Copper: color, mining features, characteristics of the metal

Native copper measuring about 4 cm

Copper

- a mineral from the class of native elements. Fe, Ag, Au, As and other elements are found in natural minerals as impurities or forming solid solutions with Cu. The simple substance copper is a ductile transition metal of golden-pink color (pink in the absence of an oxide film). One of the first metals widely mastered by man due to its relative availability for extraction from ore and low melting point. It is one of the seven metals known to man since very ancient times. Copper is an essential element for all higher plants and animals.

1. Structure
2. Properties
3. Reserves and production
4. Origin
5. Application
6. Classification
7. Physical properties
8. Optical properties
9. Crystallographic properties

See also:

Gold

— structure and physical properties

Aluminum

— structure and physical properties

STRUCTURE

Crystal structure of copper

Cubic system, hexaoctahedral type of m3m symmetry, crystal structure - cubic face-centered lattice. The model is a cube of eight atoms in the corners and six atoms located in the center of the faces (6 faces). Each atom of a given crystal lattice has a coordination number of 12. Native copper occurs in the form of plates, spongy and solid masses, thread-like and wire-like aggregates, as well as crystals, complex twins, skeletal crystals and dendrites. The surface is often covered with films of “copper green” (malachite), “copper blue” (azurite), copper phosphates and other products of its secondary alteration.

Copper Cu

Chemical symbol Cu, atomic weight 63.54. Copper is a typical metal, so its atoms are connected to each other by a metallic bond. The electronic configuration of the outer and outer electron layers of copper is as follows: 3s 2 3p 6 3d 10 4s 1.

In appearance, copper is a red substance with a characteristic metallic luster. Copper is a fairly soft metal, but much harder than alkaline metals. It should be noted the high ductility of copper, which it exhibits not only in a heated state, but also in a cold state. Due to its softness and ductility, copper can be cold worked. Hence the widespread use of this metal for the manufacture of artistic products using embossing. Not only copper itself, but also all metals of this subgroup have high ductility.

PROPERTIES

Native copper crystals, Lake Superior, Kinawee County, Michigan, USA. Size 12 x 8.5 cm

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. Thin films of copper have a greenish-blue color when exposed to light.

Along with osmium, cesium and gold, copper is one of the four metals that have a distinct coloration that is different from the gray or silver of other metals. This color tint is explained by the presence of electronic transitions between the filled third and half-empty fourth atomic orbitals: the energy difference between them corresponds to the wavelength of orange light. The same mechanism is responsible for the characteristic color of gold.

Copper has high thermal and electrical conductivity (it ranks second in electrical conductivity among metals after silver). Specific electrical conductivity at 20 °C: 55.5-58 MS/m. Copper has a relatively large temperature coefficient of resistance: 0.4%/°C and is weakly dependent on temperature over a wide temperature range. Copper is diamagnetic.

There are a number of copper alloys: brass - with zinc, bronze - with tin and other elements, cupronickel - with nickel and others.

Copper is an alkali metal

Native copper measuring about 4 cm

Copper

- a mineral from the class of native elements. Fe, Ag, Au, As and other elements are found in natural minerals as impurities or forming solid solutions with Cu. The simple substance copper is a ductile transition metal of golden-pink color (pink in the absence of an oxide film). One of the first metals widely mastered by man due to its relative availability for extraction from ore and low melting point. It is one of the seven metals known to man since very ancient times. Copper is an essential element for all higher plants and animals.

See also:

RESERVES AND PRODUCTION

Copper specimen, 13.6 cm. Kinawi Peninsula, Michigan, USA

The average copper content in the earth's crust (clarke) is (4.7-5.5) 10−3% (by mass). In sea and river water the copper content is much lower: 3·10−7% and 10−7% (by weight), respectively. Most copper ore is mined by open pit mining. The copper content in the ore ranges from 0.3 to 1.0%. World reserves in 2000 were, according to experts, 954 million tons, of which 687 million tons were proven reserves; Russia accounted for 3.2% of total and 3.1% of confirmed world reserves. Thus, at the current rate of consumption, copper reserves will last approximately 60 years. Copper is obtained from copper ores and minerals. The main methods for obtaining copper are pyrometallurgy, hydrometallurgy and electrolysis. The pyrometallurgical method involves obtaining copper from sulfide ores, for example, chalcopyrite CuFeS2. The hydrometallurgical method involves dissolving copper minerals in dilute sulfuric acid or ammonia solution; From the resulting solutions, copper is replaced by metallic iron.

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.

ORIGIN

Small nugget of copper

Typically, native copper is formed in the oxidation zone of some copper sulfide deposits in association with calcite, native silver, cuprite, malachite, azurite, brochantite and other minerals. The masses of individual clusters of native copper reach 400 tons. Large industrial deposits of native copper, along with other copper-containing minerals, are formed when volcanic rocks (diabases, melaphyres) are exposed to hydrothermal solutions, volcanic vapors and gases enriched in volatile copper compounds (for example, the Lake Superior deposit, USA). Native copper is also found in sedimentary rocks, mainly in cuprous sandstones and shales. The most famous deposits of native copper are the Turin mines (Urals), Dzhezkazgan (Kazakhstan), in the USA (on the Keweenaw Peninsula, in the states of Arizona and Utah).

Copper what is it

One of the best conductors of heat and electricity, however, to use it for these purposes, copper is usually well cleaned of impurities of other metals, since even minor contaminations greatly reduce its electrical conductivity.

