Chemical properties of niobium. World niobium market
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Physical properties niobium
Niobium is a shiny silver-gray metal.
Elemental niobium is an extremely refractory (2468°C) and high-boiling (4927°C) metal, very resistant to many aggressive environments. All acids, with the exception of hydrofluoric acid, have no effect on it. Oxidizing acids “passivate” niobium, covering it with a protective oxide film (No. 205). But at high temperatures, the chemical activity of niobium increases. If at 150...200°C only a small amount is oxidized surface layer metal, then at 900...1200°C the thickness of the oxide film increases significantly.
The crystal lattice of Niobium is body-centered cubic with parameter a = 3.294A.
Pure metal is ductile and can be rolled into thin sheets (up to a thickness of 0.01 mm) in a cold state without intermediate annealing.
One can note such properties of niobium as high melting and boiling points, lower electron work function compared to other refractory metals - tungsten and molybdenum. The last property characterizes the ability to electronic emissions(electron emission), which is used for the use of niobium in electrovacuum technology. Niobium also has a high transition temperature to the superconducting state.
Density 8.57 g/cm3 (20 °C); melting point 2500 °C; boiling point 4927 °C; vapor pressure (in mm Hg; 1 mm Hg = 133.3 n/m2) 1 10-5 (2194 °C), 1 10-4 (2355 °C), 6 10- 4 (at melting point), 1·10-3 (2539 °C).
At ordinary temperatures, niobium is stable in air. The onset of oxidation (tarnish film) is observed when the metal is heated to 200 - 300°C. Above 500°, rapid oxidation occurs with the formation of Nb2O5 oxide.
Thermal conductivity in W/(m·K) at 0°C and 600°C is 51.4 and 56.2, respectively, and the same in cal/(cm·sec·°C) is 0.125 and 0.156. Specific volume electrical resistance at 0°C 15.22·10-8 ohm·m (15.22·10-6 ohm·cm). The transition temperature to the superconducting state is 9.25 K. Niobium is paramagnetic. Electron work function 4.01 eV.
Pure Niobium is easily processed by cold pressure and retains satisfactory mechanical properties at high temperatures. Its tensile strength at 20 and 800 °C is respectively 342 and 312 Mn/m2, the same in kgf/mm234.2 and 31.2; relative elongation at 20 and 800 °C is 19.2 and 20.7%, respectively. The hardness of pure Niobium according to Brinell is 450, technical 750-1800 Mn/m2. Impurities of certain elements, especially hydrogen, nitrogen, carbon and oxygen, greatly impair the ductility and increase the hardness of Niobium.
Chemical properties niobium
Niobium is especially valued for its resistance to inorganic and organic substances.
There is a difference in the chemical behavior of powdered and lump metal. The latter is more stable. Metals have no effect on it, even if heated to high temperatures. Liquid alkali metals and their alloys, bismuth, lead, mercury, and tin can be in contact with niobium for a long time without changing its properties. Even such strong oxidizing agents as perchloric acid, aqua regia, not to mention nitric, sulfuric, hydrochloric and all the others, cannot do anything with it. Alkali solutions also have no effect on niobium.
There are, however, three reagents that can convert niobium metal into chemical compounds. One of them is a melt of hydroxide of an alkali metal:
4Nb+4NaOH+5O2 = 4NaNbO3+2H2O
The other two are hydrofluoric acid (HF) or its mixture with nitric acid (HF+HNO). In this case, fluoride complexes are formed, the composition of which largely depends on the reaction conditions. In any case, the element is part of an anion of type 2- or 2-.
If you take powdered niobium, it is somewhat more active. For example, in molten sodium nitrate it even ignites, turning into an oxide. Compact niobium begins to oxidize when heated above 200°C, and the powder becomes covered with an oxide film already at 150°C. In this case, one of the wonderful properties This metal retains its ductility.
In the form of sawdust, when heated above 900°C, it completely burns to Nb2O5. Burns vigorously in a stream of chlorine:
2Nb + 5Cl2 = 2NbCl5
When heated, it reacts with sulfur. It is difficult to alloy with most metals. There are, perhaps, only two exceptions: iron, with which solid solutions of different ratios are formed, and aluminum, which has the compound Al2Nb with niobium.
