Interesting Facts. Iron heated to 5000 degrees Celsius becomes gaseous. It is most likely that this name comes from the ancient Aryan root "ZIL", which denoted tin and white metals in general (including silver - "zilber", and the name "zinc" was derived from the same word by the L-N aberration). From him, apparently, comes the Sanskrit “pity”, which means “metal, ore”. Iron is one of the most abundant elements in solar system, especially on planets terrestrial group in particular on Earth. A significant part of the iron of the terrestrial planets is located in the cores of the planets, where its content is estimated to be about 90%.
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Iron
"Iron Lesson" - Confucius. 3. Crushed the ashes to powder. 4. Transfer the ash to a test tube and add 10ml HCI. 5 . Compared the color intensity of the analyzed solutions. Laboratory experience: Research results: Keep your diet balanced, be healthy! Close the cork and mix vigorously by shaking.
"Iron compounds" - Physical properties: Pure iron is a silvery-white ductile metal. The electronic formula of the structure of the atom: 1s 2s 2p 3s 3p 3d 4s. By donating electrons to the outer level, iron is oxidized to an oxidation state of +2. The most common metal in the world after aluminum is iron. To an oxidation state of +2, iron is oxidized by interacting with weak oxidizing agents.
"Iron metal" - Chemical properties of iron. 1 - reducing agent, oxidation process 1 - oxidizing agent, reduction process. physical properties. Methodical development lesson. Chalcopyrite with quartz inclusions Primorsky Krai. Biological role gland. The main source of iron for humans is food. Iron is a metal of medium chemical activity.
"Chemistry of iron" - The structure of a simple substance. Most widely used in modern industry. Dependence of properties on the structure. The interaction of iron with simple substances. Important from a biological point of view. Substance properties. Interaction of iron with complex substances. to non-metals. Test simulator. Attitude to simple substances.
"Properties of iron" - Iron in nature. Reagent. iron compounds. Iron. The structure of the iron atom. properties of iron. Text construction. Normal condition iron atom. Qualitative reaction. Formula. physical properties. Chemical properties. Laboratory work. Third wheel. Catch the error. Check yourself. genetic series.
Copper alloying iron
Relegated iron
The word "also", mentioned in the text of the verse "We also sent down iron" , indicates that other elements, not only iron, were brought down to Earth from outer space. Moreover, if we consider the special mention gland in this verse, in the light of the discoveries made by science at the end of the 20th century, the meaning of the verse leads us to a very interesting conclusion. The well-known microbiologist Michael Denton, in his book The Purpose of Nature, makes the following comment:
“Among all metals iron is the most vital and important for a person. Accumulation gland in the core of a star provokes a supernova explosion and, thus, makes it possible for atoms to spread throughout the universe gland necessary for life. Temperature formed by atoms gland, and the force of gravity inside the core at the initial stage of the formation of the Earth caused chemical changes in the Earth and, as a result, provided the prerequisites for the development of the atmosphere and hydrosphere. molten iron, located inside the core of the Earth, performs the function of a powerful magnet and forms the magnetic belt of the Earth. Thanks to this belt, high-energy Van Allen belts are formed, which protect the Earth from the effects of sizzling cosmic radiation and from the destruction of the Earth's ozone layer under the influence of cosmic rays ...
If there were no atoms gland, then the very emergence of the carbon basis of life would be impossible, there would be no supernovae, the Earth would not reach the temperature that existed at the initial stage of its formation, there would be no atmosphere and hydrosphere, there would be no protective magnetic belt, Van Allen radiation belts , there would be no ozone layer, there would be no metals (which make up human blood hemoglobin), no metals would form that could reduce the reactivity of oxygen, no metabolic processes would occur that could resist oxidation.
Mathematical Phenomenon gland
see also
Notes
Literature
- Encyclopedic Dictionary of a Young Physicist. M., 1984, 1991
Iron plays an important role in the life of almost all organisms, with the exception of some bacteria. In the body of animals, iron is part of many enzymes and proteins involved in redox reactions, mainly in the process of respiration. Normally, iron enters enzymes in the form of a complex called heme. In particular, this complex is present in hemoglobin, the most important protein that ensures the transport of oxygen with blood to all organs of humans and animals. And it is he who stains the blood in a characteristic red color.
The human body contains about 5 g of iron. Of these, 57% is blood hemoglobin, 7% is muscle myoglobin, 16% is associated with tissue enzymes, and 20% is a reserve deposited in the liver, spleen, bone marrow and kidneys.
