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Tantalum metal characteristics and properties. Chemical properties of tantalum Electronic configuration of the tantalum atom

Rapid development modern technologies today is certainly associated with the use of effective materials and substances that have quite practical and very useful properties and features.

From this perspective, it is worth paying attention to such a unique chemical element as tantalum. And this is not surprising, because due to its strength characteristics, today the use of tantalum is becoming quite relevant in many areas of industry.

To broaden the horizons of the layman in this topic, we will describe in detail the physicochemical features of tantalum and talk about where this metal is very successfully used today.

Technical features of tantalum

First of all, it should be understood that tantalum is a gray metal with a brilliant tint, which can be easily machined.

Among the features of the metal, it is worth noting a number of the following important aspects:

  • serial number in the periodic table - 73;
  • atomic weight - 180;
  • the density of the substance is 60 g / cm 3;
  • melting point - 3015 0 С;
  • the boiling point of the substance is 5300 0 C.

metal properties

Thanks to these characteristics, tantalum undoubtedly has the following advantageous properties:

  1. Tantalum is a refractory metal, and as a result, the element has the following properties:
  • small index of linear expansion;
  • good level of thermal conductivity;
  • high mechanical strength and ductility.
  1. It has excellent anti-corrosion properties. It is worth noting that tantalum under normal conditions is practically inert to sea water, but if it is saturated with oxygen, then the metal in this case only tarnishes.
  2. Tantalum has good resistance to the following types of salts:
  • chlorides of iron and copper;
  • nitrates;
  • sulfates;
  • salts of organic acids, however, provided that they do not contain fluorine or fluorides in their composition.
  1. Tantalum begins to lose its strength characteristics when it reacts with fluorine. It is also worth considering the fact that tantalum does not enter into a chemical reaction with bromine, iodine and liquid chlorine, unless a temperature of 150 0 C is reached.
  2. Tantalum is sufficiently resistant to liquid structure metals having a low melting temperature.
  3. Tantalum has excellent stability characteristics in air at temperatures up to 400 0 C, while a protective film of oxide appears during storage or processing.
  4. Tantalum, melted by the electron beam method, has an increased plasticity property, which, when the metal is deformed, allows a greater degree of compression to be performed.
  5. It is well converted into sheet metal, which lends itself well to forging.
  6. Works well for cold forming. However, you need to understand that this metal should not be deformed in a hot state, since when heated, tantalum begins to absorb nitrogen, carbon dioxide, oxygen, and, as a result, the material becomes quite brittle.
  7. One of the main operations for processing tantalum is cutting the material on high-speed equipment.

As for the connection of tantalum parts, it can be done in the following ways:

  • welding;
  • soldering;
  • connection with rivets.

Here it is worth taking into account the fact that the last two methods are used quite rarely, so the quality of tantalum welded joints always remains at a high level.

Areas of application of tantalum

These properties allow it to be widely used in different areas industry. Let us note in detail the main directions for the use of such a unique material as tantalum.

Metallurgical industry

Metallurgy is the main consumer of this metal. The metallurgical industry consumes 45% of the produced tantalum.

The main application of tantalum is in a number of the following important aspects:

  • metal is the main alloying element in the manufacture of heat-resistant and anti-corrosion steel grades;
  • Tantalum carbide is a reliable protection for steel molds in foundries.

Electrical industry

First of all, it is worth noting the fact that a quarter of the tantalum produced in the world is used in the electrical industry. And this is not surprising, because the following types of electrical products are produced using this metal:

  • tantalum capacitors of an electrolytic type are characterized by the stability of their functioning;
  • widely used in the manufacture of such structural elements of lamps as anodes, indirectly heated cathodes and grids;
  • tantalum wire is used in the production of cryotron parts, which are integral elements of computer technology;
  • heaters for furnaces with high-temperature operation are very successfully made from this metal.

Interesting fact! Tantalum capacitors tend to self-repair. For example, with a sudden occurrence of high voltage, a spark destroyed the insulating layer. In this case, an insulating oxide film is instantly formed at the site of the defect, while the capacitor will continue to function in normal operating mode!


Chemical industry

It is necessary, first of all, to note the fact that 20% of the used tantalum goes to the needs chemical industry. In particular, this metal is used in the following cases:

  • production of the following types of acids:
  1. nitrogen;
  2. deer;
  3. sulfuric;
  4. phosphoric;
  5. acetic.
  • production of hydrogen peroxide, bromine and chlorine;
  • production of chemical equipment of the following types:
  1. aerators;
  2. distillation plants;
  3. coils of various types;
  4. agitators;
  5. valve.

AT medical industry no more than 5% of the tantalum mined in the world is used. In medicine, this metal is very successfully used in plastic and bone surgery, as it is used to make tantalum elements for fastening bones, suturing, and so on. This is achieved due to the fact that tantalum does not harm the vital activity of the organism, while it does not irritate living tissue.

Tantalum (Ta) is an element with atomic number 73 and atomic weight 180.948. It is an element of a secondary subgroup of the fifth group, the sixth period periodic system Dmitri Ivanovich Mendeleev. Tantalum in the free state under normal conditions is a platinum gray metal with a slightly lead tint, which is a consequence of the formation of an oxide film (Ta 2 O 5). Tantalum is a heavy, refractory, rather hard, but not brittle metal, at the same time it is very malleable, well machinable, especially in its pure form.

In nature, tantalum is found in the form of two isotopes: stable 181 Ta (99.99%) and radioactive 180 Ta (0.012%) with a half-life of 10 12 years. Of the artificially obtained radioactive 182 Ta (half-life 115.1 days) is used as an isotope tracer.

The element was discovered in 1802 by the Swedish chemist A. G. Ekeberg in two minerals found in Finland and Sweden. It was named after the hero of ancient Greek myths Tantalus due to the difficulty of identifying it. For a long time, the minerals columbite containing columbium (niobium) and tantalite containing tantalum were considered one and the same. After all, these two elements are frequent companions of each other and are similar in many respects. This opinion was considered true for a long time among chemists of all countries, only in 1844 the German chemist Heinrich Rose again studied columbites and tantalites from various places and found in them a new metal, similar in properties to tantalum. It was niobium. Plastic pure metallic tantalum was first obtained by the German scientist W. von Bolton in 1903.

The main deposits of tantalum minerals are located in Finland, Scandinavia, North America, Brazil, Australia, France, China and a number of other countries.

