0.12 grams kill a person in 5 hours. How cyanide works potassium. One of the most powerful poisons is the salt of hydrocyanic acid. It is also called blueberry. The composition of the substance includes the 19th element. However, pure potassium is a boon for the body, not a killer.

Even a child needs at least 600 milligrams of an element per day. Otherwise, the work of the muscles, including the heart, is disrupted. Convulsions occur, neuralgia may develop.

It is possible to fill the deficit by eating dried apricots, seafood, nuts, citrus fruits, bananas. Move these products closer and continue your acquaintance with element #19.

Chemical and physical properties of potassium

The name of the element was given by one of its compounds, known since antiquity, - potassium carbonate. The Arabs called it "al-kali" and used it when washing clothes. Reacting with water potassium salts"Give birth" to an alkaline environment. Tissues are cleaned in it to this day.

Over the centuries, carbonate has found other uses. The substance has become a food stabilizer. How does this role potassium? Water and oil, for example, do not mix. But, in the presence of carbonate, it is still possible to obtain a homogeneous composition. The package will be marked "E501".

At potassium mass connections. The 19th element is included in the first group periodic system, and it contains only alkali metals. All of them have only 1 electron in the outer electronic level.

This makes the elements active reducing agents. Electronic potassium formula four-layer. Therefore, the metal is in the 4th period of the periodic table. That is, the outer electron is removed from the nucleus and is easily detached and replaced.

In its purest form potassium is a substance firm yet lightweight. The density of the element is only 0.06 grams per cubic centimeter. The atomic mass is also small - 39.098 grams per mole. By the way, in potassium there are only atoms. They form the crystal lattice. A simple substance does not form molecules.

Mass of potassium small, like most indicators of the metal. It cannot even boast of hardness, even though the state of aggregation of matter under normal conditions is such. The element is given less than 1 point.

Potassium is easily cut with a knife, as if it were not metal, but cheese. It is not difficult to melt the substance. Enough heating to 63.5 degrees. Achieving a boil is more difficult, you need an indicator of 700 on the Celsius scale.

Being a metal, the element has a characteristic. The color of the substance is silvery-white, with a grayish tint. If there is water nearby, it is better to admire the ingots from a distance.

Immersed in a liquid, potassium explodes. The metal also reacts easily with oxygen, instantly oxidizing. There are no special conditions for this. All you need is an atmosphere and potassium.

Which result of the reaction of a metal with oxygen? An oxide of the 19th element is formed. There is also a flame. Lighting up in air, potassium flashes purple. The reaction is one way to identify an alkali metal.

Oxygen is one of the halogens, that is, elements of the 17th group of the periodic table. Potassium easily reacts with each of them according to the principle of addition. Substances are combined into one. This is how it turns out potassium chloride, iodite, bromide, fluoride and more. Attachment always takes place at elevated temperatures.

The 19th element also interacts with some complex substances. It's not just water. React with metal can and any acid. Potassium displaces hydrogen atoms from matter. So, from mixing with hydrochloric acid, hydrogen and chloride are “born”. The reaction takes place under normal conditions.

Interaction with oxides is possible only at elevated temperatures. Most reactions proceed according to the exchange scheme. This is where the restorative properties come into play. potassium. Reaction with cuprum oxide, for example, gives an oxide of the 19th element and pure cuprum.

According to the principle of recovery, the interaction with salts also takes place. If they include elements that are less active from a chemical point of view, potassium replaces their atoms. As a result, pure metals are mined. So, the combination with chloride gives aluminum already in its pure form.

Reactions with metal hydroxides occur only if they are located to the right of potassium in the series of electrochemical activity. Take, for example, barium, more precisely, its hydroxide. The union with the 19th element guarantees the presence of already potassium hydroxide. The barium will be released.

Application of potassium

Potassium is needed not only by the human body, but by their industry. Metal cyanide is purchased by gold miners. The reagent helps them extract precious elements from ore. It makes it easier to get not only, but also silver.

In the field of oil production, metal formate comes in handy. It serves as a drilling fluid, that is, it is used potassium solution. Fluoride metal is used in metallurgy as a. So industrialists call additives that reduce the melting point. Fluxes also facilitate the separation of waste rock and slag from metal.

Potassium tetrafluorobromate is present at nuclear power plants. Without it, you cannot get uranium hexafluoride. It is the stage of separation of uranium from impurities of rare earth elements. With the help of potassium, fluorides, rhenium are also obtained, and the nuclear industry cannot do without them.

Potassium carbonate found its place in the glass industry. Small additions of the substance improve optical properties products. The carbonic form of the metal is also used in soap making. Pyrotechnics contain chlorate of the 19th element, and household chemicals contain phosphate.

potassium sulfate- a popular fertilizer for plants. In general, approximately 90% of the mined salts of the 19th metal are used specifically for the production of top dressings. They accelerate the growth of crops, increase productivity, provoke lush flowering. So, instead of sulfate, you can choose potassium nitrate. In addition to fertilizer, it is quoted as food supplement, flavor enhancer.

The element was not missed and the medical field of view. Potassium Orotate- a medicine used in diseases of the biliary tract and liver. Potassium permanganate- antiseptic. potassium magnesium- a duet included in "Panangin". It makes up for the deficiency of both elements.

Best of all, metals are absorbed in pairs. If combined in the preparation sodium And potassium, you can debug the conduction of nerve impulses in the body. So, there are a lot of areas of application of the 19th element. It is in the hands of mankind that potassium is not uncommon.

Potassium mining

In nature, the most common potassium salts. Most of them are in Russia, in the Urals. No wonder one of the cities in the region is called Solikamsk. Large deposits are also being developed in Belarus. The third largest potassium reserves in the world were discovered 10 years ago in Brazil.

If pure metal is to be isolated, fossils are mixed with liquid sodium. The electrolysis of potassium chloride also works. The current is carried out in its mixture with the carbonate of the 19th element at a temperature of about 800 degrees Celsius.

After the reaction, potassium requires purification. Vacuum distillation helps. Sometimes, potassium hydroxide is subjected to electrolysis. The method is not common. Difficult to follow safety rules. The industrialists are not satisfied with the current output either.

Potassium price

Non-ferrous metal exchanges ask for at least $1,000 for the 19th element. This is the price tag for a ton of metal. For potassium compounds, the cost varies. It all depends on the demand for the substance, the volume of supplies. Potassium nitrate, for example, is sold at 60-75 rubles per kilogram.

Ororat medicine also costs about 50 rubles. For 100 tablets potassium iodite asking 140-170 rubles. A 10-millimeter ampoule of chloride of the 19th element costs customers 30-40 rubles.

The same amount of permanganate costs the same. A 40-kilogram bag of fertilizer in the form of sulfate is offered for 3,200 - 3,700 rubles. Prices are average. They vary from region to region and supplier to supplier. Often, sellers' requests depend on the volume of supplies. Wholesalers are offered discounts.

Mankind has been familiar with potassium for more than a century and a half. In a lecture given in London on November 20, 1807, Humphry Davy reported that during the electrolysis of caustic potash, he obtained "small balls with a strong metallic luster ... Some of them burned out with an explosion immediately after their formation." This was potassium.

Potassium is a wonderful metal. It is remarkable not only because it is cut with a knife, floats in water, flashes on it with an explosion and burns, coloring the flame in purple. And not only because this element is one of the most active chemically. All this can be considered natural, because it corresponds to the position of the alkali metal potassium in the periodic table. Potassium is remarkable for its indispensability for all living things and is remarkable as an all-around "odd" metal.

Please note: its atomic number is 19, atomic mass is 39, in the outer electron layer - one electron, valence 1+. According to chemists, this explains the exceptional mobility of potassium in nature. It is part of several hundred minerals. It is found in the soil, in plants, in the organisms of humans and animals. He is like a classic Figaro: here – there – everywhere.

1. Potassium

(Kalium), K, a chemical element of the 1st group of the periodic system of Mendeleev; atomic number 19, atomic mass 39.098; silver-white, very light, soft and fusible metal. The element consists of two stable isotopes - 39 K (93.08%), 41 K (6.91%) and one weakly radioactive 40 K (0.01%) with a half-life of 1.32 × 10 9 years.