What qualities of niobium help it resist the action of strong acids - oxidizing agents? It turns out that this does not refer to the properties of the metal, but to the characteristics of its oxides. Upon contact with oxidizing agents, a thin (therefore unnoticeable) but very dense layer of oxides appears on the metal surface. This layer becomes an insurmountable barrier on the way of the oxidizing agent to a clean metal surface. Only certain chemical reagents, in particular fluorine anion, can penetrate through it. Consequently, the metal is essentially oxidized, but practically the results of oxidation are imperceptible due to the presence of a thin protective film. Passivity towards dilute sulfuric acid is used to create an AC rectifier. It is designed simply: platinum and niobium plates are immersed in a 0.05 m sulfuric acid solution. Niobium in a passivated state can conduct current if it is a negative electrode - a cathode, that is, electrons can pass through the oxide layer only from the metal side. The path for electrons out of the solution is closed. Therefore, when they pass through such a device alternating current, then only one phase passes, for which platinum is the anode and niobium is the cathode.
niobium metal halogen
In fact, niobium, like all other metals, is gray. However, using passivating oxide layer, we make our metal glow with the most beautiful flowers . But niobium is not just a metal that is pleasing to the eye. Like tantalum, it is stable in many chemical substances ah and is easy to mold even at low temperatures.
Niobium is different in that high level of corrosion resistance it combines with light weight. We use this material to produce coin inserts in all colors, corrosion-resistant evaporation bowls for use in plating technology, and shape-resistant crucibles for growing diamonds. Due to its high level of biocompatibility, niobium is also used as a material for implants. Niobium's high transition temperature also makes it an ideal material for superconducting cables and magnets.
Guaranteed cleanliness.
You can be confident in the quality of our products. As source material We use only the purest niobium. So we guarantee you extremely high purity of the material.
Coins and diamonds. Areas of application of niobium.
The applications of our niobium are as diverse as the properties of the material itself. Below we will briefly introduce two of them:
Valuable and colorful.
Our niobium appears in the most favorable light in the production of coins. As a result of anodization, niobium is formed on the surface. thin layer oxide. Due to the refraction of light, this layer glows different colors. We can influence these colors by changing the layer thickness. From red to blue: any color possible.
Excellent formability and durability.
High corrosion resistance and excellent formability make niobium an ideal material for crucibles used for the production of artificial polycrystalline diamonds (PCD). Our niobium crucibles are used for high temperature synthesis under high pressure.
Pure niobium obtained by smelting.
We supply our smelted niobium in the form of sheets, strips or rods. We can also manufacture products with complex geometries from it. Our pure niobium has the following properties:
- high melting point of 2,468 °C
- high ductility at room temperature
- recrystallization at temperatures from 850 °C to 1,300 °C (depending on the degree of deformation and purity)
- high resistance in aqueous solutions and molten metals
- high ability to dissolve carbon, oxygen, nitrogen and hydrogen (risk of increased brittleness)
- superconductivity
- high level of biological compatibility
Good in all respects: characteristics of niobium.
Niobium belongs to the group of refractory metals. Refractory metals are metals whose melting point exceeds the melting point of platinum (1,772 °C). In refractory metals, the energy that binds individual atoms is extremely high. Refractory metals are different high melting point in combination with low steam pressure, high elastic modulus And high thermal stability. Refractory metals also have low coefficient of thermal expansion. Compared to other refractory metals, niobium has a relatively low density, which is only 8.6 g/cm3
IN periodic table chemical elements niobium is in the same period as molybdenum. In this regard, its density and melting point are comparable to the density and melting point of molybdenum. Like tantalum, niobium is susceptible to hydrogen embrittlement. For this reason heat treatment niobium is performed in a high vacuum rather than in a hydrogen environment. Both niobium and tantalum also have high corrosion resistance in all acids and good formability.
Niobium has highest transition temperature among all the elements, and it constitutes -263.95 °C. Below this temperature, niobium is superconducting. Moreover, niobium has a number of extremely specific properties:
| Properties | ||
|---|---|---|
| Atomic number | 41 | |
| Atomic mass | 92.91 | |
| Melting temperature | 2,468 °C / 2,741 K | |
| Boiling temperature | 4,900 °C / 5,173 K | |
| Atomic volume | 1.80 · 10-29 [m3] | |
| Steam pressure | at 1 800 °C at 2,200 °C | 5 10-6 [Pa] 4 10-3 [Pa] |
| Density at 20 °C (293 K) | 8.55 [g/cm3] | |
| Crystal structure | body-centered cubic | |
| Lattice constant | 3.294 10 –10 [m] | |
| Hardness at 20 °C (293 K) | deformed recrystallized | 110–180 60–110 |
| Modulus of elasticity at 20 °C (293 K) | 104 [GPa] | |
| Poisson's ratio | 0.35 | |
| Coefficient of linear thermal expansion at 20 °C (293 K) | 7.1 10 –6 [m/(m K)] | |
| Thermal conductivity at 20 °C (293 K) | 52 [W/(m K)] | |
| Specific heat at 20 °C (293 K) | 0.27 [J/(g K)] | |
| Electrical conductivity at 20 °C (293 K) | 7 10-6 | |
| Electrical resistivity at 20 °C (293 K) | 0.14 [(Ohm mm2)/m] | |
| Speed of sound at 20 °C (293 K) | Longitudinal wave Transverse wave | 4 920 [m/s] 2 100 [m/s] |
| Electron work function | 4.3 [eV] | |
| Thermal neutron capture cross section | 1.15 10-28 [m2] | |
| Recrystallization temperature (annealing duration: 1 hour) | 850 - 1 300 [°C] | |
| Superconductivity (transition temperature) | < -263.95 °C / < 9.2 K | |
Thermophysical properties.
