Minerals: Uranium ores. Uranium element

In recent years, the topic of nuclear energy has become increasingly relevant. To produce nuclear energy, it is common to use a material such as uranium. It is a chemical element belonging to the actinide family.

The chemical activity of this element determines the fact that it is not contained in free form. For its production, mineral formations called uranium ores are used. They concentrate such an amount of fuel that allows the extraction of this chemical element to be considered economically rational and profitable. At the moment, in the bowels of our planet the content of this metal exceeds the reserves of gold in 1000 times(cm. ). In general, deposits of this chemical element in soil, aquatic environment and rock are estimated at more than 5 million tons.

In the free state, uranium is a gray-white metal, which is characterized by 3 allotropic modifications: rhombic crystalline, tetragonal and body-centered cubic lattices. The boiling point of this chemical element is 4200 °C.

Uranium is a chemically active material. In air, this element slowly oxidizes, easily dissolves in acids, reacts with water, but does not interact with alkalis.

Uranium ores in Russia are usually classified according to various criteria. Most often they differ in terms of education. Yes, there are endogenous, exogenous and metamorphogenic ores. In the first case, they are mineral formations formed under the influence of high temperatures, humidity and pegmatite melts. Exogenous uranium mineral formations occur in surface conditions. They can form directly on the surface of the earth. This occurs due to the circulation of groundwater and the accumulation of sediments. Metamorphogenic mineral formations appear as a result of the redistribution of initially dispersed uranium.

According to the level of uranium content, these natural formations can be:

• super rich (over 0.3%);
• rich (from 0.1 to 0.3%);
• privates (from 0.05 to 0.1%);
• poor (from 0.03 to 0.05%);
• off-balance sheet (from 0.01 to 0.03%).

Modern uses of uranium

Today, uranium is most often used as fuel for rocket engines and nuclear reactors. Given the properties of this material, it is also intended to increase the power of a nuclear weapon. This chemical element has also found its application in painting. It is actively used as yellow, green, brown and black pigments. Uranium is also used to make cores for armor-piercing projectiles.

Mining uranium ore in Russia: what is needed for this?

The extraction of radioactive ores is carried out using three main technologies. If ore deposits are concentrated as close as possible to the surface of the earth, then it is customary to use open-pit technology for their extraction. It involves the use of bulldozers and excavators, which dig large holes and load the resulting minerals into dump trucks. Then it is sent to the processing complex.

When this mineral formation is located deeply, it is customary to use underground mining technology, which involves creating a mine up to 2 kilometers deep. The third technology differs significantly from the previous ones. In-ground leaching to develop uranium deposits involves drilling wells through which sulfuric acid is pumped into the deposits. Next, another well is drilled, which is necessary to pump the resulting solution to the surface of the earth. Then it goes through a sorption process, which allows the salts of this metal to be collected on a special resin. The last stage of SPV technology is cyclic treatment of the resin with sulfuric acid. Thanks to this technology, the concentration of this metal becomes maximum.

Uranium ore deposits in Russia

Russia is considered one of the world leaders in the mining of uranium ores. Over the past few decades, Russia has consistently ranked among the top 7 leading countries in this indicator.

The largest deposits of these natural mineral formations are:

The largest uranium mining deposits in the world - leading countries

Australia is considered the world leader in uranium mining. More than 30% of all world reserves are concentrated in this state. The largest Australian deposits are Olympic Dam, Beverly, Ranger and Honemoon.

Australia's main competitor is Kazakhstan, which contains almost 12% of the world's fuel reserves. Canada and South Africa each contain 11% of the world's uranium reserves, Namibia - 8%, Brazil - 7%. Russia closes the top seven with 5%. The list of leaders also includes countries such as Namibia, Ukraine and China.