Hemoglobin is a complex protein that also contains a non-protein heme group, which accounts for about 4% of the mass of hemoglobin. Heme is a complex of iron (II) with a macrocyclic ligand - porphyrin and has flat structure. In this complex, the iron atom is bonded to four donor nitrogen atoms of the macroring in such a way that the iron atom is located in the center of this porphyrin ring. The iron atom forms the fifth bond with the nitrogen atom of the imidazole group of histidine, the amino acid residue of globin (Fig. 4).
Iron complexes other than heme are found, for example, in the enzyme methane monooxygenase, which oxidizes methane to methanol, in the important enzyme ribonucleotide reductase, which is involved in DNA synthesis. Inorganic iron is found in some bacteria and is sometimes used by them to bind atmospheric nitrogen.
The daily requirement of a person is about 15 mg of iron. A lot of iron in plum juice, dried apricots, raisins, nuts, pumpkin and sunflower seeds. 10 g of sprouted wheat contains 1 mg of iron. Black bread, bran, wholemeal bread are also rich in iron. It should be noted that the body absorbs only 10% of all iron received from food. Vitamins and foods of plant origin promote the absorption of iron, and in the presence of oxalic and phytic acids, iron is not absorbed.
With insufficient intake of iron in the body, drugs containing it are used. Even ordinary iron filings were once used for these purposes. It is known from history that Count A.P. Bestuzhev-Ryumin (1693–1766) proposed drops (they were called “Bestuzhev’s”) as a tonic and aphrodisiac, which were a solution of iron trichloride in a mixture of ethanol and ethyl ether. Now, powdered iron in tablets or capsules and preparations based on ferrocene are usually used to eliminate iron deficiency.
- Iron enters the body of animals and humans with food, the richest in it is the liver, meat, eggs, legumes, bread, cereals, and beets. Interestingly, once spinach was erroneously included in this list (due to a typo in the analysis results - an “extra” zero after the decimal point was lost).
- Based on indirect data, it can be concluded that the core of the Earth is mainly an alloy of iron. Its radius is approximately 3470 km, while the radius of the Earth is 6370 km.
- Free iron has been found on the moon. Determination of the age of lunar minerals using radioactive isotopes showed that they crystallized from 3.2 to 4.2 billion years ago. This roughly coincides with the age of the oldest minerals found on Earth.
Iron (denoted by the chemical symbol Fe, pronounced ferrum in Latin) is a silvery-white metal. Iron without impurities of other elements is soft, flexible and ductile (it can be drawn into a thin wire).
At room temperature, iron is easily magnetized. However, it is difficult to magnetize it when heated. Magnetic properties iron disappear at a temperature of about +800 °C.
In its pure natural state, iron is found only in a few places on Earth, for example, in western Greenland. Pure iron is sometimes found in meteorites. Much more iron occurs in the form of chemical compounds. Iron is extracted from ores containing such minerals as hematite, goethite, magnetite, siderite and pyrite.
Iron is also one of the constituents of hemoglobin, a complex protein found in red blood cells - erythrocytes. RBCs carry oxygen and carbon dioxide in the human body. Iron easily enters into chemical reactions. It, for example, reacts with halogens (fluorine, chlorine, bromine, iodine), with sulfur, phosphorus and carbon.
Iron is soluble in most dilute acids. It can burn in the presence of oxygen. At the same time, pure iron is used for the production of galvanized sheet metal and electromagnets.
In medicine, iron-containing preparations are prescribed for patients with anemia (with too low a content of red blood cells in the blood). On contact with moist air, iron oxidizes to hydroxide (Fe2Os + H20), a reddish-brown layered substance also called rust.
Iron can be forged. To do this, it is red-hot, and then repeatedly flattened or squeezed. This process makes iron more durable and wear-resistant.
Steel is a malleable alloy of iron (base) with carbon (with a carbon content of 0.1-1.5%). Steel is the same Chemical properties like iron. Steel is usually hardened to improve its mechanical properties. To do this, it is first heated red-hot, and then lowered into a cold liquid. This gives the steel greater hardness (hardened steel). Steel is used as structural materials, in the manufacture of tools, weapons. There are special grades of steel with special properties (stainless, heat-resistant).
Cast iron is an alloy of iron (base) with carbon (2-5%). Cast iron tends to be brittle due to its high carbon content. In a smaller amount, cast iron contains impurities - silicon, sulfur, phosphorus and manganese. Various products can be cast from cast iron, such as, for example, frying pans or fence grates. Cast iron is used in steelmaking.
