Copper(lat. cuprum), cu, chemical element of group I of the periodic system of Mendeleev; atomic number 29, atomic mass 63.546; soft, malleable red metal. Natural metal consists of a mixture of two stable isotopes - 63 cu (69.1%) and 65 cu (30.9%).
Historical reference. M. is one of the metals known since ancient times. Man's early acquaintance with M. was facilitated by the fact that it occurs in nature in a free state in the form of nuggets, which sometimes reach significant sizes. Metal and its alloys played a major role in the development of material culture. Due to the easy reduceability of oxides and carbonates, metal was apparently the first metal that man learned to reduce from oxygen compounds contained in ores. The Latin name M. comes from the name of the island of Cyprus, where the ancient Greeks mined copper ore. In ancient times, to process rock, it was heated over a fire and quickly cooled, and the rock cracked. Already under these conditions, restoration processes were possible. Subsequently, restoration was carried out in fires with a large amount of coal and with the injection of air through pipes and bellows. The fires were surrounded by walls that were gradually raised, which led to the creation of a shaft furnace. Later, reduction methods gave way to oxidative smelting of sulfide copper ores to produce intermediate products—matte (an alloy of sulfides), in which metal is concentrated, and slag (an alloy of oxides).
Distribution in nature. The average content of metal in the earth's crust (clarke) is 4.7 10 -3% (by mass); in the lower part of the earth's crust, composed of basic rocks, there is more of it (1 10 -2%) than in the upper (2 10 -3%), where granites and other acidic igneous rocks predominate. M. migrates vigorously both in the hot waters of the depths and in the cold solutions of the biosphere; Hydrogen sulfide precipitates various mineral sulfides from natural waters, which are of great industrial importance. Among the numerous minerals of minerals, sulfides, phosphates, sulfates, and chlorides predominate; native minerals, carbonates, and oxides are also known.
M. is an important element of life; it is involved in many physiological processes. The average content of M in living matter is 2 × 10 -4%, organisms known to be concentrators of M. In taiga and other humid climate landscapes, M is relatively easily leached from acidic soils; here in some places there is a deficiency of M and associated diseases of plants and animals (especially on sand and peat bogs). In steppes and deserts (with weakly alkaline solutions characteristic of them), M. is inactive; In areas of mineral deposits, there is an excess of it in soils and plants, causing domestic animals to get sick.
There is very little M in river water, 1·10 -7%. The moss brought into the ocean by runoff relatively quickly turns into marine silt. Therefore, clays and shales are somewhat enriched in M (5.7 × 10 -3%), and sea water is sharply undersaturated with M (3 × 10 -7%).
In the seas of past geological epochs, in places there was a significant accumulation of minerals in silts, which led to the formation of deposits (for example, Mansfeld in the German Democratic Republic). Migrates vigorously in the underground waters of the biosphere; the accumulation of M ores in sandstones is associated with these processes.
Physical and chemical properties. The color of M. is red, pink when broken, and greenish-blue when translucent in thin layers. The metal has a face-centered cubic lattice with the parameter A= 3.6074 å; density 8.96 g/cm 3(20 °C). Atomic radius 1.28 å; ionic radii cu + 0.98 å; cu 2+ 0.80 å; t pl. 1083 °C; t kip. 2600 °C; specific heat capacity (at 20 °C) 385.48 j/(kg K) , that is 0.092 feces/(G ·°C). The most important and widely used properties of M.: high thermal conductivity - at 20 °C 394.279 Tue/(m K) , that is 0.941 feces/(cm · sec ·°C); low electrical resistance - at 20 °C 1.68 10 -8 ohm m. Thermal coefficient of linear expansion is 17.0 · 10 -6. The vapor pressure above M. is negligible, pressure 133.322 n/m 2(that is 1 mmHg Art.) is achieved only at 1628 °C. M. is diamagnetic; atomic magnetic susceptibility 5.27 10 -6. Brinell hardness 350 Mn/m 2(that is 35 kgf/mm 2); tensile strength 220 Mn/m 2(that is 22 kgf/mm 2); relative elongation 60%, elastic modulus 132 10 3 Mn/m 2(that is, 13.2 10 3 kgf/mm 2). By hardening, the tensile strength can be increased to 400-450 Mn/m 2, while the elongation decreases to 2%, and the electrical conductivity decreases by 1-3%. Annealing of hardened metal should be carried out at 600-700 °C. Small impurities bi (thousandths of %) and pb (hundredths of %) make M. red-brittle, and the s impurity causes brittleness in the cold.
In terms of chemical properties, M. occupies an intermediate position between the elements of the first triad of group VIII and the alkali elements of group I of the periodic system. M, like fe, Co, ni, is prone to complex formation, gives colored compounds, insoluble sulfides, etc. The similarity with alkali metals is insignificant. Thus, M forms a number of monovalent compounds, but the 2-valent state is more typical for it. Salts of monovalent magnesium are practically insoluble in water and are easily oxidized to compounds of 2-valent magnesium; divalent salts, on the contrary, are highly soluble in water and are completely dissociated in dilute solutions. Hydrated Cu 2+ ions are blue. Compounds in which M is 3-valent are also known. Thus, by the action of sodium peroxide on a solution of sodium cuprite na 2 cuo 2, the oxide cu 2 o 3 is obtained - a red powder that begins to release oxygen already at 100 ° C. cu 2 o 3 is a strong oxidizing agent (for example, it releases chlorine from hydrochloric acid).