Some compounds of K. (for example, potash, extracted from wood ash) were already known in antiquity; however, they were not distinguished from sodium compounds. Only in the 18th century the difference between "vegetable alkali" (potash K 2 CO 3) and "mineral alkali" (soda Na 2 CO 3) was shown. In 1807, G. Davy isolated potassium and sodium by electrolysis of slightly moistened solid caustic potash and sodium (KOH and NaOH) and named them potassium and sodium. In 1809 L.V. Gilbert proposed the name "potassium" (from Arabic al-kali - potash) and "natronium" (from Arabic natrun - natural soda); last I.Ya. Berzelius in 1811 changed to "sodium". The names "potassium" and "sodium" have been preserved in Great Britain, the USA, France and some other countries. In Russia, these names in the 1840s. were replaced by "potassium" and "sodium", adopted in Germany, Austria and the Scandinavian countries.

2. Distribution in nature

Potassium is a common element: the content in the lithosphere is 2.50% by weight. In magmatic processes, potassium, like sodium, accumulates in acid magmas, from which granites and other rocks crystallize (the average content of potassium is 3.34%). K. is a part of feldspars and micas. In basic and ultrabasic rocks rich in iron and magnesium, there is little calcium. On the earth's surface, sodium, unlike sodium, migrates weakly. When weathered rocks K. partially passes into the water, but from there it is quickly captured by organisms and absorbed by clay, therefore the waters of the rivers are poor in K. and much less than sodium enters the ocean. In the ocean, K. is absorbed by organisms and bottom silts (for example, it is part of glauconite); therefore, oceanic waters contain only 0.038% K. - 25 times less than sodium. In past geological epochs, especially in the Permian period (about 200 million years ago), at the late stages of evaporation of sea water in lagoons, after the precipitation of NaCl, K. and magnesium salts crystallized - carnallite KCI × MgCI 2 × 6H 2 O, etc. ( The Solikamsk deposit in the USSR, the Shtasfurt deposit in the GDR, etc., see Potassium salts). In most soils, there are few soluble K. compounds, and cultivated plants need potassium fertilizers.

The radioactive isotope 40 K is an important source of deep heat, especially in past epochs when this isotope was abundant. The decay of 40 K produces 40 Ca and argon 40 Ar, which escapes into the atmosphere. Some minerals of K. do not lose argon, and its content can be used to determine the absolute age of rocks (the so-called potassium-argon method).

The geochemical cycle of potassium, one of the chemical elements that make up 99.9% of the mass of the earth's crust. Its clarke is 2.50%, and the geochemical cycle consists of a variety of processes occurring in the earth's crust, an intense biological cycle, and somewhat limited water migration from land to the ocean. Clarke of potassium in stony meteorites is 0.085%, in the substance of the upper mantle is even less - 0.03%, in igneous rocks of basic composition (basalts) - 0.81%, in rocks rich in silicon (granites) - 3.34%. Thus, the gradual concentration of this element from the mantle substance to the upper part of the earth's crust is obvious. Apparently, potassium, together with other alkaline and alkaline earth elements, aluminum and silicon, was smelted from the mantle substance and accumulated in the earth's crust. Potassium takes an active part in the magmatic process, its bulk is included in the solid matter at the last stages of crystallization. It is part of the most common deep-seated silicates. In the weathering zone, during the rearrangement of the crystal-chemical structures of silicates, most of the potassium remains in the composition of new minerals and only partially passes into a soluble state.

K. is one of the biogenic elements, a constant component of plants and animals. The daily requirement for K. in an adult (2–3 G.) covered by meat and vegetable products; in infants, the need for K. (30 mg/kg) is completely covered by breast milk, in which 60–70 mg% K. Many marine organisms extract K. from the water. Plants receive K. from the soil. In animals, the content of K. averages 2.4 g/kg. Unlike sodium, K. is concentrated mainly in cells, in the extracellular environment it is much less. In the cell, K. is unevenly distributed.

K. ions participate in the generation and conduction of bioelectric potentials in nerves and muscles, in the regulation of contractions of the heart and other muscles, maintain osmotic pressure and hydration of colloids in cells, and activate certain enzymes. Metabolism To. is closely connected with a carbohydrate exchange; K.'s ions influence protein synthesis. K + in most cases cannot be replaced by Na + . Cells selectively concentrate K + . Inhibition of glycolysis, respiration, photosynthesis, violation of the permeability of the outer cell membrane lead to the release of K + from cells, often in exchange for Na +. K. is allocated from an organism mainly with urine. The content of K. in the blood and tissues of vertebrates is regulated by adrenal hormones - corticosteroids. K. is distributed unevenly in plants: there is more of it in the vegetative organs of the plant than in the roots and seeds. A lot of K. in legumes, beets, potatoes, tobacco leaves and fodder cereal grasses (20–30 G ./kg dry matter). With a lack of K. in soils, plant growth slows down, and the incidence increases. Norm potash fertilizers depends on the type of page - x. crops and soils.

In the biosphere, trace elements Rb and Cs accompany K. Li + and Na + ions are K + antagonists; therefore, not only the absolute concentrations of K + and Na + are important, but also the optimal K + /Na + ratios in cells and the environment. The natural radioactivity of organisms (gamma radiation) is almost 90% due to the presence of the natural radioisotope 40 K in the tissues.

In medicine since medicinal purposes CH 3 COOK acetate is used as a diuretic (usually against edema caused by heart failure) and KCl chloride in case of K. deficiency in the body (it develops during treatment with certain hormonal drugs, digitalis, with a large loss of fluid with vomiting and diarrhea, with the use of certain diuretics and etc.). Perchlorate KClO 4 inhibits the production of thyroxine (hormone thyroid gland) and is used in thyrotoxicosis. Potassium permanganate KMnO 4 (potassium permanganate) is used as an antiseptic.

Feldspars are a group of the most common rock-forming minerals that make up more than 50% of terrestrial and lunar rocks and are included in meteorites. Composition P. sh. is determined mainly by the ratio of components in the ternary system: NaAISi 3 O 8 – KAISi 3 O 8 – CaAl 2 Si 2 O 8 , i.e. these are Na, K, Ca aluminosilicates (with an admixture of Ba, Sr, Pb, Fe, Li, Rb, Cs, Eu, Ce, etc.). The basis of the structure of all P. sh. are a three-dimensional framework consisting of tetrahedral groups (Al, Si) O 4 in which from one third to a half of the Si atoms are replaced by Al. Large cavities of this framework contain monovalent K+ and Na+ cations (at the Al:Si = 1:3 ratio) or divalent Ca2+ and Ba2+ cations (at Al:Si = 1:2).

In the P. sh. two series of solid solutions are distinguished: KAISi 3 O 8 - NaAISi 3 O 8 (potassium, or alkaline, P. sh. and NaAISi 3 O 0 - CaAI 2 Si 2 O 8 - plagioclases) . Barium P. sh are seldom found. BaAI 2 Si 2 O 8 - Celsian and solid solutions KAISi 3 O 0 - BaAl 2 Si 2 O 8 - hyalophane (up to 10–30% Ba).

Big number varieties of P. sh. conditioned complex relationships composition [of the main components and impurities], the ordering of the distribution of Al and Si in structural positions, the decomposition of solid solutions, submicroscopic twinning.

Among the essential potassium P. sh. distinguish between sanidine, which has monoclinic symmetry, with a disordered distribution of Si and Al, a maximum microcline (triclinic) with a completely ordered distribution of Si and Al, intermediate microclines, and an orthoclase (presumably pseudomonoclinic), consisting of submicroscopically twinned triclinic domains.

High-temperature kalinatrovye P. sh. are disordered and form a continuous series of solid solutions; low-temperature ones undergo disintegration with the formation of perthites—regular germination of microcline or orthoclase and soda P. sh. – albite. All varieties of plagioclases are high-temperature (disordered in relation to the distribution of aluminum and silicon), low-temperature (ordered) and intermediate.

