20°C (68°F) is 0.14983 ohm. The conductivity of copper on the mass basis is surpassed by several light metals, notably aluminum. The relative values are 100 for aluminum, 50 for copper, and 44 for silver.

By far the largest use of copper is in the electrical industry, and therefore high electrical conductivity is its most important single property, although for industrial use this property must be accompanied by suitable characteristics in other respects. See also Conductor (electricity).

Copper-containing proteins provide diverse biochemical functions, including copper uptake and transport (ceruloplasmin), copper storage (metallothionen), protective roles (superoxide dismutase), catalysis of substrate oxygenation (dopamine β-monooxygenase), biosynthesis of connective tissue (lysyl oxidase), terminal oxidases for oxygen metabolism (cytochrome c oxidase), oxygen transport (hemocyanin), and electron transfer in photosynthetic pathways (plastocyanin). See also Enzyme.


TechEncyclopedia:

copper

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(Cu) A reddish-brown metal that is highly conductive and widely used for electrical wire. When a signal "runs over copper," it means that a metal wire is used rather than a glass wire (optical fiber). See copper chip.

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A dietary essential trace metal, which forms the prosthetic group of a number of enzymes. The Reference Nutrient Intake is 1.2 mg/day. Toxic in excess, and it is recommended that not more than 2-10 mg/day should be consumed habitually. Rich sources include: meat, poultry, game, fish and shellfish, avocado, nuts, pulses, bread, chocolate, beer, cider, coconut, mushrooms.

An essential element involved in many processes including red blood cell formation, respiration, and bone formation. Copper deficiencies are rare, mainly because most domestic water supplies are contaminated with copper from pipes, but low intakes can lead to anaemia. Oysters and liver are good sources of dietary copper. In the UK, the adult Reference Nutrient Intake for copper is 1.2 mg each day. In the USA, the estimated safe and adequate daily intake of copper is 1.5-3.0 mg. Blood levels of copper often decrease after exercise indicating that athletes may need higher than normal intakes. Copper and zinc appear to be antagonistic; high intakes of one tend to reduce the absorption of the other. Copper toxicity is rare, but intakes greater than 20 mg cause vomiting and nausea.

Conventional electron-carrying network cable with a core conductor of copper — or aluminum! Opposed to light pipe or, say, a short-range microwave link.


A lustrous reddish metal, highly ductile and malleable; has high tensile strength, is an excellent electrical and thermal conductor, is available in a wide variety of shapes; widely used for downspouts, electrical conductors, flashing, gutters, roofing, etc.



[Ma]

One of the first metals (Cu) to be exploited by human communities. In its native form it can be worked without prior treatment. It was later extracted from a range of ores: carbonates (including malachite and azurite); oxides (including cuprite and melaconite); and sulphides (including chalcanthite). Shaping could be done by hammering, casting, or a combination of the two. Copper provides the main constituent for a number of alloys, the most widely used being bronze. The development of copper metallurgy happened independently in several parts of the world: in western Asia around 6000 bc; in Europe around 4000 bc; in the Longshan Culture of China around 2500 bc; in South America around 1500 bc in Peru, Bolivia, and Ecuador; ad 100 in central America; and in North America amongst the Old Copper Cultures of the Great Lakes region around 3000 bc.

An essential element involved in many processes including red blood cell formation, blood-sugar regulation, and bone formation. Deficiency may cause anaemia and feelings of lassitude.


    Description
    Precautions
    Interactions
    Complications
    Resources

Copper is an essential mineral that plays an important role in iron absorption and transport. It is considered a trace mineral because it is needed in very small amounts. Only 70-80 mg of copper are found in the body of a normal healthy person. Even though the body needs very little, copper is an important nutrient that holds many vital functions in the body.

What is the Purpose of Copper?

Copper is essential for normal development of the body because it:

  • Participates in a wide variety of important enzymatic reactions in the body.
  • Is a component of or a cofactor for approximately 50 different enzymes. These enzymes need copper to function properly.
  • Is essential for iron absorption and transport. Iron is needed to make hemoglobin, a main component of red blood cells. Therefore, copper deficiency is often linked to iron-deficiency anemia.
  • Is required to build elastin and collagen, which are an important components of bones and connective tissues. Therefore, copper is believed to protect the bones and joints against degeneration and osteoporosis.
  • Is required for melanin production. People with copper deficiency may have pale skin and hair.
  • Is a key mineral for the immune system. Copper promotes wound healing. Studies show that premature infants or children with genetic copper defects are at high risk of getting infections and would significantly improve with copper supplementation.
  • Attacks free radicals. Copper is a strong antioxidant. It works by attaching itself to the enzyme Superoxide dismutase (SOD). Copper also binds to a protein to form ceruloplasmin, which is an antioxidant.
  • Helps the body produce energy. Copper participates in many oxidative reactions that break down fats in fat tissue to produce much needed energy. Copper deficiency has been associated with high cholesterol levels.
  • Is necessary for normal functioning of insulin. Copper deficiency is also associated with poor blood glucose control.
  • Is needed for normal functioning of the cardiovascular system
  • Protects the structure and function of the nervous system, including the brain. Copper protects nerve.
fiber by maintaining myelin, the insulating sheath that surrounds nerve cells. It also aids the transmission of nerve signals in the brains.

Copper supplements may be beneficial in treating or preventing copper deficiency. Copper deficiency used to be relatively rare because the body requires so little of it, only about 2 mg per day. In addition, it is available naturally in a variety of foods such as whole grains, shellfish, nuts, beans, and leafy vegetables. Additional sources of copper are the copper water pipes that run through homes or the copper cookware in the kitchen. These sources leach copper into the water we drink and the food we eat. The level of copper in drinking water is sometimes so high that it becomes a public concern. However, scientists now realize that copper deficiency, especially borderline cases, is more common than once thought. Copper deficiency is currently on the rise due to a decrease of whole foods in the diet and high consumption of fatty and processed foods.

