What is the metal platinum and where is it found. What are the properties of platinum? Platinum Description

Platinum is one of the unique precious metals, the physical properties of which are still not fully understood. Nevertheless, taking into account the available data on platinum, its physical and chemical properties, we can confidently speak about certain areas of application of platinum, which, in particular, determine the investment attractiveness of this precious metal.

Physical properties

One of the main characteristics of platinum is that this precious metal is very refractory and hardly volatile. At the same time, platinum has the ability to crystallize into face-centered cubic lattices.

Scientists note that in the presence of the effect of reducing agents on salt solutions, platinum can be obtained in the form of the so-called "niello", a distinctive feature of which is high dispersion.

Being in a hot state, platinum has the ability to roll and weld well.

Did you know that one of the characteristic properties of platinum is the unique ability of the precious metal to absorb certain gases on the surface, in particular, oxygen and hydrogen.

Platinum is a precious metal

The main characteristics of platinum include the following:

1. The density of the precious metal at a temperature of -20 degrees Celsius reaches 21.45 g/dm3.
2. Platinum has a grayish-white, lustrous color.
3. The radius of the platinum atom is 0.138 nm.
4. Platinum melts at temperatures above 1769 degrees Celsius.
5. The boiling point of platinum is 4590 degrees Celsius.
6. The specific heat capacity of platinum is 25.9 J.

Applications

To main areas of application of platinum relate:

1. Industry and technology.
2. Medicine and dentistry.
3. Jewelry business.
4. monetary industry.
5. Chemical industry.
6. Mirror making.
7. Manufacture of various glass products and others.

Consider each of the areas of application of platinum in more detail.

Industry and technology. Platinum in Russia began to be used in the form of an alloying additive in the production of high-strength steels in the first quarter of the nineteenth century. Today, platinum is actively used, in particular, in dentistry, jewelry and medicine.

In the oil refining industry, it is with the help of platinum catalysts, which are installed on catalytic reforming units, that products such as:

• high octane gasoline;
• aromatic hydrocarbons;
• technical hydrogen.

Did you know that platinum is also used in the manufacture of special mirrors for laser technology, which uses durable electrical contacts and alloys of platinum and iridium for radio engineering.

Automotive industry actively uses platinum in the manufacture of special automotive catalysts. In this case, the unique catalytic properties of platinum are used, which allow for post-combustion and exhaust gas neutralization processes.

Platinum is used in pharmaceuticals

The medicine. The share of platinum used in medicine is insignificant, but it has no analogues in this industry.

Thus, platinum is used in the manufacture of surgical instruments, which makes it possible to sterilize such instruments in the flame of an alcohol burner without oxidizing the metal.

It is interesting! Some platinum compounds, mainly tetrachloroplatinates, are actively used as cytostatics, but today more effective drugs have already been invented to combat cancer.

Jewelry industry. Most platinum jewelry contains ninety-five percent pure precious metal. The undoubted advantage of platinum jewelry is the minimization of quantitative indicators of impurities, which allows platinum jewelry to retain its color and brilliance and not fade over a long period of time.

Did you know that every year the share of consumption of platinum by the global jewelry industry is about fifty tons.

Until 2001, most platinum jewelry was consumed in Japan, but since 2001 the People's Republic of China has accounted for about fifty percent of the world's platinum jewelry sales.

The main properties of platinum, which determine its popularity in the jewelry industry, are:

1. High plasticity.
2. Unique durability.
3. High density.

monetary industry. Platinum, along with gold and silver, is one of the main precious metals that perform a monetary function.

It is important to note that platinum began to be used as a subject for the production of coins several millennia later than gold and silver.

The first platinum coins in the world were coins of the Russian Empire, issued between 1828 and 1845.

The minting of platinum coins in the Russian Empire was finally stopped in 1846. Although by this time the level of extraction of Ural platinum was about two thousand pounds, which is identical to thirty-two thousand kilograms. A little less than half of this volume was minted into the coin - 14669 kilograms.

A huge amount of platinum that had accumulated at the St. Petersburg Mint, both in the form of coins and in raw form, was sold to the English company Johnson, Matte and Co. while not mining platinum at all.

After 1846, platinum coins were not put into circulation in any country in the world. Modern platinum coins are investment.

The Bank of Russia issued investment platinum coins from 1992 to 1995. The coins issued by the Bank of Russia had denominations of twenty-five, fifty and one hundred and fifty rubles.

Chemical industry. Special platinum containers - crucibles, used in the chemical industry when it is necessary to carry out a reaction when heated in air. In the event that it becomes necessary to carry out high-temperature synthesis, in which it is necessary to exclude air access, special platinum ampoules, which are actually disposable utensils that are used to carry out one chemical reaction. However, after such a reaction, the platinum ampoule can be cleaned and remelted into a new ampoule.

Platinum is also used as a material for thermocouples. In this case, platinum is part of the platinum-rhodium alloy from which the thermocouple conductors are made. It is platinum-rhodium thermocouples that are best suited for use in laboratory practice due to the fact that with their help it is possible to measure the temperature in air up to the maximum limit values ​​of 1600-1700 degrees Celsius.