Changes in the degree of order and composition of plagioclases manifest themselves, while maintaining triclinic symmetry, in very complex changes in the structure and in the formation of two regions of extremely fine immiscibility - in the series of oligoclases and labradors, accompanied by iridescence.

Precise definitions of the composition and structural state (orderliness) P. sh. are carried out using diagrams of optical orientation, angles of optical axes, etc., measured on a Fedorov table, as well as radiographic (diffractometric) methods.

Plagioclases and microclines are almost always polysynthetically twinned; form microscopic intergrowths of many individuals according to various characteristic twin laws .

Tabular or prismatic shape P. sh. in rocks it is determined by well-developed faces (010) and (001), along which perfect cleavage is formed at a right angle or close to it, and by faces (110). Hardness P. sh. according to the mineralogical scale 6–6.5; density 2500–2800 kg / m 3 P. sh. themselves are colorless: various colors (gray, pink, red, green, black, etc.) are given to them by the smallest inclusions of hematite, iron hydroxides, hornblende, pyroxene, etc.; The color of amazonite, a blue-green or green microcline, is associated with the Pb electronic center that replaces K. In the luminescence spectra of P. sh. the bands of Pb 2+ , Fe 3+ , Ce 3+ , Eu 2+ differ. According to the spectra of electron paramagnetic resonance in P. sh. electronic centers Ti 3+ and hole centers Al–O - –Al are established, which are formed as a result of capture by defects of the lattice, respectively, of an electron or a hole.

P. sh. serve as the basis for the classification of rocks. The most important types of rocks are mainly composed of P. sh.: intrusive - granites, syenites (alkaline P. sh. and plagioclases), gabbro, diorites (plagioclases); effusive - andesites, basalts; metamorphic - gneisses, crystalline schists, contact and regionally metamorphosed rocks, pegmatites. In sedimentary rocks P. sh. occur in the form of detrital grains and neoplasms (authigenic P. sh.). Lunar rocks (lunar basalts, gabbro, anorthosites) contain only plagioclases.

The value of P. sh. is determined by the fact that, due to the wide variations in composition and properties, they are used in geological and petrographic studies of massifs of igneous and metamorphic rocks. Isotope ratio 40 K / 40 Ar of potassium hydroxide P. sh. used to determine the absolute age of rocks .

Alkaline P. sh. pegmatites and low-iron rocks are used in the ceramic, glass, porcelain and faience industries. Feldspar rocks (labradorites) serve as facing material. Amazonite, moonstone (iris oligoclase) are used as ornamental stones.

Micas, a group of minerals - aluminosilicates of a layered structure with the general formula R 1 R 2-3 (OH, F) 2, where R 1 = K, Na; R 2 \u003d Al, Mg, Fe, Li (see Natural silicates). The main structural element of S. is represented by a three-layer package of two tetrahedral layers with an octahedral layer located between them, consisting of R 2 cations. Two of the six oxygen atoms of the octahedra are replaced by hydroxyl groups (OH) or fluorine. The packets are linked into a continuous structure through K + (or Na +) ions with a coordination number of 12. According to the number of octahedral cations in the chemical formula, dioctahedral and trioctahedral C. are distinguished: Al + cations occupy two of the three octahedra, leaving one empty, while Mg cations 2 + , Fe 2+ and Li + with Al + occupy all octahedra. C. crystallize in a monoclinic (pseudotrigonal) system. The relative arrangement of the hexagonal cells of the surfaces of three-layer packages is due to their rotation around the axis With at various angles, multiples of 60°, in combination with a shift along the axes A And V elementary cell. This determines the existence of polymorphic modifications (polytypes) of S., distinguished radiographically. Monoclinic symmetry polytypes are common.

By chemical composition distinguish the following groups of S. Aluminum S.:

muscovite KAl 2 (OH) 2,

paragonite NaAl 2 (OH) 2,

magnesian-ferruginous S.:

phlogopite KMg 3 (OH, F) 2,

lepidomelan Kfe 3 (OH, F) 2 ;

lithium:

lepidolite Kli 2-x Al 1+x (OH. F) 2 ,

zinnwaldite KLiFeAl (OH, F) 2

Tainiolite KLiMg 2 (OH, F) 2 .

There are also vanadium S. - roscoelite KV 2 (OH) 2, chromic S. - chromic muscovite, or fuchsite, etc. Isomorphic substitutions are widely manifested in S.: K + is replaced by Na +, Ca 2+, Ba 2+, Rb + , Cs + and others; Mg 2+ and Fe 2+ of the octahedral layer - Li +, Sc 2+, Jn 2+, etc.; Al 3+ is replaced by V 3+ , Cr 3+ , Ti 4+ , Ga 3+ etc. Perfect isomorphism between Mg 2+ and Fe 2+ (continuous solid solutions of phlogopite - biotite) and limited isomorphism between Mg 2+ - Li + and Al 3+ –Li + , as well as a variable ratio of oxide and ferrous iron. In tetrahedral layers, Si 4+ can be replaced by Al 3+ , and Fe 3+ ions can replace tetrahedral Al 3+ ; the hydroxyl group (OH) is replaced by fluorine. S. often contain various rare elements (Be, B, Sn, Nb, Ta, Ti, Mo, W, U, Th, Y, TR, Bi); often these elements are in the form of submicroscopic minerals-impurities: columbite, wolframite, cassiterite, tourmaline, etc. When K + is replaced by Ca 2+, minerals of the so-called group are formed. brittle S. - margarite CaAl 2 (OH) 2, etc., harder and less elastic than S. proper. When interlayer cations K + are replaced by H 2 O, a transition to hydromicas, which are essential components of clay minerals, is observed. Consequences of the layered structure of S. and the weak connection between the packages: the lamellar appearance of minerals, perfect (basal) cleavage, the ability to split into extremely thin leaves that retain flexibility, elasticity and strength. S.'s crystals can be twinned according to the "mica law" with the intergrowth plane (001); often have pseudohexagonal outlines. Hardness on a mineralogical scale 2.5–3; density 2770 kg / m 3(muscovite), 2200 kg / m 3(phlogopite), 3300 kg / m 3(biotite). Muscovite and phlogopite are colorless and transparent in thin plates; shades of brown, pink, green are due to impurities Fe 2+, Mn 2+, Cr 2 + Glandular S. - brown, brown, dark green and black, depending on the content and ratio of Fe 2 + and Fe3+. S. is one of the most common rock-forming minerals in intrusive, metamorphic, and sedimentary rocks, as well as an important mineral resource.

There are 3 types of industrial S.: sheet S.; small S. and scrap (waste from the production of sheet S.); intumescent S. (for example, vermiculite). Industrial deposits of high-quality sheet silver (muscovite and phlogopite) are rare. Industrial requirements for sheet S. are reduced to the perfection of crystals and their sizes; to fine S. - the purity of the mica material. Large muscovite crystals are found in granitic pegmatites (Mamsko-Chuysky district of the Irkutsk region, Chupino-Lukhsky district of the Karelian ASSR, Ensko-Kolsky district of the Murmansk region - in the USSR, deposits of India, Brazil, USA). Phlogopite deposits are confined to massifs of ultrabasic and alkaline rocks (Kovdorskoye on the Kola Peninsula) or to deeply metamorphosed Precambrian rocks of primary carbonate (dolomite) composition (Aldan mica-bearing region of the Yakut ASSR, Slyudyansky region on Lake Baikal in the USSR), as well as to gneisses (Canada and Malagasy Republic). Muscovite and phlogopite are high-quality electrical insulating materials indispensable in electrical, radio and aircraft engineering. Deposits of lepidolite, one of the main industrial minerals of lithium ores, are associated with granitic pegmatites of the soda-lithium type. In the glass industry, special optical glasses are made from lepidolite.

S. is developed by underground or open methods with the use of drilling and blasting. S.'s crystals are selected manually from the rock mass.

Methods developed industrial synthesis C. Large sheets obtained by gluing C. plates (micanites) are used as a high-quality electrical and thermal insulating material. From scrap and fine sugar, ground sugar is obtained, which is consumed in the construction, cement, and rubber industries, in the production of paints, plastics, and so on. Small S. is especially widely used in the USA.