Like all refractory metals, niobium has a high melting point and is relatively high density. The thermal conductivity of niobium is comparable to that of tantalum, but lower than that of tungsten. Niobium's coefficient of thermal expansion is higher than that of tungsten, but still significantly lower than that of iron or aluminum.
The thermophysical properties of niobium change with temperature changes:
Coefficient of linear thermal expansion of niobium and tantalum
Specific heat capacity of niobium and tantalum
Thermal conductivity of niobium and tantalum
Mechanical properties.
The mechanical properties of niobium depend primarily on its cleanliness and, in particular, the content of oxygen, nitrogen, hydrogen and carbon. Even small concentrations of these elements can have a significant effect. Other factors affecting the properties of niobium include production technology, degree of deformation And heat treatment.
Like almost all refractory metals, niobium has body-centered cubic crystal lattice. The temperature of the brittle-ductile transition of niobium is below room temperature. For this reason, niobium extremely easy to mold.
At room temperature, the elongation at break is more than 20%. As the degree of cold working of a metal increases, its strength and hardness increases, but at the same time the elongation at break decreases. Although the material loses its ductility, it does not become brittle.
At room temperature, the elastic modulus of niobium is 104 GPa, which is less than that of tungsten, molybdenum or tantalum. The elastic modulus decreases with increasing temperature. At a temperature of 1800 °C it is 50 GPa.
Elastic modulus of niobium compared to tungsten, molybdenum and tantalum
Due to its high ductility, niobium is optimally suited for molding processes such as bending, stamping, pressing or deep drawing. To prevent cold welding It is recommended to use tools made of steel or hard metal. Niobium is difficult to produce cutting. The chips are difficult to separate. For this reason, we recommend using tools with chip evacuation steps. Niobium is different excellent weldability compared to tungsten and molybdenum.
Do you have questions about machining refractory metals? We will be happy to help you using our many years of experience.
Chemical properties.
Niobium is naturally coated with a dense layer of oxide. The oxide layer protects the material and provides high corrosion resistance. At room temperature, niobium is not stable in only a few inorganic substances: concentrated sulfuric acid, fluorine, hydrogen fluoride, hydrofluoric acid and oxalic acid. Niobium is stable in aqueous solutions of ammonia.
Alkaline solutions, liquid sodium hydroxide and potassium hydroxide also have a chemical effect on niobium. Elements that form interstitial solid solutions, particularly hydrogen, can also make niobium brittle. Corrosion resistance Niobium decreases with increasing temperature and upon contact with solutions consisting of several chemical substances. At room temperature, niobium is completely stable in the environment of any non-metallic substances, with the exception of fluorine. However, at temperatures above about 150 °C, niobium reacts with chlorine, bromine, iodine, sulfur and phosphorus.
| Corrosion resistance in water, aqueous solutions and non-metallic environments | ||
|---|---|---|
| Water | Hot water< 150 °C | persistent |
| Inorganic acids | Hydrochloric acid< 30 % до 110 °C Серная кислота < 98 % до 100 °C Азотная кислота < 65 % до 190 °C Фтористо-водородная кислота < 60 % Фосфорная кислота < 85 % до 90 °C | persistent persistent persistent unstable persistent |
| Organic acids | Acetic acid< 100 % до 100 °C Щавелевая кислота < 10 % Молочная кислота < 85 % до 150 °C Винная кислота < 20 % до 150 °C | persistent unstable persistent persistent |
| Alkaline solutions | Sodium hydroxide< 5 % Гидроксид калия < 5 % Аммиачные растворы < 17 % до 20 °C Карбонат натрия < 20 % до 20 °C | unstable unstable persistent persistent |
| Salt solutions | Ammonium chloride< 150 °C Calcium chloride< 150 °C Ferric chloride< 150 °C Potassium chlorate< 150 °C Biological fluids< 150 °C Magnesium sulfate< 150 °C Sodium nitrate< 150 °C Tin chloride< 150 °C | persistent persistent persistent persistent persistent persistent persistent persistent |
| Nonmetals | Fluorine Chlorine< 100 °C Bromine< 100 °C Iodine< 100 °C Sulfur< 100 °C Phosphorus< 100 °C Bor< 800 °C | unstableresistant persistent persistent persistent persistent persistent |
Niobium is stable in some metal melts such as Ag, Bi, Cd, Cs, Cu, Ga, Hg, K, Li, Mg, Na and Pb, provided these melts contain a small amount of oxygen. Al, Fe, Be, Ni, Co, as well as Zn and Sn all have a chemical effect on niobium.