Iron is a chemical element having the 26th atomic number V periodic table Dmitri Ivanovich Mendeleev. The metal is silvery white in color, denoted by the symbols Fe (from the Latin Ferrum). In its pure form, iron is a ductile transition metal, used by humans in various fields from a long time ago. A small amount of impurities or additives make iron harder, for example, carbon impurities turn iron into steel. Naturally occurring iron is a mixture of four nuclides having mass numbers 54 (the proportion of content in the natural mixture is 5.82% by mass), 56 (the proportion of content in the natural mixture is 91.66%), 57 (the proportion of content in the natural mixture is 2.19%) and 58 (the content in the natural mixture is 0.33%).
Iron became known to man in ancient times, but it became widespread much later, because. in its pure form, the metal is extremely rare, and the extraction of metal from iron ore requires the necessary production process. For the first time, probably, a person became acquainted with the iron contained in meteorites. So, in the ancient Egyptian language, iron sounds like “beni-pet” and means “heavenly iron”, the ancient Greek name “sideros” comes from the Latin “sidus”, which means “ heavenly body”, Hittite texts of the 14th century BC recall iron as a metal that fell from the sky.
The method of obtaining iron from ore was invented in the 2nd century BC in Western Asia. Then the method became widespread in Babylon, Greece and Egypt. IN Ancient Rus' and Europe, iron was obtained by the raw-dough method, in the 12th - 13th centuries the bloomery method became more common, in mid-eighteenth century, the crucible process, known in Syria in the early Middle Ages, but forgotten, became widespread, the puddling process began to develop, by the end of the 19th century, processes were developed that made it possible to obtain iron at an industrial level: open-hearth Bessemer and Thomas processes. Later, the electric steelmaking process arose, which made it possible to obtain high-quality steel.
Iron with its alloys is the most important structural material in industrial production and technology. From steel, i.e. an alloy of iron with carbon, they make most of the structures in heavy industry and engineering. Railways, machine tools, trucks and cars, power plants and ship hulls, as well as many other structures, are made mostly of steel. The production scale of the steel-producing and steel-consuming industries today is one of the main indicators of the technical and economic level of development of the region or the state as a whole.
The content of iron ore in the earth's crust is quite large. Ore deposits are located throughout the globe, and the extraction and production of metal does not constitute any particular difficulties. Iron is quite easily smelted from iron ore. Iron became an inexpensive and very common material, largely due to the ubiquity of iron ore, as well as the relative ease of processing the ore and producing the metal. A variety of structural materials are produced on the basis of various properties and characteristics. For example, cast iron is a durable metal with a low melting point, by casting the metal can be given any desired shape. Depending on the composition, steel can be a strong and ductile material used in the manufacture of, for example, shaped steel, which is used in the construction of bridges and ships, or a refractory and very hard metal, which serves as a material in the manufacture of metal-cutting tools, etc.
Biological properties
With the exception of a few bacteria, iron, as a trace element, plays one of the most important roles in the life of all living organisms. In animals, iron can be found in many proteins and enzymes that are involved in redox reactions, mainly in the process of respiration. Iron, as a rule, is part of enzymes in the form of a complex called heme. This complex is present in hemoglobin, which is the most important protein that ensures the delivery of oxygen through the blood to all organs in the body of animals and humans. Hemoglobin is what gives blood its characteristic red color.
The body of a healthy person contains approximately 5 grams of iron. More than half of this iron (57%) is in hemoglobin in the blood, 16% in tissue enzymes, 7% in muscle tissue myoglobin, and 20% is debugged in organs such as the liver, kidneys, spleen and bone marrow as a reserve.
Hemoglobin is a complex protein containing, among other things, a non-protein heme group, which accounts for approximately 4% of all hemoglobin in the body. Heme is an iron(II) complex with a macrocyclic porphyrin ligand; heme has a characteristic planar structure. In this complex, the Fe atom binds to four donor A atoms of the macroring in such a way that the Fe atom is located in the very center of this porphyrin ring. The iron atom forms the fifth bond with the nitrogen atom of the imidazole group of histidine, that is, the amino acid residue of globin.
Those iron complexes other than heme are found, for example, in the very important enzyme ribonucleotide reductase involved in DNA synthesis, in the enzyme methane monooxygenase, which converts methane to methanol. Inorganic iron compounds are found in some members of the bacterial kingdom, in some cases they use iron to fix nitrogen from the air.