3. Behavior in various geological processes

It exists in water as the K+ cation. Potassium plays an important role in the life of plants and animals. It takes part in photosynthesis, affects the metabolism of carbohydrates, nitrogen and phosphorus. Therefore, potassium is eagerly absorbed by plants and is actively involved in the biological cycle. Its clarke in living matter is very high and is 0.3%, like that of nitrogen. It is important to note that potassium, like phosphorus, is concentrated in fruits and seeds, in intensively growing plant organs. With a lack of potassium in the soil, the crop yield is sharply reduced. A significant part of K+ cations from natural waters is captured by land plants. In addition, a huge amount of cations of this element absorb (sorb) clay minerals. As a result, only a small part of this element enters the runoff basins in comparison with its amount in the deep rocks that have undergone weathering. The living matter of the land and the products of weathering (clay) firmly retain potassium. Therefore, 1,206 million tons of potassium participate in the annual biological cycle on the continents, and only 920 million tons in the World Ocean. The average potassium content in sea water is low - 0.038%. Potassium delivered by rivers is consumed very quickly. Partially, it is absorbed by living organisms, but significant masses of the element leave by some as yet unknown ways. The "disappearance" of potassium from the ocean is another mystery of geochemistry. According to A.P. Vinogradov, only 2.6% of the amount that was brought by rivers remained in the World Ocean.

One of the cycles of its migration, potassium begins from the soil. It is extracted from it by the roots of plants, accumulates in their dead remains, partially passes into the body of an animal or a person, and returns with humus to the soil from which it was extracted by a living cell.
Most of the potassium follows this path, but individual atoms manage to reach the large oceans and, together with other salts, determine the salinity of sea water, although it still contains forty times more sodium atoms than potassium.

Potassium is one of the 6 main elements (oxygen, silicon, aluminum, iron, calcium, potassium) that make up 96% of all soil chemicals. It contains 2.5% in the earth's crust. As life developed on earth, potassium from rocks was actively involved in the biological cycle, passed into a mobile state, and, in accordance with the intensity and direction of regional biological processes, accumulated in the root layer of the soil, being fixed in its mineral and organic parts, leached due to migration and erosion, alienated with biomass.

In the soil, in contrast to the parent rock, potassium is found not only in mineral structures, but also in a complex organomineral colloidal complex, residues of plant, animal and microbiological origin.

The state and regime of potassium in the horizons of the soil profile are closely related to the mineralogical composition of parent rocks, their granulometric composition, zonal specificity, and the nature of land use. The minerals that determine the total content of potassium in the soil (about 1.5% on average) and in the parent rock are mainly potassium feldspars, micas, and illites.

Usually no more than 5% of potassium is available to plants in clay soils and 1.5% in sandy ones. The mineralogical and organomineral composition of the soil determines such an important property as the ability to fix or absorb potassium. Potassium fixation increases as the soil dries out. Sometimes fixed potassium is retained by minerals so firmly that it becomes inaccessible to plants. Potassium fixation is especially pronounced on fairly “depleted” soils. The restriction in the provision of plants with potassium with a decrease in soil moisture arises not only as a result of fixation processes, but also as a result of a weakening of the rate of potassium movement to the roots.

The movement of most nutrients in the soil to the root system is carried out either by diffusion or together with soil moisture. Diffusion fluxes are the main route of potassium transport from the soil to the plant. They are created with the appearance of a concentration gradient of the element as a result of its absorption by the roots. As well as the movement of water, it occurs when there is a gradient of water potential in the soil-plant system. The more developed the aerial parts of the plant and the higher their need for water and nutrients, the higher the corresponding gradient. The supply of potassium to plants with a mass flow of water is not large and sharply weakens as they age. The dimensions of potassium diffusion are closely related to the processes of interaction of its various forms in the soil, its moisture content, and the adsorption capacity of the root system.

At high humidity of the environment, the roots mobilize potassium from a larger volume of soil, which increases the degree of its availability even at a low content. On the contrary, at low humidity, the possibility of diffusion is limited, despite the high concentration gradient.

Weakened provision of plants with potassium can be observed not only in the arid zone, but also in a temperate climate during the period of lack of precipitation, which often coincides with periods of maximum potassium consumption. The introduction of potash fertilizers without taking into account regional weather conditions may not give the expected effect.

Another reason for the insufficient supply of potassium to plants may be the limited rate of transition from the absorbed state to the available state, which does not correspond to the size of its consumption by plants. For example, potassium consumption by potatoes per day can reach 5 or even 10 kg/ha. Only thanks to a scientifically based fertilization system can a daily deficiency in potassium nutrition be avoided.

Along with the parameters characterizing soil properties (potential reserves of potassium, buffer capacity, granulometric composition, acidity, content of humus and nutrients, depth and properties of the root layer), it is necessary to take into account the factors of water and heat balance, comparing all this with the expected productivity of agricultural crops and features of their potassium nutrition.

The optimal regime of potassium nutrition of plants, providing a given productivity, can only be created using a systematically determined block of indicators. Their number and frequency of determination depend on the task and zonal conditions.

So, taking into account the stock of potassium forms available for plants in the soil is very important, since modern agriculture is unthinkable without a sufficient level of potassium nutrition for agricultural crops.

4. Deposits

There is a precedent in geological science when a whole epoch in the history of the earth - Perm - got its name from the name of a settlement - a city in the western Urals, the capital of the Perm Territory. In 1841, the English geologist Roderick Murchison (Murchison, 1792-1871), traveling in the Urals, discovered the Permian period - the last (sixth) system of the Paleozoic era of the Earth's history (follows the Carboniferous period and precedes the Triassic period of the Mesozoic era). The beginning of Perm is determined at 285 million years ago, and the duration is 55 million years.

Over 250 million years ago, during the Permian period of the Paleozoic era, the vast Perm Sea was located almost over the entire territory of modern Eurasia. However, the rise of vast platform areas divided the giant sea into semi-noticeable pools - lagoons. Under the influence of the sun, the concentration of salts in the lagoons increased sharply, and then sodium, potassium, and magnesium salts began to precipitate. Thus, one of the world's largest deposits of potassium-magnesium salts (VMKMS) was gradually formed over many millennia.

The field is located in the Western Urals, in the Perm region and is a giant lenticular deposit with an area of 6.5 thousand km 2 , elongated from north to south by 200 km and up to 50 km wide.

Salt formations belong to the Filippovsky (anhydrites, carbonates) and Irensky (anhydrites, salts) horizons of the Kungurian stage of the Lower Permian and the lower part of the Solikamsk horizon (clays, marls, salts) of the Ufimian stage of the Upper Permian. The carbonate-sulfate type of the section of the Filippovsky horizon (limestones, dolomites, anhydrites) is widespread in most of the Solikamsk depression. The Irensky horizon (Bereznikovskaya suite) includes clay-anhydrite, salt-bearing and transitional strata. The salt-bearing sequence is divided into underlying rock salt (140–400 m), sylvinite (20 m), sylvinite–carnallite (60–70 m) zones, and cover rock salt (0–55 m). After the Saskatchewan deposit (Canada, 37% of the world's reserves of potassium salts), the Kama deposit is the largest in the world. Reserves of only potash salts at the Verkhnekamskoye deposit in categories A + B + C1 + C2 are more than 120 billion tons. This is 31.4% of the world's potassium chloride reserves.

The global potash industry has recently experienced several shocks. In October last year, the market was alarmed by the news about the accident at the Uralkali mine in Berezniki (Perm Territory), in January 2007, the North American company Mosaic announced the possibility of stopping production at one of its mines due to an emergency. Flooding of mines - the main risk for the potash industry since its inception in the century before last - still happens.

Today, the global potash industry is on the rise. Stable demand for potash fertilizers is ensured by all agriculturally developed countries, while China, Brazil and India, which are experiencing economic growth, increase their purchases of potassium chloride from year to year, heating up demand in international markets.