The world's largest uranium deposits are:

Reserves and production volumes of uranium ore in Russia

The explored reserves of uranium in our country are estimated at more than 400 thousand tons. At the same time, the predicted resources are more than 830 thousand tons. As of 2017, there are 16 uranium deposits in Russia. Moreover, 15 of them are concentrated in Transbaikalia. The main deposit of uranium ore is considered to be the Streltsovskoe ore field. In most domestic deposits, production is carried out using the shaft method.

• Uranium was discovered back in the 18th century. In 1789, the German scientist Martin Klaproth managed to produce metal-like uranium from ore. Interestingly, this scientist is also the discoverer of titanium and zirconium.
• Uranium compounds are actively used in the field of photography. This element is used to color positives and enhance negatives.
• The main difference between uranium and other chemical elements is its natural radioactivity. Uranium atoms tend to change independently over time. At the same time, they emit rays invisible to the human eye. These rays are divided into 3 types - gamma, beta and alpha radiation (see).

Uranium is a chemical element of the actinide family with atomic number 92. It is the most important nuclear fuel. Its concentration in the earth's crust is about 2 parts per million. Important uranium minerals include uranium oxide (U 3 O 8), uraninite (UO 2), carnotite (potassium uranyl vanadate), otenite (potassium uranyl phosphate), and torbernite (hydrous copper uranyl phosphate). These and other uranium ores are sources of nuclear fuel and contain many times more energy than all known recoverable fossil fuel deposits. 1 kg of uranium 92 U provides the same energy as 3 million kg of coal.

History of discovery

The chemical element uranium is a dense, hard metal with a silvery-white color. It is ductile, malleable and polishable. In the air, metal oxidizes and, when crushed, ignites. Conducts electricity relatively poorly. The electronic formula of uranium is 7s2 6d1 5f3.

Although the element was discovered in 1789 by the German chemist Martin Heinrich Klaproth, who named it after the recently discovered planet Uranus, the metal itself was isolated in 1841 by the French chemist Eugene-Melchior Peligot by reduction from uranium tetrachloride (UCl 4) with potassium.

Radioactivity

The creation of the periodic table by Russian chemist Dmitri Mendeleev in 1869 focused attention on uranium as the heaviest known element, which it remained until the discovery of neptunium in 1940. In 1896, French physicist Henri Becquerel discovered the phenomenon of radioactivity in it. This property was later found in many other substances. It is now known that uranium, radioactive in all its isotopes, consists of a mixture of 238 U (99.27%, half-life - 4,510,000,000 years), 235 U (0.72%, half-life - 713,000,000 years) and 234 U (0.006%, half-life - 247,000 years). This allows, for example, to determine the age of rocks and minerals to study geological processes and the age of the Earth. To do this, they measure the amount of lead, which is the end product of the radioactive decay of uranium. In this case, 238 U is the initial element, and 234 U is one of the products. 235 U gives rise to the decay series of actinium.

Discovery of a chain reaction

The chemical element uranium became the subject of widespread interest and intensive study after German chemists Otto Hahn and Fritz Strassmann discovered nuclear fission in it at the end of 1938 when it was bombarded with slow neutrons. In early 1939, Italian-American physicist Enrico Fermi suggested that among the products of atomic fission there could be elementary particles capable of generating a chain reaction. In 1939, American physicists Leo Szilard and Herbert Anderson, as well as French chemist Frederic Joliot-Curie and their colleagues confirmed this prediction. Subsequent studies showed that, on average, 2.5 neutrons are released when an atom fissions. These discoveries led to the first self-sustaining nuclear chain reaction (12/02/1942), the first atomic bomb (07/16/1945), its first use in warfare (08/06/1945), the first nuclear submarine (1955) and the first full-scale nuclear power plant ( 1957).

Oxidation states

The chemical element uranium, being a strong electropositive metal, reacts with water. It dissolves in acids, but not in alkalis. Important oxidation states are +4 (as in UO 2 oxide, tetrahalides such as UCl 4, and the green water ion U4+) and +6 (as in UO 3 oxide, UF 6 hexafluoride, and the uranyl ion UO 2 2+). In an aqueous solution, uranium is most stable in the composition of the uranyl ion, which has a linear structure [O = U = O] 2+. The element also has states +3 and +5, but they are unstable. Red U 3+ oxidizes slowly in water, which does not contain oxygen. The color of the UO 2+ ion is unknown because it undergoes disproportionation (UO 2+ is both reduced to U 4+ and oxidized to UO 2 2+) even in very dilute solutions.