Copper

AgeRecommended Dietary Allowance (mcg/day)
Children 0–6 mos200 (AI)
Children 7–12 mos220 (AI)
Children 1–3 yrs340
Children 4–8 yrs440
Children 9–13 yrs700
Adolescents 14–18 yrs890
Adults 19≥ yrs900
Pregnant women1,000
Breastfeeding women1,300
FoodCopper (mcg)
Beef, liver, 3 oz1,240
Oysters, cooked, 6 med374
Chocolate, semisweet, 1 cup176
Mushrooms, shitake, cooked, 1 cup130
Cashews, dry roasted, 1 oz70
Peas, black-eyed, cooked, ½ cup70
Soybeans, boiled, 1 cup70
Beans, white, canned, 1 cup60
Sunflower seeds, ¼ cup 359
Chickpeas, cooked, 1 cup57
Baked beans, with pork, 1 cup54
Lentils, cooked, 1 cup50
V-8 juice, canned, 1 cup48
Potato skin, baked, 147
Raisins, seedless, 1 cup46
Salmon, baked, 3 oz30
AI = Adequate Intake 
mcg = microgram 
copper, metallic chemical element; symbol Cu [Lat. cuprum=copper]; at. no. 29; at. wt. 63.546; m.p. 1,083.4°C; b.p. 2,567°C; sp. gr. 8.96 at 20°C; valence +1 or +2. Copper and some of its alloys have been used by humanity since the Bronze Age. One of the first metals known to humans, copper was smelted as long ago as c. 5000 B.C. Cyprus, from which the metal's name originally comes, was a major source of copper in the ancient world.

Properties

Copper is a reddish metal with a face-centered cubic crystalline structure. It is malleable, ductile, and an extremely good conductor of both heat and electricity. It is softer than iron but harder than zinc and can be polished to a bright finish. It is found in Group 11 of the periodic table, together with silver and gold. Copper has low chemical reactivity. In moist air it slowly forms a greenish surface film (usually a mixture of carbonate, sulfate, hydroxide, and oxide) called patina; this coating protects the metal from further attack. Copper dissolves in hot concentrated hydrochloric or sulfuric acid but is little affected by cold solutions of these acids; it also dissolves in nitric acid. Salt water corrodes copper, forming a chloride.

Compounds

The most important chemical compound of copper is copper sulfate pentahydrate, also called bluestone or blue vitriol. Other compounds include Paris green, Bordeaux mixture, a cyanide, a chloride, oxides, and a basic carbonate. Verdigris is basic copper acetate.

Sources and Ores

Small amounts of copper are found uncombined, particularly near Lake Superior in Michigan. Copper ores are found in various parts of the world. In the United States (the chief producer of copper) ores are mined in Arizona, Utah, Montana, New Mexico, Nevada, and Michigan. Copper ores are also found in Canada, South America (in Chile and Peru), S central Africa, Russia (in the Ural Mts.), and to a limited extent in Europe and the British Isles.

The principal ore of copper is chalcopyrite, a sulfide of copper and iron, also called copper pyrite. Other important ores are chalcocite, or copper glance, a shiny lead-gray copper sulfide; bornite, a lustrous reddish-brown sulfide of copper and iron; cuprite, a red cuprous oxide ore; and malachite, a bright green carbonate ore. Azurite is a blue crystalline basic carbonate of copper found with other copper ores. Chrysocolla is a bluish-green copper silicate ore. Another important source of copper is secondary (scrap) copper, which is produced from discarded copper and copper alloys.

Commercial Preparation

Copper metal is prepared commercially in various ways. Copper sulfide ores, usually containing only 1% to 2% copper, are concentrated to 20% to 40% copper by the flotation process. They are then usually roasted to remove some of the sulfur and other impurities, and then smelted with iron oxide in either a blast furnace or a reverberatory furnace to produce copper matte, a molten solution of copper sulfide mixed with small amounts of iron sulfide. The matte is transferred to a converter, where it is treated by blowing air through it to remove the sulfur (as sulfur dioxide, a gas) and the iron (as a slag of ferrous oxide). The resulting copper is 98% to 99% pure; it is called blister copper because its surface is blistered by escaping gases when it solidifies during casting.

Most copper is further purified by electrolysis. The blister copper is refined in a furnace and cast into anodes. Thin sheets of pure copper are used as cathodes. A solution of copper sulfate and sulfuric acid is used as the electrolyte. When the anode and cathode are immersed in the electrolyte and an electric current is passed, the anode is dissolved in the electrolyte and pure copper metal is deposited on the cathode. Soluble impurities, usually nickel and arsenic, remain dissolved in the electrolyte. Insoluble impurities, often including silver, gold, and other valuable metals, settle out of the electrolyte; they may be collected and purified.

Copper oxide ores are usually treated by a different process, called leaching, in which the copper in the ore is dissolved in a leaching solution (usually dilute sulfuric acid); pure copper is recovered by electrolysis. Alternatively, the solution is treated with iron to precipitate the so-called cement copper, which is impure.

Importance and Uses

Copper is present in minute amounts in the animal body and is essential to normal metabolism. It is a component of hemocyanin, the blue, oxygen-carrying blood pigment of lobsters and other large crustaceans. It is needed in the synthesis of hemoglobin, the red, oxygen-carrying pigment found in the blood of humans, although it is not a component of hemoglobin.

The chief commercial use of copper is based on its electrical conductivity (second only to that of silver); about half the total annual output of copper is employed in the manufacture of electrical apparatus and wire. Copper is also used extensively as roofing, in making copper utensils, and for coins and metalwork. Copper tubing is used in plumbing, and, because of its high heat conductivity, in heat-exchanging devices such as refrigerator and air-conditioner coils. Powdered copper is sometimes used as a pigment in paints. An important use of copper is in alloys such as brass, bronze, gunmetal, Monel metal, and German silver. Compounds of copper are widely used as insecticides and fungicides; as pigments in paints; as mordants (fixatives) in dyeing; and in electroplating.



Cu
Cubic -- hexoctahedral

Environment

In the upper levels of copper sulfide veins and in some types of volcanic rock.

Crystal description

Usually in distorted, often rounded, complex crystals, with cubes, dodecahedrons, and octahedrons predominant. Often in hackly masses (Michigan) and in sheets without recognizable crystal forms.

Physical properties

Copper color. Luster metallic; hardness 2Ɖ-3; specific gravity 8.9. Malleable and ductile.