M.'s chemical activity is low. The compact metal does not interact with dry air and oxygen at temperatures below 185 °C. In the presence of moisture and co2, a green film of basic carbonate forms on the surface of metal. When metal is heated in air, surface oxidation occurs; below 375 °C, cuo is formed, and in the range of 375-1100 °C, with incomplete oxidation of metal, a two-layer scale is formed, in the surface layer of which there is cuo, and in the inner layer - cu 2 o. Wet chlorine interacts with M. already at normal temperature, forming chloride cucl 2, which is highly soluble in water. M easily combines with other halogens. M. shows a special affinity for sulfur and selenium; so, it burns in sulfur vapor. M. does not react with hydrogen, nitrogen, and carbon even at high temperatures. The solubility of hydrogen in solid metal is insignificant and at 400 °C it is 0.06 mg at 100 G M. Hydrogen and other flammable gases (co, ch 4), acting at high temperatures on metal ingots containing cu 2 o, reduce it to metal with the formation of co 2 and water vapor. These products, being insoluble in metal, are released from it, causing the appearance of cracks, which sharply worsens the mechanical properties of metal.
When nh 3 is passed over hot metal, cu 3 n is formed. Already at a hot temperature, M. is exposed to nitrogen oxides, namely no, n 2 o (with the formation of cu 2 o) and no 2 (with the formation of cuo). Carbides cu 2 c 2 and cuc 2 can be obtained by the action of acetylene on ammonia solutions of M salts. The normal electrode potential of M for the reaction cu 2+ + 2e ® Cu is +0.337 V, and for the reaction cu2+ + e -> Cu is +0.52 V. Therefore, iron is displaced from its salts by more electronegative elements (iron is used in industry) and does not dissolve in non-oxidizing acids. In nitric acid, M. dissolves with the formation of cu(no 3) 2 and nitrogen oxides, in a hot concentration of h 2 so 4 - with the formation of cuso 4 and so 2, in heated diluted h 2 so 4 - when air is blown through the solution. All salts of M. are poisonous.
M. in the di- and monovalent state forms numerous very stable complex compounds. Examples of complex compounds of monovalent M.: (nh 4) 2 cubr 3; k 3 cu(cn) 4 - double salt type complexes; [Сu (sc (nh 2)) 2 ]ci and others. Examples of complex compounds of 2-valent M.: cscuci 3, k 2 cucl 4 - a type of double salts. Ammonium complex compounds of M. are of great industrial importance: [Cu (nh 3) 4] so 4, [Cu (nh 3) 2] so 4.
Receipt. Copper ores are characterized by a low M content. Therefore, before smelting, finely ground ore is subjected to mechanical enrichment; in this case, valuable minerals are separated from the bulk of the waste rock; As a result, a number of commercial concentrates (for example, copper, zinc, pyrite) and tailings are obtained.
In world practice, 80% of metals are extracted from concentrates using pyrometallurgical methods based on melting the entire mass of the material. During the smelting process, due to the greater affinity of magnesium for sulfur and the greater affinity of waste rock and iron components for oxygen, magnesium is concentrated in the sulfide melt (matte), and the oxides form slag. The matte is separated from the slag by settling.
In most modern plants, smelting is carried out in reverberatory or electric furnaces. In reverberatory furnaces, the working space is elongated in the horizontal direction; hearth area 300 m 2 and more (30 m? 10 m), the heat necessary for melting is obtained by burning carbon fuel (natural gas, fuel oil, pulverized coal) in the gas space above the surface of the bath. In electric furnaces, heat is obtained by passing an electric current through molten slag (the current is supplied to the slag through graphite electrodes immersed in it).
However, both reflective and electric melting, based on external heat sources, are imperfect processes. Sulfides, which make up the bulk of copper concentrates, have a high calorific value. Therefore, smelting methods are increasingly being introduced that use the heat of combustion of sulfides (oxidizer - heated air, air enriched with oxygen, or technical oxygen). Fine, pre-dried sulfide concentrates are blown with a stream of oxygen or air into a furnace heated to a high temperature. Particles burn in suspension (oxygen-flash smelting). Sulfides can also be oxidized in the liquid state; these processes are being intensively studied in the USSR and abroad (Japan, Australia, Canada) and are becoming the main direction in the development of pyrometallurgy of sulfide copper ores.
Rich lump sulfide ores (2-3% cu) with a high sulfur content (35-42% s) are in some cases directly sent for smelting in shaft furnaces (furnaces with a vertical working space). In one of the varieties of shaft smelting (copper-sulfur smelting), fine coke is added to the charge, which reduces so 2 to elemental sulfur in the upper horizons of the furnace. Copper is also concentrated in the matte in this process.
The resulting liquid matte (mainly cu 2 s, fes) is poured into a converter - a cylindrical tank made of sheet steel, lined with magnesite bricks on the inside, equipped with a side row of tuyeres for air injection and a device for rotating around an axis. Compressed air is blown through the matte layer. The conversion of mattes occurs in two stages. First, iron sulfide is oxidized, and quartz is added to the converter to bind the iron oxides; converter slag is formed. Then copper sulfide is oxidized to form metallic metal and so 2. This rough M. is poured into molds. Ingots (and sometimes directly molten rough metal) are sent for fire refining in order to extract valuable satellites (au, ag, se, fe, bi and others) and remove harmful impurities. It is based on the greater affinity of impurity metals for oxygen than copper: fe, zn, co and partially ni and others pass into slag in the form of oxides, and sulfur (in the form of so 2) is removed with gases. After removing the slag, metal is “teased” to restore the cu 2 o dissolved in it by immersing the ends of raw birch or pine logs in liquid metal, after which it is cast into flat molds. For electrolytic refining, these ingots are suspended in a bath of cuso 4 solution acidified with h 2 so 4 . They serve as anodes. When a current is passed, the anodes dissolve, and pure metal is deposited on the cathodes—thin copper sheets, also obtained by electrolysis in special matrix baths. To separate dense, smooth deposits, surface-active additives (wood glue, thiourea, and others) are introduced into the electrolyte. The resulting cathode metal is washed with water and melted. Noble metals, se, te and other valuable satellites of metal are concentrated in the anode sludge, from which they are extracted by special processing. Nickel concentrated in the electrolyte; By removing some of the solutions for evaporation and crystallization, ni can be obtained in the form of nickel sulfate.
