Copper

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

• 1 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.
• 2 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.

• 3 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.
• 4 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.
• 5 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.

• 6 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.
• 7 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.

• 8 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.
• 9 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.
• 10 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

• 11 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.

—Chris Cavette

Copper

Description

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.

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.

General use

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.

It was discovered in 2001 that vegetarian diets generally contain more copper, but that the absorption efficiency was lower for lactoovo vegetarians than for nonvegetarians. The study also showed that the increased amounts of copper in the vegetarian diets allow for greater copper content.

Besides dietary causes, certain diseases or conditions may reduce copper absorption, transport or increase its requirements, resulting in abnormally low copper blood levels. Increased copper intake through diet or supplementation may be necessary in the following conditions:

• premature infants fed only cow's milk
• pregnant women
• malnutrition
• celiac disease, sprue, cystic fibrosis, or short-bowel syndrome (these diseases cause poor absorption of dietary copper)

• kidney disease
• high consumption of zinc or iron (these minerals interfere with copper absorption)
• highly processed foods (copper is stripped away during food processing)
• Menkes syndrome (copper deficiency is caused by genetic defects of copper transport; Menkes syndrome patients cannot use copper supplied by the diet efficiently)

Symptoms of copper deficiency include:

• anemia
• malnourished infants
• prominently dilated veins
• pale hair or skin
• poorly formed bones
• nervous system disorders
• high cholesterol levels
• heart disease
• loss of taste
• increased susceptibility to infections
• infertility
• birth defects

Exceeding the daily requirement is dangerous, however, because copper toxicity commonly occurs. Copper toxicity is a very serious medical problem. Acute toxicity due to ingestion of too much supplement, for example, may cause nausea, vomiting , abdominal pain, diarrhea, dizziness, headache , and a metallic taste in the mouth. Chronic toxicity is often caused by genetic defects of copper metabolism, such as Wilson's disease. In this disease, copper is not eliminated properly and is allowed to accumulate to toxic levels. Copper is therefore present at high concentration where it should not be, such as in the liver, the lens of the eye, kidneys, or brain.

Disease prevention

Copper is a good antioxidant. It works together with an antioxidant enzyme, superoxide dismutase (SOD), to protect cell membranes from being destroyed by free radicals. Free radicals are any molecules that are missing one electron. Because this is an unbalanced and unstable state, a radical is desperately finding ways to complete its pair. Therefore, it reacts to any nearby molecules to either steal an electron or give away the unpaired one. In the process, free radicals initiate chain reactions that destroy cell structures. Like other antioxidants , copper scavenges or cleans up these highly reactive radicals and changes them into inactive, less harmful compounds. Therefore, it can help prevent cancer . In 2001, a study reported that concentrations of copper sulfate and ascorbate may inhibit breast cancer growth. With further study, the combination may even prove useful as a chemotherapy agent for certain breast cancer patients.

Copper may also help prevent degenerative diseases or conditions such as premature aging , heart disease, autoimmune diseases, arthritis, cataracts, Alzheimer's disease , or diabetes.

Osteoporosis

Copper may play a role in preventing osteoporosis. Calcium and vitamin D have long been considered the mainstay of osteoporosis treatment and prevention. However, a recent study has shown that they can be even more effective in increasing bone density and preventing osteoporosis if they are used in combination with copper and two other trace minerals, zinc and manganese .

Rheumatoid arthritis

Copper has been a folklore remedy for rheumatoid arthritis since 1500 b.c. in ancient Egypt. Some people believe that wearing jewelry made of copper may relieve arthritic symptoms. To evaluate the effect of copper for the treatment of rheumatoid arthritis, Dr. Walker and his colleagues conducted a study of 77 arthritic patients. Patients were divided into two groups: treatment group wearing copper jewelry and placebo group wearing nothing or aluminum jewelry. In this study, patients who wore copper bracelets felt significantly better than those in the placebo group. In addition, patients in the treatment group reported recurrences of symptoms after the bracelets were removed. To explain the effects of the copper bracelets, these researchers suggested that copper contained in the bracelets was dissolved in sweat and then absorbed through the skin. They suspected that copper's effectiveness may be related to its role as an antioxidant. They also believe that copper may function as both an anti-inflammatory agent and as an antioxidant. Thus, it is possibly effective in reducing inflammatory response to such conditions as rheumatoid arthritis.