Composition

Fairly pure as a rule, often alloyed with small amounts of silver, arsenic, iron, etc.

Tests

Small bits fuse on charcoal to black-coated copper button; malleable, soluble in acids, giving greenish solutions. Colors flame blue-green.

Distinguishing characteristics

Almost inescapable green and blue stains on rock outcrops, known as "copper blooms," are a guide to deposits of copper and its associated minerals. The malleability and the color are distinguishing characteristics.

Occurrence

Since weathering processes free copper from its primary ore, chalcopyrite (CuFeS 2 ), it is likely to be found in the cap rock (the gossan) of copper-bearing sulfide veins, particularly in arid climates. Native copper is also found in ancient lava flows, where iron and oxygen have robbed the magma of sulfur. It is abundant in this form in Michigan's Upper Peninsula, where copper has been deposited in a thick series of flows, and this is the only economic source where all the copper is in the native state. Great masses found in these deposits were hard to remove because of their size and the difficulty of breaking them up. Nuggets from this deposit carried south by the glacier were scattered across the north-central states and were manufactured by the Indians into copper artifacts. Native copper was once found in Chessy, France, and Cornwall, England. Today it is abundant in some of the Arizona mines still working in the upper levels, like Morenci and Ajo. Surprisingly, it is not a major mineral in Chile, though that country contains rich sources of the metal.



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copper

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pronunciation

IN BRIEF: A reddish metal.

pronunciation They discovered the plumbing was made of copper pipes.

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A chemical element, atomic number 29, atomic weight 63.54, symbol Cu. It is necessary for bone formation and for the formation of blood because it occurs in several oxidative enzymes including one involved in the transformation of inorganic iron into hemoglobin.

  • c. acetoarsenite — an oldfashioned green pigment used in plaster, wallpaper, etc. A possible cause of chronic arsenic poisoning in very old houses. Called also Paris green.
  • c.-associated hepatopathy — see bedlington terrier copper-associated hepatopathy.
  • c. calcium edetate — used as a prophylactic in lambs and calves against swayback and hypocuprosis. Overdosing causes liver damage and severe subcutaneous edema and ascites.
  • c.-chrome–arsenate poisoning — the preservative in ‘treated pine’. Nibbling the wood causes poisoning in confined animals.
  • copper–molybdenum–sulfate relationship — molybdenum combines with sulfur in the rumen to form Cu–Mo–S complexes (copper–thiomolybdates) which reduce the availability of copper in the ingesta.
  • c. naphthenate — a complex of copper and naphthenic acid, used as a fungicide and insecticide. A treatment for footrot in cattle and sheep, and for thrush in horses.
  • c. nutritional deficiency — in ruminants this causes anemia and demyelination in the central nervous system. The deficiency may be primary or secondary due to intervention of high dietary intakes of sulfate and molybdenum. In pigs incoordination and anemia have been recorded. Horses appear unaffected. Called also enzootic ataxia, swayback, coast disease, pine, peat scours, teart, falling disease, hypocuprosis, licking sickness, liksucht. Copper deficiency is rare in dogs and cats and is most likely to occur from excessive supplementation with calcium, which reduces absorption of many minerals, including copper.
  • c. oxide needles — short lengths given orally to cattle to prevent or control copper deficiency. They lodge in papillae of the rumen and over several months pass to the abomasum where acid digestion makes copper available. They are effective in the control of secondary copper deficiency associated with high molybdenum concentrations in the diet by avoiding the binding of copper in thiomolybdenates which occurs in the rumen.
  • c. poisoning — may be acute because of accidental administration of inorganic preparations of copper, usually as a worm drench. Chronic poisoning is usually due to grazing on pasture growing on soils naturally rich in copper. The prevalence may be increased by the presence of converter plants, especially subterranean clover, which have a high uptake of copper, or of plants which cause liver damage and the sudden discharge of large amounts of copper which have accumulated in the liver. Such plants are Heliotropium, Senecio and Echium spp. Copper compounds reported to have caused poisoning in animals include the subacetate, oxychloride, chloride, oxide, naphthenate, carbonate, arsenite, sulfate.
  • — Acute poisoning is characterized by gastroenteritis; chronic poisoning is a syndrome of acute hemolytic anemia caused by a sudden elevation of blood copper levels. The obvious signs are jaundice, hemoglobinuria and pallor of mucosae. Poisoning by organic copper preparations administered therapeutically causes nephrosis and death due to uremia. Called also toxemic jaundice. See also bedlington terrier copper-associated hepatopathy.
  • c. storage disease — see bedlington terrier copper-associated hepatopathy.
  • c. sulfate — used as a parasiticide in aquariums and in the treatment of foot rot in cattle.

n

A malleable, reddish-brown metallic element. Copper is a component of several important enzymes in the body and is essential to good health. Copper deficiency is rare, because only 2 to 5 mg daily are necessary, and that amount is easily obtained in a normal diet.

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Cu

Ag
Appearance
red-orange metallic luster

Native copper (~4 cm in size)
General properties
Name, symbol, number copper, Cu, 29
Pronunciation /ˈkɒpər/ kop-ər
Element category transition metal
Group, period, block 114, d
Standard atomic weight 63.546(3)
Electron configuration [Ar] 3d10 4s1
Electrons per shell 2, 8, 18, 1 (Image)
Physical properties
Phase solid
Density (near r.t.) 8.94 g·cm−3
Liquid density at m.p. 8.02 g·cm−3
Melting point 1357.77 K, 1084.62 °C, 1984.32 °F
Boiling point 2835 K, 2562 °C, 4643 °F
Heat of fusion 13.26 kJ·mol−1
Heat of vaporization 300.4 kJ·mol−1
Molar heat capacity 24.440 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1509 1661 1850 2089 2404 2834
Atomic properties
Oxidation states +1, +2, +3, +4
(mildly basic oxide)
Electronegativity 1.90 (Pauling scale)
Ionization energies
(more)
1st: 745.5 kJ·mol−1
2nd: 1957.9 kJ·mol−1
3rd: 3555 kJ·mol−1
Atomic radius 128 pm
Covalent radius 132±4 pm
Van der Waals radius 140 pm
Miscellanea
Crystal structure face-centered cubic
Magnetic ordering diamagnetic[1]
Electrical resistivity (20 °C) 16.78 nΩ·m
Thermal conductivity 401 W·m−1·K−1
Thermal expansion (25 °C) 16.5 µm·m−1·K−1
Speed of sound (thin rod) (r.t.) (annealed)
3810 m·s−1
Young's modulus 110–128 GPa
Shear modulus 48 GPa
Bulk modulus 140 GPa
Poisson ratio 0.34
Mohs hardness 3.0
Vickers hardness 369 MPa
Brinell hardness 874 MPa
CAS registry number 7440-50-8
Most stable isotopes
Main article: Isotopes of copper
iso NA half-life DM DE (MeV) DP
63Cu 69.15% 63Cu is stable with 34 neutrons
65Cu 30.85% 65Cu is stable with 36 neutrons
· r