The chemical properties of copper and its analogues are very different from the properties of the alkali metals located in the main subgroup of group I. So, they are located in the voltage series after hydrogen. The oxidation state of copper in redox reactions is +1 or +2. Copper usually does not exhibit other oxidation states. Copper fuses quite easily with other metals to form a number of alloys, the most common of which are bronze (an alloy consisting of copper and tin) and brass (an alloy of copper and zinc).

At normal temperatures, copper gradually reacts with oxygen, carbon dioxide and air moisture, turning into basic copper carbonate. This process occurs very slowly and explains the reason why copper products become covered with a green coating over time. When calcined on a gas burner, copper becomes covered with a black coating of copper oxide CuO. Heated copper reacts quite easily with chlorine, forming copper (II) chloride, and with some other non-metals. Copper usually does not react with dilute acids, since it cannot displace hydrogen, but it reacts with dilute nitric acid without displacing hydrogen, but with the release of nitric oxide. With concentrated sulfuric and nitric acid, copper also enters into an oxidation-reduction reaction, which also occurs without displacing hydrogen. In all these reactions, copper mainly exhibits its highest valence II. Monivalent copper compounds are much more difficult to obtain.

APPLICATION

Copper bracelets

Due to its low resistivity, copper is widely used in electrical engineering for the manufacture of power cables, wires or other conductors, for example, in printed circuit wiring. Copper wires, in turn, are also used in the windings of energy-saving electric drives and power transformers. Another useful quality of copper is its high thermal conductivity. This allows it to be used in various heat removal devices and heat exchangers, which include well-known radiators for cooling, air conditioning and heating. Alloys using copper are widely used in various fields of technology, the most widespread of which are the above-mentioned bronze and brass. Both alloys are general names for a whole family of materials, which in addition to tin and zinc may include nickel, bismuth and other metals. In jewelry, alloys of copper and gold are often used to increase the resistance of products to deformation and abrasion, since pure gold is a very soft metal and is not resistant to these mechanical influences. The predicted new mass use of copper promises to be its use as bactericidal surfaces in medical institutions to reduce intra-hospital bacterial transfer: doors, handles, water stop valves, railings, bed rails, table tops - all surfaces touched by the human hand.

Copper - Cu

Copper subgroup

Let's begin our consideration of elements of side subgroups with the copper subgroup. The elements of the copper subgroup include copper Cu, silver Ag and gold Au, located in the secondary subgroup of group I. The distribution of electrons across energy levels for these elements is given in Table. 22.

The radii of the atoms of the elements of the side subgroup are much smaller than the radii of the atoms of the elements of the main subgroup, therefore the electron of the outer electron layer is very difficult to tear away from the atom. As can be seen from table. 22, these elements have a similar structure not only of the external, but also of the pre-external layer, and we have the right to expect great similarity in chemical properties from them. In table 23 shows the physical properties of metals of the copper subgroup. ■ 5. Compare the radii of atoms of alkali metals and metals of the copper subgroup of the same periods. What conclusion can be drawn? 6. Why do elements of the copper subgroup hold the electron of the outer layer more tightly than in alkali metal atoms? 7. To which group of metals according to density should the metals of the copper subgroup be classified? (See answer)

PHYSICAL PROPERTIES

Features of popular copper alloys

Alloy M1 is manufactured in accordance with GOST 859-2014, is a highly plastic and well-processed metal, and has the highest copper content (99.9%). Additional elements include zinc, nickel, phosphorus, iron, arsenic, oxygen, tin, bismuth (total no more than 0.1%). The electrical resistivity is 0.018 μOhm. The alloy can be of two types - hard (M1t) and soft (M1m), they differ in strength and fluidity. Rolled metal is in demand in the automotive and aircraft industries, in the creation of current conductors, cryogenic equipment, wire and rods.

Alloy M2 has a lower copper ratio in the composition (99.7%). The remaining 0.3% comes from nickel, iron, antimony, oxygen, tin, lead, sulfur, and arsenic. This grade is ductile and does not rust, is excellent in pressure processing and is used for the manufacture of copper-based alloys and refrigeration parts.

Alloy M3 is technical copper; it contains the smallest percentage of metal among those presented (99.5%). The same elements as in M2 are used as alloying components, only in a larger proportion (up to 0.5%), which makes this alloy the most affordable. Optimally suitable for metal products that are sold by rolling methods, as well as cast alloys.

CRYSTALLOGRAPHIC PROPERTIES

Biological value for humans

Copper belongs to the category of vital elements, and the body of an adult contains about 100 grams of this metal. A reassessment of the toxicity of this substance was carried out in 2003 by the World Health Organization. Studies have found that copper is not a cause of diseases of the digestive tract, and does not provoke the development of Wilson-Konovalov disease (hepatocerebral dystrophy affecting the liver and brain), as previously thought. Scientists have concluded that a lack of copper is more harmful to human health than its excess.

The bactericidal properties of copper have been known for a long time, and recent studies in this area have confirmed the effectiveness of the metal in the prevention of swine flu and infection by Staphylococcus aureus. In experiments, it was found that 99% of pathogenic bacteria die on a copper surface within 2 hours. Therefore, copper and its alloys are widely used for water disinfection. In Europe, door handles, locks, hinges and railings are made from this metal, which are installed in medical institutions and public places.