The daily human need for iron is approximately 15 milligrams. A lot of iron is found in plum juice, raisins, nuts, dried apricots, sunflower and pumpkin seeds. In germinated wheat, the iron content is 1 milligram per 10 grams of weight. Bread is also rich in iron: with bran, wholemeal bread products, etc. It should be understood that of all the iron consumed with food, only 20 percent is absorbed by the body. Foods and vitamins of plant origin help the absorption of iron. Iron is not absorbed at all if phytic or oxalic acids are present in food.
If the body is deficient in iron, they begin to use special medications based on medicinal plants. Once upon a time, ordinary iron filings were widely used for such purposes. History left a mention that Count Bestuzhev-Ryumin (years of life 1693-1766) offered special drops as an aphrodisiac and tonic, which were nothing more than a solution of iron trichloride, mixed with ethanol and ethyl ether. Such drops even got the name “Bestuzhev drops” from their creator. In modern medicine, to eliminate the lack of iron in the body, preparations in tablets and capsules containing iron powder, as well as drugs based on ferrocene, are used.
- - The first iron, like metal, fell into the hands of a man "from heaven". No wonder people considered iron to be a heavenly metal, because. for the first time it was mined from meteorites falling to the surface of the earth. In the most ancient objects made of iron, there is a significant proportion of nickel impurities; it is this iron that is found in meteorites. The largest iron meteorite was found in 1920 in southwest Africa. The meteorite was named "Goba", it weighed 60 tons.
- - Iron in the body of animals and humans comes with food. The most iron-rich foods are meat, liver, eggs, legumes, cereals, bread, and beets. It is interesting to note that once spinach was erroneously included in this list (due to a typo in the records of the analysis results, namely, the “extra” zero after the separating comma was lost).
- - Many indirect data confirm the fact that the core of our planet mainly consists of iron alloys. The radius of the Earth's core is approximately 3470 km, while the radius of the Earth itself is 6370 km.
- Iron has been found in free form on the moon. The process of determining the age of lunar minerals using radioactive isotopes showed that they were crystallized about 3.2 - 4.2 billion years ago. These figures roughly match the age of the most ancient minerals ever discovered on Earth.
- - Repeated clinical experiments have confirmed the fact that nettle does an excellent job of treating anemia, while not inferior to synthetic iron preparations. In the village, every housewife knows that chickens lay better when dried nettles are added to the feed. Folk herbalists often advise to be treated with fresh nettle juice, which is squeezed from the trunks and leaves of young plants, you need to collect nettles before flowering. This is done quite simply: you need to collect, rinse, pass through a juicer or mixer with a small amount of water, and then just squeeze the juice. The resulting juice should be taken three tablespoons per day. Nettle juice does not have a pleasant taste, but it is very useful. It can be diluted with honey. Nettle juice keeps well for several days in the refrigerator.
- In 1941, the United States of America joined world war. The American National Conference on Defense Nutrition decided to fortify bread and flour with iron to prevent anemia in the American population. The first sign of iron deficiency is fatigue, as well as anemia caused by this, and, as you know, war does not tolerate tired people! But there is one but ... North America they produced only white bread and white flour (thus it was pure starch), but the valuable part of the grain went to waste. In one kilogram of wholemeal flour made from unrefined grains, the iron content is approximately 30 milligrams, and in one kilogram of refined flour made from refined grains - 8.2 milligrams. In accordance with the then norms, one kilogram of fortified flour had to contain approximately 26 milligrams of iron. Between 1968 and 1970, testing of this action began in ten US states. Thirty thousand families consuming iron-fortified flour and bread were subjected to a thorough examination. As a result, they all had a lack of iron in the body.
Story
Iron has been known since ancient times. The very first products made of iron were found during archaeological excavations. Objects date back to IV thousands of years BC, this is the legacy of the ancient Egyptian and ancient Sumerian civilizations. Iron products of that time were decorations and tips for weapons. In the manufacture of these items used meteoric iron, or rather, an alloy of iron and nickel, which is found in meteorites falling to the ground. In many languages, there are reminiscences about iron as a heavenly metal.
In Mesopotamia, Egypt, Anatolia in the II-III centuries. BC. the first products made of remelted iron began to appear, they no longer contained nickel. Mostly iron was used in cult accessories. Most likely, at that distant time, iron was the most expensive metal, even more expensive than gold.
At times ancient Greece weapons were made mainly of bronze. But in the 23rd song of the Iliad, Homer said that at the end of the discus thrower Achilles awarded the winner with an iron disc. In the middle of the 2nd century BC, the production of iron was widespread in Asia Minor (Near East), but bronze products still accounted for the most part.