Nuclear fuel

When exposed to slow neutrons, fission of the uranium atom occurs in the relatively rare isotope 235 U. This is the only naturally occurring fissile material, and it must be separated from the isotope 238 U. However, after absorption and negative beta decay, uranium-238 turns into the synthetic element plutonium, which is split under the influence of slow neutrons. Therefore, natural uranium can be used in converter and breeder reactors, in which fission is supported by rare 235 U and plutonium is produced simultaneously with transmutation of 238 U. The fissile 233 U can be synthesized from the widely occurring naturally occurring isotope thorium-232 for use as nuclear fuel. Uranium is also important as the primary material from which synthetic transuranium elements are obtained.

Other uses of uranium

Compounds of the chemical element were previously used as dyes for ceramics. Hexafluoride (UF 6) is a solid with an unusually high vapor pressure (0.15 atm = 15,300 Pa) at 25 °C. UF 6 is chemically very reactive, but despite its corrosive nature in the vapor state, UF 6 is widely used in gaseous diffusion and gas centrifuge methods for producing enriched uranium.

Organometallic compounds are an interesting and important group of compounds in which metal-carbon bonds connect the metal to organic groups. Uranocene is an organouranic compound U(C 8 H 8) 2 in which the uranium atom is sandwiched between two layers of organic rings associated with cyclooctatetraene C 8 H 8. Its discovery in 1968 opened up a new field of organometallic chemistry.

Depleted natural uranium is used as radiation protection, ballast, in armor-piercing shells and tank armor.

Recycling

The chemical element, although very dense (19.1 g/cm3), is a relatively weak, non-flammable substance. Indeed, the metallic properties of uranium seem to place it somewhere between silver and the other true metals and non-metals, so it is not used as a structural material. The main value of uranium lies in the radioactive properties of its isotopes and their ability to fission. In nature, almost all (99.27%) of the metal consists of 238 U. The rest is 235 U (0.72%) and 234 U (0.006%). Of these natural isotopes, only 235 U is directly fissioned by neutron irradiation. However, when it is absorbed, 238 U forms 239 U, which ultimately decays into 239 Pu, a fissile material of great importance for nuclear power and nuclear weapons. Another fissile isotope, 233 U, can be formed by neutron irradiation of 232 Th.

Crystal forms

The characteristics of uranium cause it to react with oxygen and nitrogen even under normal conditions. At higher temperatures it reacts with a wide range of alloying metals to form intermetallic compounds. The formation of solid solutions with other metals is rare due to the special crystal structures formed by the atoms of the element. Between room temperature and the melting point of 1132 °C, uranium metal exists in 3 crystalline forms known as alpha (α), beta (β) and gamma (γ). Transformation from α- to β-state occurs at 668 °C and from β to γ ​​at 775 °C. γ-uranium has a body-centered cubic crystal structure, while β has a tetragonal crystal structure. The α phase consists of layers of atoms in a highly symmetrical orthorhombic structure. This anisotropic distorted structure prevents alloying metal atoms from replacing uranium atoms or occupying the space between them in the crystal lattice. It was found that only molybdenum and niobium form solid solutions.

Ore

The Earth's crust contains about 2 parts per million of uranium, which indicates its widespread occurrence in nature. The oceans are estimated to contain 4.5 × 10 9 tons of this chemical element. Uranium is an important constituent of more than 150 different minerals and a minor component of another 50. Primary minerals found in magmatic hydrothermal veins and pegmatites include uraninite and its variant pitchblende. In these ores the element occurs in the form of dioxide, which due to oxidation can range from UO 2 to UO 2.67. Other economically significant products from uranium mines are autunite (hydrated calcium uranyl phosphate), tobernite (hydrated copper uranyl phosphate), coffinit (black hydrated uranium silicate) and carnotite (hydrated potassium uranyl vanadate).