| Corrosion resistance in molten metals | |||
|---|---|---|---|
| Aluminum | unstable | Lithium | temperature resistant< 1 000 °C |
| Beryllium | unstable | Magnesium | temperature resistant< 950 °C |
| Lead | temperature resistant< 850 °C | Sodium | temperature resistant< 1 000 °C |
| Cadmium | temperature resistant< 400 °C | Nickel | unstable |
| Cesium | temperature resistant< 670 °C | Mercury | temperature resistant< 600 °C |
| Iron | unstable | Silver | temperature resistant< 1 100 °C |
| Gallium | temperature resistant< 400 °C | Bismuth | temperature resistant< 550°C |
| Potassium | temperature resistant< 1 000 °C | Zinc | unstable |
| copper | temperature resistant< 1200 °C | Tin | unstable |
| Cobalt | unstable | ||
Niobium does not react with inert gases. For this reason, clean inert gases can be used as shielding gases. However, as the temperature increases, niobium actively reacts with oxygen, nitrogen and hydrogen contained in the air. Oxygen and nitrogen can be eliminated by annealing the material in a high vacuum at temperatures above 1,700 °C. Hydrogen is already eliminated at 800 °C. This process results in material loss due to the formation of volatile oxides and structure recrystallization.
Do you want to use niobium in your industrial oven? Please note that niobium may react with components made from refractory oxides or graphite. Even very stable oxides such as aluminum, magnesium or zirconium oxide can be reduced by high temperature, if they come into contact with niobium. Upon contact with graphite, carbides can form, which lead to increased brittleness of niobium. Although niobium can generally be easily combined with molybdenum or tungsten, it can react with hexagonal boron nitride and silicon nitride. The temperature limits shown in the table apply to vacuum. When using shielding gas these temperatures are approximately 100°C-200°C lower.
Niobium, which becomes brittle when exposed to hydrogen, can be regenerated by annealing in high vacuum at 800 °C.
Prevalence in nature and preparation.
In 1801, English chemist Charles Hatchett examined a heavy black stone brought from America. He discovered that the stone contained an element unknown at that time, which he called Colombia according to his country of origin. The name by which it is now known, niobium, was given to it in 1844 by its second discoverer, Heinrich Rose. Heinrich Rose became the first person to separate niobium from tantalum. Before this, it was impossible to distinguish between these two materials. Rose gave the metal the name " niobium"named after the daughter of King Tantalus Niobia. Thus, he wanted to emphasize the close relationship of the two metals. Metallic niobium was first obtained by reduction in 1864 by K.V. Blomstrand. Niobium received its official name only about 100 years later after much debate. International Association of Theoretical and applied chemistry recognized "niobium" as the official name of the metal.
Niobium most often occurs in nature as columbite, also known as niobite. chemical formula which (Fe,Mn) [(Nb,Ta)O3]2. To others important source Niobium is a pyrochlore, calcium niobate of complex structure. Deposits of this ore are located in Australia, Brazil and some African countries.
The mined ore is enriched various methods, and the result is a concentrate with a content of (Ta,Nb)2O5 up to 70%. The concentrate is then dissolved in hydrofluoric and sulfuric acid. After this, fluoride compounds of tantalum and niobium are extracted by extraction. Niobium fluoride is oxidized by oxygen to form niobium pentoxide and then reduced by carbon at 2,000°C to form niobium metal. Through additional electron beam melting, high purity niobium is obtained.
It’s worth starting with the fact that niobium is inextricably linked with a substance such as tantalum. This is even despite the fact that these materials were not discovered at the same time.
What is niobium
What is known today about such a substance as niobium? He is chemical element, which is located in group 5 of the periodic table, having an atomic number of 41, as well as an atomic mass of 92.9. Like many other metals, this substance is characterized by a steel-gray luster.
One of the most important physical parameters This is its refractoriness. It is thanks to this characteristic that the use of niobium has become widespread in many industries. The melting point of this substance is 2468 degrees Celsius, and the boiling point is 4927 degrees Celsius.
The chemical properties of this substance are also at a high level. It is characterized high level resistance to influence negative temperatures, as well as exposure to most aggressive environments.
Production
It is worth saying that the presence of ore that contains the element Nb (niobium) is much greater than that containing tantalum, but the problem lies in the scarcity of the element itself in this ore.
Most often, in order to obtain this element, a thermal reduction process is carried out, in which aluminum or silicon is involved. As a result of this operation, ferroniobium and ferrotantaloniobium compounds are obtained. It is worth noting that receiving metal version This substance is produced from the same ore, but more complex technology is used. Niobium crucibles and other resulting materials are characterized by very high performance characteristics.