Copper (play /ˈkɒpər/ kop-ər) is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.

The metal and its alloys have been used for thousands of years. In the Roman era, copper was principally mined on Cyprus, hence the origin of the name of the metal as сyprium (metal of Cyprus), later shortened to сuprum. Its compounds are commonly encountered as copper(II) salts, which often impart blue or green colors to minerals such as turquoise and have been widely used historically as pigments. Architectural structures built with copper corrode to give green verdigris (or patina). Decorative art prominently features copper, both by itself and as part of pigments.

Copper(II) ions are water-soluble, where they function at low concentration as bacteriostatic substances, fungicides, and wood preservatives. In sufficient amounts, they are poisonous to higher organisms; at lower concentrations it is an essential trace nutrient to all higher plant and animal life. The main areas where copper is found in animals are tissues, liver, muscle and bone.

Contents

Characteristics

Physical

A copper disc (99.95% pure) made by continuous casting and etching.
Copper just above its melting point keeps its pink luster color when enough light outshines the orange incandescence color.

Copper, silver and gold are in group 11 of the periodic table, and they share certain attributes: they have one s-orbital electron on top of a filled d-electron shell and are characterized by high ductility and electrical conductivity. The filled d-shells in these elements do not contribute much to the interatomic interactions, which are dominated by the s-electrons through metallic bonds. Contrary to metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This explains the low hardness and high ductility of single crystals of copper.[2] At the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress thereby increasing its hardness. For this reason, copper is usually supplied in a fine-grained polycrystalline form, which has greater strength than monocrystalline forms.[3]

The low hardness of copper partly explains its high electrical (59.6×106 S/m) and thus also high thermal conductivity, which are the second highest among pure metals at room temperature.[4] This is because the resistivity to electron transport in metals at room temperature mostly originates from scattering of electrons on thermal vibrations of the lattice, which are relatively weak for a soft metal.[2] The maximum permissible current density of copper in open air is approximately 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively.[5] As with other metals, if copper is placed against another metal, galvanic corrosion will occur.[6]

Together with osmium (bluish), and gold (yellow), copper is one of only three elemental metals with a natural color other than gray or silver.[7] Pure copper is orange-red and acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells is such that it corresponds to orange light. The same mechanism accounts for the yellow color of gold.[2]

Chemical

Unoxidized copper wire (left) and oxidized copper wire (right).

Copper forms a rich variety of compounds with oxidation states +1 and +2, which are often called cuprous and cupric, respectively.[8] It does not react with water, but it slowly reacts with atmospheric oxygen forming a layer of brown-black copper oxide. In contrast to the oxidation of iron by wet air, this oxide layer stops the further, bulk corrosion. A green layer of verdigris (copper carbonate) can often be seen on old copper constructions, such as the Statue of Liberty, the largest copper statue in the world built using repoussé and chasing.[9] Hydrogen sulfides and sulfides react with copper to form various copper sulfides on the surface. In the latter case, the copper corrodes, as is seen when copper is exposed to air containing sulfur compounds.[10] Oxygen-containing ammonia solutions give water-soluble complexes with copper, as do oxygen and hydrochloric acid to form copper chlorides and acidified hydrogen peroxide to form copper(II) salts. Copper(II) chloride and copper comproportionate to form copper(I) chloride.[11]

Isotopes

There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper; they both have a spin of 3/2.[12] The other isotopes are radioactive, with the most stable being 67Cu with a half-life of 61.83 hours.[12] Seven metastable isotopes have been characterized, with 68mCu the longest-lived with a half-life of 3.8 minutes. Isotopes with a mass number above 64 decay by β-, whereas those with a mass number below 64 decay by β+. 64Cu, which has a half-life of 12.7 hours, decays both ways.[13]

62Cu and 64Cu have significant applications. 64Cu is a radiocontrast for X-ray imaging, and complexed with a chelate can be used for treating cancer. 62Cu is used in 62Cu-PTSM that is a radioactive tracer for positron emission tomography.[14]

Occurrence

Copper can be found as either native copper or as part of minerals. Native copper is a polycrystal, with the largest described single crystal measuring 4.4×3.2×3.2 cm.[15] The largest mass of elemental copper weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula in Michigan, US.[16] There are many examples of copper-containing minerals: chalcopyrite and chalcocite are copper sulfides, azurite and malachite are copper carbonates and cuprite is a copper oxide.[4] Copper is present in the Earth's crust at a concentration of about 50 parts per million (ppm),[16] and is also synthesized in massive stars.[17]

Production

Chuquicamata in Chile is one of the world's largest open pit copper mines.
World production trend
Copper output in 2005
Copper prices 2003–2011 in USD per tonne

Most copper 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, United States and El Chino Mine in New Mexico, United States. According to the British Geological Survey, in 2005, Chile was the top mine producer of copper with at least one-third world share followed by the United States, Indonesia and Peru.[4] The amount of copper in use is increasing and the quantity available is barely sufficient to allow all countries to reach developed world levels of usage.[18]

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.[19] Recycling is a major source of copper in the modern world.[20] 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.