It is estimated that more than 90% of known low-cost uranium reserves are located in Australia, Kazakhstan, Canada, Russia, South Africa, Niger, Namibia, Brazil, China, Mongolia and Uzbekistan. Large deposits are found in the conglomerate rock formations of Elliot Lake, located north of Lake Huron in Ontario, Canada, and in the South African Witwatersrand gold mine. Sand formations in the Colorado Plateau and Wyoming Basin of the western United States also contain significant uranium reserves.

Production

Uranium ores are found in both near-surface and deep (300-1200 m) deposits. Underground, the thickness of the seam reaches 30 m. As in the case of ores of other metals, uranium is mined at the surface using large earth-moving equipment, and the development of deep deposits is carried out using traditional methods of vertical and inclined mines. World production of uranium concentrate in 2013 amounted to 70 thousand tons. The most productive uranium mines are located in Kazakhstan (32% of all production), Canada, Australia, Niger, Namibia, Uzbekistan and Russia.

Uranium ores typically contain only small amounts of uranium-containing minerals and are not smeltable by direct pyrometallurgical methods. Instead, hydrometallurgical procedures must be used to extract and purify the uranium. Increasing the concentration significantly reduces the load on the processing circuits, but none of the conventional beneficiation methods commonly used for mineral processing, such as gravity, flotation, electrostatic and even manual sorting, are applicable. With few exceptions, these methods result in significant uranium loss.

Burning

Hydrometallurgical processing of uranium ores is often preceded by a high-temperature calcination stage. Firing dehydrates the clay, removes carbonaceous materials, oxidizes sulfur compounds to harmless sulfates, and oxidizes any other reducing agents that may interfere with subsequent processing.

Leaching

Uranium is extracted from roasted ores by both acidic and alkaline aqueous solutions. For all leaching systems to function successfully, the chemical element must either initially be present in the more stable hexavalent form or be oxidized to this state during processing.

Acid leaching is usually carried out by stirring a mixture of ore and lixiviant for 4-48 hours at ambient temperature. Except in special circumstances, sulfuric acid is used. It is supplied in quantities sufficient to obtain the final liquor at a pH of 1.5. Sulfuric acid leaching schemes typically use either manganese dioxide or chlorate to oxidize tetravalent U4+ to hexavalent uranyl (UO22+). Typically, approximately 5 kg of manganese dioxide or 1.5 kg of sodium chlorate per ton is sufficient for U 4+ oxidation. In either case, oxidized uranium reacts with sulfuric acid to form the uranyl sulfate complex anion 4-.

Ore containing significant amounts of essential minerals such as calcite or dolomite is leached with a 0.5-1 molar solution of sodium carbonate. Although various reagents have been studied and tested, the main oxidizing agent for uranium is oxygen. Typically, the ore is leached in air at atmospheric pressure and at a temperature of 75-80 °C for a period of time that depends on the specific chemical composition. Alkali reacts with uranium to form the readily soluble complex ion 4-.

Solutions resulting from acid or carbonate leaching must be clarified before further processing. Large-scale separation of clays and other ore slurries is achieved through the use of effective flocculating agents, including polyacrylamides, guar gum and animal glue.

Extraction

The 4- and 4- complex ions can be sorbed from their respective ion exchange resin leach solutions. These specialty resins, characterized by their adsorption and elution kinetics, particle size, stability and hydraulic properties, can be used in a variety of processing technologies, such as fixed bed, moving bed, basket resin and continuous resin. Typically, solutions of sodium chloride and ammonia or nitrates are used to elute sorbed uranium.

Uranium can be isolated from acidic ore liquors by solvent extraction. Alkylphosphoric acids, as well as secondary and tertiary alkylamines, are used in industry. Generally, solvent extraction is preferred over ion exchange methods for acid filtrates containing more than 1 g/L uranium. However, this method is not applicable to carbonate leaching.