Methods for obtaining niobium
Currently, some of the most developed directions for obtaining this material are aluminothermic, sodiumthermic and carbothermic. The difference between these types also lies in the precursors that are used to reduce niobium. Let's say K2NbF7 is used in the sodium thermal method. But, for example, in the aluminothermic method, niobium pentoxide is used.
If we talk about the carbothermic method of production, then this technology involves mixing Nb with soot. This process must take place in a high temperature and hydrogen environment. As a result of this operation, niobium carbide will be obtained. The second stage is that the hydrogen environment is replaced by a vacuum, and the temperature is maintained. At this point, its oxide is added to the niobium carbide and the metal itself is obtained.
It is important to note that among the forms of metal produced, niobium in ingots is quite common. This product is intended for the production of metal-based alloy, as well as various other semi-finished products.
A stack of this material can also be produced, which is divided into several categories depending on the purity of the substance. The least amount of impurities is contained in the beaker labeled NBSh-00. The NBSh-0 class is characterized by a higher presence of elements such as iron, titanium and tantalum silicon. The category that has the highest impurity indicator is NBS-1. It can be added that niobium in ingots does not have such a classification.
Alternative production methods
Alternative methods include crucibleless electron beam zone melting. This process makes it possible to obtain Nb single crystals. Niobium crucibles are produced using this method. It belongs to powder metallurgy. It is used to first obtain an alloy of this material, and then its pure sample. The presence of this method is the reason why advertisements for the purchase of niobium are quite common. This method allows you to use it to get pure metal not the ore itself, which is quite difficult to extract, or the concentrate from it, but secondary raw materials.
To one more alternative method production can include rolled niobium. It is worth noting that most different companies prefer to purchase rods, wire or sheet metal.
Rolled and foil
Foil made from this material is a fairly common semi-finished product. He is the most thin sheet rental of this substance. Used for the production of certain products and parts. Niobium foil is obtained from pure raw materials by cold rolling of Nb ingots. The resulting products are characterized by such indicators as high resistance to corrosion, aggressive environments, and high temperatures. Rolled niobium and its ingots also provide such characteristics as wear resistance, high ductility, and good machinability.
Products obtained in this way are most often used in such fields as aircraft manufacturing, rocket science, medicine (surgery), radio engineering, electrical engineering, nuclear energy, and nuclear energy. Niobium foil is packaged in coils and stored in a dry place, protected from moisture, as well as in a place protected from mechanical influence from outside.
Applications in electrodes and alloys
The use of niobium is very widespread. It can be used, like chromium and nickel, as a material that is part of the iron alloy used to make electrodes. Due to the fact that niobium, like tantalum, is capable of forming superhard carbide, it is often used to produce superhard alloys. It can be added that they are currently trying to use this material to improve the properties of alloys obtained on the basis
Since niobium is a raw material capable of creating carbide elements, it, like tantalum, is used as an alloying mixture in the production of steel. It is worth noting that for a long time the use of niobium as an impurity in tantalum was considered a negative effect. However, today the opinion has changed. It was found that Nb can act as a substitute for tantalum, and with great success, since due to its lower atomic mass you can use a smaller amount of the substance, maintaining all the old capabilities and effects of the product.
Applications in electrical engineering
It is worth emphasizing that the use of niobium, like its brother tantalum, is possible in rectifiers due to the fact that they have the property of unipolar conductivity, that is, these substances pass electrical current in only one direction. It is possible to use this metal to create devices such as anodes, which are used in powerful generators and amplification tubes.
It is very important to note that the use of niobium has reached nuclear energy. In this industry, products made from this substance are used as structural materials. This became possible because the presence of Nb in the parts makes them resistant to heat and also gives them high quality chemical resistance.
Excellent physical characteristics This metal has led to its widespread use in rocketry, jet aircraft, and gas turbines.
Niobium production in Russia
If we talk about the reserves of this ore, there are about 16 million tons in total. The largest deposit, occupying approximately 70% of the total volume, is located in Brazil. About 25% of the reserves of this ore are located in Russia. This indicator is considered a significant part of all niobium reserves. The largest deposit of this substance is located in Eastern Siberia, as well as on Far East. Today in the territory Russian Federation The extraction and production of this substance is carried out by the Lovozersky GOK company. It can be noted that the Stalmag company was also involved in the production of niobium in Russia. It developed the Tatar deposit of this ore, but was closed in 2010.
You can also add that it is engaged in the production of niobium oxide. They obtain it by processing loparite concentrate. This enterprise produces from 400 to 450 tons of this substance, most of which is exported to countries such as the USA and Germany. Part of the remaining oxide goes to the Chepetsk Mechanical Plant, which produces both pure niobium and its alloys. There are significant capacities there, allowing the production of up to 100 tons of material per year.