Due to the fact that tantalum has a number of valuable properties - good ductility, high strength, weldability, corrosion resistance at moderate temperatures, refractoriness and a number of others important qualities- the application of the seventy-third element is very wide. The most important areas of application of tantalum are electronics and mechanical engineering. Approximately a quarter of the world's tantalum production goes to the electrical and vacuum industry. In electronics, it is used to make electrolytic capacitors, anodes for high-power lamps, and grids. In the chemical industry, tantalum is used to make machine parts used in the production of acids, because this element has exceptional chemical resistance. Tantalum does not dissolve even in such a chemically aggressive environment as aqua regia! In tantalum crucibles, metals, such as rare earths, are melted. Heaters of high-temperature furnaces are made from it. Due to the fact that tantalum does not interact with living tissues of the human body and does not harm them, it is used in surgery to hold bones together in case of fractures. However, the main consumer of such a valuable metal is metallurgy (over 45%). AT last years tantalum is increasingly used as an alloying element in special steels - heavy-duty, corrosion-resistant, heat-resistant. In addition, many structural materials quickly lose their thermal conductivity: a poorly heat-conducting oxide or salt film forms on their surface. Structures made of tantalum and its alloys do not face such problems. The oxide film formed on them is thin and conducts heat well, moreover, it has protective anti-corrosion properties.

Not only pure tantalum is of value, but also its compounds. So the high hardness of tantalum carbide is used in the manufacture of carbide tools for high-speed metal cutting. Tantalum-tungsten alloys give heat resistance to parts made from them.

Biological properties

Due to its high biological compatibility - the ability to get along with living tissues without causing irritation and rejection of the body - tantalum has found wide application in medicine, mainly in reconstructive surgery - to restore the human body. Thin plates of tantalum are used for damage to the cranium - they close the fractures in the skull. Medicine knows the case when an artificial ear was made from a tantalum plate, while the skin transplanted from the thigh took root so well and quickly that soon the artificial organ could not be distinguished from the real one. Tantalum threads are used in the restoration of damaged muscle tissue. Surgeons fasten the walls of the abdominal cavity with tantalum plates after operations. Even blood vessels can be connected using tantalum staples. Networks of this unique material are used in the manufacture of ocular prostheses. Tendons are replaced with threads of this metal and even nerve fibers are sewn together.

Tantalum pentoxide Ta 2 O 5 is no less widely used - its mixture with a small amount of iron trioxide is proposed to be used to accelerate blood coagulation.

In the last decade, a new branch of medicine has been developing, based on the use of short-range static electric fields to stimulate positive biological processes in the human body. And electric fields are formed not due to traditional electrical energy sources with mains or battery power supply, but due to autonomously functioning electret coatings (a dielectric that retains an uncompensated electric charge for a long time) deposited on implants for various purposes, widely used in medicine.

At present, positive results of the use of electret films of tantalum pentoxide have been obtained in the following areas of medicine: maxillofacial surgery (the use of implants coated with Ta 2 O 5 eliminates the occurrence of inflammatory processes, reduces the time of engraftment of the implant); orthopedic dentistry (covering prostheses made of acrylic plastics with a film of tantalum pentoxide eliminates all possible pathological manifestations caused by intolerance to acrylates); surgery (the use of an electret applicator in the treatment of defects in the skin and connective tissue with long-term non-healing wound processes, bedsores, neurotrophic ulcers, thermal lesions); traumatology and orthopedics (acceleration of bone tissue development in the treatment of fractures and diseases of the human musculoskeletal system under the influence of a static field created by an electret coating film).

All these unique scientific developments became possible thanks to scientific work specialists from St. Petersburg State Electrotechnical University (LETI).

In addition to the above areas where unique coatings of tantalum pentoxide are already being applied or introduced, there are developments that are at the very initial stages. These include developments for the following areas of medicine: cosmetology (production of a material based on coatings of tantalum pentoxide, which will replace the "golden threads"); cardiac surgery (application of electret films on inner surface artificial blood vessels, prevents the formation of blood clots); arthroplasty (reducing the risk of rejection of prostheses that are in constant interaction with bone tissue). In addition, a surgical instrument coated with a film of tantalum pentoxide is being created.

It is known that tantalum is very resistant to aggressive media, a number of facts testify to this. So at a temperature of 200 ° C, this metal is not affected by seventy percent nitric acid! In sulfuric acid at a temperature of 150 ° C, tantalum corrosion is also not observed, and at 200 ° C, the metal corrodes, but only by 0.006 mm per year!

A case is known when in one enterprise using gaseous hydrogen chloride, stainless steel parts failed after a couple of months. However, as soon as steel was replaced by tantalum, even the thinnest parts (0.3 ... 0.5 mm thick) turned out to be practically indefinite - their service life increased to 20 years!

Tantalum, along with nickel and chromium, is widely used as an anti-corrosion coating. They cover parts of a wide variety of shapes and sizes: crucibles, pipes, sheets, rocket nozzles and much more. Moreover, the material on which the tantalum coating is applied can be very diverse: iron, copper, graphite, quartz, glass, and others. What is most interesting is that the hardness of the tantalum coating is three to four times higher than the hardness of technical tantalum in annealed form!

Due to the fact that tantalum is a very valuable metal, the search for its raw materials continues today. Mineralogists have discovered that ordinary granites, in addition to other valuable elements, also contain tantalum. An attempt to extract tantalum from granite rocks was made in Brazil, the metal was obtained, but such production did not reach an industrial scale - the process turned out to be extremely expensive and complicated.

Modern electrolytic tantalum capacitors are stable in operation, reliable and durable. Miniature capacitors made from this material used in various electronic systems, in addition to the above advantages, they have one unique quality: they can make their own repairs on their own! How does this happen? Suppose that the integrity of the insulation is violated due to a voltage drop, or for another reason - instantly an insulating oxide film forms again at the breakdown site, and the capacitor continues to work as if nothing had happened!

Undoubtedly, the term “smart metal”, which appeared in the middle of the 20th century, that is, a metal that helps smart machines work, can rightfully be attributed to tantalum.

In some areas, tantalum replaces, and sometimes even competes with, platinum! So in jewelry work, tantalum often replaces the more expensive noble metal in the manufacture of bracelets, watch cases and other jewelry. In another area, tantalum successfully competes with platinum - standard analytical weights made of this metal are not inferior in quality to platinum ones.

In addition, tantalum is used as a substitute for the more expensive iridium in the production of nib nibs for automatic pens.

Due to its unique chemical properties, tantalum has found application as a material for cathodes. So tantalum cathodes are used in the electrolytic separation of gold and silver. Their value lies in the fact that the precipitate of precious metals can be washed off them with aqua regia, which does not harm tantalum.

One can definitely talk about the fact that there is something symbolic, if not even mystical, in the fact that the Swedish chemist Ekeberg, trying to saturate a new substance with acids, was struck by his "thirst" and named the new element in honor of the mythical villain who killed his own son and who betrayed the gods. And two hundred years later, it turned out that this element is able to literally “sew” a person and even “replace” his tendons and nerves! It turns out that the martyr languishing in the underworld, atoning for his guilt with the help of a person, is trying to beg forgiveness from the gods ...