The uranium is then purified by dissolving in nitric acid to form uranyl nitrate, extracted, crystallized and calcined to form UO 3 trioxide. Reduced dioxide UO2 reacts with hydrogen fluoride to form thetafluoride UF4, from which uranium metal is reduced by magnesium or calcium at a temperature of 1300 °C.

Tetrafluoride can be fluorinated at 350 °C to form UF 6 hexafluoride, which is used to separate enriched uranium-235 by gaseous diffusion, gas centrifugation or liquid thermal diffusion.

Uranium (U) mining is of great importance to modern society. This heaviest metal is used in the nuclear industry as fuel, and nuclear weapons are made from it. For peaceful purposes they are used for the production of glass and paints and varnishes. Pure uranium does not occur in natural conditions; it is part of minerals and ores.

World reserves

At the moment, uranium mining is carried out in a large number of deposits. In the earth's layer at a depth of twenty kilometers there is an impressive number of tons of uranium ore, capable of supplying humanity with fuel for many centuries to come. Uranium is mined in 28 countries around the world. But the world's main reserves belong to 10 countries, which share 90% of the market.

Australia. There are 19 large deposits in this country. U reserves in them amount to 661,000 tons (the share occupies 31.18% of all world deposits).

Kazakhstan. It has 16 major U production points. The volume of deposits is 629,000 tons, which is 11.81% of the total share of reserves in the world.

Russia. The Russian Federation's share in the global uranium industry is 9.15%. U reserves amount to 487,000 tons. U production is forecast to increase to 830 thousand tons.

Canada. Ore reserves are at around 468,000 tons, which occupies 8.80% of the world market. Uranium production is 9 thousand tons per year.

Niger. The country's uranium deposits amount to 421,000 tons, which is 7.9% of the total share of world reserves. 4.5 thousand tons of U per year are mined in 4 deposits.

SOUTH AFRICA. U reserves in the country amount to 297,000 tons; which accounts for about 6% of the world's reserves. In South Africa, 540 tons of uranium are mined per year.

Brazil. The country's indicator is 276,700 tons of uranium ore. U production for the year is 198 tons per year.

Namibia. The country's uranium reserves amount to 261,000 tons. Namibia has four large U deposits.

USA. Total U reserves in the United States are 207,000 tons.

China. The country’s indicator is 166,000 tons. About 1.5 thousand tons of uranium ore are mined in the DPRK per year.

The world's largest uranium deposits

In Russia, control over the main uranium mining assets is exercised by the Rosatom corporation. It unites the International Mining Division of Uranium One and has a portfolio of shares in the USA, Kazakhstan and Tanzania.

Characteristics of uranium ores

Types of uranium

Natural uranium consists of the interaction of 3 isotopes: U238, U235, U234. The radioactive properties of the metal are affected by isotopes 238 and its daughter nucleotide 234. Due to the presence of these atoms in U, uranium is used in the production of fuel for nuclear power plants and nuclear weapons. Although the activity of the U235 isotope is 21 times weaker, it is capable of maintaining a nuclear chain reaction without third-party active elements.

In addition to natural isotopes, there are also artificial U atoms.

At least 23 species are known. The isotope U233 deserves special attention; it is formed when thorium-232 is irradiated with neutrons and fissions under the influence of thermal neutrons. This ability makes U233 an optimal energy source for nuclear reactors.

Ore classification

The term natural uranium ore refers to a mineral formation with a high concentration of uranium. When developing uranium deposits, as a rule, other radioactive metals - radium and polonium - are obtained adjacently. The rocks that contain uranium can vary in composition. The structure of the layers influences the method of extracting valuable metal.

According to the conditions of formation, ore can be divided into:

• endogenous;
• exogenous;
• metamorphogenic.

According to the type of mineralization, uranium ores are distinguished:

• primary;
• oxidized;
• mixed.