Along with pyrometallurgical methods, hydrometallurgical methods are also used for obtaining minerals (mainly from poor oxidized and native ores). These methods are based on the selective dissolution of copper-containing minerals, usually in weak solutions of h 2 so 4 or ammonia. From a solution, metal is either precipitated with iron or isolated by electrolysis with insoluble anodes. Combined hydroflotation methods, in which oxygen compounds of metal are dissolved in sulfuric acid solutions, and sulfides are separated by flotation, are very promising when applied to mixed ores. Autoclave hydrometallurgical processes, which take place at elevated temperatures and pressure, are also becoming widespread.
Application. The great role of metal in technology is due to a number of its valuable properties and, above all, its high electrical conductivity, plasticity, and thermal conductivity. Thanks to these properties, M. is the main material for wires; over 50% of mined metal is used in the electrical industry. All impurities reduce the electrical conductivity of metal, and therefore in electrical engineering the highest grade metal is used, containing at least 99.9% Cu. High thermal conductivity and corrosion resistance make it possible to manufacture from metal critical parts of heat exchangers, refrigerators, vacuum devices, etc. About 30-40% of metal is used in the form of various alloys, among which the most important are brass(from 0 to 50% zn) and various types bronze; tin, aluminum, lead, beryllium, etc. In addition to the needs of heavy industry, communications, and transport, a certain amount of metal (mainly in the form of salts) is consumed for the preparation of mineral pigments, control of pests and plant diseases, as microfertilizers, and catalysts oxidative processes, as well as in the leather and fur industries and in the production of artificial silk.
L. V. Vanyukov.
Copper as an artistic material is used with copper age(jewelry, sculpture, utensils, dishes). Forged and cast products made of metal and alloys are decorated with chasing, engraving, and embossing. The ease of processing of metal (due to its softness) allows craftsmen to achieve a variety of textures, careful elaboration of details, and fine modeling of the form. Products made from metal are distinguished by the beauty of their golden or reddish tones, as well as their ability to acquire shine when polished. M. is often gilded, patinated, tinted, and decorated with enamel. Since the 15th century, metal has also been used for the manufacture of printing plates.
Copper in the body. M. - necessary for plants and animals trace element. The main biochemical function of M. is participation in enzymatic reactions as an activator or as part of copper-containing enzymes. The amount of M in plants ranges from 0.0001 to 0.05% (per dry matter) and depends on the type of plant and the M content in the soil. In plants, M. is a component of enzyme oxidases and the protein plastocyanin. In optimal concentrations, M. increases the cold resistance of plants and promotes their growth and development. Among animals, the richest in M. are some invertebrates (mollusks and crustaceans in hemocyanin contains 0.15-0.26% M.). When taken with food, M. is absorbed in the intestines, binds to the blood serum protein - albumin, then is absorbed by the liver, from where it returns to the blood as part of the protein ceruloplasmin and is delivered to organs and tissues.
M. content in humans varies (per 100 G dry weight) from 5 mg in the liver up to 0.7 mg in bones, in body fluids - from 100 mcg(per 100 ml) in the blood up to 10 mcg in the cerebrospinal fluid; total M. in the adult human body is about 100 mg. M. is part of a number of enzymes (for example, tyrosinase, cytochrome oxidase) and stimulates the hematopoietic function of the bone marrow. Small doses of M. affect the metabolism of carbohydrates (decrease in blood sugar), minerals (decreased amount of phosphorus in the blood), etc. An increase in M. in the blood leads to the conversion of mineral iron compounds into organic ones, stimulates the use of iron accumulated in the liver during synthesis hemoglobin.
With a deficiency of M., cereal plants are affected by the so-called processing disease, and fruit plants are affected by exanthema; in animals, the absorption and use of iron decreases, which leads to anemia accompanied by diarrhea and exhaustion. Copper microfertilizers are used and animals are fed with M salts. M. poisoning leads to anemia, liver disease, and Wilson's disease. In humans, poisoning rarely occurs due to the subtle mechanisms of absorption and excretion of M. However, in large doses, M. causes vomiting; when M. is absorbed, general poisoning may occur (diarrhea, weakening of breathing and cardiac activity, suffocation, coma).
I. F. Gribovskaya.
In medicine, M. sulfate is used as an antiseptic and astringent in the form of eye drops for conjunctivitis and eye pencils for the treatment of trachoma. A solution of M. sulfate is also used for skin burns with phosphorus. Sometimes M. sulfate is used as an emetic. M. nitrate is used as an eye ointment for trachoma and conjunctivitis.
Lit.: Smirnov V.I., Metallurgy of copper and nickel, Sverdlovsk - M., 1950; Avetisyan Kh. K., Metallurgy of blister copper, M., 1954; Ghazaryan L. M., Pyrometallurgy of copper, M., 1960; Metallurgist's Guide to Non-Ferrous Metals, edited by N. N. Murach, 2nd ed., vol. 1, M., 1953, vol. 2, M., 1947; Levinson N. p., [Products made of non-ferrous and ferrous metal], in the book: Russian decorative art, vol. 1-3, M., 1962-65; hadaway w. s., illustrations of metal work in brass and copper mostly south Indian, madras, 1913; Wainwright g. a., the occurrence of tin and copper near bybios, “journal of Egyptian archaeology”, 1934, v. 20, pt 1, p. 29-32; bergs? e p., the gilding process and the metallurgy of copper and lead among the precolumbian Indians, kbh., 1938; Frieden E., The role of copper compounds in nature, in the book: Horizons of Biochemistry, translation from English, M., 1964; him. Biochemistry of copper, in the book: Molecules and Cells, translation from English, in. 4, M., 1969; Biological role of copper, M., 1970.
download abstract
Copper is an element of the secondary subgroup of the first group, the fourth period of the periodic table of chemical elements of D.I. Mendeleev, with atomic number 29. It is designated by the symbol Cu (lat. Cuprum).