The price of copper has historically been unstable,[21] and it quintupled from the 60-year low of US$0.60/lb (US$1.32/kg) in June 1999 to US$3.75 per pound (US$8.27/kg) in May 2006. It dropped to US$2.40/lb (US$5.29/kg) in February 2007, then rebounded to US$3.50/lb (US$7.71/kg) in April 2007.[22] In February 2009, weakening global demand and a steep fall in commodity prices since the previous year's highs left copper prices at US$1.51/lb.[23]

Methods

The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS2) and to a lesser extent chalcocite (Cu2S).[24] These minerals are concentrated from crushed ores to the level of 10–15% copper by froth flotation or bioleaching.[25] Heating this material with silica in flash smelting removes much of the iron as slag. The process exploits the greater ease of converting iron sulfides into its oxides, which in turn react with the silica to form the silicate slag, which floats on top of the heated mass. The resulting copper matte consisting of Cu2S is then roasted to convert all sulfides into oxides:[24]

2 Cu2S + 3 O2 → 2 Cu2O + 2 SO2

The cuprous oxide is converted to blister copper upon heating:

2 Cu2O → 4 Cu + O2

The Sudbury matte process converted only half the sulfide to oxide and then used this oxide to remove the rest of the sulfur as oxide. It was then electrolytically refined and the anode mud exploited for the platinum and gold it contained. This step exploits the relatively easy reduction of copper oxides to copper metal. Natural gas is blown across the blister to remove most of the remaining oxygen and electrorefining is performed on the resulting material to produce pure copper:[26]

Cu2+ + 2 e → Cu

Recycling

Copper, like aluminium, is 100% recyclable without any loss of quality whether in a raw state or contained in a manufactured product. In volume, copper is the third most recycled metal after iron and aluminium. It is estimated that 80% of the copper ever mined is still in use today.[27] According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of Copper in use in society is 35–55 kg. Much of this is in more-developed countries (140–300 kg per capita) rather than less-developed countries (30–40 kg per capita).

The process of recycling copper follows roughly the same steps as is used to extract copper, but requires fewer steps. High purity scrap copper is melted in a furnace and then reduced and cast into billets and ingots; lower purity scrap is refined by electroplating in a bath of sulfuric acid.[28]

Compounds

A sample of copper(I) oxide.

Binary compounds

As for other elements, the simplest compounds of copper are binary compounds, i.e. those containing only two elements. The principal ones are the oxides, sulfides and halides. Both cuprous and cupric oxides are known. Among the numerous copper sulfides, important examples include copper(I) sulfide and copper(II) sulfide.

The cuprous halides with chlorine, bromine, and iodine are known, as are the cupric halides with fluorine, chlorine, and bromine. Attempts to prepare copper(II) iodide give cuprous iodide and iodine.[8]

2 Cu2+ + 4 I → 2 CuI + I2

Coordination chemistry

Copper(II) gives a deep blue coloration in the presence of ammonia ligands. The one used here is tetramminecopper(II) sulfate.

Copper, like all metals, forms coordination complexes with ligands. In aqueous solution, copper(II) exists as [Cu(H2O)6]2+. This complex exhibits the fastest water exchange rate (speed of water ligands attaching and detaching) for any transition metal aquo complex. Adding aqueous sodium hydroxide causes the precipitation of light blue solid copper(II) hydroxide. A simplified equation is:

Cu2+ + 2 OH → Cu(OH)2

Aqueous ammonia results in the same precipitate. Upon adding excess ammonia, the precipitate dissolves, forming tetraamminecopper(II):

Cu(H2O)4(OH)2 + 4 NH3 → [Cu(H2O)2(NH3)4]2+ + 2 H2O + 2 OH

Many other oxyanions form complexes; these include copper(II) acetate, copper(II) nitrate, and copper(II) carbonate. Copper(II) sulfate forms a blue crystalline pentahydrate, which is the most familiar copper compound in the laboratory. It is used in a fungicide called the Bordeaux mixture.[29]

Ball-and-stick model of the complex [Cu(NH3)4(H2O)2]2+, illustrating the octahedral coordination geometry common for copper(II).

Polyols, compounds containing more than one alcohol functional group, generally interact with cupric salts. For example, copper salts are used to test for reducing sugars. Specifically, using Benedict's reagent and Fehling's solution the presence of the sugar is signaled by a color change from blue Cu(II) to reddish copper(I) oxide.[30] Schweizer's reagent and related complexes with ethylenediamine and other amines dissolve cellulose.[31] Amino acids form very stable chelate complexes with copper(II). Many wet-chemical tests for copper ions exist, one involving potassium ferrocyanide, which gives a brown precipitate with copper(II) salts.

Organocopper chemistry

Compounds that contain a carbon-copper bond are known as organocopper compounds. They are very reactive towards oxygen to form copper(I) oxide and have many uses in chemistry. They are synthesized by treating copper(I) compounds with Grignard reagents, terminal alkynes or organolithium reagents;[32] in particular, the last reaction described produces a Gilman reagent. These can undergo substitution with alkyl halides to form coupling products; as such, they are important in the field of organic synthesis. Copper(I) acetylide is highly shock-sensitive but is an intermediate in reactions such as the Cadiot-Chodkiewicz coupling[33] and the Sonogashira coupling.[34] Conjugate addition to enones[35] and carbocupration of alkynes[36] can also be achieved with organocopper compounds. Copper(I) forms a variety of weak complexes with alkenes and carbon monoxide, especially in the presence of amine ligands.[37]

Copper(III) and copper(IV)

Complexes of copper(III) are frequent intermediates in reactions of organocopper compounds. Dicopper oxo complexes also feature copper(III).[38] Fluoride ligands, being highly basic, stabilize metal ions in high oxidation states; indeed, representative copper(III) and copper(IV) complex are fluorides. These include K3CuF6 and Cs2CuF6.[8] With di- and tripeptides, purple-colored complexes of copper(III) have been observed, this high oxidation state being stabilized by the deprotonated amide ligands.[39]

History

Copper Age

A corroded copper ingot from Zakros, Crete, shaped in the form of an animal skin typical for that era.