The largest potassium deposits are located in the Canadian province of Saskatchewan and in the Russian Verkhnekamye (Perm Territory). Russia, which annually produces about 10 million tons of potassium chloride, accounts for about 20 percent of world production. Potassium is also mined by Belarusians, Germans, Israelis, Jordanians - in total there are about a dozen more or less large producers in the world who sell it to consumers from 150 countries. And aggravation of competition among potash producers is not expected in the near future. After all, in order to create a potash production with a capacity of 1 million tons per year from scratch at an already explored deposit, according to Canadian potash workers, it is necessary to invest at least $1 billion, moreover, the first tons of fertilizers can be obtained in 5-7 years.

Of course, in the potash industry, along with profitable production, there are certain risks. The risks are due to the fact that potassium, magnesium and sodium salts are soluble when groundwater enters the mine space. This theoretically can lead to subsidence of the earth's surface.

The first potash mine near the German town of Aschersleben sank in 1886. Since then, about 80 more mines located on different continents have shared its fate. None of them have ever been saved from flooding.

Each potash deposit has its own characteristics. For example, dome-shaped deposits are often found in Germany. For Canada, a columnar occurrence of salts is typical, in which they are located almost vertically. The Verkhnekamskoye deposit is practically flat, and the potassium here is deposited in layers at a depth of 300–500 meters. Wherein the main task when extracting potassium, leave the upper and lower layers intact. Going beyond them is fraught with an influx of groundwater and subsequent flooding of the mine. Neglect of this rule leads to disastrous results. In particular, even in late XIX– at the beginning of the 20th century, several mines in Germany (Aschersleben-3, Asse-1, Gedwigsburg, etc.) were flooded due to the extraction of cainite, a sparingly soluble mineral that is located in the roof of a salt dome and, together with other insoluble rocks, forms a “hat”, protecting the deposit from groundwater.

North American potash producers could not avoid problems either. At the connected K-1 and K-2 mines near Esterhazy, Canada, Mosaic has been extracting potash under brine flow conditions for several years. At the end of January 2007, the flow of brines into the Mosaic mine increased sharply - up to 25 thousand gallons per minute (US gallon is 3.79 liters). The company's management said that if the brine flow does not decrease, it will consider the issue of mothballing the mine. However, already in early March, Mosaic announced that the inflow had stabilized at the level of 5 thousand gallons per minute, which allows further exploitation of the mine.

Flooding can last from a few days to several years. An example of catastrophic flooding was the mine of the French-Congolese company "Company de potas du Congo", which developed a deposit in the Congo. The potash mine she built did not work even for several years. In 1977, within three days, the flow of brines into the mine increased from 17 to 10,000 cubic meters. m/hour.

The first case of mine flooding in our country occurred in 1986. Then the accident occurred near Berezniki at the mining department No. 3 of Uralkali. A small trickle of water in a few weeks turned into a powerful stream. Soon the mine had to be closed, and a few months later, a funnel about a hundred meters deep formed at the site of water breakthrough into the mine - groundwater eroded the salt layer, a void formed in the bowels, into which the overlying layers collapsed.

The next accident happened 9 years later in the northern part of the Verkhnekamskoye field, which is being developed by the Silvinit company. On January 5, 1995, as a result of an earthquake with a magnitude of 5 on the Richter scale at the mine of the second mining department of Silvinit OJSC, a sinkhole with a depth of more than four meters was formed within a few seconds on an area of 950 by 750 m. Two mines were at once under the threat of flooding, which at one time, in order to facilitate the task of mine builders, were connected by a working. In addition, there is a risk for residential development in Solikamsk, under which the mine is located. From a large-scale catastrophe, the city was then saved by a happy accident. A 20-meter layer of plastic clay descended from the overlying layers, which “sealed” the aquifer, preventing water from entering the mine.

Then the authorities of the Perm region and industrial enterprises were seriously concerned about the possibility of new accidents. The Verkhnekamskoye field began to be actively developed in the 1930s–1950s. In those years, the country was in dire need of raw materials for non-ferrous metallurgy and fertilizers, and there was no time to think about the dangers that a not too thoughtful development of the deposit could lead to. When the risks of underground salt mining were studied in more detail, the cities of Berezniki and Solikamsk were already built over the mines.

Scientists believe that the most effective measure of protection against possible surface subsidence as a result of the development of deposits is the backfilling of voids with waste from potash production - rock salt. From the beginning of the development of the deposit in the 1930s until the order of the USSR Ministry of Chemical Industry in 1971, the laying was not carried out in principle. During this time, millions of cubic meters of voids have accumulated under the cities. But even after the order, stowing work was financed by the state on a residual basis. It was only in 2002 that the legislature of the Perm region adopted programs for filling voids near Berezniki and Solikamsk. Both programs were expected to be completed by 2008. More than 70 percent of the funding was provided by the Uralkali and Silvinit companies, the rest - the regional budget and local budgets.

In Berezniki, the program was carried out ahead of schedule. By mid-2006, it was more than 90 percent complete. As a result, surface subsidence has practically ceased in the city. An accident prevented the completion of the backfilling work.

In October 2006, the mine of the first mining department of Uralkali began to receive water from the brine horizon. After 10 days, the brine flow sharply intensified up to 1200 cubic meters per hour. Pumping equipment could no longer cope with it, and the mine had to be closed.

The reasons for what happened at the first potash plant in Berezniki were examined by a state commission formed by Rostekhnadzor. As follows from her final protocol, main reason accidents became features of the geological structure of this section of the Verkhnekamskoye field. “There was a very complex and rare geological anomaly here,” explained Stanislav Yuzhanin, head of the Perm Interregional Department of Rostekhnadzor. – There is usually clay above the brine horizon. In this place, it is absent and replaced by a readily soluble rock. Part of it was washed away by groundwater, resulting in a weakened zone.” Another factor that influenced the situation was the extraction of potash ore in the emergency area on two layers at once, located one under the other. Ore mining was carried out in the 60s of the last century according to regulatory documents that time. The ban on the development of two seams under the urban area was introduced only in the 1970s. But under the influence of increased subsidence of rocks in the weakened zone, the water-protective thickness of the mine cracked, and the waters of the brine horizon poured into it.

For the life of Berezniki, the accident did not have dramatic consequences due to the almost completed backfilling work, however, it affected the urban infrastructure located in the accident zone. Breakthrough of the water-protective layer occurred in the area railway and the gas pipeline leading to the local thermal power plant, which means that the failure with a high degree of probability should occur there. Within two weeks after the accident, TGC-9 built a new gas pipeline. The movement of passenger trains in the dangerous section was stopped, and a bypass track was built in a short time.

The accident at the first mine of Uralkali is one of the most difficult in the history of the potash industry. If only because there are no cases in the world when an emergency mine was located directly under an industrial city with a population of 180 thousand people. But there were situations when smaller settlements were located on the surface.

Most of the cases of flooding occur in Germany. Only in the vicinity of Stasfurt and Aschersleben there are about 30 mines, most of which were flooded at the end of the 19th - beginning of the 20th century.

The consequences of the flooding of the mine in Ronnenberg (a suburb of Hannover) were very dramatic. When more than 7 million cubic meters of water entered the potash mine in the summer of 1975 within two weeks, surface subsidence reached 25 cm per day, and cracks began to appear in the houses, some of the inhabitants of Ronnenberg even had to be evacuated. True, after a few days they returned to their homes. Now in this city it is difficult to find even a hint of traces of past destruction - all the houses have long been repaired and put in order, and only a salt dump on the outskirts reminds of the potash past of the city.

Bibliographic list

1. English, vol. 3, M., 1966; Bykhover N.A., Economics of mineral raw materials, M., 1969; Volkov K.I., Zagibalov P.N., Metsik M.S., Properties, extraction and processing of mica, [Irkutsk], 1971.

2. Potassium, in the book: Brief Chemical Encyclopedia, v. 2, M., 1963; Nekrasov B.V., Fundamentals of General Chemistry, vol. 3, M., 1970; Remi G., Course of inorganic chemistry, trans. from German, vol. 1, M., 1963.

3. Dir U.A., Howie R.A., Zusman L. Zh., Rock-forming minerals, transl. from English, vol. 4, M., 1966; Marfunin A.S., Feldspars - phase relationships, optical properties, geological distribution, M., 1962.