Niobium metal and its cost
Despite the fact that the scope of application of this substance is quite wide, its main purpose is the space and nuclear industries. For this reason, Nb is classified as a strategic material.
The main parameters that affect the cost of niobium:
- alloy purity, a large number of impurities reduce the price;
- form of material delivery;
- volumes of supplied material;
- location of the ore receiving point ( different regions need different quantities of the element, which means the price for it is different).
Approximate list of prices for materials in Moscow:
- niobium grade NB-2 costs between 420-450 rubles per kg;
- niobium shavings cost from 500 to 510 rubles per kg;
- a stick of the NBSh-00 brand costs from 490 to 500 rubles per kg.
It is worth noting that, despite the enormous cost of this product, the demand for it is only increasing.
Tantalum and niobium are rare metals whose applications are implemented in the field of high technologyand production of high quality modern materials. The main applications of tantalum and niobium differ significantly: tantalum - important material electronic technology, Niobium is a valuable alloying metal. The state of their markets also varies significantly, although in some industrial sources raw materials, in particular in columbite, tantalum and niobium coexist as the main beneficial components.
home The area of application of niobium is steel production. Ferroniobium is used primarily as an additive in high-strength low-alloy steels (HSLS) for oil and gas pipelines, bridges, building structures, car bodies and trucks, tool steels and railway tracks. Niobium doubles the strength and rigidity of such steels.
Special alloyswith niobium are used for the production of parts jet engines, missile units,fire protectionand combustion equipment; zirconium with niobium additive -in nuclear engineering; niobium-titanium and niobium-tin alloys – for the manufacture of superconducting magnetic coils used in nuclear magnetic resonance diagnostics,particle accelerators,Magnetic levitation transport.
Other applications include glass additives to achieve higher refractive index in corrective optical lenses, jewelry applications, medical devices, such as pacemakers, acoustic filters and glass coatings for computer screens.
Relatively new area applications – solid electrolyte capacitors, whichused in expensive electronics (laptops, cars, flat panel TVs) to increasereliability, mainly replacing traditional aluminum and in some applicationstantalum capacitors.
The price of niobium is usually 1/6 the price of tantalum, making it an inexpensive alternative substitute for the latter in similar applications: chemical engineering, nuclear power equipment, electronics,cutting tools.
Consumptionniobium in the world is growing steadily, especially intensively in last years. In the early 1990s. 13-16 thousand tons were used in the world Nb , in 1995-1997. – 16-20 thousand tons, in 1998-2003. – 23-27 thousand tons. In 2005, world consumption of niobium increased to 43 thousand tons, by 47% compared to 29.3 thousand tons in 2004. This acceleration is explained by the intensification of economic development in China and sharp growth prices for vanadium, which competes with niobium,as an alloying component in steel production. In 2006-2007 Ferroniobium consumption continued to increase due to the growing needs of the ferrous metallurgy of China, Japan, the Republic of Korea and Taiwan and 45 thousand tons in terms of Nb. According to some estimates, in 2007 the total world consumption of niobium was a record, amounting to 58.2 thousand tons (83 thousand tons in terms of Nb 2 O 5) .
Total consumption of metallic niobium, its alloys and chemical compounds in 2006 reached 8.1 thousand tons, having increased by 2.2 times compared to 2000. The use ofniobium products, in particular pentoxide,in new areas of application, such as lenses for digital cameras(20% per year).
In general, the global structure of niobium consumption is stable: ferroniobium accounts for85-90% of the total volume of use,for consumption of other products – 10-15%.
The main consumers of niobium are the USA, Japan, China and other countries Western Europe. The range of countries consuming niobium is expanding; in the 1990s, notable consumers, in addition to China, included South Korea, India, Brazil.
IN Russia Currently, niobium consumption is estimated according to various sources from 1400 to 2400 (in the early 2000s - 350-400 tons). The main volume of niobium consumption in Russia was realized in the ferrous metallurgy.
Mineral resource base. Brazil is the leader in niobium reserves, with proven reservesamount to 3.8 million tons Nb 2 O 5 . Australia (460 thousand tons) and Canada (130 thousand tons) also contain large reserves.Relatively small reservesniobium is available in niobium-tantalum raw materials in many countries in Europe, Asia and Africa.
The Arasha deposit is the largest in the world and unique in terms of reserves and quality of niobium ores.contains practically inexhaustible reserves - 460 million tons of ore with an average Nb content 2 O 5 more than 2.5% (11.4 million tons of Nb 2 O 5 Nb 2 O 5 ), which at existing demand for niobium enough for ~170 years.
Industrial raw materials. Near The niobium industry receives 90% of its raw materials from sourcesnot related to the development of tantalum-containing ores. The main industrial mineral of niobium ores is pyrochlore.