Platinum is the best catalyst in the oxidation of ammonia to nitric oxide, which is used in one of the main processes for the production of nitric acid.

Platinum in this case is used in the form of a grid made of platinum wire, the diameter of which varies between five and nine hundredths of a millimeter. The material of such nets also contains another precious metal of the platinum group - rhodium, the content ratio of which here varies within five to ten percent.

platinum catalysts. One of the most important and one of the most fundamental applications of platinum is the manufacture of catalysts, which are used to speed up a number of critical reactions, including:

• hydrogenation of fats;
• hydrogenation of cyclic and aromatic hydrocarbons;
• hydrogenation of olefins, aldehydes, acetylene, ketones;
• oxidation of SO2 to SO3 in sulfuric acid production;
• synthesis of vitamins and individual pharmaceutical preparations.

We have already mentioned the use of platinum in the oil refining industry above. Its importance here cannot be underestimated.

In general, the physical properties of platinum, which we mentioned in the first section of this article, determine the variety of applications for platinum. Finally, I would like to note that platinum is a unique precious metal, the possibilities for investing in it are endless. Investments in platinum are attractive in the medium and long term, since no analogues of this precious metal have been found in many industries, and it will be actively used, which will undoubtedly provoke a reduction in the reserves of this precious metal in the world and, accordingly, an increase in its market value. .

Platinum is a rare, shiny, silver-colored metal. It occupies a special place among other precious metals, being usually more expensive than gold and silver.

This is due to the fact that the extraction of platinum is an extremely laborious process and this metal is very rare. For example, to obtain one ounce of gold, it is enough to refine three tons of ore, and to extract a similar amount of platinum, it is necessary to process up to ten tons of rock.

History of metal use

Platinum has been known since before our era. It was used in ancient Egypt to make a variety of jewelry. It was also common among the Inca tribes, but was forgotten over time. In the photo you can see platinum items discovered by archaeologists:

Only after a long time, the discovery of this substance was due to Spanish travelers who explored South America. Initially, it was not appreciated, as the name suggests. "Platina" in Spanish can be formulated as "little silver".
Accordingly, platinum was valued much less than precious metals. Often it was even considered immature gold or the wrong silver (due to color) and simply thrown away. It is characterized by refractoriness and high density. Therefore, it was considered unsuitable for any use.

However, an interesting property was later discovered - this precious metal has the ability to easily fuse with gold. Jewelers took this into account and actively began to mix platinum into gold items, thereby lowering the cost of their manufacture. Moreover, this was done so skillfully that it was almost impossible to detect a fake. Due to the high density of platinum, even its small volume increased the weight of the finished product, but this was compensated by the addition of a certain amount of silver to the alloy, which did not affect the color. Such fraud was nevertheless recognized, and the import of the precious metal into Europe was prohibited by law for some time.

As an independent chemical element, platinum was recognized only in the middle of the eighteenth century. Careful study of its qualities made it possible to find the first use of this metal.

The physical and operational properties of platinum, especially resistance to various influences and high density, served as the basis for making useful equipment from it. In particular, platinum retorts have been successfully used to concentrate caustic sulfuric acid.

Such vessels were originally made by forging or pressing, since at that time scientific progress could not provide the required temperature in furnaces for melting. By the end of the nineteenth century, it was possible to melt platinum, using for this purpose the flame that occurs during the combustion of explosive gas.

Platinum in Russia

The history of this noble metal in Russia dates back to 1819, when it was first found in the Urals, not far from Yekaterinburg. Five years later, deposits of platinum were found in the Nizhny Tagil district. Placers turned out to be so abundant that Russia quickly became the leader in production worldwide.

In the photo you can see the largest nugget mined at these deposits:

Its weight was 12 kg (unfortunately, it was later melted down).

Ural platinum was actively bought by foreign companies, exports especially increased after an industrial method was developed for purifying it from impurities and creating pure silver ingots. Initially, it was in great demand abroad in England and France, later the USA and Germany joined them.

In the process of research, scientists discovered some elements that make up native platinum. Palladium and rhodium were the first to replenish Mendeleev's periodic table, and later iridium and osmium were isolated. And the final element in the platinum group was ruthenium, discovered in 1844.

Due to the fact that the volumes of platinum mined in the Urals were extremely high and most of the metal simply did not find worthy use, in 1828 it was decided to issue platinum coins. The photo shows the first Russian-made coins made from this precious metal.

By that time, a way had already been found to produce various high-quality products. This method, called powder metallurgy, is widely used today. At the moment, Russian platinum coins of the 19th century are of tremendous value. The cost of one copy can reach up to 5000 US dollars.

For the manufacture of jewelry, most of the mined platinum was used until the middle of the twentieth century, after which it began to be used more often for technical purposes. It is applied in the following industries:

• Automotive industry (for the manufacture of catalysts);
• Electrical engineering (creation of elements for electric furnaces exposed to high temperatures);
• Petrochemical and organic synthesis;
• Synthesis of ammonia.