In the XII - X centuries. BC. in Asia Minor there was a leap in the production of metal devices. Now weapons and other items were made not from bronze, but from iron. Such a jump was most likely caused not by the advent of progressive methods of iron production, but by interruptions in the supply of tin, one of the main components of bronze. The period of mass transition to the production of iron products is called the Iron Age.
In ancient times, the main method of obtaining iron was the raw-blowing method. Alternating layers of charcoal and iron ore were calcined in special furnaces. As a result of such calcination, a doughy spongy or blooming iron was obtained. Such iron was freed from slag during the forging process. In the first furnaces, the temperature was quite low, even below the melting temperature of cast iron. Therefore, iron was low-carbon, and, therefore, brittle. To increase the strength of the metal, iron objects were additionally calcined again in the presence of coal, as a result, the surface of the metal was saturated with carbon, and the products became noticeably stronger, much stronger than the same products made of bronze.
With the development of iron production, more advanced forges began to appear (in Rus' they called blast furnaces or domnitsa), after some time people learned to reach the melting temperature of cast iron. Initially, cast iron was considered a by-product, from which there is no benefit. IN English language there is an expression "pig iron", which in translation into Russian means "pig iron" or "pigs", and in turn the name "cast iron" came from the word "pigs". After some time, the fact was discovered that with additional burning of cast iron in a furnace, when a high temperature is reached, the cast iron is melted into iron of very high strength. The two-stage process proved to be not only more efficient, but also more profitable. For several subsequent centuries, just such a two-stage method was used.
The first mention of the production of iron from meteorites in China dates back to the same time as in ancient European countries. Probably, starting from the 8th century BC, the production of iron products began to develop there. In the 1st century BC, China learned how to produce cast iron.
Being in nature
In terms of prevalence in nature, iron is the second metal after aluminum and is in fourth place among all elements, second only to oxygen, aluminum and silicon. Content chemical element in the earth's crust by mass is 4.65%. More than 300 minerals are known that are contained in the composition of iron ores (sulfides, oxides, silicates, phosphates, carbonates, titanates, etc.).
The most important iron ore minerals are: magnomagnetite, Titanomagnetite, Magnetite, Hematite, hydrohematite, Siderite, Goethite, hydrogoethite, ferruginous chlorites (thuringite chamosite, etc.). In industrial ores, the iron content is 16 - 70%. There are rich (less than 50% iron), ordinary (50-25% iron) and poor (≥ 25% iron) iron ores. Depending on what chemical composition iron ore, it is used for smelting iron after enrichment or in its natural form. Iron ores, the metal content of which is less than 50%, are enriched up to 60%, mainly by magnetic separation or gravity enrichment. Loose or sulphurous (less than 0.3% sulfur) rich ores and enrichment concentrates are lumped by agglomeration, and pellets are produced from concentrates. Iron ores that go into the blast-furnace charge should not contain S, P and Cu more than 0.1 - 0.3% and As, Sn, Zn, Pb 0.05-0.09%, because. melting conditions or steel quality may deteriorate. The admixture of silicon, nickel, titanium and tungsten in iron ore is useful in most cases. Mn, Cr and Ni improve the quality of steel, titanium and tungsten are simultaneously extracted in the processes of enrichment and metallurgical processing.
Iron ore deposits are divided into three groups by origin: magmatogenic, metamorphogenic and exogenous. Igneous are divided into: igneous - these are dike-like, sheet-like and irregular deposits of titanomagnetites, which are associated with gabbro-pyroxenite rocks (Liganga in Tanzania, Bushveld deposits in South Africa), apatite-magnetite deposits, which are associated with syenitediorites and syenites (Ellivars and Kiruna in Sweden , Lebyazhinskoe in the Urals), skarn or contact-metasomatic, appear near intrusive massifs or at contacts, etc.
Exogenous deposits: sedimentary - mechanical and chemical sediments of lake and sea basins, more rarely in deltas and river valleys, occur in the process of local enrichment of basin waters with iron compounds, as well as as a result of the drift of ferruginous land products into the waters; compose lenses or layers among sedimentary, less often - volcanic-sedimentary rocks; this includes deposits of brown iron ore, part of silicate ores, siderites (Kerch in Ukraine, Ayat in Kazakhstan; Lan-Diel in Germany, etc.). Deposits of the weathering crust appear after the weathering of iron-bearing rocks; eluvial or residual deposits are distinguished, where weathering products are enriched in iron (as a result of removal from rock other elements) and remain in place (Ukraine - the ores of Krivoy Rog, Russia - the Kursk magnetic anomaly, USA - the region of Lake Superior) and cementation (infiltration), here iron is removed from weathered rocks, and then deposited again in the horizons lying below (Russia - Alapaevskoe field of the Urals).