Atomic number - 29
Atomic mass - 63.546
Density, kg/m³ - 8960
Melting point, °C - 1083
Heat capacity, kJ/(kg °C) - 0.385
Electronegativity - 1.9
Covalent radius, Å - 1.17
1st ionization potential, eV - 7.73
Copper occurs in nature both in compounds and in native form. Of industrial importance are chalcopyrite CuFeS2, also known as copper pyrite, chalcocite Cu2S and bornite Cu5FeS4. Together with them, other copper minerals are also found: covellite CuS, cuprite Cu2O, azurite Cu3(CO3)2(OH)2, malachite Cu2CO3(OH)2. Sometimes copper is found in native form; the mass of individual clusters can reach 400 tons. Copper sulfides are formed mainly in medium-temperature hydrothermal veins. Copper deposits are also often found in sedimentary rocks - cuprous sandstones and shales. The most famous deposits of this type are Udokan in the Chita region, Dzhezkazgan in Kazakhstan, the copper belt of Central Africa and Mansfeld in Germany.
Most copper ore is mined by open pit mining. The copper content in the ore ranges from 0.4 to 1.0%. Physical properties of copper
Copper is a golden-pink ductile metal; in air it quickly becomes covered with an oxide film, which gives it a characteristic intense yellowish-red hue. Copper has high thermal and electrical conductivity (it ranks second in electrical conductivity after silver). It has two stable isotopes - 63Cu and 65Cu, and several radioactive isotopes. The longest-lived of these, 64Cu, has a half-life of 12.7 hours and two decay modes with different products.
The color of Copper is red, pink when broken, and greenish-blue when translucent in thin layers. The metal has a face-centered cubic lattice with parameter a = 3.6074 Å; density 8.96 g/cm3 (20 °C). Atomic radius 1.28 Å; ionic radii of Cu+ 0.98 Å; Сu2+ 0.80 Å; tmelt 1083 °C; boiling point 2600 °C; specific heat capacity (at 20 °C) 385.48 J/(kg K), i.e. 0.092 cal/(g °C). The most important and widely used properties of Copper: high thermal conductivity - at 20 °C 394.279 W/(m K), that is, 0.941 cal/(cm sec °C); low electrical resistance - at 20 °C 1.68·10-8 ohm·m. Thermal coefficient of linear expansion is 17.0·10-6. The vapor pressure above Copper is negligible; a pressure of 133.322 n/m2 (i.e. 1 mm Hg) is achieved only at 1628 °C. Copper is diamagnetic; atomic magnetic susceptibility 5.27·10-6. The Brinell hardness of Copper is 350 Mn/m2 (i.e. 35 kgf/mm2); tensile strength 220 MN/m2 (i.e. 22 kgf/mm2); relative elongation 60%, elastic modulus 132·103 MN/m2 (i.e. 13.2·103 kgf/mm2). By hardening, the tensile strength can be increased to 400-450 Mn/m2, while the elongation is reduced to 2%, and the electrical conductivity is reduced by 1-3.
Copper(lat. Cuprum), Cu, chemical element of group I of the periodic system of Mendeleev; atomic number 29, atomic mass 63.546; soft, malleable red metal. Natural metal consists of a mixture of two stable isotopes - 63 Cu (69.1%) and 65 Cu (30.9%).
Historical reference. M. is one of the metals known since ancient times. Man's early acquaintance with M. was facilitated by the fact that it occurs in nature in a free state in the form of nuggets (see. Native copper), which sometimes reach significant sizes. Metal and its alloys played a major role in the development of material culture (see. Bronze Age). Due to the easy reduceability of oxides and carbonates, metal was apparently the first metal that man learned to reduce from oxygen compounds contained in ores. The Latin name M. comes from the name of the island of Cyprus, where the ancient Greeks mined copper ore. In ancient times, to process rock, it was heated over a fire and quickly cooled, and the rock cracked. Already under these conditions, restoration processes were possible. Subsequently, restoration was carried out in fires with a large amount of coal and with the injection of air through pipes and bellows. The fires were surrounded by walls that were gradually raised, which led to the creation of a shaft furnace. Later, reduction methods gave way to oxidative smelting of sulfide copper ores to produce intermediate products—matte (an alloy of sulfides), in which metal is concentrated, and slag (an alloy of oxides).
Distribution in nature. The average content of metal in the earth's crust (clarke) is 4.7 10 -3% (by mass); in the lower part of the earth's crust, composed of basic rocks, there is more of it (1 10 -2%) than in the upper part (2 %). 10 -3%), where granites and other acidic igneous rocks predominate. M. migrates vigorously both in the hot waters of the depths and in the cold solutions of the biosphere; Hydrogen sulfide precipitates various mineral sulfides from natural waters, which are of great industrial importance. Among the numerous minerals of minerals, sulfides, phosphates, sulfates, and chlorides predominate; native minerals, carbonates, and oxides are also known.
M. is an important element of life; it is involved in many physiological processes. The average content of M in living matter is 2·10 -4%; organisms are known to be concentrators of M. In taiga and other landscapes of humid climates, M is relatively easily leached from acidic soils; here in some places there is a deficiency of M and associated diseases of plants and animals (especially on sand and peat bogs). In steppes and deserts (with weakly alkaline solutions characteristic of them), M. is inactive; In areas of mineral deposits, there is an excess of it in soils and plants, causing domestic animals to get sick.
There is very little M in river water, 1·10 -7%. The moss brought into the ocean by runoff relatively quickly turns into marine silt. Therefore, clays and shales are somewhat enriched in M (5.7·10 -3%), and sea water is sharply undersaturated with M (3·10 -7%).
In the seas of past geological epochs, in places there was a significant accumulation of minerals in silts, which led to the formation of deposits (for example, Mansfeld in the German Democratic Republic). Migrates vigorously in the underground waters of the biosphere; the accumulation of M ores in sandstones is associated with these processes.