Preparations

Copper is contained in many multivitamin/mineral preparations. It is also available as a single ingredient in the form of tablets. These tablets should be swallowed whole with a cup of water, preferably with meals, to avoid stomach upset. A person may choose any of the following preparations: copper gluconate, copper sulfate, or copper citrate. However, copper gluconate may be the least irritating to the stomach.

Zinc and copper compete with each other for absorption in the gastrointestinal tract. As a result, excessive copper intake may cause zinc deficiency, and vice versa. Therefore, a person should take zinc and copper supplements together in ratios of 10:1 or 15:1.

Precautions

Those adding copper supplements to their diets should consider:

• Informing their doctors for proper instruction and monitoring of side effects. Copper toxicity due to excessive doses of copper supplements has been reported.
• Although there currently is no recommended daily allowance (RDA) established for copper, 2 mg of copper per day is considered sufficient and safe. Nausea and vomiting may occur in persons taking more than 20 mg of copper daily.
• It is not known if copper supplementation may harm a growing fetus. However, as with any drugs, pregnant or nursing women should not take copper or any other supplements or drugs without first consulting their doctors.
• In certain areas, drinking water may contain high levels of copper. Periodic checks of copper levels in drinking water may be necessary.
• Because individual antioxidants often work together as a team to defend the body against free radicals, the balance between copper, zinc, and iron must be maintained. Excessive intake of one nutrient might result in a deficiency of other minerals and decreased resistance to infections and increased risk of heart disease, diabetes, arthritis, and other diseases.

Side effects

A person should stop taking copper supplements and seek medical help immediately if having the following signs or symptoms:

• anemia
• nausea
• vomiting
• abdominal pain

Interactions

Factors that increase copper concentrations

Certain disorders have been known to increase copper levels. Persons with these conditions should not take copper supplements as they may cause copper toxicity.

• recent heart attacks
• lupus erythematosus
• cirrhosis of the liver
• schizophrenia
• leukemia and some other forms of cancer
• viral infections
• ulcerative colitis (This inflammatory bowel disease may cause accumulation of copper in the body. Excessive amount of copper may worsen many symptoms of this disease by increasing susceptibility to infections and inhibiting wound healing.)
• Wilson's disease (This disease causes accumulation of copper in the tissues. As a result, patients have liver disease, mental retardation, tremor and poor muscle coordination. They also have copper deposits in the cornea of the eye. To manage this disease, patients are put on a low-copper diet and given penicillamine, a drug that attaches itself to copper and increases its excretion.)

Resources

BOOKS

Lieberman,, Shari and Nancy Bruning. "Copper." In The Real Vitamin & Mineral Book: Using Supplements for Optimum Health Garden City Park, NY: Avery Publishing Group, 1997.

Passwater, Richard A. All About Antioxidants. Garden City Park, NY: Avery Publishing Group, 1998.

PERIODICALS

Gonzalez, M. J, et al. "Inhibition of Human Breast Carcinoma Cell Proliferation by Ascorbate and Copper."The Journal of Nutrition 131, no. 11 (November 2001): 3142S.

Hunt, Janet R., and Richard A. Vanderpool. "Apparent Copper Absorption from a Vegetarian Diet."American Journal of Clinical Nutrition 74, no. 6 (December 2001): 803–805.

Reginster, Jean-Yves, Anne Noel Taquet, and Christiane Gosset. "Therapy for Osteoporosis: Miscellaneous and Experimental Agents."Endocrinology and Metabolism Clinics (June 1998): 453–463.