Grain size classification:

• dispersed (<0,015 мм);
• fine-grained (0.015–0.1 mm);
• fine-grained (0.1–3 mm);
• medium-grained (3 to 25 mm);
• coarse-grained (> 25 mm).

• molybdenum;
• anadium;
• uranium-cobalt-nickel-bismuth;
• monoore.

Classification by chemical composition:

• carbonate;
• iron oxide;
• silicate;
• sulfide;
• caustobiolic.

Ore is divided according to processing method:

• soda solution is used if carbonate is present in the chemical composition of the ore;
• acid is used for silicate rocks;
• The blast furnace smelting method is used if the composition is iron oxide.

• poor (< 0,1%);
• ordinary (0.25–0.1%);
• average (0.5–0.25%);
• rich (1–0.5%);
• very rich (>1% U).

It makes sense to mine uranium if its content in the earth layer is at least 0.5%. If there is less than 0.015% uranium in the rock layer, it is mined as a by-product.

Uranium ore mining methods

There are three main methods of uranium mining:

• open (or quarry);
• mine (underground);
• leaching.

All these methods depend on many factors. For example, on the depth of rock deposits, isotope composition, etc.

It is applicable in the case when the rock is shallow and to extract it, it is enough to arm yourself with special equipment:

• dump trucks;
• bulldozers;
• loaders.

The open-pit method of uranium mining has been used for quite some time. One of the advantages of this method is the minimal risk of exposure of miners to radiation. But a significant disadvantage of the open method is the irreparable environmental damage to the plot of land that is under development.

The mine mining method is more expensive from a material point of view. To extract uranium, they drill mines up to two kilometers deep; if mining is carried out deeper than this mark, the fuel will be very expensive. In any case, mining companies are required to equip miners with all related equipment and radiation protection. AND Install the necessary ventilation systems to remove radon and supply the mine with fresh air. At the mine, metal is extracted from the rock mass using the drill and blast method.

The leaching method of uranium mining is considered optimal. Wells are drilled into the rock, through which a solution is pumped - a leaching reagent with a special chemical composition. It dissolves in the depths of ore deposits and is saturated with valuable metal compounds.

conclusions

Uranium mining using underground leaching causes significantly less harm to the environment than the methods outlined above. Over time, reclamation processes occur on the developed plot of land. The use of this method can reduce economic costs. But it has its limitations. It is not used only in sandstone and below the groundwater level.

Video: Uranium mining

A discovery on a planetary scale. This can be called the discovery of Uranus by scientists. The planet was discovered in 1781.

Its discovery became the reason for naming one of elements of the periodic table. Uranus metal was isolated from resin blende in 1789.

The hype around the new planet had not yet subsided, therefore, the idea of ​​​​naming the new substance lay on the surface.

At the end of the 18th century there was no concept of radioactivity. Meanwhile, this is the main property of terrestrial uranium.

Scientists who worked with him were exposed to radiation without knowing it. Who was the pioneer, and what other properties of the element are, we will tell further.

Properties of uranium

Uranium - element, discovered by Martin Klaproth. He fused resin with caustic. The fusion product was incompletely soluble.

Klaproth realized that the supposed , and are not present in the composition of the mineral. Then, the scientist dissolved the blende in .

Green hexagons fell out of the solution. The chemist exposed them to yellow blood, that is, potassium hexacyanoferrate.

A brown precipitate precipitated from the solution. Klaproth restored this oxide with linseed oil and calcined it. The result was a powder.

I had to calcinate it already by mixing it with brown. Grains of new metal were found in the sintered mass.

Later it turned out that it was not pure uranium, and its dioxide. The element was obtained separately only 60 years later, in 1841. And another 55 years later, Antoine Becquerel discovered the phenomenon of radioactivity.

Radioactivity of uranium due to the ability of the element’s nucleus to capture neutrons and fragment. At the same time, impressive energy is released.

It is determined by the kinetic data of radiation and fragments. It is possible to ensure continuous fission of nuclei.