Physical and chemical properties. The color of M. is red, pink when broken, and greenish-blue when translucent in thin layers. The metal has a face-centered cubic lattice with the parameter A= 3.6074 ; density 8.96 g/cm 3(20°C). Atomic radius 1.28; ionic radii Cu + 0.98; Cu 2+ 0.80; t pl. 1083 °C; t kip. 2600 °C; specific heat capacity (at 20 °C) 385.48 j/(kg K), that is 0.092 feces/(G·°C). The most important and widely used properties of M.: high thermal conductivity - at 20 °C 394.279 Tue/(m K), that is 0.941 feces/(cm·sec·°C); low electrical resistance - at 20 °C 1.68 10 -8 ohm m. Thermal coefficient of linear expansion is 17.0·10 -6. The vapor pressure above M. is negligible, pressure 133.322 n/m 2(that is 1 mmHg Art.) is achieved only at 1628 °C. M. is diamagnetic; atomic magnetic susceptibility 5.27·10 -6. Brinell hardness 350 Mn/m 2(that is 35 kgf/mm 2); tensile strength 220 Mn/m 2(that is 22 kgf/mm 2); relative elongation 60%, elastic modulus 132 10 3 Mn/m 2(that is, 13.2 10 3 kgf/mm 2). By hardening, the tensile strength can be increased to 400-450 Mn/m 2, while the elongation decreases to 2%, and the electrical conductivity decreases by 1-3%. Annealing of cold-worked metal should be carried out at 600-700 °C. Small impurities of Bi (thousandths of %) and Pb (hundredths of %) make M. red-brittle, and the admixture of S causes brittleness in the cold.
In terms of chemical properties, metal occupies an intermediate position between the elements of the first triad of group VIII and the alkali elements of group I of the periodic system. M, like Fe, Co, and Ni, is prone to complex formation and produces colored compounds, insoluble sulfides, etc. The similarity with alkali metals is insignificant. Thus, M forms a number of monovalent compounds, but the 2-valent state is more typical for it. Salts of monovalent magnesium are practically insoluble in water and are easily oxidized to compounds of 2-valent magnesium; divalent salts, on the contrary, are highly soluble in water and are completely dissociated in dilute solutions. Hydrated Cu 2+ ions are blue. Compounds in which M is 3-valent are also known. Thus, by the action of sodium peroxide on a solution of sodium cuprite Na 2 CuO 2, the oxide Cu 2 O 3 is obtained - a red powder that begins to release oxygen already at 100 ° C. Cu 2 O 3 is a strong oxidizing agent (for example, it releases chlorine from hydrochloric acid).
M.'s chemical activity is low. Compact metal does not interact with dry air and oxygen at temperatures below 185 °C. In the presence of moisture and CO 2, a green film of basic carbonate forms on the surface of metal. When metal is heated in air, surface oxidation occurs; below 375 °C, CuO is formed, and in the range of 375-1100 °C, with incomplete oxidation of metal, two-layer scale is formed, in the surface layer of which there is CuO, and in the inner layer - Cu 2 O (see. Copper oxides). Wet chlorine interacts with minerals already at normal temperatures, forming CuCl 2 chloride, which is highly soluble in water. M easily combines with other halogens (see. Copper halides). M. shows a special affinity for sulfur and selenium; so, it burns in sulfur vapor (see. Copper sulfides). M. does not react with hydrogen, nitrogen, and carbon even at high temperatures. The solubility of hydrogen in solid metal is insignificant and at 400 °C it is 0.06 mg at 100 G M. Hydrogen and other flammable gases (CO, CH 4), acting at high temperatures on metal ingots containing Cu 2 O, reduce it to metal with the formation of CO 2 and water vapor. These products, being insoluble in metal, are released from it, causing the appearance of cracks, which sharply worsens the mechanical properties of metal.
When NH 3 is passed over hot metal, Cu 3 N is formed. Already at a hot temperature, metal is exposed to nitrogen oxides, namely NO, N 2 O (with the formation of Cu 2 O) and NO 2 (with the formation of CuO). Carbides Cu 2 C 2 and CuC 2 can be obtained by the action of acetylene on ammonia solutions of M salts. The normal electrode potential of M for the reaction Cu 2+ + 2e Cu is +0.337 V, and for the reaction Cu + + e Cu is +0.52 V. Therefore, iron is displaced from its salts by more electronegative elements (iron is used in industry) and does not dissolve in non-oxidizing acids. In nitric acid, M. dissolves with the formation of Cu(NO 3) 2 and nitrogen oxides, in a hot concentration of H 2 SO 4 - with the formation of CuSO 4 and SO 2, in heated diluted H 2 SO 4 - when air is blown through the solution. All salts of M. are poisonous (see. Copper carbonates, Copper nitrate, Copper sulfate).
M. in the di- and monovalent state forms numerous very stable complex compounds. Examples of complex compounds of monovalent metal: (NH 4) 2 CuBr 3; K 3 Cu(CN) 4 - double salt type complexes; [Cu (SC (NH 2)) 2 ]CI and others. Examples of complex compounds of 2-valent metal: CsCuCI 3, K 2 CuCl 4 - a type of double salts. Ammonia complex compounds of M are of great industrial importance: [Cu (NH 3) 4 ] SO 4 , [Cu (NH 3) 2 ] SO 4 .
Receipt. Copper ores are characterized by a low M content. Therefore, before smelting, finely ground ore is subjected to mechanical enrichment; in this case, valuable minerals are separated from the bulk of the waste rock; As a result, a number of commercial concentrates (for example, copper, zinc, pyrite) and tailings are obtained.
In world practice, 80% of metals are extracted from concentrates using pyrometallurgical methods based on melting the entire mass of the material. During the smelting process, due to the greater affinity of magnesium for sulfur and the greater affinity of waste rock and iron components for oxygen, magnesium is concentrated in the sulfide melt (matte), and the oxides form slag. The matte is separated from the slag by settling.