Story

Tantalus is the hero of ancient Greek myths, the Lydian or Phrygian king, the son of Zeus. He divulged the secrets of the Olympic gods, stole ambrosia from their feast and treated the Olympians to a dish prepared from the body of his own son Pelops, whom he also killed. For his atrocities, Tantalus was sentenced by the gods to eternal torment of hunger, thirst and fear in the underworld of Hades. Since then, he has been standing up to his neck in transparent crystal clear water, branches leaning towards his head under the weight of ripe fruits. Only he cannot quench either thirst or hunger - the water goes down as soon as he tries to get drunk, and the branches are lifted by the wind, at the hands of a hungry killer. A rock hangs over Tantalus's head, which can collapse at any moment, forcing the unfortunate sinner to suffer forever from fear. Thanks to this myth, the expression "tantalum torment" arose, denoting unbearable suffering, incorporeal attempts to free oneself from torment. Apparently, in the course of unsuccessful attempts by the Swedish chemist Ekeberg to dissolve the “earth” discovered by him in 1802 in acids and isolate a new element from it, it was this expression that came to his mind. More than once it seemed to the scientist that he was close to the goal, but he failed to isolate a new metal in its pure form. This is how the “martyr” name of the new element appeared.

The discovery of tantalum is closely related to the discovery of another element - niobium, which appeared a year earlier and was originally called Columbia, which was given to it by the discoverer Gatchet. This element is a twin of tantalum close to it in a number of properties. It was this proximity that misled chemists, who, after much debate, came to the erroneous conclusion that tantalum and columbium were one and the same element. This delusion lasted for more than forty years, until in 1844 the famous German chemist Heinrich Rose, in the course of re-studying columbites and tantalites from various deposits, proved that columbium is an independent element. The Columbia studied by Gatchet was niobium with a high content of tantalum, which led the scientific world astray. In honor of such a family proximity of the two elements, Rosa gave Colombia a new name, Niobium - in honor of the daughter of the Phrygian king Tantalus Niobia. And although Rose also made the mistake of allegedly discovering another new element, which he named Pelopius (in honor of Tantalus's son Pelops), his work became the basis for a strict distinction between niobium (columbium) and tantalum. Only, even after Rose's evidence, tantalum and niobium were confused for a long time. So tantalum was called columbium, in Russia columbum. Hess, in his Foundations of Pure Chemistry, up to their sixth edition (1845), speaks only of tantalum, without mentioning Columbia; Dvigubsky (1824) has a name - tantalium. Such errors and reservations are understandable - a method for separating tantalum and niobium was developed only in 1866 by the Swiss chemist Marignac, and as such, pure elemental tantalum did not yet exist: after all, scientists were able to obtain this metal in a pure compact form only in the 20th century. The first who was able to obtain metallic tantalum was the German chemist von Bolton, and this happened only in 1903. Earlier, of course, attempts were made to obtain pure metallic tantalum, but all the efforts of chemists were unsuccessful. For example, the French chemist Moissan received a metal powder, according to him - pure tantalum. However, this powder, obtained by reducing tantalum pentoxide Ta 2 O 5 with carbon in an electric furnace, was not pure tantalum, the powder contained 0.5% carbon.

As a result, a detailed study of the physicochemical properties of the seventy-third element became possible only at the beginning of the twentieth century. For several more years, tantalum did not find practical use. Only in 1922 could it be used in AC rectifiers.

Being in nature

The average content of the seventy-third element in the earth's crust (clarke) is 2.5∙10 -4% by weight. Tantalum is a characteristic element of acidic rocks - granite and sedimentary shells, in which its average content reaches 3.5 ∙ 10 -4%, as for ultrabasic and basic rocks - the upper parts of the mantle and deep parts of the earth's crust, the concentration of tantalum there is much lower: 1 .8∙10 -6%. In rocks of igneous origin, tantalum is dispersed, as well as in the biosphere, since it is isomorphic with many chemical elements.

Despite the low content of tantalum in the earth's crust, its minerals are very widespread - there are more than a hundred of them, both tantalum minerals proper and tantalum-containing ores, all of them were formed in connection with magmatic activity (tantalite, columbite, loparite, pyrochlore and others). In all minerals, tantalum is accompanied by niobium, which is explained by the extreme chemical similarity of the elements and the almost identical sizes of their ions.

Actually tantalum ores have a ratio of Ta 2 O 5: Nb 2 O 5 ≥1. The main minerals of tantalum ores are columbite-tantalite (Ta 2 O 5 content 30-45%), tantalite and manganotantalite (Ta 2 O 5 45-80%), wojinite (Ta, Mn, Sn) 3 O 6 (Ta 2 O 5 60-85%), microlite Ca 2 (Ta, Nb) 2 O 6 (F, OH) (Ta 2 O 5 50-80%) and others. Tantalite (Fe, Mn)(Ta, Nb) 2 O 6 has several varieties: ferrotantalite (FeO>MnO), manganotantalite (MnO>FeO). Tantalite comes in many shades from black to red-brown. The main minerals of tantalum-niobium ores, from which, along with niobium, much more expensive tantalum is extracted, are columbite (Ta 2 O 5 5-30%), tantalum-containing pyrochlore (Ta 2 O 5 1-4%), loparite (Ta 2 O 5 0.4-0.8%), hatchettolite (Ca, Tr, U) 2 (Nb, Ta) 2 O 6 (F, OH)∙nH 2 O (Ta 2 O 5 8-28%), ixiolite (Nb , Ta, Sn, W, Sc) 3 O 6 and some others. Tantalo-niobates containing U, Th, TR are metamict, highly radioactive, and contain variable amounts of water; polymorphic modifications are common. Tantalo-niobates form small disseminations, large segregations are rare (crystals are typical mainly for loparite, pyrochlore and columbite-tantalite). Coloration black, dark brown, brownish yellow. Usually translucent or slightly translucent.

There are several main industrial and genetic types of tantalum ore deposits. Rare-metal pegmatites of the natro-lithium type are represented by zoned vein bodies consisting of albite, microcline, quartz, and, to a lesser extent, spodumene or petalite. Rare-metal tantalum-bearing granites (apogranites) are represented by small stocks and domes of microcline-quartz-albite granites, often enriched in topaz and lithium micas, containing fine dissemination of columbite-tantalite and microlite. Weathering crusts, deluvial-alluvial and alluvial placers, arising in connection with the destruction of pegmatites, contain cassiterite and minerals of the columbite-tantalite group. Loparite-bearing nepheline syenites of lujavrite and foyalite composition.