4. Kaplansky S.Ya., Mineral exchange, M. - L., 1938; Vishnyakov S.I., Metabolism of macronutrients in farm animals, M., 1967; Sutcliff J.-F., Absorption of mineral salts by plants, trans. from English, M., 1964.

Chemical element potassium

Introduction

1. Potassium

(Kalium), K, a chemical element of the 1st group of the periodic system of Mendeleev; atomic number 19, atomic mass 39.098; silver-white, very light, soft and fusible metal. The element consists of two stable isotopes - 39K (93.08%), 41K (6.91%) and one weakly radioactive 40K (0.01%) with a half-life of 1.32×109 years.

Some compounds of K. (for example, potash, extracted from wood ash) were already known in antiquity; however, they were not distinguished from sodium compounds. Only in the 18th century a distinction was made between "vegetable lye" (potash K2CO3) and "mineral lye" (soda Na2CO3). In 1807, G. Davy isolated potassium and sodium by electrolysis of slightly moistened solid caustic potash and sodium (KOH and NaOH) and named them potassium and sodium. In 1809 L.V. Gilbert proposed the name "potassium" (from Arabic al-kali - potash) and "natronium" (from Arabic natrun - natural soda); last I.Ya. Berzelius in 1811 changed to "sodium". The names "potassium" and "sodium" have been preserved in Great Britain, the USA, France and some other countries. In Russia, these names in the 1840s. were replaced by "potassium" and "sodium", adopted in Germany, Austria and the Scandinavian countries.

2. Distribution in nature

Potassium is a common element: the content in the lithosphere is 2.50% by weight. In magmatic processes, potassium, like sodium, accumulates in acid magmas, from which granites and other rocks crystallize (the average content of potassium is 3.34%). K. is a part of feldspars and micas. In basic and ultrabasic rocks rich in iron and magnesium, there is little calcium. On the earth's surface, sodium, unlike sodium, migrates weakly. During the weathering of rocks, K. partially passes into water, but from there it is quickly captured by organisms and absorbed by clay, so the waters of rivers are poor in K. and much less of it enters the ocean than sodium. In the ocean, K. is absorbed by organisms and bottom silts (for example, it is part of glauconite); therefore, oceanic waters contain only 0.038% K. - 25 times less than sodium. In past geological epochs, especially in the Permian period (about 200 million years ago), at the late stages of evaporation of sea water in lagoons, after the precipitation of NaCl, K. and magnesium salts crystallized - carnallite KCICHMgCI2CH6H2O, etc. (Solikamsk deposit in the USSR, Shtasfurt in GDR, etc., see Potassium salts). There are few soluble potassium compounds in most soils, and cultivated plants need potassium fertilizers.

The radioactive isotope 40K is an important source of deep heat, especially in past epochs when this isotope was abundant. The decay of 40K produces 40Ca and 40Ar argon, which escapes into the atmosphere. Some minerals of K. do not lose argon, and its content can be used to determine the absolute age of rocks (the so-called potassium-argon method).

K. is one of the biogenic elements, a constant component of plants and animals. The daily requirement for K. in an adult (2–3 g) is covered by meat and plant products; in infants, the need for K. (30 mg / kg) is completely covered by breast milk, in which 60-70 mg% K. Many marine organisms extract K. from the water. Plants receive K. from the soil. In animals, the content of K. averages 2.4 g/kg. Unlike sodium, K. is concentrated mainly in cells, in the extracellular environment it is much less. In the cell, K. is unevenly distributed.

K. ions participate in the generation and conduction of bioelectric potentials in nerves and muscles, in the regulation of contractions of the heart and other muscles, maintain osmotic pressure and hydration of colloids in cells, and activate certain enzymes. Metabolism To. is closely connected with a carbohydrate exchange; K.'s ions influence protein synthesis. K + in most cases cannot be replaced by Na +. Cells selectively concentrate K+. Inhibition of glycolysis, respiration, photosynthesis, violation of the permeability of the outer cell membrane lead to the release of K + from cells, often in exchange for Na +. K. is allocated from an organism mainly with urine. The content of K. in the blood and tissues of vertebrates is regulated by adrenal hormones - corticosteroids. K. is distributed unevenly in plants: there is more of it in the vegetative organs of the plant than in the roots and seeds. There is a lot of K. in legumes, beets, potatoes, tobacco leaves, and fodder cereal grasses (20–30 g/kg of dry matter). With a lack of K. in soils, plant growth slows down, and the incidence increases. The rate of potash fertilizers depends on the type of page - x. crops and soils.

In the biosphere, trace elements Rb and Cs accompany K. Li+ and Na+ ions are K+ antagonists; therefore, not only the absolute concentrations of K+ and Na+ are important, but also the optimal ratios of K+/Na+ in cells and the environment. The natural radioactivity of organisms (gamma radiation) is almost 90% due to the presence of the natural radioisotope 40K in the tissues.

In medicine, for therapeutic purposes, CH3COOK acetate is used as a diuretic (often against edema caused by heart failure) and KCl chloride in case of K deficiency in the body (it develops during treatment with certain hormonal drugs, digitalis, with a large loss of fluid with vomiting and diarrhea, when used some diuretics, etc.). Perchlorate KClO4 inhibits the production of thyroxine (thyroid hormone) and is used for thyrotoxicosis. Potassium permanganate KMnO4 (potassium permanganate) is used as an antiseptic.

Polev s e w A you, a group of the most common rock-forming minerals that make up more than 50% of terrestrial and lunar rocks and are included in meteorites. Composition P. sh. is determined mainly by the ratio of components in the ternary system: NaAISi3O8 – KAISi3O8 – CaAl2Si2O8, i.e. these are Na, K, Ca aluminosilicates (with an admixture of Ba, Sr, Pb, Fe, Li, Rb, Cs, Eu, Ce, etc.). The basis of the structure of all P. sh. are a three-dimensional framework consisting of tetrahedral groups (Al, Si) O4, in which from one third to a half of the Si atoms are replaced by Al. Large cavities of this framework contain monovalent K+ and Na+ cations (at Al:Si = 1:3) or divalent Ca2+ and Ba2+ cations (at Al:Si = 1:2).

In the P. sh. two series of solid solutions are distinguished: KAISi3O8 - NaAISi3O8 (potassium, or alkaline, P. sh. and NaAISi3O0 - CaAI2Si2O8 - plagioclases). Barium P. sh are seldom found. BaAI2Si2O8 – Celsian and solid solutions KAISi3O0 – BaAl2Si2O8 – hyalophane (up to 10–30% Ba).

A large number of varieties of P. sh. due to complex ratios of the composition [of the main components and impurities], the orderliness of the distribution of Al and Si in structural positions, the decomposition of solid solutions, submicroscopic twinning.

Plagioclases and microclines are almost always polysynthetically twinned; form microscopic intergrowths of many individuals according to various characteristic twin laws.

Tabular or prismatic shape P. sh. in rocks it is determined by well-developed faces (010) and (001), along which perfect cleavage is formed at a right angle or close to it, and by faces (110). Hardness P. sh. according to the mineralogical scale 6–6.5; density 2500–2800 kg/m3 F. w. themselves are colorless: various colors (gray, pink, red, green, black, etc.) are given to them by the smallest inclusions of hematite, iron hydroxides, hornblende, pyroxene, etc.; The color of amazonite, a blue-green or green microcline, is associated with the Pb electronic center that replaces K. In the luminescence spectra of P. sh. the Pb2+, Fe3+, Ce3+, and Eu2+ bands differ. According to the spectra of electron paramagnetic resonance in P. sh. Ti3+ electronic centers and Al–O–Al hole centers are established, which are formed as a result of the capture of an electron or a hole by lattice defects, respectively.