The chain reaction is started when natural uranium is enriched with its 235th isotope. It’s not like it’s added to metal.

On the contrary, the low-radioactive and ineffective 238th nuclide, as well as the 234th, are removed from the ore.

Their mixture is called depleted, and the remaining uranium is called enriched. This is exactly what industrialists need. But we’ll talk about this in a separate chapter.

Uranus radiates, both alpha and beta with gamma rays. They were discovered by seeing the effect of metal on a photographic plate wrapped in black.

It became clear that the new element was emitting something. While the Curies were investigating what exactly, Maria received a dose of radiation that caused the chemist to develop blood cancer, from which the woman died in 1934.

Beta radiation can destroy not only the human body, but also the metal itself. What element is formed from uranium? Answer: - brevy.

Otherwise it is called protactinium. Discovered in 1913, just during the study of uranium.

The latter turns into brevium without external influences and reagents, only from beta decay.

Externally uranium – chemical element- colors with a metallic sheen.

This is what all actinides look like, to which substance 92 belongs. The group starts with number 90 and ends with number 103.

Standing at the top of the list radioactive element uranium, manifests itself as an oxidizing agent. Oxidation states can be 2nd, 3rd, 4th, 5th, 6th.

That is, the 92nd metal is chemically active. If you grind uranium into powder, it will spontaneously ignite in air.

In its usual form, the substance will oxidize upon contact with oxygen, becoming covered with an iridescent film.

If you bring the temperature to 1000 degrees Celsius, chem. uranium element connect with . A metal nitride is formed. This substance is yellow in color.

Throw it into water and it will dissolve, just like pure uranium. All acids also corrode it. The element displaces hydrogen from organic elements.

Uranium also pushes it out of salt solutions, , , , . If such a solution is shaken, particles of the 92nd metal will begin to glow.

Uranium salts unstable, disintegrate in light or in the presence of organic matter.

The element is perhaps only indifferent to alkalis. The metal does not react with them.

Discovery of uranium is the discovery of a superheavy element. Its mass makes it possible to isolate the metal, or more precisely, the minerals with it, from the ore.

It is enough to crush it and pour it into water. The uranium particles will settle first. This is where metal mining begins. Details in the next chapter.

Uranium mining

Having received a heavy sediment, industrialists leach the concentrate. The goal is to convert the uranium into solution. Sulfuric acid is used.

An exception is made for tar. This mineral is not soluble in acid, therefore alkalis are used. The secret of difficulties is in the 4-valent state of uranium.

Acid leaching also does not work with,. In these minerals, the 92nd metal is also 4-valent.

This is treated with hydroxide, known as caustic soda. In other cases, oxygen purge is good. There is no need to stock up on sulfuric acid separately.

It is enough to heat the ore with sulfide minerals to 150 degrees and direct an oxygen stream at it. This leads to the formation of acid, which washes away Uranus.

Chemical element and its application associated with pure forms of metal. To remove impurities, sorption is used.

It is carried out on ion exchange resins. Extraction with organic solvents is also suitable.

It remains to add alkali to the solution to precipitate the ammonium uranates, dissolve them in nitric acid and subject them.

The result will be oxides of the 92nd element. They are heated to 800 degrees and reduced with hydrogen.

The final oxide is converted to uranium fluoride, from which pure metal is obtained by calcium-thermal reduction. , as you can see, is not a simple one. Why try so hard?

Applications of uranium

The 92nd metal is the main fuel of nuclear reactors. A lean mixture is suitable for stationary ones, and for power plants an enriched element is used.

The 235th isotope is also the basis of nuclear weapons. Secondary nuclear fuel can also be obtained from metal 92.

Here it is worth asking the question, what element does uranium transform into?. From its 238th isotope, , is another radioactive, superheavy substance.

At the very 238th uranium great half life, lasts 4.5 billion years. Such long-term destruction leads to low energy intensity.

If we consider the use of uranium compounds, its oxides are useful. They are used in the glass industry.