In addition, deposits of complex tantalum-niobium ores, represented by carbonatites and associated forsterite-apatite-magnetite rocks, are involved in industrial use; microcline-albite riebeckite alkaline granites and granosyenites and others. Some amount of tantalum is extracted from wolframites of greisen deposits.

The largest deposits of titanium ores are located in Canada (Manitoba, Bernick Lake), Australia (Greenbushes, Pilbara), Malaysia and Thailand (tantalum-bearing tin placers), Brazil (Paraiba, Rio Grande do Norte), a number of African states (Zaire, Nigeria, Southern Rhodesia).

Application

Tantalum found its technical application quite late - at the beginning of the 20th century it was used as a material for the filaments of electric lamps, which was due to such a quality of this metal as refractoriness. However, it soon lost its importance in this area, supplanted by the less expensive and more refractory tungsten. Again, tantalum became “technically unsuitable” until the twenties of the 20th century, when it began to be used in AC rectifiers (tantalum, coated with an oxide film, passes current in only one direction), and a year later, in radio tubes. After that, the metal gained recognition and soon began to conquer more and more new areas of industry.

Nowadays, tantalum, due to its unique properties, is used in electronics (production of capacitors of high specific capacitance). Approximately a quarter of the world production of tantalum goes to the electrical and vacuum industry. Due to the high chemical inertness of both tantalum itself and its oxide film, electrolytic tantalum capacitors are very stable in operation, reliable and durable: their service life can reach more than twelve years. In radio engineering, tantalum is used in radar equipment. Mini tantalum capacitors are used in radio transmitters, radar installations and other electronic systems.

The main consumer of tantalum is metallurgy, which uses over 45% of the metal produced. Tantalum is actively used as an alloying element in special steels - heavy-duty, corrosion-resistant, heat-resistant. The addition of this element to ordinary chromium steels increases their strength and reduces brittleness after hardening and annealing. The production of heat-resistant alloys is a great necessity for rocket and space technology. In cases where rocket nozzles are cooled by a liquid metal that can cause corrosion (lithium or sodium), it is simply impossible to do without an alloy of tantalum and tungsten. In addition, heat-resistant steels are used to manufacture heaters for high-temperature vacuum furnaces, heaters, and stirrers. Tantalum carbide (melting point 3,880 °C) is used in the production of hard alloys (mixtures of tungsten and tantalum carbides - grades with the TT index, for the most difficult metalworking conditions and shock rotary drilling of the strongest materials (stone, composites).

Steels alloyed with tantalum are widely used, for example, in chemical engineering. After all, such alloys have exceptional chemical resistance, they are plastic, heat-resistant and heat-resistant, it is thanks to these properties that tantalum has become an indispensable structural material for the chemical industry. Tantalum equipment is used in the production of many acids: hydrochloric, sulfuric, nitric, phosphoric, acetic, as well as bromine, chlorine and hydrogen peroxide. Coils, distillers, valves, mixers, aerators and many other parts of chemical apparatus are made from it. Sometimes - the whole apparatus. Tantalum cathodes are used in the electrolytic separation of gold and silver. The advantage of these cathodes is that the deposit of gold and silver can be washed off them with aqua regia, which does not harm the tantalum.

In addition, tantalum is used in instrumentation (X-ray equipment, control instruments, diaphragms); in medicine (material for reconstructive surgery); in nuclear power - as a heat exchanger for nuclear power systems (tantalum is the most stable of all metals in superheated melts and cesium-133 vapor). The high ability of tantalum to absorb gases is used to maintain a deep vacuum (electrovacuum devices).

In recent years, tantalum has been used as a jewelry material, due to its ability to form durable oxide films of any color on the surface.

Tantalum compounds are also widely used. Tantalum pentoxide is used in nuclear technology for melting glass that absorbs gamma radiation. Potassium fluorotantalate is used as a catalyst in the production of synthetic rubber. Tantalum pentoxide also plays the same role in the production of butadiene from ethyl alcohol.

Production

It is known that ores containing tantalum are rare and poor in this particular element. The main raw materials for the production of tantalum and its alloys are tantalite and loparite concentrates containing only 8% Ta 2 O 5 and more than 60% Nb 2 O 5 . In addition, even those ores that contain only hundredths of a percent (Ta, Nb) 2 O 5 are processed!

The technology for the production of tantalum is quite complex and is carried out in three stages: opening or decomposition; separating tantalum from niobium and obtaining their pure chemical compounds; recovery and refining of tantalum.

The opening of tantalum concentrate, in other words, the extraction of tantalum from ores, is carried out with the help of alkalis (fusion) or with the help of hydrofluoric acid (decomposition) or a mixture of hydrofluoric and sulfuric acids. Then they proceed to the second stage of production - extraction extraction and separation of tantalum and niobium. The latter task is very difficult due to the similarity of the chemical properties of these metals and the almost identical size of their ions. Until recently, metals were separated only by the method proposed as early as 1866 by the Swiss chemist Marignac, who took advantage of the different solubility of potassium fluorotantalate and potassium fluoroniobate in dilute hydrofluoric acid. In modern industry, several methods are used for separating tantalum and niobium: extraction with organic solvents, selective reduction of niobium pentachloride, fractional crystallization of complex fluoride salts, separation using ion exchange resins, and rectification of chlorides. Currently, the most commonly used method of separation (it is also the most perfect) is extraction from solutions of tantalum and niobium fluoride compounds containing hydrofluoric and sulfuric acids. At the same time, tantalum and niobium are also purified from impurities of other elements: silicon, titanium, iron, manganese and other related elements. As for loparite ores, their concentrates are processed by the chlorine method, with the production of a condensate of tantalum and niobium chlorides, which are further separated by the rectification method. Separation of a mixture of chlorides consists of the following stages: preliminary distillation (separation of tantalum and niobium chlorides from accompanying impurities), main distillation (to obtain pure NbCl 5 and TaCl 5 concentrate) and final distillation of the tantalum fraction (obtaining pure TaCl 5). Following the separation of related metals, the tantalum phase is precipitated and purified to obtain high purity potassium fluorotantalate (using KCl).

Tantalum metal is obtained by reducing its compounds of high purity, for which several methods can be used. This is either the reduction of tantalum from pentoxide with soot at a temperature of 1800–2000 °C (carbothermal method), or the reduction of potassium fluorotantalate with sodium when heated (sodium thermal method), or electrochemical reduction from a melt containing potassium fluorotantalate and tantalum oxide (electrolytic method). One way or another, the metal is obtained in powder form with a purity of 98-99%. In order to obtain metal in ingots, it is sintered in the form of blanks pre-compressed from powder. Sintering occurs by passing current at a temperature of 2,500–2,700 °C or by heating in a vacuum at 2,200–2,500 °C. After that, the purity of the metal increases significantly, becoming equal to 99.9-99.95%.