Metamorphogenic (or metamorphosed) deposits are pre-existing, mostly sedimentary deposits transformed under high pressure and temperature. Siderites and iron hydroxides in this case, as a rule, pass into magnetite and hematite. Metamorphic processes can be supplemented by hydrothermal-metasomatic formations of magnetite ores. There are similar deposits in Russia, India, Ukraine, USA, Australia, etc.
Application
Pure iron is used rather limitedly. It is used in the production of cores for electric magnets, as a catalyst in the flow chemical processes, in some other areas. But iron-based alloys such as steel and cast iron are the basis of modern technology throughout the world. Many iron compounds also find their uses. For example, iron (III) sulfate is used in water treatment, cyanide and iron oxides are used as pigments in the production of various dyes, and other iron compounds are used in other areas.
Iron with its alloys is the most important structural material in industrial production and technology. Almost all structures of mechanical engineering and heavy industries are made mainly from iron-carbon alloys. Steel is used to make cars, machines, and railways, and ship hulls with power plants, and frames of bridges and buildings, and much more. By the scale of steel production, one can judge the general technical and economic level of development of a particular state or region. In the share of global production of products made from metal, steel ranks first with a share of 95%.
Iron can sometimes be included in other alloys as an impurity. For example, nickel alloys. In the manufacture of long-term computer memory devices such as floppy disks and hard disks, magnetic iron oxide is a very important, even indispensable material.
Ferric chloride, i.e. iron chloride III, radio amateurs use in practice in the process of etching printed circuit boards. Iron sulphate (ferrous sulfate decahydrate) mixed with copper sulphate is used in construction and horticulture to combat harmful fungi. Iron is used as an anode in the production of iron-nickel batteries, as well as iron-air batteries.
The black and white laser printers that are so common today use ultrafine magnetite powder as the toner. A number of iron-based alloys have unique ferromagnetic properties, due to which they have found wide application in electrical engineering in the production of various electric motors of magnetic cores of transformers.
For the production of iron alloys for critical purposes and steels, completely new processes are used - electroslag remelting, vacuum process, electron beam and plasma melting, etc. Methods are being developed for producing steel in units with a continuous process, which will make it possible to automate the process and obtain High Quality metal.
Iron-based materials are produced that are able to withstand the effects of low and high temperatures, high pressures and vacuum, high alternating voltages, aggressive environments, nuclear radiation, etc. The production of iron and iron alloys is steadily growing.
Since ancient times, iron has been used as an art material in India, Egypt and Mesopotamia. Since medieval times, many works of art made of iron have been preserved in European countries (Italy, England, Russia, France, etc.) - door hinges, wrought iron fences, wall brackets, weather vanes, light fittings, chest fittings. Products forged through rods, as well as objects made of perforated sheet iron (often with a mica lining) are distinguished by a clear linear-graphic silhouette, planar forms, and are effectively visible against the background of light and air. In the 20th century, iron was widely used in the manufacture of fences, gratings, openwork interior partitions, monuments, candlesticks, and other elements of external and internal design.
Production
Iron production
Cast iron is produced in vertical furnaces called blast furnaces. Pig iron is obtained from a mixture that contains pieces of enriched ore in the presence of coke and fluxes. Oxygen-enriched air is blown into the blast furnace from below. The carbon contained in the coke burns out, and the carbon dioxide obtained in this way is reduced at the expense of monoxide to an excess of carbon. The carbon monoxide produced in the furnace reduces the iron oxide contained in the ore in succession to iron as a metal:
3Fe 2 O 3 + CO \u003d 2Fe 3 O 4 + CO 2
2Fe 3 O 4 + 2CO \u003d 6FeO + 2CO 2
FeO + CO \u003d Fe + CO 2
CaCO 3 \u003d Ca + CO 2
As a result, lime is formed, which contributes to the transfer of silicate impurities into liquid slag. The blast furnace process produces almost as much slag as cast iron.
Today, the blast furnace is a large facility producing 1,000 tons of pig iron per day. The height of the furnace is about 30 mm, and the diameter at the level of the shoulders is about 8 meters. The lower part of the furnace is cooled with water.
Steel production
Steel production is the remelting of cast iron in the presence of oxidizers. During the smelting of steel, the content of C is reduced to one and a half - two percent. Oxide FeO, formed under oxidizing conditions, reacts with impurities and carbon, oxidizing them, while being reduced to Fe.