In most modern plants, smelting is carried out in reverberatory or electric furnaces. In reverberatory furnaces, the working space is elongated in the horizontal direction; hearth area 300 m 2 and more (30 m 10 m), the heat necessary for melting is obtained by burning carbon fuel (natural gas, fuel oil, pulverized coal) in the gas space above the surface of the bath. In electric furnaces, heat is obtained by passing an electric current through molten slag (the current is supplied to the slag through graphite electrodes immersed in it).
However, both reflective and electric melting, based on external heat sources, are imperfect processes. Sulfides, which make up the bulk of copper concentrates, have a high calorific value. Therefore, smelting methods are increasingly being introduced that use the heat of combustion of sulfides (oxidizer - heated air, air enriched with oxygen, or technical oxygen). Fine, pre-dried sulfide concentrates are blown with a stream of oxygen or air into a furnace heated to a high temperature. Particles burn in suspension (oxygen-flash smelting). Sulfides can also be oxidized in the liquid state; these processes are being intensively studied in the USSR and abroad (Japan, Australia, Canada) and are becoming the main direction in the development of pyrometallurgy of sulfide copper ores.
Rich lump sulfide ores (2-3% Cu) with a high sulfur content (35-42% S) are in some cases directly sent for smelting in shaft furnaces (furnaces with a vertical working space). In one of the varieties of shaft smelting (copper-sulfur smelting), fine coke is added to the charge, which reduces SO 2 to elemental sulfur in the upper horizons of the furnace. Copper is also concentrated in the matte in this process.
The resulting liquid matte (mainly Cu 2 S, FeS) is poured into a converter - a cylindrical tank made of sheet steel, lined with magnesite bricks on the inside, equipped with a side row of tuyeres for air injection and a device for rotating around an axis. Compressed air is blown through the matte layer. The conversion of mattes occurs in two stages. First, iron sulfide is oxidized, and quartz is added to the converter to bind the iron oxides; converter slag is formed. Then copper sulfide is oxidized to form metallic metal and SO 2 . This rough M. is poured into molds. Ingots (and sometimes directly molten rough metal) are sent for fire refining in order to extract valuable satellites (Au, Ag, Se, Fe, Bi, and others) and remove harmful impurities. It is based on the greater affinity of impurity metals for oxygen than copper: Fe, Zn, Co and partially Ni and others pass into slag in the form of oxides, and sulfur (in the form of SO 2) is removed with gases. After removing the slag, metal is “teased” to restore the Cu 2 O dissolved in it by immersing the ends of raw birch or pine logs in liquid metal, after which it is cast into flat molds. For electrolytic refining, these ingots are suspended in a bath of CuSO 4 solution acidified with H 2 SO 4 . They serve as anodes. When a current is passed, the anodes dissolve, and pure metal is deposited on the cathodes—thin copper sheets, also obtained by electrolysis in special matrix baths. To separate dense, smooth deposits, surface-active additives (wood glue, thiourea, and others) are introduced into the electrolyte. The resulting cathode metal is washed with water and melted. Noble metals, Se, Te and other valuable satellites of metal are concentrated in the anode sludge, from which they are extracted by special processing. Nickel concentrated in the electrolyte; By removing some of the solutions for evaporation and crystallization, Ni can be obtained in the form of nickel sulfate.
Along with pyrometallurgical methods, hydrometallurgical methods are also used for obtaining minerals (mainly from poor oxidized and native ores). These methods are based on the selective dissolution of copper-containing minerals, usually in weak solutions of H 2 SO 4 or ammonia. From a solution, metal is either precipitated with iron or isolated by electrolysis with insoluble anodes. Combined hydroflotation methods, in which oxygen compounds of metal are dissolved in sulfuric acid solutions, and sulfides are separated by flotation, are very promising when applied to mixed ores. Autoclave hydrometallurgical processes, which take place at elevated temperatures and pressure, are also becoming widespread.
Application. The great role of metal in technology is due to a number of its valuable properties and, above all, its high electrical conductivity, plasticity, and thermal conductivity. Thanks to these properties, M. is the main material for wires; over 50% of mined metal is used in the electrical industry. All impurities reduce the electrical conductivity of metal, and therefore high-grade metal containing at least 99.9% Cu is used in electrical engineering. High thermal conductivity and corrosion resistance make it possible to manufacture from metal critical parts of heat exchangers, refrigerators, vacuum devices, etc. About 30-40% of metal is used in the form of various alloys, among which the most important are brass(from 0 to 50% Zn) and various types bronze; tin, aluminum, lead, beryllium, etc. (for more details, see Copper alloys). In addition to the needs of heavy industry, communications, and transport, a certain amount of metal (mainly in the form of salts) is consumed for the preparation of mineral pigments, control of pests and plant diseases, as microfertilizers, catalysts for oxidation processes, as well as in the leather and fur industries and in production of artificial silk.
L. V. Vanyukov.
Copper as an artistic material is used with copper age(jewelry, sculpture, utensils, dishes). Forged and cast products from metal and alloys (see. Bronze) are decorated with chasing, engraving and embossing. The ease of processing of metal (due to its softness) allows craftsmen to achieve a variety of textures, careful elaboration of details, and fine modeling of the form. Products made from metal are distinguished by the beauty of their golden or reddish tones, as well as their ability to acquire shine when polished. M. are often gilded and patinated (see. Patina), tinted, decorated with enamel. Since the 15th century, metal has also been used for the manufacture of printing plates (see. Engraving).