Columbite concentrates,containing 65% (Nb,Ta) 2 O 5 with the ratio Nb:Ta = (8-10):1, andcolumbite-tantalite concentrates containing from 25 to 40% Nb 2 O 5 , are used to obtain various connections niobium, primarily oxides. A small portion of niobium is produced fromtin slag, in whichcontains from 2 to 10% Nb 2 O 5 and approximately the same Ta 2 O 5 . In Russia niobium raw materials are loparite concentrates.
By mining and production Brazil is in the lead in niobium by a wide margin. Of the total volume of niobium in concentrates (86-88.6 thousand tons Nb 2 O 5 in the last three years), Brazil accounts for more than 90% - 81-83 thousand tons. Canada produces 7-9%, other countries produce 1% or less. In Brazil and Canada Pyrochlore deposits are being developed. On the world marketpyrochlore concentrates are not sold; they are directly in the mine areaprocessed into ferroniobium. Fromcolumbite-tantalite and tantalite concentratesby-product production of niobium amounts to in recent years just over 400 tons.
In Brazil The main producer of niobium raw materials and products is the companyCompanhia Brasileira de Metalurgia e Mineracão (CBMM)), controlling80-90% of niobium supplies to the world market. CBMM is a fully integrated company within the Arash region there is a large modern mining and metallurgical complex, which includes a quarry, obage fabric and plants that process pyrochlore concentrates into standard grade ferroniobium and other niobium products: niobium pentoxide, special alloys and metallic niobium.Development of the deposit is underway open method without the involvement of drilling and blasting operations, which ensures a very low cost of ore mining.
IN Russia niobium raw materials are minedin recent years at two fields: Lovozerskoye in the Murmansk region. (loparite concentrates) and Tatarsky in the Krasnoyarsk Territory (pyrochlore concentrates). The production of loparite concentrate at Lovozersky has been declining in recent years. Development of the Tatar deposit was suspended in 2005 due to technological difficulties, but has now been resumed with a productivity of 150 thousand tons of ore and the production of 14 thousand tons of crude Nb concentrate 2 O 5 . The producer of ferroniobium is the Klyuchevskoy Ferroalloy Plant (KZF), which in recent years has begun use African pyrochlore raw materials from the Luesh deposit in the Democratic Republic of Congo,the development of which KZF partially financed.
Niobium pentoxide and hydroxide from loparite concentrate, as well as niobium compounds for optics and electronics, are produced by the Solikamsk Magnesium Plant, whichprovides about 10% of world production of niobium pentoxide.In 2006, production amounted to 656 tons in terms of Nb 2 O 5 . Most of the products are exported. Niobium metal is produced in small quantities at the Luch plant in Podolsk.
Some there are processing enterprisesin the territory former USSR. Production of niobium products was recently resumed at the Sillamäe plant in Estonia,which uses hydroxide as a raw materialniobium from the Solikamsk Metallurgical Plant and concentrates imported from Brazil and Nigeria. On your ownequipment factory rare metals Silmet companycapable of producing 120 tons per month of ferroniobium and producing 80-90 tons per month of niobium pentoxide.Part of it is finished products, part is sent to a metallurgical factory to produce niobium metal and Nb-Ni alloy.
The Irtysh Chemical Plant in Kazakhstan (now “Irtysh Chemical and Metallurgical Plant, JSC"). In the 1990s, niobium production first decreased sharply and then stopped altogether; for a long time the enterprise was on the verge of bankruptcy. Since August 2000, the enterprise has processed about 10 thousand tons of imported raw materials (niobium hydroxide from an American company), releasing 5-7 tons of metallic niobium per month. However,plans to double were reportedproduction volume.Niobium metal is produced in small quantities at Ulba Metallurgical Plant in Ust-Kamenogorsk, which imports raw materials from African countries and Russia. UMP estimated its need for niobium raw materials in 2005 at 120 tons of niobium.
Recycled raw materialsapparently doesn't play significant role in the production of niobium, although it can be extracted from niobium-containing steels and superalloys. Treatment from scrap is not effective due tolow contentniobium The US Geological Survey estimates it could be as high as 20% of apparent consumption.
World market conditions and prices.A characteristic feature of the niobium market is its relative stability, due to the large potential for expanding production capacity. This feature was clearly demonstrated by the situation that arose from the middle2000s. Growth in niobium consumption was particularly strong in 2004-2005, but Brazilian companies responded quickly to increased demand for ferroniobium, soconsumption and production remained generally balanced. Stability of the niobium market in large is also determined by the fact thatthe dominant Brazilian company SVMM is veryis responsible for maintaining stability in this market.
Niobium is a non-exchange metal, and prices are usually negotiable. They may vary depending on the quality of the product and the volume of supply. Prices for the main type of niobium raw material – pyrochlore concentrates – have not been published since 1994; in 1992-1993 on the US market they were $6.06/kg Nb 2 O 5 in concentrate, on the Western European market – $5.84/kg. Prices for tantalite-columbite concentrate are given in the “Tantalum” section.