In the Bessemer (oxygen-converter) method of obtaining steel, a special container is used for smelting, i.e. converter, which is a retort-shaped reservoir.
Inside the converter, liquid iron is poured, purged with a mixture of oxygen, air and hydrocarbons, a charge is loaded that contains steel scrap, ore, cast iron and fluxes, then pure oxygen is supplied.
Before starting the BOF process, it is necessary to tilt the converter towards the loading bay, and the scrap metal is poured through the neck. After that, liquid metal from a blast furnace is poured into the converter, which contains approximately 1.5% silicon and 4.5% carbon. Carbon is oxidized to CO 2 or CO, and silicon to SiO 2 . Lime is added along the loading tray to form a slag with silicon dioxide. Most of the silicon is removed with the slag
There is also an oxygen-converter process with the supply of oxygen in a fuel jet through the bottom of the converter. At the bottom of the converter, the tuyeres are protected by synchronous blowing natural gas. This process is faster and more productive than the top blowdown process, but it is not as efficient in melting scrap metal. But it is possible to combine the lower purge with the upper one.
electric oven. At first, electric furnaces were used only for smelting tool and stainless steels, which were previously smelted in crucibles. But over time, electric furnaces have taken an important place in the production of steel from scrap metal in cases where the conversion of pig iron is not needed. Now about 30% of unrefined steel is produced in electric furnaces. The most common are electric arc furnaces. The floor of such a furnace is lined with refractory bricks, the vault is cooled with water. There are three holes in the vault into which carbon electrodes are inserted. An arc discharge occurs between the scrap metal and the electrodes at the bottom of the furnace. In a large furnace, the current reaches 100,000 A.Physical properties
Iron can have two crystal lattices: α- or γ-body-centered cubic and face-centered cubic. Below a temperature of 910°C, it is stable with the α-modification of the bcc lattice (at 20°C a = 2.86645 Å), the γ-modification is stable at 910°C - 1400°C, the fcc lattice (a = 3.64 Å) . Upon reaching 1400°C, the bcc lattice, δ-Fe (a = 2.94 Å), is again formed, which is stable up to a temperature of 1539°C. α - ferromagnetic modification up to the Curie current (769°C). Modifications δ-Fe and γ-Fe are paramagnetic.
In 1868, D. K. Chernov discovered the polymorphic transformations of iron and steel after heating and cooling. Carbon forms interstitial solid solutions with iron, where carbon atoms have a small atomic radius (0.77 Å), they are located in the interstices of the metal crystal lattice, which consists of larger atoms. Iron has an atomic radius of 1.26 Å.
The combination of quenching and tempering (heating to a relatively low temperature to reduce internal stress) gives the steel the required combination of ductility and hardness.
The physical properties of iron are directly dependent on the purity of the metal. In industrial materials, iron is usually accompanied by impurities of nitrogen, carbon, oxygen, phosphorus, hydrogen, and sulfur. Even very small concentrations of these impurities significantly change the properties of iron. For example, sulfur causes the so-called red brittleness, and phosphorus (up to 10 -20% P) such a property as cold brittleness, carbon and nitrogen affect the ductility of iron, the admixture of hydrogen increases brittleness (hydrogen brittleness). Reducing the content of impurities to 10 -7 -10 -9% leads to big changes physical properties of the metal, and in particular increases ductility.
let's consider physical properties pure iron (impurities not more than 0.01% by weight). So, the atomic radius of iron is 1.26 Å, the ionic radii are Fe3+O.67 Å, Fe2+O.80 Å. Melting point 1539 °C, boiling point about 3200 °C, density (at 20 °C) is 7.874 g/cm3. The temperature coefficient of linear expansion of iron (at 20 ° C) is 11.7 10 -6, the thermal conductivity of the metal (at 25 ° C) is 74.04 W / (m * K) \u003d
The heat capacity of iron strongly depends on the structure, changing with temperature in a complex way. The average specific heat capacity of iron (at 0-1000°C) is 640.57 J/(kg K) = . Specific electrical resistance(at 20°C) is equal to 9.7 10-8 ohm m = , Young's modulus is 190-210 10 3 MN/m. 2 \u003d \u003d (19-21 10 3 kgf / mm 2), the temperature coefficient of electrical resistance (at 0-100 ° C) is 6.51 10 -3, the temperature coefficient of Young's modulus is 4 10 -6, Short-term strength at break is 170-210Mn/m2, shear modulus is 84.0 10 3 MN/m2, elongation is 45-55%, metal hardness according to Brinell is 350-450 MN/m2, yield strength is 100Mn/m2 , and the impact strength of iron is 300 MN/m 2 .