Uauy, Ricardo, Manuel Olivarez, and Mauricio Gonzales. "Essentiality of Copper in Humans."American Journal of Clinical Nutrition 67 suppl (1998): 952S–959S.

OTHER

"Copper" The Merck Manual of Diagnosis and Therapy. [cited October 2002]. <http://www.merck.com>. Rosenstein, Elliot D., and Jacques R. Caldwell. "Therapies: Trace Elements in the Treatment of Rheumatic Conditions." In Rheumatic Diseases Clinics of North America. Part II. [cited May 2000]. <http://www.mdconsult.com>.

Mai Tran

Teresa G. Odle

Copper

melting point: 1,084.62°C
boiling point: 2,927°C
density: 8.96 g/cm³
most common ions: Cu⁺, Cu²⁺

Copper was first used by humans more than 10,000 years ago. A copper pendant discovered in what is now northern Iraq has been dated to about 8700 b.c.e. For nearly five millennia copper was the only metal known to humans. Early copper artifacts—first decorative, then utilitarian—were undoubtedly hammered out from "native copper," pure copper found in conjunction with copper-bearing ores in a few places around the world. By 5000 b.c.e., the dawn of metallurgy had arrived, as evidence exists of the smelting of simple copper oxide ores such as malachite and azurite.

Known worldwide copper resources are estimated at nearly 2.6 trillion kilograms (5.8 trillion pounds), of which only about 12 percent (300 billion kilograms; 804 billion pounds) has been mined throughout history. Nearly all of this mined copper is still in circulation, as copper's recycling rate is higher than that of any other engineering metal.

As a molten liquid, copper may be poured to form cake or slabs from which plate, sheet, strip, and foil are rolled; billet or logs from which tube, rod, bar, and forgings are extruded; wire rod from which wire is drawn; and ingot or bricks from which copper may be alloyed with other metals or used by foundries for casting.

There are more than 450 copper alloys , including brasses, bronzes, copper-nickels, nickel-silvers, and other specialty alloys. Copper is naturally a salmon color and may oxidize or patinate to gradually become dark brown or a greenish blue. Its alloys may range from pink to brown to gold to silver in color.

Copper is used extensively for its high thermal and electrical conductivity and corrosion resistance. In the United States, the most predominant of thousands of copper and copper alloy applications include building construction (largely sheet, tube, building wire, and hardware), 45 percent; electrical and electronic products, 26 percent; transportation equipment, 9 percent; industrial machinery and equipment, 10 percent; and consumer products, 10 percent.

see also Electrochemistry.

Ken Geremia

Internet Resources

Copper in Your Home. Available from <http://www.copper.org/copperhome/homepage.html>.

The Copper Page. Available from <http://www.copper.org/>.

The Standards & Properties for Copper and Copper Alloys. Available from <http://properties.copper.org/>.

copper mines, existing from the Bronze Age, in Schull and Derrycahon, Co. Cork, and Killarney, Co. Kerry, have been radio‐carbon dated to 1500 bc. In modern times, due to rising demand in the late 18th and 19th centuries, there were highly productive copper mines at Allihies, Co. Cork, Bunmahon, Co. Waterford, and Avoca and Ballymurtagh, Co. Wicklow. The price peaked, in the mid‐19th century, at £100 a ton, falling to a low of £90 in 1875. By 1899, due to both overseas competition and falling demand, the output for the whole of Ireland had dropped to only 533 tons annually. Production remained low until the start of the Second World War. Following the Minerals Development Act (1940), the state mining company, Minrai Teoranta, began general exploration. Post‐war copper deposits have been found at Avoca, Tynagh, Co. Galway, Gortdrum, Aherlow, Mallow, Ballyvergin, and Silvermines in Munster, and Navan, Co. Meath.