Copper in the body. M. - necessary for plants and animals trace element. The main biochemical function of M. is participation in enzymatic reactions as an activator or as part of copper-containing enzymes. The amount of M in plants ranges from 0.0001 to 0.05% (per dry matter) and depends on the type of plant and the M content in the soil. In plants, M. is a component of enzyme oxidases and the protein plastocyanin. In optimal concentrations, M. increases the cold resistance of plants and promotes their growth and development. Among animals, the richest in M. are some invertebrates (mollusks and crustaceans in hemocyanin contains 0.15-0.26% M.). When taken with food, M. is absorbed in the intestines, binds to the blood serum protein - albumin, then is absorbed by the liver, from where it returns to the blood as part of the protein ceruloplasmin and is delivered to organs and tissues.
M. content in humans varies (per 100 G dry weight) from 5 mg in the liver up to 0.7 mg in bones, in body fluids - from 100 mcg(per 100 ml) in the blood up to 10 mcg in the cerebrospinal fluid; total M. in the adult human body is about 100 mg. M. is part of a number of enzymes (for example, tyrosinase, cytochrome oxidase) and stimulates the hematopoietic function of the bone marrow. Small doses of M. affect the metabolism of carbohydrates (decrease in blood sugar), minerals (decreased amount of phosphorus in the blood), etc. An increase in M. in the blood leads to the conversion of mineral iron compounds into organic ones, stimulates the use of iron accumulated in the liver during synthesis hemoglobin.
With a deficiency of M., cereal plants are affected by the so-called processing disease, and fruit plants are affected by exanthema; in animals, the absorption and use of iron decreases, which leads to anemia accompanied by diarrhea and exhaustion. Copper microfertilizers and feeding animals with copper salts are used (see. Microfertilizers). M. poisoning leads to anemia, liver disease, and Wilson's disease. In humans, poisoning rarely occurs due to the subtle mechanisms of absorption and excretion of M. However, in large doses, M. causes vomiting; when M. is absorbed, general poisoning may occur (diarrhea, weakening of breathing and cardiac activity, suffocation, coma).
I. F. Gribovskaya.
In medicine, M. sulfate is used as an antiseptic and astringent in the form of eye drops for conjunctivitis and eye pencils for the treatment of trachoma. A solution of M. sulfate is also used for skin burns with phosphorus. Sometimes M. sulfate is used as an emetic. M. nitrate is used as an eye ointment for trachoma and conjunctivitis.
Lit.: Smirnov V.I., Metallurgy of copper and nickel, Sverdlovsk - M., 1950; Avetisyan Kh. K., Metallurgy of blister copper, M., 1954; Ghazaryan L. M., Pyrometallurgy of copper, M., 1960; Metallurgist's Guide to Non-Ferrous Metals, edited by N. N. Murach, 2nd ed., vol. 1, M., 1953, vol. 2, M., 1947; Levinson N.P., [Products made of non-ferrous and ferrous metal], in the book: Russian decorative art, vol. 1-3, M., 1962-65; Hadaway W. S., Illustrations of metal work in brass and copper mostly South Indian, Madras, 1913; Wainwright G. A., The occurrence of tin and copper near bybios, "Journal of Egyptian archaeology", 1934, v. 20, pt 1, p. 29-32; BergsÆe P., The gilding process and the metallurgy of copper and lead among the precolumbian Indians, Kbh., 1938; Frieden E., The role of copper compounds in nature, in the book: Horizons of Biochemistry, translation from English, M., 1964; him. Biochemistry of copper, in the book: Molecules and Cells, translation from English, in. 4, M., 1969; Biological role of copper, M., 1970.
Copper- an element of a secondary subgroup of the first group, the fourth period of the periodic system of chemical elements of D.I. Mendeleev, with atomic number 29. Denoted by the symbol Cu (lat. Cuprum).
Copper occurs in nature both in compounds and in native form. Of industrial importance are chalcopyrite CuFeS2, also known as copper pyrite, chalcocite Cu2S and bornite Cu5FeS4. Together with them, other copper minerals are also found: covellite CuS, cuprite Cu2O, azurite Cu3(CO3)2(OH)2, malachite Cu2CO3(OH)2. Sometimes copper is found in native form; the mass of individual clusters can reach 400 tons. Copper sulfides are formed mainly in medium-temperature hydrothermal veins. Copper deposits are also often found in sedimentary rocks - cuprous sandstones and shales. The most famous deposits of this type are Udokan in the Chita region, Dzhezkazgan in Kazakhstan, the copper belt of Central Africa and Mansfeld in Germany.
Most copper ore is mined by open pit mining. The copper content in the ore ranges from 0.4 to 1.0%. Physical properties of copper
Copper is a golden-pink ductile metal; in air it quickly becomes covered with an oxide film, which gives it a characteristic intense yellowish-red hue. Copper has high thermal and electrical conductivity (it ranks second in electrical conductivity after silver). It has two stable isotopes - 63Cu and 65Cu, and several radioactive isotopes. The longest-lived of these, 64Cu, has a half-life of 12.7 hours and two decay modes with different products.
The color of Copper is red, pink when broken, and greenish-blue when translucent in thin layers. The metal has a face-centered cubic lattice with parameter a = 3.6074 Å; density 8.96 g/cm3 (20 °C). Atomic radius 1.28 Å; ionic radii of Cu+ 0.98 Å; Сu2+ 0.80 Å; tmelt 1083 °C; boiling point 2600 °C; specific heat capacity (at 20 °C) 385.48 J/(kg K), i.e. 0.092 cal/(g °C). The most important and widely used properties of Copper: high thermal conductivity - at 20 °C 394.279 W/(m K), that is, 0.941 cal/(cm sec °C); low electrical resistance - at 20 °C 1.68·10-8 ohm·m. Thermal coefficient of linear expansion is 17.0·10-6. The vapor pressure above Copper is negligible; a pressure of 133.322 n/m2 (i.e. 1 mm Hg) is achieved only at 1628 °C. Copper is diamagnetic; atomic magnetic susceptibility 5.27·10-6. The Brinell hardness of Copper is 350 Mn/m2 (i.e. 35 kgf/mm2); tensile strength 220 MN/m2 (i.e. 22 kgf/mm2); relative elongation 60%, elastic modulus 132·103 MN/m2 (i.e. 13.2·103 kgf/mm2). By hardening, the tensile strength can be increased to 400-450 Mn/m2, while the elongation is reduced to 2%, and the electrical conductivity is reduced by 1-3.