Until 2007, niobium prices remainedfairly stable, more than doubled in 2007, both due to strong growth in demand and due to the need to bring them into line with increased production costs and to compensate for capital costs for expanding production capacity.
According to the message trading system Metaltorg dated October 23, 2008, Chinese suppliers of niobium pentoxide kept prices at 17.7–18.5 dollars/kg for material with a purity of at least 99%.
Ferroniobium prices ($/kgNb alloy) have increased sharply since mid-2007. By May 2008, prices for one-time transactions (spot price) increased to 39.7-41.9 dollars/kgat producer prices t 35.3-36.4 dollars/kg. In November 2008 it was reported basic negotiable price 43-46 USD/kg, but by March 2009 prices had dropped to 34 USD/kg. Current EU price for FeNb is ~$41/kg, as it was in October 2008.
Niobium was discovered in 1801 by the English chemist Charles Getcher and was named columbium by him, after the mineral in which it was contained. IN pure form Niobium was isolated only in 1907, which was associated with great difficulties in obtaining it. Niobium got its name in honor of the heroine Greek mythology Niobe, daughter of Tantalus, son of Zeus, who was the personification of doubt and suffering.
Niobium ores are common in the earth's crust in various minerals; this element is contained in ores in the form of the minerals columbite, pyrochrole, loparite, and lovchorite. All these minerals are separated through beneficiation methods and converted into niobium concentrate.
Niobium is considered a rare element, its content in the earth's crust is 3.2.10-5%, in nature it is almost always found together with tantalum in the form of a mixture of pentoxide Nb2O5 and Ta2O5, and it contains 8-10 times less than niobium.
About 120 minerals containing niobium are known in nature, but only some of them are suitable for industrial processing - niobium is mainly extracted from columbite (up to 77% niobium pentoxide, there is tantalum), loparite (11% niobium pentoxide), pyrochrome (up to 65% niobium pentoxide niobium).
Niobium metal is white in color with a strong shine. Pure niobium is plastic: it can be forged and stretched. Niobium is welded at a red-hot temperature, surpassing tantalum in these properties.
In air, niobium is very resistant to oxidation; when heated, it becomes covered thin film oxide, changing its color as the heating temperature increases from yellow, then blue, to brownish-blue. Niobium metal powder, heated to 400°C, vigorously oxidizes in air, decomposing water with the release of hydrogen. With nitrogen, when heated to 1000°C, it forms nitride. Capable of absorbing hydrogen, forming a hydride, which is very fragile. Reacts vigorously with chlorine at temperatures of 200°C and above. It combines with bromine and iodine only at higher temperatures. It combines with sulfur when heated, forming the sulfides NbS and Nb2S3.
Metallic compact niobium is insoluble in hydrochloric, nitric, sulfuric acids and in aqua regia; it dissolves slowly in hydrofluoric acid; dissolution accelerates upon contact with platinum.
Alkali solutions have no effect on niobium, but molten alkalis and carbon-alkaline salts form niobates. At high temperatures, niobium takes oxygen away from CO2, SO2, P2O5, As2O5, Cr2O3.
RECEIPT.
Niobium - metal - Nb
The main method of enrichment of ores containing columbite and tantalite is gravitational enrichment (wet jigging, enrichment on tables). The result is a concentrate containing, in addition to tantalite and columbite, cassiterite, wolframite and some other minerals. Further enrichment is carried out using flotation and electromagnetic separation. Processing of tantalum-niobium concentrates consists of two stages: the production of tantalum and niobium oxides, followed by the separation of tantalum and niobium, and then the isolation of pure compounds as raw materials for metal production.
There are several ways to process niobium concentrates, including:
the concentrate is treated with a mixture of sulfuric and oxalic acids when heated, niobium goes into solution, from which it can be isolated in the form of pentoxide.
the finely ground concentrate is fused with NaOH in an iron crucible when heated to a temperature of 800-1000°C. After fusion, the melt is poured onto baking sheets, cooled, crushed and then leached with water. This removes a small part of the impurities of silicon, tin, tungsten, aluminum, sulfur, and phosphorus in the form of soluble sodium salts. Then the precipitate containing sodium niobate or tantalate and alkaline compounds of impurities is treated with weak, then strong hydrochloric acid impurities are removed, the remaining Nb2O5 precipitate is dissolved in HF and, with the addition of KF, it is converted into a double salt K2NbOF5, highly soluble in water (unlike the tantalum salt K2TaF7, which is thus separated from niobium).
Metallic niobium is obtained in various ways:
reduction of niobium chloride upon heating;
metallothermic reduction of niobium pentoxide with aluminum;
methods used to reduce tantalum, taking into account the slightly increased volatility of niobium at high temperatures compared to tantalum.