Oxides act as dyes. Can be obtained from pale yellow to dark green. The material fluoresces in ultraviolet rays.

This property is used not only in glasses, but also in uranium glazes for. Uranium oxides in them range from 0.3 to 6%.

As a result, the background is safe and does not exceed 30 microns per hour. Photo of uranium elements, or rather, products with his participation, are very colorful. The glow of glass and dishes attracts the eye.

Uranium price

For a kilogram of unenriched uranium oxide they give about 150 dollars. Peak values ​​were observed in 2007.

Then the cost reached 300 dollars per kilo. The development of uranium ores will remain profitable even at a price of 90-100 conventional units.

Who discovered the element uranium, did not know what its reserves were in the earth's crust. Now, they are counted.

Large deposits with a profitable production price will be depleted by 2030.

If new deposits are not discovered, or alternatives to the metal are not found, its cost will creep up.

Under normal conditions, the radioactive element uranium is a metal with a large atomic (molecular) mass - 238.02891 g/mol. According to this indicator, it ranks second, because The only thing heavier than it is plutonium. The production of uranium is associated with the sequential implementation of a number of technological operations:

• concentration of rock, its crushing and sedimentation of heavy fractions in water
• concentrate leaching or oxygen purge
• conversion of uranium into a solid state (oxide or tetrafluoride UF 4)
• obtaining uranyl nitrate UO 2 (NO 3) 2 by dissolving the raw material in nitric acid
• crystallization and calcination to obtain UO 3 oxide
• reduction with hydrogen to obtain UO 2
• obtaining UF 4 tetrafluoride by adding hydrogen fluoride gas
• reduction of uranium metal using magnesium or calcium

Uranium minerals

The most common U minerals are:

• pitchblende (uraninite) is the most famous oxide, which is called “heavy water”
• Carnotite
• Tyuyamunit
• Torburnite
• Samarskit
• Brannerite
• Kasolite
• Slander

Uranium production

According to the Russian company Rosatom, one of the world leaders in the global uranium market, more than 3 thousand tons of uranium were mined on the planet in 2014. At the same time, according to representatives of the mining division of this state corporation, the volume of Russian reserves of this metal is 727.2 thousand tons (3rd place in the world), which guarantees an uninterrupted supply of the necessary raw materials for many decades.

The main chemical properties of uranium are presented in the table:

The element U, like curium and plutonium, is an artificially produced element of the actinide family. Its chemical properties are in many ways similar to those of tungsten, molybdenum and chromium. Uranium is characterized by variable valency, as well as a tendency to form (UO 2) + 2 - uranyl, which is a complex ion.

Uranium enrichment methods

As is known, natural U contains 3 isotopes:

• 238U (99.2745%)
• 235U (0.72%)
• 234U (0.0055%)

Uranium enrichment means an increase in the share of the 235U isotope in the metal - the only one that is capable of an independent nuclear chain reaction.

To understand how uranium is enriched, it is necessary to take into account the degree of its enrichment:

• content 0.72% - can be used in some power reactors
• 2-5% – used in most power reactors
• up to 20% (low enriched) – for experimental reactors
• more than 20% (highly enriched or weapons grade) – nuclear reactors, weapons.

How is uranium enriched? There are many methods for enriching uranium, but the most applicable are the following:

• electromagnetic – acceleration of elementary particles in a special accelerator and their twisting in a magnetic field
• aerodynamic – blowing uranium gas through special nozzles
• gas centrifugation - the uranium gas in the centrifuge moves and, by inertia, pushes heavy molecules towards the walls of the centrifuge
• gas diffusion method of uranium enrichment - “sifting” light uranium isotopes through small pores of special membranes

The main application of uranium is fuel for nuclear reactors, nuclear power plant reactors, and nuclear power plants. In addition, the 235U isotope is used in nuclear weapons, while the unenriched metal with a high proportion of 238U makes it possible to obtain secondary nuclear fuel - plutonium.