Copper occurs naturally as native copper and was known to some of the oldest civilizations on record. It has a history of use that is at least 10,000 years old, and estimates of its discovery place it at 9000 BC in the Middle East;[40] a copper pendant was found in northern Iraq that dates to 8700 BC.[41] There is evidence that gold and meteoric iron (but not iron smelting) were the only metals used by humans before copper.[42] The history of copper metallurgy is thought to have followed the following sequence: 1) cold working of native copper, 2) annealing, 3) smelting, and 4) the lost wax method. In southeastern Anatolia, all four of these metallurgical techniques appears more or less simultaneously at the beginning of the Neolothic c. 7500 BC.[43] However, just as agriculture was independently invented in several parts of the world (including Pakistan, China, and the Americas) copper smelting was invented locally in several different places. It was probably discovered independently in China before 2800 BC, in Central America perhaps around 600 AD, and in West Africa about the 9th or 10th century AD.[44] Investment casting was invented in 4500–4000 BC in Southeast Asia[40] and carbon dating has established mining at Alderley Edge in Cheshire, UK at 2280 to 1890 BC.[45] Ötzi the Iceman, a male dated from 3300–3200 BC, was found with an axe with a copper head 99.7% pure; high levels of arsenic in his hair suggest his involvement in copper smelting.[46] Experience with copper has assisted the development of other metals; in particular, copper smelting led to the discovery of iron smelting.[46] Production in the Old Copper Complex in Michigan and Wisconsin is dated between 6000 and 3000 BC.[47][48] Natural bronze, a type of copper made from ores rich in silicon, arsenic, and (rarely) tin, came into general use in the Balkans around 5500 BC. Previously the only tool made of copper had been the awl, used for punching holes in leather and gouging out peg-holes for wood joining. However, the introduction of a more robust form of copper led to the widespread use, and large-scale production of heavy metal tools, including axes, adzes, and axe-adzes.[citation needed]

Bronze Age

Alloying copper with tin to make bronze was first practiced about 4000 years after the discovery of copper smelting, and about 2000 years after "natural bronze" had come into general use. Bronze artifacts from Sumerian cities and Egyptian artifacts of copper and bronze alloys date to 3000 BC.[49] The Bronze Age began in Southeastern Europe around 3700 - 3300 BC, in Northwestern Europe about 2500 BC. It ended with the beginning of the Iron Age, 2000-1000 BC in the Near East, 600 BC in Northern Europe. The transition between the Neolithic period and the Bronze Age was formerly termed the Chalcolithic period (copper-stone), with copper tools being used with stone tools. This term has gradually fallen out of favor because in some parts of the world the Calcholithic and Neolithic are coterminous at both ends. Brass, an alloy of copper and zinc, is of much more recent origin. It was known to the Greeks, but became a significant supplement to bronze during the Roman Empire.[49]

Antiquity and Middle Ages

In alchemy the symbol for copper, perhaps a stylized mirror, was also the symbol for the goddess and planet Venus.
Chalcolithic copper mine in Timna Valley, Negev Desert, Israel.

In Greece, copper was known by the name chalkos (χαλκός). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as aes Cyprium, aes being the generic Latin term for copper alloys and Cyprium from Cyprus, where much copper was mined. The phrase was simplified to cuprum, hence the English copper. Aphrodite and Venus represented copper in mythology and alchemy, due to its lustrous beauty, its ancient use in producing mirrors, and its association with Cyprus, which was sacred to the goddess. The seven heavenly bodies known to the ancients were associated with the seven metals known in antiquity, and Venus was assigned to copper.[50]

Britain's first use of brass occurred around the 3rd–2nd century BC. In North America, copper mining began with marginal workings by Native Americans. Native copper is known to have been extracted from sites on Isle Royale with primitive stone tools between 800 and 1600.[51] Copper metallurgy was flourishing in South America, particularly in Peru around 1000 AD; it proceeded at a much slower rate on other continents. Copper burial ornamentals from the 15th century have been uncovered, but the metal's commercial production did not start until the early 20th century.

The cultural role of copper has been important, particularly in currency. Romans in the 6th through 3rd centuries BC used copper lumps as money. At first, the copper itself was valued, but gradually the shape and look of the copper became more important. Julius Caesar had his own coins made from brass, while Octavianus Augustus Caesar's coins were made from Cu-Pb-Sn alloys. With an estimated annual output of around 15,000 t, Roman copper mining and smelting activities reached a scale unsurpassed until the time of the Industrial Revolution; the provinces most intensely mined were those of Hispania, Cyprus and in Central Europe.[52][53]

The gates of the Temple of Jerusalem used Corinthian bronze made by depletion gilding. It was most prevalent in Alexandria, where alchemy is thought to have begun.[54] In ancient India, copper was used in the holistic medical science Ayurveda for surgical instruments and other medical equipment. Ancient Egyptians (~2400 BC) used copper for sterilizing wounds and drinking water, and later on for headaches, burns, and itching. The Baghdad Battery, with copper cylinders soldered to lead, dates back to 248 BC to AD 226 and resembles a galvanic cell, leading people to believe this was the first battery; the claim has not been verified.[55]

Modern period

Acid mine drainage affecting the stream running from the disused Parys Mountain copper mines

The Great Copper Mountain was a mine in Falun, Sweden, that operated from the 10th century to 1992. It produced two thirds of Europe's copper demand in the 17th century and helped fund many of Sweden's wars during that time.[56] It was referred to as the nation's treasury; Sweden had a copper backed currency.[57]

The uses of copper in art were not limited to currency: it was used by Renaissance sculptors, in pre-photographic technology known as the daguerreotype, and the Statue of Liberty. Copper plating and copper sheathing for ships' hulls was widespread; the ships of Christopher Columbus were among the earliest to have this feature.[58] The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876.[59] The German scientist Gottfried Osann invented powder metallurgy in 1830 while determining the metal's atomic mass; around then it was discovered that the amount and type of alloying element (e.g., tin) to copper would affect bell tones. Flash smelting was developed by Outokumpu in Finland and first applied at Harjavalta in 1949; the energy-efficient process accounts for 50% of the world’s primary copper production.[60]

The Intergovernmental Council of Copper Exporting Countries, formed in 1967 with Chile, Peru, Zaire and Zambia, played a similar role for copper as OPEC does for oil. It never achieved the same influence, particularly because the second-largest producer, the United States, was never a member; it was dissolved in 1988.[61]

Applications

Assorted copper fittings

The major applications of copper are in electrical wires (60%), roofing and plumbing (20%) and industrial machinery (15%). Copper is mostly used as a metal, but when a higher hardness is required it is combined with other elements to make an alloy (5% of total use) such as brass and bronze.[16] A small part of copper supply is used in production of compounds for nutritional supplements and fungicides in agriculture.[29][62] Machining of copper is possible, although it is usually necessary to use an alloy for intricate parts to get good machinability characteristics.