The value of P. sh. is determined by the fact that, due to the wide variations in composition and properties, they are used in geological and petrographic studies of massifs of igneous and metamorphic rocks. The ratio of 40K/40Ar isotopes of potassium hydroxide P. sh. used to determine the absolute age of rocks.

sl Yu dy, a group of minerals - aluminosilicates of a layered structure with the general formula R1R2-3 (OH, F)2, where R1 = K, Na; R2 = Al, Mg, Fe, Li (see Natural silicates). The main structural element of S. is represented by a three-layer package of two tetrahedral layers with an octahedral layer located between them, consisting of R2 cations. Two of the six oxygen atoms of the octahedra are replaced by hydroxyl groups (OH) or fluorine. The packets are linked into a continuous structure through K+ (or Na+) ions with a coordination number of 12. According to the number of octahedral cations in the chemical formula, dioctahedral and trioctahedral C. are distinguished: Al+ cations occupy two of the three octahedra, leaving one empty, while Mg2+, Fe2+ cations and Li+ with Al+ occupy all octahedra. C. crystallize in a monoclinic (pseudotrigonal) system. The relative arrangement of the hexagonal cells of the surfaces of the three-layer packages is due to their rotation around the c axis at different angles, multiples of 60°, in combination with a shift along the a and b axes of the elementary cell. This determines the existence of polymorphic modifications (polytypes) of S., distinguished radiographically. Monoclinic symmetry polytypes are common.

According to the chemical composition, the following groups of S. Aluminum S. are distinguished:

muscovite KAl2(OH)2,

paragonite NaAl2 (OH)2,

magnesian-ferruginous S.:

phlogopite KMg3 (OH, F)2,

lepidomelan Kfe3 (OH, F)2;

lithium:

lepidolite Kli2-xAl1+x (OH. F)2,

zinnwaldite KLiFeAl (OH, F)2

tainiolite KLiMg2 (OH, F)2.

There are also vanadium steels—roscoelite KV2(OH)2, chromic silver—chromium muscovite, or fuchsite, and others. Isomorphic substitutions are widely manifested in silver: K+ is replaced by Na+, Ca2+, Ba2+, Rb+, Cs+, and others; Mg2+ and Fe2+ of the octahedral layer - Li+, Sc2+, Jn2+, etc.; Al3+ is replaced by V3+, Cr3+, Ti4+, Ga3+, etc. Perfect isomorphism between Mg2+ and Fe2+ (continuous solid solutions of phlogopite - biotite) and limited isomorphism between Mg2+ - Li+ and Al3+ - Li+, as well as a variable ratio of oxide and ferrous iron are observed. In tetrahedral layers, Si4+ can be replaced by Al3+, and Fe3+ ions can replace tetrahedral Al3+; the hydroxyl group (OH) is replaced by fluorine. S. often contain various rare elements (Be, B, Sn, Nb, Ta, Ti, Mo, W, U, Th, Y, TR, Bi); often these elements are in the form of submicroscopic minerals-impurities: columbite, wolframite, cassiterite, tourmaline, etc. When K + is replaced by Ca2 +, minerals of the so-called group are formed. Brittle S. - margarite CaAl2 (OH) 2, etc., are harder and less elastic than S. proper. When interlayer K + cations are replaced by H2O, a transition to hydromicas, which are essential components of clay minerals, is observed. Consequences of the layered structure of S. and the weak connection between the packages: the lamellar appearance of minerals, perfect (basal) cleavage, the ability to split into extremely thin leaves that retain flexibility, elasticity and strength. S.'s crystals can be twinned according to the "mica law" with the intergrowth plane (001); often have pseudohexagonal outlines. Hardness on a mineralogical scale 2.5–3; density 2770 kg/m3 (muscovite), 2200 kg/m3 (phlogopite), 3300 kg/m3 (biotite). Muscovite and phlogopite are colorless and transparent in thin plates; shades of brown, pink, and green are due to impurities of Fe2+, Mn2+, Cr2+, and others. Ferrous S. are brown, brown, dark green, and black, depending on the content and ratio of Fe2+ and Fe3+. S. is one of the most common rock-forming minerals in intrusive, metamorphic, and sedimentary rocks, as well as an important mineral resource.

S. is developed by underground or open methods with the use of drilling and blasting. S.'s crystals are selected manually from the rock mass.

Methods have been developed for the industrial synthesis of S. Large sheets obtained by gluing S. plates (micanites) are used as a high-quality electrical and thermal insulating material. From scrap and fine sugar, ground sugar is obtained, which is consumed in the construction, cement, and rubber industries, in the production of paints, plastics, and so on. Small S. is especially widely used in the USA.

3. Behavior in various geological processes

4. Deposits

The field is located in the Western Urals, in the Perm region and is a giant lenticular deposit with an area of 6.5 thousand km2, stretched from north to south for 200 km and a width of up to 50 km.

Each potash deposit has its own characteristics. For example, dome-shaped deposits are often found in Germany. For Canada, a columnar occurrence of salts is typical, in which they are located almost vertically. The Verkhnekamskoye deposit is practically flat, and the potassium here is deposited in layers at a depth of 300–500 meters. At the same time, the main task in the extraction of potassium is to leave the upper and lower layers intact. Going beyond them is fraught with an influx of groundwater and subsequent flooding of the mine. Neglect of this rule leads to disastrous results. In particular, at the end of the 19th - beginning of the 20th century, several mines in Germany (Aschersleben-3, Asse-1, Hedwigsburg, etc.) were flooded due to the extraction of cainite, a sparingly soluble mineral that is located in the roof of a salt dome and, together with other forms a “hat” with insoluble rocks that protects the deposit from groundwater.

Page 1

Potassium metal, which does not have a wide industrial application, is obtained by electrolysis of molten potassium chloride. It was first obtained by Davy in 1807. After cesium and rubidium, it has the greatest reduction potential of all metals. It oxidizes rapidly in humid air and is usually stored in kerosene. It decomposes water so strongly that the hydrogen released burns with a violet flame.

Potassium metal in the amount necessary to obtain 1 g of hydride is placed in an iron boat with a total area of 5–10 cm2 in reactor A or B.

Potassium metal in the amount of 5 - 10 g is loaded into a 100 ml autoclave with a manometer containing a pinnate stirrer. The autoclave is purged with pure hydrogen and closed. Upon reaching 68 C (melting point of potassium), when the autoclave is heated, a stirrer is turned on. As hydrogen is absorbed by potassium, the latter is added to the autoclave from a balloon. The reaction is carried out in two modes.

Potassium metal in di-n-butyl ether decomposes hexaphenyldisilane, but this method has no advantages over the above method. Sodium dispersed in ether, tetraline, xylene, or dioxane does not degrade hexaphenyldisilane. However, triphenylsilyl sodium has not found such widespread use as triphenylsilyl lithium or triphenylsilyl potassium.

Potassium metal donates one electron to tetraphenylbutatriene.

Potassium metal is purified by melting under hot isooctane. The metal is washed several times with isooctane until it becomes shiny. After cooling, potassium is removed with tweezers and quickly placed in a thick-walled Pyrex tube; the tube is then evacuated and gently heated to melt the potassium, which is then distributed over its walls to form a mirror covering most of the surface. About 0.5 g of potassium is prepared in this way.

Potassium metal reacts with water even more vigorously than sodium, and therefore work must be done with particular care.

Potassium metal is usually obtained by electrolysis of molten KOH hydroxide or by reduction of its salts with sodium or calcium carbide.

Potassium metal is obtained by electrolysis of caustic potassium KOH.

Potassium metal is also used in metallothermy and in organic syntheses, and syntheses often use an exclusively active eutectic alloy.

Potassium metal is used to produce potassium peroxide. It serves as a catalyst in some organic syntheses. An alloy of potassium and sodium is used as a liquid metal coolant in nuclear reactors. Potassium is used in solar cells - devices that directly convert light energy into electrical energy. Potassium carbonate - potash K2CO3 is used in large quantities in the production of special types of glass. But the main use of potassium is as a fertilizer. More than 90% of the extracted potassium compounds are used for soil fertilization.

Metallic potassium is more active than sodium. It, like sodium, decomposes water, but ignites at the same time. During the combustion of potassium, potassium superoxide, or superoxide, K02 is mainly formed (p.

Potassium(Kalium), K, a chemical element of Group I of Mendeleev's Periodic Table; atomic number 19, atomic mass 39.098; silver-white, very light, soft and fusible metal. The element consists of two stable isotopes - 39 K (93.08%), 41 K (6.91%) and one weakly radioactive 40 K (0.01%) with a half-life of 1.32 10 9 years.