For further refining and obtaining tantalum ingots, electric vacuum melting is used in arc furnaces with a consumable electrode, and for deeper refining, electron beam melting is used, which significantly reduces the content of impurities in tantalum, increases its plasticity and reduces the transition temperature to a brittle state. Tantalum of such purity retains high ductility at temperatures close to absolute zero! The surface of the tantalum ingot is melted (to give the required indicators on the surface of the ingot) or processed on a lathe.

Physical Properties

Only at the beginning of the 20th century did scientists get their hands on pure metallic tantalum and were able to study in detail the properties of this light gray metal with a slightly bluish lead tint. What are the qualities of this element? Definitely, tantalum is a heavy metal: its density is 16.6 g / cm 3 at 20 ° C (for comparison, iron has a density of 7.87 g / cm 3, the density of lead is 11.34 g / cm 3) and for transporting one cubic meter this element would require six three-ton trucks. High strength and hardness are combined in it with excellent plastic characteristics. Pure tantalum lends itself well to machining, is easily stamped, processed into the thinnest sheets (about 0.04 mm thick) and wire (tantalum elasticity modulus 190 Gn / m 2 or 190 10 2 kgf / mm 2 at 25 ° C). In the cold, the metal can be processed without significant work hardening, it is subjected to deformation with a compression ratio of 99% without intermediate firing. The transition of tantalum from a plastic state to a brittle state is not observed even when it is cooled to -196 °C. Tensile strength of high purity annealed tantalum is 206 MN/m2 (20.6 kgf/mm2) at 27°C and 190 MN/m2 (19 kgf/mm2) at 490°C; elongation 36% (at 27°C) and 20% (at 490°C). Tantalum has a cubic body-centered lattice (a = 3.296 A); atomic radius 1.46 A, ionic radii Ta 2+ 0.88 A, Ta 5+ 0.66 A.

As mentioned earlier, tantalum is a very hard metal (the Brinell hardness of sheet tantalum in the annealed state is 450-1250 MPa, in the deformed state 1250-3500 MPa). Moreover, it is possible to increase the hardness of the metal by adding a number of impurities to it, for example, carbon or nitrogen (the Brinell hardness of a tantalum sheet after the absorption of gases during heating increases to 6000 MPa). As a result, interstitial impurities contribute to an increase in Brinell hardness, tensile strength, and yield strength, but reduce ductility characteristics and increase cold brittleness, in other words, make the metal brittle. Other characteristic features of the seventy-third element are its high thermal conductivity, at 20-100 ° C this value is 54.47 W / (m∙K) or 0.13 cal / (cm sec ° C) and refractoriness (perhaps the most an important physical property of tantalum) - it melts at almost 3,000 ° C (more precisely, at 2,996 ° C), yielding in this only to tungsten and rhenium. The boiling point of tantalum is also extremely high: 5,300 °C.

As for other physical properties of tantalum, its specific heat capacity at temperatures from 0 to 100 ° C is 0.142 kJ / (kg K) or 0.034 cal / (g ° C); temperature coefficient of linear expansion of tantalum 8.0 10 -6 (at temperatures of 20-1500 °C). The specific electrical resistance of the seventy-third element at 0 ° C is 13.2 10 -8 ohm m, at 2000 ° C 87 10 -8 ohm m. At 4.38 K, the metal becomes a superconductor. Tantalum is paramagnetic, specific magnetic susceptibility is 0.849 10 -6 (at 18 °C).

So, tantalum has a unique set of physical properties: high heat transfer coefficient, high ability to absorb gases, heat resistance, refractoriness, hardness, plasticity. In addition, it is distinguished by high strength - it lends itself well to pressure treatment by all existing methods: forging, stamping, rolling, drawing, twisting. Tantalum is characterized by good weldability (welding and soldering in argon, helium, or in vacuum). In addition, tantalum has exceptional chemical and corrosion resistance (with the formation of an anode film), low vapor pressure and low electron work function, and, in addition, it gets along well with living tissue of the body.

Chemical properties

Definitely, one of the most valuable properties of tantalum is its exceptional chemical resistance: in this respect it is second only to noble metals, and even then not always. It is resistant to hydrochloric, sulfuric, nitric, phosphoric and organic acids of all concentrations (up to a temperature of 150 °C). In terms of its chemical stability, tantalum is similar to glass - it is insoluble in acids and their mixtures; even aqua regia does not dissolve it, against which gold and platinum and a number of other valuable metals are powerless. The seventy-third element is soluble only in a mixture of hydrofluoric and nitric acids. Moreover, the reaction with hydrofluoric acid occurs only with metal dust and is accompanied by an explosion. Even in hot hydrochloric and sulfuric acids, tantalum is more stable than its twin brother niobium. However, tantalum is less resistant to alkalis - hot solutions of caustic alkalis corrode the metal. Salts of tantalic acids (tantalates) are expressed by the general formula: xMe 2 O yTa 2 O 5 H 2 O, these include MeTaO 3 metatantalates, Me 3 TaO 4 orthotantalates, salts of the Me 5 TaO 5 type, where Me is an alkali metal; in the presence of hydrogen peroxide, pertantalates are also formed. The most important are alkali metal tantalates - KTaO 3 and NaTaO 3; these salts are ferroelectrics.

The high corrosion resistance of tantalum is also indicated by its interaction with atmospheric oxygen, or rather, high resistance to this effect. The metal begins to oxidize only at 280 ° C, being covered with a protective film of Ta 2 O 5 (tantalum pentoxide is the only stable metal oxide), which protects the metal from the action of chemical reagents and prevents the flow of electric current from the metal to the electrolyte. However, as the temperature rises to 500 °C, the oxide film gradually becomes porous, stratifies and separates from the metal, depriving the surface of the protective layer against corrosion. Therefore, it is advisable to carry out hot pressure treatment in a vacuum, since the metal is oxidized to a considerable depth in air. The presence of nitrogen and oxygen increases the hardness and strength of tantalum, simultaneously reducing its ductility and making the metal brittle, and, as mentioned earlier, tantalum forms a solid solution and oxide Ta 2 O 5 with oxygen (with an increase in the O 2 content in tantalum, a sharp increase in strength properties occurs and a strong decrease in ductility and corrosion resistance). Tantalum reacts with nitrogen to form three phases - a solid solution of nitrogen in tantalum, tantalum nitrides: Ta 2 N and TaN - in the temperature range from 300 to 1100 ° C. It is possible to get rid of nitrogen and oxygen in tantalum under high vacuum conditions (at temperatures above 2,000 °C).