Electronics and related devices

Copper electrical busbars distributing power to a large building

The electrical properties of copper are exploited in copper wires and devices such as electromagnets. Integrated circuits and printed circuit boards increasingly feature copper in place of aluminium because of its superior electrical conductivity (see Copper interconnect for main article); heat sinks and heat exchangers use copper as a result of its superior heat dissipation capacity to aluminium. Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens use copper, as do wave guides for microwave radiation.[63]

Architecture and industry

Copper roof on the Minneapolis City Hall, coated with patina
Old copper utensils in a Jerusalem restaurant

Because of the waterproof nature of copper, it has been used as the roofing material of many buildings since ancient times. The green color on these buildings is due to a long-term chemical reaction: copper is first oxidized to copper(II) oxide, then to cuprous and cupric sulfide and finally to copper(II) carbonate, also called verdigris, which is highly corrosion-resistant.[64] The copper used in this application is phosphorus deoxidized copper (Cu-DHP).[65] Lightning rods use copper as a means to divert electric current throughout the ground instead of destroying the main structure.[66] Copper has excellent brazing and soldering properties and can be welded; the best results are obtained with gas metal arc welding.[67]

Copper in alloys

Numerous copper alloys exist, many with important uses. Brass is an alloy of copper and zinc and bronze usually refers to copper-tin alloys, but can refer to any alloy of copper such as aluminium bronze. Copper is one of the most important constituents of carat silver and gold alloys and carat solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys.[68]

The alloy of copper and nickel, called cupronickel, is used in low-denomination statuary coins, often for the outer cladding. The US 5-cent coin called nickel consists of 75% copper and 25% nickel and has a homogeneous composition. The 90% copper/10% nickel alloy is remarkable by its resistance to corrosion and is used in various parts being exposed to seawater. Alloys of copper with aluminium (about 7%) have a pleasant golden color and are used in decorations.[16] Copper alloys with tin are part of lead-free solders.[69]

Antibiofouling applications

Copper has long been used as a biostatic surface to line parts of ships to protect against barnacles and mussels. It was originally used pure, but has since been superseded by Muntz metal. Bacteria will not grow on a copper surface because it is biostatic. Similarly, as discussed in copper alloys in aquaculture, copper alloys have become important netting materials in the aquaculture industry for the fact that they are antimicrobial and prevent biofouling even in extreme conditions[70] and have strong structural and corrosion-resistant[71] properties in marine environments.

Other uses

Copper compounds in liquid form are used as a wood preservative, particularly in treating original portion of structures during restoration of damage due to dry rot. Together with zinc, copper wires may be placed over non-conductive roofing materials to discourage the growth of moss. Textile fibers use copper to create antimicrobial protective fabrics,[72] as do ceramic glazes, stained glass and musical instruments. Electroplating commonly uses copper as a base for other metals such as nickel.

Copper is one of three metals, along with lead and silver, used in a museum materials testing procedure called the Oddy test. In this procedure, copper is used to detect chlorides, oxides, and sulfur compounds.

Copper is also commonly found in jewelry, and folklore states that copper bracelets relieve arthritis symptoms, though this is not proven.[73]

Biological role

Rich sources of copper include oysters, beef and lamb liver, Brazil nuts, blackstrap molasses, cocoa, and black pepper. Good sources include lobster, nuts and sunflower seeds, green olives, avocados, and wheat bran.

Copper proteins have diverse roles in biological electron transport and oxygen transportation, processes that exploit the easy interconversion of Cu(I) and Cu(II).[74] The biological role for copper commenced with the appearance of oxygen in earth's atmosphere.[75] The protein hemocyanin is the oxygen carrier in most mollusks and some arthropods such as the horseshoe crab (Limulus polyphemus).[76] Because hemocyanin is blue, these organisms have blue blood, not the red blood found in organisms that rely on hemoglobin for this purpose. Structurally related to hemocyanin are the laccases and tyrosinases. Instead of reversibly binding oxygen, these proteins hydroxylate substrates, illustrated by their role in the formation of lacquers.[74]

Copper is also a component of other proteins associated with the processing of oxygen. In cytochrome c oxidase, which is required for aerobic respiration, copper and iron cooperate in the reduction of oxygen. Copper is also found in many superoxide dismutases, proteins that detoxify superoxides, by converting it (by disproportionation) to oxygen and hydrogen peroxide:

2 HO2 → H2O2 + O2

Several copper proteins, such as the "blue copper proteins", do not interact directly with substrates, hence they are not enzymes. These proteins relay electrons by the process called electron transfer.[74]

Photosynthesis functions by an elaborate electron transport chain within the thylakoid membrane. A central "link" in this chain is plastocyanin, a blue copper protein.