The configuration of the outer electron shell of the iron atom is 3d64s2. Iron has a variable valency (compounds of bi- and ferric iron are more stable). Iron forms Fe 2 O 3 oxide, FeO oxide, and Fe 3 O 4 oxide oxide with oxygen. At ordinary temperatures in moist air, iron becomes covered with loose rust. Rust, due to its porosity, does not prevent the access of air and moisture to the metal surface, therefore it does not protect iron from further oxidation. Because of different types millions of tons of iron are lost every year. As a result of heating iron in dry air above a temperature of 200 ° C, its surface is covered with a thin oxide film that protects the metal from corrosion at ordinary temperatures, which underlies the technical method of protecting iron - the burnishing method.
Chemical properties
When iron is heated on steam, the metal is oxidized with the release of Fe 3 O 4 (at temperatures below 570 ° C) or FeO (at temperatures above 570 ° C), as well as the release of hydrogen.
Hydroxide such as Fe (OH) 2 is formed as a result of the action of ammonia or caustic alkalis on aqueous solutions of Fe 2+ salts in a nitrogen or hydrogen atmosphere, has the form of a white precipitate. Subsequently, contact with air, the hydroxide first turns green, and then blackens, but after that it quickly turns into red-brown Fe (OH) 3. Ferrous oxide FeO exhibits its main properties. A Fe 2 O 3 oxide is amphoteric and has a poorly expressed oxidizing function, reacts with basic oxides (for example, with MgO), forms ferrites, i.e. compounds such as Fe2O3 nMeO, which have ferromagnetic properties, are widely used in radio electronics. Hexavalent iron, which exists in the form of ferrates, also has acidic properties. For example, K 2 FeO 4 , a salt not isolated in the usual state of iron acid.
Iron is able to easily react with hydrogen halides and halogens, while giving salts. A striking example is the chlorides FeCl 3 and FeCl 2. As a result of heating iron together with sulfur, sulfides FeS 2 and FeS are formed. Iron also has carbides - Fe 2 C (ε-carbide), Fe 3 C (cementite), which precipitate from solid solutions of carbon in iron when these solutions are cooled. Fe 3 C can also be released from a solution of carbon in liquid iron if C concentrations are high. Nitrogen, almost like carbon, carbon, forms interstitial solid solutions with iron. The nitrides Fe2N and Fe4N are isolated from these solutions. With hydrogen, iron is capable of producing only unstable hydrides, whose composition has not been precisely established. Due to heating, iron reacts quite vigorously with phosphorus and silicon, and phosphides (for example, Fe3P) and silicides (for example, Fe3Si) are formed.
Iron compounds with many elements (oxygen, sulfur, and others), which form a crystalline structure, have a variable composition (for example, in the composition of monosulfide, the sulfur content can vary from 50 to 53.3%). This phenomenon is explained by the presence of defects in the crystal structure. For example, in iron oxide FeO, some Fe 2+ ions in the lattice sites are replaced by Fe 3+ ions. In order to preserve such a property as electrical neutrality, some lattice sites that belong to ions of the Fe 2+ type remain empty, and the phase under normal conditions is written by the formula Fe 0.947 O.
The value of the normal electrode potential of iron in aqueous solutions of Fe salts for the reaction
Fe<- Fe 2+ +2
Fe -> Fe 2+ +2
is equal to 0.44 V, and for the reaction
Fe<- Fe 3+ +3
Fe -> Fe 3+ +3
equal to - 0.036 in. Thus, in the series of activities, iron takes place to the left of hydrogen. The element can easily dissolve in dilute acids, releasing hydrogen and forming Fe 2+ ions.
Iron interacts quite peculiarly with nitric acid. Nitric acid concentrate (density 1.45 g / cm 3) passivates iron as a result of the appearance of an oxide film on the metal surface, and more dilute nitric acid dissolves iron, forming Fe 3+ and Fe 2+ ions, or is reduced to MH 3 or N 2 O and N 2 .
Ferrous salt solutions are not stable in air: Fe 2+ oxidizes over time and turns into Fe 3+. Aqueous solutions iron salts as a result of the hydrolysis process carry out an acidic reaction. The addition of thiocyanate ions SCN to solutions of Fe 3+ salts contributes to the appearance of a bright blood-red color as a result of the formation of Fe (SCN) 3, and this, in turn, allows the presence of one part of Fe 3+ in about 106 parts of H 2 O. Iron is characterized by the formation of complex compounds.