Copper is a ductile golden-pink metal with a characteristic metallic luster. In the periodic system of D.I. Mendeleev, this chemical element is designated as Cu (Cuprum) and is located under serial number 29 in group I (side subgroup), in the 4th period.
The Latin name Cuprum comes from the name of the island of Cyprus. There are known facts that in Cyprus back in the 3rd century BC there were copper mines and local craftsmen smelted copper. You can buy copper from the company « ».
According to historians, society has been familiar with copper for about nine thousand years. The most ancient copper products were found during archaeological excavations in the area of modern Turkey. Archaeologists have discovered small copper beads and plates used to decorate clothing. The finds date back to the turn of the 8th-7th millennium BC. In ancient times, copper was used to make jewelry, expensive dishes, and various tools with thin blades.
A great achievement of ancient metallurgists can be called the production of an alloy with a copper base - bronze.
Basic properties of copper
1. Physical properties.
In air, copper acquires a bright yellowish-red hue due to the formation of an oxide film. Thin plates have a greenish-blue color when examined through them. In its pure form, copper is quite soft, malleable and easily rolled and drawn. Impurities can increase its hardness.
The high electrical conductivity of copper can be called the main property that determines its predominant use. Copper also has very high thermal conductivity. Impurities such as iron, phosphorus, tin, antimony and arsenic affect the basic properties and reduce electrical and thermal conductivity. According to these indicators, copper is second only to silver.
Copper has high densities, melting points and boiling points. An important property is also good resistance to corrosion. For example, at high humidity, iron oxidizes much faster.
Copper lends itself well to processing: rolled into copper sheet and copper rod, drawn into copper wire with a thickness brought to thousandths of a millimeter. This metal is diamagnetic, that is, it is magnetized against the direction of the external magnetic field.
Copper is a relatively low-active metal. Under normal conditions in dry air, its oxidation does not occur. It reacts easily with halogens, selenium and sulfur. Acids without oxidizing properties have no effect on copper. There are no chemical reactions with hydrogen, carbon and nitrogen. In humid air, oxidation occurs to form copper (II) carbonate - the top layer of platinum.
Copper is amphoteric, meaning it forms cations and anions in the earth's crust. Depending on the conditions, copper compounds exhibit acidic or basic properties.
Methods for obtaining copper
In nature, copper exists in compounds and in the form of nuggets. The compounds are represented by oxides, bicarbonates, sulfur and carbon dioxide complexes, as well as sulfide ores. The most common ores are copper pyrite and copper luster. The copper content in them is 1-2%. 90% of primary copper is mined using the pyrometallurgical method and 10% using the hydrometallurgical method.
1.
The pyrometallurgical method includes the following processes: enrichment and roasting, smelting for matte, purging in a converter, electrolytic refining.
Copper ores are enriched by flotation and oxidative roasting. The essence of the flotation method is as follows: copper particles suspended in an aqueous medium adhere to the surface of air bubbles and rise to the surface. The method allows you to obtain copper powder concentrate, which contains 10-35% copper.
Copper ores and concentrates with a significant sulfur content are subject to oxidative roasting. When heated in the presence of oxygen, sulfides are oxidized, and the amount of sulfur is reduced by almost half. Poor concentrates containing 8-25% copper are roasted. Rich concentrates containing 25-35% copper are melted without resorting to roasting.
The next stage of the pyrometallurgical method for producing copper is smelting for matte. If lump copper ore with a large amount of sulfur is used as a raw material, then smelting is carried out in shaft furnaces. And for powdered flotation concentrate, reverberatory furnaces are used. Melting occurs at a temperature of 1450 °C.
In horizontal converters with side blowing, the copper matte is blown with compressed air in order for the oxidation of sulfides and ferrum to occur. Next, the resulting oxides are converted into slag, and sulfur into oxide. The converter produces blister copper, which contains 98.4-99.4% copper, iron, sulfur, as well as small amounts of nickel, tin, silver and gold.
Blister copper is subject to fire and then electrolytic refining. Impurities are removed with gases and converted into slag. As a result of fire refining, copper is formed with a purity of up to 99.5%. And after electrolytic refining, the purity is 99.95%.
2. The hydrometallurgical method involves leaching copper with a weak solution of sulfuric acid, and then separating copper metal directly from the solution. This method is used for processing low-grade ores and does not allow for the associated extraction of precious metals along with copper.
Copper Applications
Due to their valuable qualities, copper and copper alloys are used in the electrical and electrical engineering industries, in radio electronics and instrument making. There are alloys of copper with metals such as zinc, tin, aluminum, nickel, titanium, silver, and gold. Less commonly used are alloys with non-metals: phosphorus, sulfur, oxygen. There are two groups of copper alloys: brass (alloys with zinc) and bronze (alloys with other elements).
Copper is highly environmentally friendly, which allows its use in the construction of residential buildings. For example, a copper roof, due to its anti-corrosion properties, can last more than a hundred years without special care or painting.
Copper in alloys with gold is used in jewelry. This alloy increases the strength of the product, increases resistance to deformation and abrasion.
Copper compounds are characterized by high biological activity. In plants, copper takes part in the synthesis of chlorophyll. Therefore, it can be seen in the composition of mineral fertilizers. A lack of copper in the human body can cause deterioration in blood composition. It is found in many food products. For example, this metal is found in milk. However, it is important to remember that excess copper compounds can cause poisoning. This is why you should not cook food in copper cookware. During boiling, large amounts of copper can leach into food. If the dishes inside are covered with a layer of tin, then there is no danger of poisoning.
In medicine, copper is used as an antiseptic and astringent. It is a component of eye drops for conjunctivitis and solutions for burns.