Dietary needs

Copper is an essential trace element in plants and animals, but not some microorganisms. The human body contains copper at a level of about 1.4 to 2.1 mg per kg of body mass.[77] Stated differently, the RDA for copper in normal healthy adults is quoted as 0.97 mg/day and as 3.0 mg/day.[78] Copper is absorbed in the gut, then transported to the liver bound to albumin. It enters the bloodstream via the plasma protein called ceruloplasmin, where its metabolism is controlled, and is excreted in bile.[79]

Copper-based disorders

Because of its role in facilitating iron uptake, copper deficiency can produce anemia-like symptoms, neutropenia, bone abnormalities, hypopigmentation, impaired growth, increased incidence of infections, osteoporosis, and abnormalities in glucose and cholesterol metabolism. Conversely, an accumulation of copper in body tissues causes Wilson's disease. Severe deficiency can be found by testing for low plasma or serum copper levels, low ceruloplasmin, and low red blood cell superoxide dismutase levels; these are not sensitive to marginal copper status. The "cytochrome c oxidase activity of leucocytes and platelets" has been stated as another factor in deficiency, but the results have not been confirmed by replication.[80]

Antimicrobial applications

Numerous antimicrobial efficacy studies have been conducted in the past 10 years regarding copper’s efficacy to destroy a wide range of bacteria, as well as influenza A virus, adenovirus, and fungi.[81]

Copper-alloy touch surfaces have natural intrinsic properties to destroy a wide range of microorganisms (e.g., E. coli O157:H7, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus, Clostridium difficile, influenza A virus, adenovirus, and fungi).[81] Some 355 copper alloys were proven to kill more than 99.9% of disease-causing bacteria within just two hours when cleaned regularly.[82] The United States Environmental Protection Agency (EPA) has approved the registrations of these copper alloys as “antimicrobial materials with public health benefits,"[82] which allows manufacturers to legally make claims as to the positive public health benefits of products made with registered antimicrobial copper alloys. In addition, the EPA has approved a long list of antimicrobial copper products made from these alloys, such as bedrails, handrails, over-bed tables, sinks, faucets, door knobs, toilet hardware, computer keyboards, health club equipment, shopping cart handles, etc. (for a comprehensive list of products, see: Antimicrobial copper-alloy touch surfaces#Approved products). Copper doorknobs are used by hospitals to reduce the transfer of disease, and Legionnaires' disease is suppressed by copper tubing in plumbing systems.[83] Antimicrobial copper alloy products are now being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil and in the subway transit system in Santiago, Chile, where copper-zinc alloy handrails will be installed in some 30 stations between 2011–2014.[84][85][86]

Precautions

NFPA 704
NFPA 704.svg
Fire diamond for copper metal

Gram quantities of various copper salts have been taken in suicide attempts and produced acute copper toxicity in humans, possibly due to redox cycling and the generation of reactive oxygen species that damage DNA.[87] Corresponding amounts of copper salts (30 mg/kg) are toxic in animals.[88] A minimum dietary value for healthy growth in rabbits has been reported to be at least 3 ppm in the diet.[89] However, higher concentrations of copper (100 ppm, 200 ppm, or 500 ppm) in the diet of rabbits may favorably influence feed conversion efficiency, growth rates, and carcass dressing percentages.[90]

Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion. Autosomal recessive mutations in copper transport proteins can disable these systems, leading to Wilson's disease with copper accumulation and cirrhosis of the liver in persons who have inherited two defective genes.[77]

See also

References

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Notes

Pourbaix diagrams for copper
Copper in water pourbiax diagram.png
Copper in sulphide media pourbiax diagram.png
Copper in 10M ammonia pourbiax diagram.png
Copper in chloride media more copper pourbiax.png
in pure water, or acidic or alkali conditions. Copper in neutral water is more noble than hydrogen. in water containing sulfide in 10 M ammonia solution in a chloride solution

Further reading

External links


Translations:

Copper

Top

Dansk (Danish)
1.
n. - kobber, kobbermønt, gruekedel, plettet ildfugl
v. tr. - forkobre

idioms:

  • copper beech    blodbøg

2.
n. - [sl] politibetjent, strisser

Nederlands (Dutch)
(rood)koper, (mv) kopergeld, koperkleurig, ketel, koperen, politieagent, vuurvlinder, verkoperen

Français (French)
1.
n. - (Chim) cuivre, couleur cuivre, (GB) petite monnaie, (GB, Hist) lessiveuse
v. tr. - enduire, couvrir, ou protéger de cuivre

idioms:

  • copper beech    hêtre pourpre

2.
n. - agent de police, flic (fam)

Deutsch (German)
1.
n. - Kupfer, Kupfermünze, Kupferkessel
v. - verkupfern, mit Kupfer beschlagen

idioms:

  • copper beech    Blutbuche, Rotbuche

2.
n. - Polizist

Ελληνική (Greek)
n. - χαλκός (κν. μπακίρι), (καθομ.) αστυνομικός, μπάτσος
adj. - χάλκινος

idioms:

  • copper beech    κόκκινη οξιά

Italiano (Italian)
rame, poliziotto, di rame

idioms:

  • copper beech    faggio rosso

Português (Portuguese)
n. - cobre (m), moeda (f)
adj. - de cobre

idioms:

  • copper beech    tipo de árvore (f) de faia com folhas cor de cobre

Русский (Russian)
медь, полицейский, медный, бурый

idioms:

  • copper beech    красный бук

Español (Spanish)
1.
n. - cobre, de cobre
v. tr. - cubrir con cobre

idioms:

  • copper beech    haya roja

2.
n. - agente de policía, policía

Svenska (Swedish)
n. - koppar, kopparmynt, stor kopparkittel, kopparrött, snut (sl.)
adj. - koppar-, kopparröd

中文(简体)(Chinese (Simplified))
1. 铜, 铜币, 铜制品, 红铜色, 镀铜于, 覆以铜皮

idioms:

  • copper beech    紫叶欧洲山毛榉

2. 警察

中文(繁體)(Chinese (Traditional))
1.
n. - 警察

2.
n. - 銅, 銅幣, 銅製品, 紅銅色
v. tr. - 鍍銅於, 覆以銅皮

idioms:

  • copper beech    紫葉歐洲山毛櫸

한국어 (Korean)
1.
n. - 구리, 동전, 취사용 보일러
v. tr. - 구리로 싸다, ~에 반대하여 돈을 걸다

2.
n. - 순경, 밀고자, 감형

日本語 (Japanese)
n. - 銅, 銅貨, 銅製品
adj. - 銅製の, 赤銅色の, 銅の

idioms:

  • copper beech    ヨーロッパブナ

العربيه (Arabic)
‏(الاسم) نحاس, , شرطي (صفه) نحاسي اللون, نحاسي‏

עברית (Hebrew)
n. - ‮נחושת, מטבע, פרפר שכנפיו כצבע הנחושת‬
v. tr. - ‮ציפה בנחושת‬
n. - ‮דוד-הרתחה, שוטר‬


 
 

 

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