Peter Collins

copper (symbol Cu) Metallic element, one of the transition metals. Reddish copper occurs native (free or uncombined) and in several ores including cuprite (an oxide) and chalcopyrite (a sulphide). The metal is extracted by smelting and is purified by electrolysis. It is malleable, a good thermal and electrical conductor, second only to silver, and is extensively used in boilers, pipes, electrical equipment and alloys, such as brass and bronze. Copper tarnishes in air, oxidizes at high temperatures and is attacked only by oxidizing acids. Properties: at.no. 29; r.a.m. 63.546; r.d. 8.96; m.p. 1.083°C (1981°F); b.p. 2567°C (4653°F); most common isotope Cu⁶³ (69.09%).

cop·per¹ / ˈkäpər/ • n. 1. a red-brown metal, the chemical element of atomic number 29. A ductile metal, it is a very good conductor of heat and electricity and is used esp. for electrical wiring. (Symbol: Cu) 2. dated a copper coin, esp. a penny. 3. a reddish-brown color like that of copper. 4. a small, typically orange or purple butterfly (genus Lycaena, family Lycaenidae) of North America and Eurasia. Its numerous species include the American copper (L. phlaeas). • v. [tr.] cover or coat (something) with copper. cop·per² • n. inf. a police officer.

Copper river, c.300 mi (480 km) long, rising in the Wrangell Mts., SE Alaska, and flowing S through the Chugach Mts. to the Gulf of Alaska. Copper deposits near the upper river, long mined by natives, attracted the attention of Russians and later Americans, but exploration was difficult because of the river's currents and the glaciers near its mouth. The great Kennecott mine (discovered 1898; abandoned 1938) was made reachable by the building of the Copper River and Northwestern RR from Cordova, which followed the river along part of its lower valley. Today the Copper is noted for its salmon.

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 BC 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.

copper the earliest metal to be used by humans; the Copper Age is the Chalcolithic period, especially in SE Europe, when weapons were made of copper. Copper was also associated by alchemists with the planet Venus.

Recorded from Old English (in form copor, coper), the word is ultimately based on late Latin cuprum, from Latin cyprium aes ‘Cyprus metal’, so named because Cyprus was the chief source.
copper-bottomed thoroughly reliable, certain not to fail; figuratively, from earlier usage referring to the copper sheathing of the bottom of a ship.

copper (Cu) An element that is required in small amounts by plants, although high concentrations of it can be toxic. It is found bound to proteins and is involved in oxidation-reduction reactions, especially those involving molecular oxygen. The signs of copper deficiency can be very varied: leaves may become chlorotic (see CHLOROSIS) or dark green; the bark of trees may blister; shrubs may become very bushy.

copper(Cu) An element that is required in small amounts by plants, although high concentrations of it can be toxic. It is found bound to proteins and is involved in oxidation-reduction reactions, especially those involving molecular oxygen. The signs of copper deficiency can be very varied: leaves may become chlorotic (see chlorosis) or dark green; the bark of trees may blister; shrubs may become very bushy.

copper 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.

copper 1 metal of reddish colour OE.; vessel made of this XVII; copper money XVIII. OE. copor, coper, corr. to MDu. coper (Du. koper), ON. koparr (cf. MLG. kopper, OHG. kupfar (G. kupfer)) — late L. cuprum, for L. cyprium (æs) ‘(metal) of Cyprus’, so named from its most noted ancient source.

copper 2 see COP.

copper •Agrippa, chipper, clipper, dipper, equipper, flipper, gripper, hipper, kipper, nipper, Pippa, ripper, shipper, sipper, skipper, slipper, stripper, tipper, tripper, whipper, zipper •crimper, shrimper, simper, whimper, Whymper •crisper, whisper •mudskipper • caliper • Philippa •juniper • gossiper •worshipper (US worshiper) •griper, piper, sniper, swiper, viper, wiper •bagpiper • sandpiper •bopper, chopper, copper, cropper, Dopper, dropper, hopper, improper, Joppa, poppa, popper, proper, shopper, stopper, swapper, topper, whopper •stomper • prosper • bebopper •teenybopper • grasshopper •clodhopper • sharecropper •name-dropper • eavesdropper •window-shopper • doorstopper •show-stopper •gawper, pauper, torpor, warper