Historical reference. Some potassium compounds (for example, potash, extracted from wood ash) were already known in antiquity; however, they were not distinguished from sodium compounds. It was not until the 18th century that a distinction was made between "vegetable alkali" (potash K 2 CO 3) and "mineral alkali" (soda Na 2 CO 3). In 1807, G. Davy by electrolysis of slightly moistened solid caustic potash and sodium (KOH and NaOH) isolated Potassium and sodium and named them potassium and sodium. In 1809, L. V. Gilbert proposed the name "potassium" (from the Arabic al-kali - potash) and "sodium" (from the Arabic natrun - natural soda); I. Ya. Berzelius changed the latter to "sodium" in 1811. The names "potassium" and "sodium" have been preserved in Great Britain, the USA, France and some other countries. In Russia, these names in the 1840s were replaced by "potassium" and "sodium", adopted in Germany, Austria and the Scandinavian countries.

Distribution of potassium in nature. Potassium is a common element: the content in the lithosphere is 2.50% by weight. In magmatic processes, potassium, like sodium, accumulates in acidic magmas, from which granites and other rocks crystallize (average potassium content is 3.34%). Potassium is a constituent of feldspars and micas. In basic and ultrabasic rocks rich in iron and magnesium, there is little potassium. On the earth's surface, potassium, unlike sodium, migrates weakly. During the weathering of rocks, potassium partially passes into the water, but from there it is quickly captured by organisms and absorbed by clay, therefore the waters of the rivers are poor in potassium and much less potassium enters the ocean than sodium. In the ocean, potassium is absorbed by organisms and bottom silts (for example, it is part of glauconite); therefore, ocean waters contain only 0.038% potassium - 25 times less than sodium. In past geological epochs, especially in the Permian period (about 200 million years ago), at the late stages of evaporation of sea water in lagoons, after the precipitation of NaCl, potassium and magnesium salts crystallized - carnallite KCl MgCl 2 6H 2 O and others (Solikamsk deposit in Russia, Stasfurt in Germany, etc.). In most soils, soluble potassium compounds are scarce, and cultivated plants need potassium fertilizers.

The radioactive isotope 40 K is an important source of deep heat, especially in past epochs when this isotope was abundant. The decay of 40 K produces 40 Ca and argon 40 Ar, which escapes into the atmosphere. Some potassium minerals do not lose argon, and its content can be used to determine the absolute age of rocks (the so-called potassium-argon method).

Physical properties of potassium. Potassium is a silver-white, very light and soft metal (easily cut with a knife). The crystal lattice of Potassium is body-centered cubic, a = 5.33 Å. Atomic radius 2.36 Å, ionic radius K + 1.33 Å. Density 0.862 g / cm 3 (20 ° C), t pl 63.55 ° C, (bp 760 ° C; thermal expansion coefficient 8.33 10 -5 (0-50 ° C); thermal conductivity at 21 ° C 97 .13 W / (m-Potassium), specific heat (at 20 ° C) 741.2 J / (kg K), that is, 0.177 cal / (g ° C), electrical resistivity (at 20 ° C) 7.118 10 -8 ohm m, temperature coefficient of electrical resistance 5.8 10 -5 (20 ° C) Brinell hardness 400 kn / m 2 (0.04 kgf / mm 2).

Chemical properties of potassium. The configuration of the outer electron shell of the Potassium atom is 4s 1, according to which its valency in compounds is constantly equal to 1. The only valence electron of the Potassium atom is more distant from its nucleus than the valence electrons of lithium and sodium, therefore the chemical activity of Potassium is higher than these two metals. In air, especially humid, potassium is rapidly oxidized, as a result of which it is stored in gasoline, kerosene or mineral oil. At room temperature Potassium reacts with halogens; with weak heating, it combines with sulfur, with stronger heating, with selenium and tellurium. When heated above 200 °C in a hydrogen atmosphere, potassium forms hydride KH, which ignites spontaneously in air. Nitrogen and Potassium do not interact even when heated under pressure, but under the influence of an electric discharge, these elements form Potassium azide KN 3 and Potassium nitride K 3 N. When Potassium is heated with graphite, carbides KC 8 (at 300 ° C) and KC 16 (at 360°C). In dry air (or oxygen), Potassium forms yellowish-white oxide K 2 O and orange peroxide KO 2 (peroxides K 2 O 2 and K 2 O 3 are also known, obtained by the action of oxygen on a solution of Potassium in liquid ammonia).

Potassium very vigorously, sometimes with an explosion, reacts with water, releasing hydrogen (2K + 2H 2 O \u003d 2KOH + H 2), as well as with aqueous solutions of acids, forming salts. Potassium slowly dissolves in ammonia; the resulting blue solution is a strong reducing agent. When heated, Potassium takes away oxygen from oxides and salts of oxygen acids with the formation of K 2 O and free metals (or their oxides). Potassium with alcohols gives alcoholates, accelerates the polymerization of olefins and diolefins, with haloalkyls and haloaryls forms potassium alkyls and potassium aryls. The presence of potassium is easily identified by the violet color of the flame.

Getting Potassium. In industry, potassium is obtained by exchange reactions between metallic sodium and KOH or KCl, respectively: KOH + Na = NaOH + K, KCl + Na = NaCl + K.

In the first case, the reaction proceeds between molten KOH hydroxide and liquid Na - countercurrent in a plate reaction column made of nickel at 380-440 °C. In the second, Na vapors are passed through the molten KCl salt at 760-800 °C; the released potassium vapor condenses. It is also possible to obtain Potassium by heating mixtures of Potassium chloride with aluminum (or silicon) and lime above 200 °C. The production of Potassium by electrolysis of molten KOH or KCl is not very common due to the low current yields of Potassium and the difficulty of ensuring the safety of the process.

The use of potassium. The main use of potassium metal is the preparation of potassium peroxide, which serves to regenerate oxygen (in submarines and others). Sodium alloys with 40-90% potassium, which remain liquid at room temperature, are used in nuclear reactors as coolants, as reducing agents in titanium production, and as oxygen scavengers. Agriculture- the main consumer of potassium salts.

potassium in the body. Potassium is one of the biogenic elements, a constant component of plants and animals. The daily requirement for potassium in an adult (2-3 g) is covered by meat and vegetable products; in infants, the need for potassium (30 mg / kg) is completely covered by breast milk, in which 60-70 mg% of potassium. Many marine organisms extract potassium from the water. Plants get potassium from the soil. In animals, the potassium content is on average 2.4 g/kg. Unlike sodium, potassium is concentrated mainly in the cells, in the extracellular environment it is much less. In the cell, potassium is unevenly distributed.

Potassium ions are involved in the generation and conduction of bioelectric potentials in nerves and muscles, in the regulation of contractions of the heart and other muscles, maintain osmotic pressure and hydration of colloids in cells, and activate some enzymes. Potassium metabolism is closely related to carbohydrate metabolism; Potassium ions affect protein synthesis. K + in most cases cannot be replaced by Na + . Cells selectively concentrate K + . Inhibition of glycolysis, respiration, photosynthesis, violation of the permeability of the outer cell membrane lead to the release of K + from cells, often in exchange for Na +. Potassium is excreted from the body mainly with urine. The content of potassium in the blood and tissues of vertebrates is regulated by adrenal hormones - corticosteroids. Potassium is distributed unevenly in plants: there is more potassium in the vegetative organs of a plant than in roots and seeds. There is a lot of potassium in legumes, beets, potatoes, tobacco leaves and fodder cereal grasses (20-30 g/kg of dry matter). With a lack of potassium in soils, plant growth slows down, and morbidity increases. The rate of potash fertilizers depends on the type of crop and soil.

In the biosphere, the microelements Rb and Cs accompany Potassium. Li + and Na + ions are K + antagonists; therefore, not only the absolute concentrations of K + and Na + are important, but also the optimal ratios of K + /Na + in cells and the environment. The natural radioactivity of organisms (gamma radiation) is almost 90% due to the presence of the natural radioisotope 40 K in the tissues.

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Chemical element potassium