Tantalum reacts weakly with hydrogen up to heating to 350 °C, the reaction rate increases significantly only from 450 °C (tantalum hydride is formed and tantalum becomes brittle). All the same heating in a vacuum (over 800 ° C), at which reduction occurs, helps to get rid of hydrogen. mechanical properties tantalum, and the hydrogen is completely removed.

Fluorine acts on tantalum already at room temperature, hydrogen fluoride also reacts with the metal. Dry chlorine, bromine and iodine have a chemical effect on tantalum at a temperature of 150 °C and above. Chlorine begins to actively interact with the metal at a temperature of 250 °C, bromine and iodine at a temperature of 300 °C. Tantalum begins to interact with carbon at very high temperatures: 1,200–1,400°C, with the formation of refractory tantalum carbides, which are very resistant to acids. With boron, tantalum combines to form borides - solid refractory compounds resistant to aqua regia. With many metals, tantalum forms continuous solid solutions (molybdenum, niobium, titanium, tungsten, vanadium, and others). With gold, aluminum, nickel, beryllium and silicon, tantalum forms limited solid solutions. Does not form any compounds of tantalum with magnesium, lithium, potassium, sodium and some other elements. Pure tantalum is resistant to many liquid metals (Na, K, Li, Pb, U-Mg and Pu-Mg alloys).

Smart metal. This term appeared in the business world in the middle of the 20th century. Smart metals have been used as materials for high-tech applications in electronics and robotics. One of these high-tech metals is tantalum. Today it is inextricably linked with such concepts as satellite communications, on-board systems, and telecommunications equipment.

What is tantalum? Historical facts

Tantalum was first discovered in 1802 by the Swedish scientist A.G. Ekeberg in two minerals found in Sweden and Finland. The oxide of this element was very stable, and even a large amount of acid could not destroy its structures. The scientist formed the impression that the metal cannot be saturated with acid. Ekeberg remembered the legend of King Tantalus, who was the son of Zeus and, as a result of punishment, could not satisfy his hunger and thirst. His suffering was called tantalum flour.

So the scientist, no matter how hard he tried, could not isolate pure metal from oxide, so he compared his work with tantalum flour. He gave the name tantalum to the chemical element, and he called the mineral that contained this metal tantalite. Only in 1903 did the German Bolton W. obtain the ductile metal tantalum in its pure form. Its industrial production began only in 1922. The first sample of industrial production of tantalum was only the size of a match head. The USA was the first to produce it, and in 1942 a plant for the production of this metal was launched.

Physical properties of tantalum

What is tantalum? silvery white. A strong oxide film on it gives a similarity in appearance with lead. The metal has high strength and hardness and at the same time ductility. In terms of plasticity, it is compared with gold.

In its pure form, it is perfectly subject to mechanical processing. It is easy to stamp, rolled into a very thin layer up to 0.04 mm. It produces high quality wire. Tantalum, what is it? It is a refractory metal, the melting point of which is approximately 3000 degrees. Only tungsten and rhenium surpass it in this property. One of its specific qualities is its high thermal conductivity. Even the oxide film that forms on it does not reduce this property.

Chemical properties

Many organic and inorganic acids - chlorine, sulfuric, hydrochloric, nitric and other aggressive media - do not cause corrosion in tantalum. The metal is oxidized when heated from 200 to 300 degrees, and a gas-saturated layer is formed on it under the oxide film. The weak chemical properties of tantalum do not allow it to dissolve even in aqua regia, which melts platinum and gold.

In practice, it has been proven that stainless steels are less resistant during operation, and parts made of them serve a much shorter period than products made of tantalum. Of all the existing acids, only hydrofluoric acid can dissolve this metal.

Alloys

The stable resistance of tantalum to acids makes it possible to use it for additives to various alloys that are used in the manufacture of metal structures. For the manufacture of rolled products - wire, strips, sheets, tubes - an alloy of tantalum with hafnium is used. tungsten and tantalum is used to make cutting inserts for various purposes. Such alloys are characterized by:

  • high strength;
  • increased hardness;
  • do not oxidize;
  • have high abrasive resistance;
  • are wear resistant;
  • have a significant viscosity;
  • provide excellent strength to the cutting edge of the tool.

Tantalum-tungsten alloy, which includes 7% tungsten, is able to withstand temperatures up to 1900 degrees. It is of considerable interest to specialists. And from an alloy of tantalum with 10% tungsten, nozzles for rocket engines are made. In space technology, materials are used that have good heat capacity or refractoriness, so tantalum alloys are widely used for its manufacture.

The role of scrap

Tantalum scrap makes up a significant share, up to 30% of supplies to the market, of the total volume. Most of the metal comes from scrap capacitors. Therefore, its supplies are directly dependent on the activity of work in the electronics industry.

And this, in turn, is determined by the global economic conditions. Other sources of scrap are spent carbides. The alloy scrap, the main element of which is nickel, also contains tantalum. In the future, consumer waste will be an important source of this metal.

Use of tantalum

The metal itself and its alloys are widely used in industry. It is used to make:

  • dry electrolytic capacitors;
  • heaters for vacuum furnaces;
  • indirect heating cathodes;
  • anti-corrosion equipment;
  • nuclear reactors;
  • superconductors;
  • ammunition with increased penetrating power;
  • mass standards that have high accuracy;
  • cutting tools of high durability.

The high resistance of the metal to corrosion helps to extend the service life of tantalum capacitors in electronic systems up to 12 years.

The jewelry industry uses this metal to make watch cases and bracelets instead of platinum. Tantalum products are also used in the medical industry. It is not rejected by the human body, therefore, it is produced from it:

  • plates for craniums and abdominal cavity;
  • paper clips that are used to connect vessels;
  • thick threads that replace tendons;
  • thin threads for stitching nerve fibers.

GOST metal

There are several methods for establishing GOST of tantalum and its oxide, for example, photometric and spectral.

The spectral method (GOST 18904.8) determines the content of impurities of calcium, tungsten, copper, cobalt, sodium, molybdenum in tantalum and its oxide. The result of the analysis is the arithmetic mean obtained from 2 determinations of different weights.

The photometric method (GOST 18904.1) determines the content of the mass fraction of tungsten and molybdenum in tantalum and oxide. In this case, the result of the analysis is calculated as the arithmetic mean of 3 determinations, which are performed from individual samples.

Deposits and mining of tantalum

What is tantalum? This is a very rare metal. In its pure form, it is practically not observed. You can meet it in the composition of minerals and in the form of its own compounds. In minerals, it is always found together with niobium, which is very similar in properties to tantalum. Deposits with tantalum compounds and minerals are found in many countries of the world.

The largest is located in France. Stocks of this metal are high in China and Thailand. In the CIS countries, the deposits are much smaller. About 420 tons of tantalum is the annual production in the world. The main plants that process metal are located in Germany and the USA. Due to the rapid development of electronics, in which the use of tantalum is not the last place, there is a shortage of this rare metal, which leads to the search for new deposits.

Tantalum prices

Most of the tantalum, and this is up to 60%, consumes its use at about 20%. Prices for this rare metal can change quickly. Demand for it is restored, then falls again. Analysts predict that supply and demand will fluctuate in the coming years, this mainly depends on economic factors.

The approximate price of tantalum per 1 kg in rubles in the Russian market is:

  • sheet - 65 660;
  • in bars - 73,030;
  • wire - 73,700.

prospects

More and more people are starting to use this smart metal in the medical industry for the needs of reconstructive surgery. It is used to make implants. Tantalum yarn compensates for muscle tissue, wire is used to fasten bones, and threads are used for suturing. In connection with the major re-equipment of world airlines for the needs of the aircraft industry, it will continue to grow. Alloys in the aircraft industry are used for aircraft engines. In addition, tantalum continues to be actively used for the production of computer equipment: processors, printers.

The demand for this metal in the chemical industry is not decreasing either. It is widely used for the production of chlorine, hydrogen peroxide, and many acids. Chemical engineering widely uses it in the manufacture of equipment in contact with aggressive media. The most serious consumer of tantalum alloys remains metallurgical industry. Demand for it is also growing in the nuclear power industry, where thermal conductivity is mainly used in combination with the plasticity and hardness of tantalum.

Tantalum has a high melting point -- 3290 K (3017 °C); boils at 5731 K (5458 °C).

The density of tantalum is 16.65 g/cm. Despite its hardness, it is plastic, like gold. Pure tantalum lends itself well to machining, is easily stamped, rolled into wire and the thinnest sheets with a thickness of hundredths of a millimeter. Tantalum is an excellent getter (gas getter), at 800 °C it is able to absorb 740 volumes of gas. Tantalum has a body-centered cubic lattice. It has paramagnetic properties. At 4.38 K it becomes a superconductor. Pure tantalum is a ductile metal, processed by pressure in the cold without significant work hardening. It can be deformed to a reduction ratio of 99% without intermediate annealing. The transition of Tantalum from the ductile to the brittle state upon cooling to -196 °C was not detected. Tantalum's properties depend to a large extent on its purity; impurities of hydrogen, nitrogen, oxygen and carbon make the metal brittle.

The electronic structure of the atom.

1s 22s 22p 63s 23p64s 23d104p65s24d105p66s24f145d3

serial number-73

Belonging to the group - A

d- element

Tantalum (V) oxide is a white powder, insoluble in either water or acids (except H2F2). Very refractory (tmelt = 1875°C). The acidic nature of the oxide is rather weakly expressed and mainly manifests itself in the reaction with alkali melts: tantalum atom oxidation of niobium

Ta2O5 + 2NaOH = 2NaTaO3 + H2O

or carbonates:

Ta2O5 + 3Na2CO3 = 2Na3TaO4 + 3CO2

Salts containing tantalum in the oxidation state -4, -5 can be of several types: NaTaO3 metatantalates, Na3TaO4 orthotantalates, but there are penta- and hexa-polyions that crystallize together with water molecules, 7- and 8-. Five-charged tantalum reacts with acids to form the TaO3+ cation and TaO(NO3)3 or Nb2O5(SO4)3 salts, continuing the "tradition" of the side subgroup introduced by the vanadium ion VO2+.

At 1000°С, Ta2O5 interacts with chlorine and hydrogen chloride:

Ta2O5 + 10HC1 \u003d\u003d 2TaC15 + 5H2O

Therefore, it can be argued that tantalum (V) oxide is also characterized by amphotericity with the superiority of acid properties over the properties of a base.

The hydroxide corresponding to tantalum (V) oxide is obtained by neutralizing acidic solutions of tantalum tetrachloride. This reaction also confirms the instability of the +4 oxidation state.

At low degrees of oxidation, the most stable compounds are halides (see Fig. 3). The easiest way to obtain them is through pyridine complexes. TaX5 pentahalides (where X is C1, Br, I) are easily reduced by pyridine (denoted by Py) with the formation of complexes of composition MX4(Py)2.

Salts of tantalum. Salts of the sixth subgroup are predominantly colorless crystals or white powders. Many of them are very hygroscopic and deliquesce in air. The oxides of these metals have amphoteric properties; therefore, most of their salts are easily hydrolyzed, turning into basic salts that are little or completely insoluble in water; salts are also known where these metals are part of the anions (for example, niobates and tantalates) Hydration and dehydration. All catalysts of this class have a strong affinity for water. The main representative of class b is alumina. Phosphoric acid or its acidic salts are also used on carriers like aluminosilicate gel and silica gel with tantalum, zirconium or hafnium oxides. In the first works on the separation of tantalum and niobium by fractionated extraction, the systems hydrochloric acid - xylene - methyldioctylamine (1952), as well as hydrochloric acid - hydrofluoric acid - diisopropyl ketone (1953) were proposed. Both metals are dissolved in aqueous solutions of acids in the form of salts, and then tantalum is extracted with an organic solvent. In the system 6/W sulfuric acid--9 Ai hydrofluoric

7. Tantalum is used to make spinnerets for drawing threads in the production of artificial fibers. Previously, such dies were made from platinum and gold. The hardest alloys are made from tantalum carbide with nickel as a cementing additive. They are so hard that they leave scratches even on diamond, which is considered the standard of hardness.

The first place in terms of the critical temperature of the transition to the superconducting state was given to niobium germanide Nb3Ge. Its critical temperature is 23.2K (approximately -250 °C). Another compound, niobium stannide, becomes a superconductor at a slightly lower temperature of -255°C. To appreciate this fact more fully, we point out that most superconductors are known only for liquid helium temperatures (2.172 K). Superconductors made from niobium materials make it possible to manufacture magnetic coils that generate extremely powerful magnetic fields. A magnet with a diameter of 16 cm and a height of 11 cm, where the winding is a tape of such material, is capable of creating a field of colossal intensity. It is only necessary to transfer the magnet to a superconducting state, i.e., to cool it, and cooling to a lower temperature is, of course, easier to produce.

The role of niobium in welding is important. While ordinary steel was being welded, this process did not present any particular difficulties and did not create any difficulties. However, when structures from special steels of complex chemical composition began to be welded, welds began to lose many of the valuable qualities of the metal being welded. Neither changes in the composition of the electrodes, nor the improvement of the designs of welding machines, nor welding in an atmosphere of inert gases gave any effect. This is where niobium came to the rescue. Steel, in which niobium is introduced as a small additive, can be welded without fear for the quality of the weld (Fig. 4) seam. The fragility of the seam is given by the carbides arising during welding, but the ability of niobium to combine with carbon and prevent the formation of carbides of other metals that violate the properties of the alloys saved the situation. The carbides of niobium itself, like tantalum, have sufficient viscosity. This is especially valuable when welding boilers and gas turbines operating under pressure and in aggressive environments.

Niobium and tantalum are able to absorb significant amounts of gases such as hydrogen, oxygen and nitrogen. At room temperature, 1 g of niobium is capable of absorbing 100 cm3 of hydrogen. But even with strong heating, this property practically does not weaken. At 500°C, niobium can still absorb 75 cm3 of hydrogen, and tantalum can absorb 10 times more. This property is used in high vacuum applications or in electronic applications where it is necessary to maintain accurate performance at high temperatures. Niobium and tantalum, deposited on the surface of parts, absorb gases like a sponge, ensuring stable operation of devices. With the help of these metals, reconstructive surgery has achieved great success. Not only tantalum plates, but also tantalum and niobium threads entered medical practice. Surgeons have successfully used these sutures to repair torn tendons, blood vessels, and nerves. Tantalum "yarn" serves to compensate for muscular strength. With its help, surgeons strengthen the walls of the abdominal cavity after surgery. Tantalum has an exceptionally strong bond between atoms. This accounts for its extremely high melting and boiling points. Mechanical qualities and chemical resistance bring tantalum closer to platinum. The chemical industry uses this favorable combination of qualities of tantalum. Parts of acid-resistant equipment of chemical plants, heating and cooling devices that have contact with an aggressive environment are prepared from it.

In the rapidly developing nuclear power industry, two properties of niobium are used. Niobium has an amazing "transparency" for thermal neutrons, that is, it is able to pass them through a layer of metal, practically without reacting with neutrons. The artificial radioactivity of niobium (obtained by contact with radioactive materials) is small. Therefore, it can be used to make containers for storing radioactive waste and installations for their processing. Another no less valuable (for a nuclear reactor) property of niobium is the absence of noticeable interaction with uranium and other metals even at a temperature of 1000 °C. Molten sodium and potassium, which are used as coolants in some types of nuclear reactors, can freely circulate through niobium pipes without causing them any harm.

Story

Tantalum was discovered in 1802 by the Swedish chemist A. G. Ekeberg in two minerals found in Finland and Sweden. However, it was not possible to isolate it in its pure form. Due to the difficulty of obtaining this element, it was named after the hero of ancient Greek mythology, Tantalus.

Subsequently, tantalum and "columbium" (niobium) were considered identical. Only in 1844, the German chemist Heinrich Rose proved that the mineral columbite-tantalite contains two different elements - niobium and tantalum.

The world's largest deposit of tantalum ores, Greenbushes, is located in Australia in the state of Western Australia, 250 km south of Perth.

Physical Properties

At temperatures below 4.45 K, it goes into the superconducting state.

isotopes

Natural tantalum consists of a mixture of a stable isotope and a stable isomer: 181 Ta (99.9877%) and 180m Ta (0.0123%). The latter is an extremely stable isomer (excited state) of the 180 Ta isotope, with a half-life of just over 8 hours.

Chemical properties

Under normal conditions, tantalum is inactive; it oxidizes in air only at temperatures above 280 ° C, becoming covered with an oxide film of Ta 2 O 5; reacts with halogens at temperatures above 250 °C. When heated, it reacts with C, B, Si, P, Se, Te, H 2 O, CO, CO 2, NO, HCl, H 2 S.

Chemically pure tantalum is exceptionally resistant to liquid alkali metals, most inorganic and organic acids, and many other aggressive media (with the exception of molten alkalis).

In terms of chemical resistance to reagents, tantalum is similar to glass. Tantalum is insoluble in acids and their mixtures, except for a mixture of hydrofluoric and nitric acids; even aqua regia does not dissolve it. The reaction with hydrofluoric acid occurs only with metal dust and is accompanied by an explosion. Very resistant to sulfuric acid of any concentration and temperature (at 200 ° C, the metal corrodes in acid by only 0.006 millimeters per year), stable in deoxygenated molten alkali metals and their superheated vapors (lithium, sodium, potassium, rubidium, cesium).

Toxicology

Prevalence

Receipt

The main raw materials for the production of tantalum and its alloys are tantalite and loparite concentrates containing about 8% Ta 2 O 5 , as well as 60% or more Nb 2 O 5 . Concentrates are decomposed by acids or alkalis, loparite concentrates are chlorinated. The separation of Ta and Nb is carried out by extraction. Tantalum metal is usually obtained by reduction of Ta 2 O 5 with carbon, or electrochemically from melts. Compact metal is produced by vacuum arc, plasma melting or powder metallurgy.

To obtain 1 ton of tantalum concentrate, it is necessary to process up to 3,000 tons of ore.

Price

Application

It was originally used to make wire for incandescent lamps. Today, tantalum and its alloys are used to make:

  • heat-resistant and corrosion-resistant alloys;
  • corrosion-resistant equipment for the chemical industry, spinnerets, laboratory glassware and crucibles for obtaining, melting, and casting rare earth elements, as well as yttrium and scandium;
  • heat exchangers for nuclear power systems (tantalum is the most stable of all metals in superheated melts and cesium vapor);
  • in surgery, tantalum sheets, foil and wire are used to fasten tissues, nerves, suturing, making prostheses that replace damaged parts of bones (due to biological compatibility);
  • tantalum wire is used in cryotrons - superconducting elements installed in computer technology;
  • in the production of ammunition, tantalum is used to make metal lining of advanced shaped charges, which improves armor penetration;
  • tantalum and niobium are used to make electrolytic capacitors (higher quality than aluminum electrolytic capacitors, but designed for lower voltage);
  • tantalum has been used in recent years as a jewelry metal, due to its ability to form durable oxide films of beautiful rainbow colors on the surface;
  • the nuclear isomer tantalum-180m2, which accumulates in the structural materials of nuclear reactors, can, along with hafnium-178m2, serve as a source of gamma rays and energy in the development of weapons and special vehicles.
  • The US Bureau of Standards and the International Bureau of Weights and Measures of France use tantalum instead of platinum to make high precision standard analytical weights;
  • Tantalum beryllide is extremely hard and resistant to oxidation in air up to 1650 ° C, used in aerospace technology;
  • Tantalum carbide (melting point 3880 ° C, hardness close to that of diamond) is used in the production of hard alloys - a mixture of tungsten and tantalum carbides (TT index grades), for the most difficult conditions of metalworking and rotary percussion drilling of the strongest materials (stone, composites), and also applied to nozzles, nozzles of rockets;
  • Tantalum(V) oxide is used in nuclear technology to melt glass that absorbs