It is also used in the manufacture of parts for glass melting furnaces, a variety of laboratory equipment, equipment for industries where resistance to chemical and thermal influences is necessary.

Basic properties

You can often hear the opinion that platinum and white gold are one and the same. But in fact, such a statement is fundamentally wrong, they are similar only in color.

Platinum is a chemical element of the periodic table (the natural classification of elements according to the electronic structure of atoms), with its own characteristic properties. Although the photo shows some resemblance to white gold in appearance.

It is a precious metal of silver color, but it still looks a little different than silver. It differs from others also in its characteristics and methods of application.

Physical and chemical properties of platinum

This element is a refractory metal with a high density, for its melting a temperature of 1769 degrees Celsius is required, and for boiling - 3800 degrees, due to the low thermal conductivity.

It is also one of the heaviest metals in the periodic table. According to this indicator, it is surpassed only by two other elements of the platinum group - osmium and iridium. The density under normal conditions is 21.45 grams per square decimeter. The specific gravity is 21.45 grams per cubic centimeter. This indicator is higher than that of gold and is almost twice the specific gravity of silver.

The hardness of platinum is another quality that has made it useful in industry and jewelry. Resistance to various external influences makes the process of processing and manufacturing products more laborious, but its operational properties more than compensate for such inconveniences.

For example, jewelry can be made entirely of pure platinum, while gold and silver require impurities in other materials to ensure strength.

It is also worth noting the high ductility of this metal. It can be used to make the thinnest sheet of foil or light wire, without losing its basic properties.

Platinum belongs to the group of noble metals, as it does not have the ability to oxidize and resists corrosion. The high inertness of the metal does not allow interaction with acids or alkalis. It can only be dissolved in "aqua regia" and liquid bromine, subject to dissolution with prolonged exposure to hot sulfuric acid.

When this substance is heated, the possibility of interaction with other chemical elements, substances and alloys increases. An increase in temperature makes it possible to obtain platinum oxide, which forms on the surface of the metal. There are several varieties of it, which are easy to distinguish by color.

The most famous are:

• Black PtO (dark grey);
• Platinum oxide PtO2 (brown);
• Oxide PtO3 (red-brown).

The speed and degree of oxidation of this metal directly depends on how freely oxygen enters the surface and what its pressure is. Other metals located on the surface of platinum can serve as an obstacle to oxidation. Therefore, the greatest oxidation should be expected from a pure metal without any impurities.

Depending on the specific compound, platinum can show different oxidation states. This indicator varies from 0 to +8.

With a fairly low resistivity, this metal is a good conductor, inferior in this property to aluminum, copper and silver. The resistivity index is close to that of iron.

Accordingly, the specific conductivity of platinum (the reciprocal of resistivity) occupies a similar position among other elements of the periodic table. Since it is a conductor, its resistivity increases as it heats up, while its conductivity, on the contrary, decreases. This property is due to the fact that the particles in the composition of platinum begin to move in a chaotic manner with increasing temperature. And this, in turn, creates obstacles for the passage of electric current.

One of the most important qualities, which is widely used in production, is the property of this noble metal to act as a catalyst for numerous chemical reactions. It is usually used in an alloy with rhodium or as platinum black - a fine powder of a characteristic black color, obtained as a result of the reduction of compounds.

Platinum resistance thermometers are now quite widespread (illustrated in the photo). This is due to the fact that this substance is practically not subject to corrosion, has a high degree of plasticity, inertness and makes it possible to use pure metal for production. An important role is played by such qualities as high resistivity and a significant temperature coefficient of resistance.

Conclusion

Most people think of platinum as a very expensive silvery white metal that is used to make jewelry. However, due to its numerous properties, it has become widespread in various fields of human activity, from medicine to the automotive industry.

Although platinum has never been used as money in its entire history, investing in platinum is considered a fairly profitable investment. One ounce of this metal exceeds the cost of a similar amount of gold by $270. If you constantly monitor the rate of precious metals, you can get a good profit.

Platinum- mineral, natural Pt from the platinum group of the class of native elements, usually contains Pd, Ir, Fe, Ni. Pure platinum is very rare, most of the samples are represented by a ferruginous variety (polyxene), and often intermetallic compounds: isoferroplatinum (Pt,Fe) 3 Fe and tetraferroplatinum (Pt,Fe)Fe. Platinum, represented by polyxene, is the most common mineral of the platinum subgroup in the earth's crust.

See also:

STRUCTURE

The crystal lattice of platinum belongs to the cubic system. The cyclohexene molecule has the shape of a regular hexagon. In the reaction system under consideration, the atomic structure of the catalyst and the reacting molecules have one common property—third-order symmetry elements. In a platinum crystal, this arrangement of atoms is inherent only in the octahedral face. The nodes contain platinum atoms. a = 0.392 nm, Z = 4, space group Fm3m

PROPERTIES

The color of polyxene is silver-white to steel-black. The dash is metallic steel grey. The luster is typical metallic. Reflectivity in polished sections is high - 65-70.
Hardness 4-4.5, for iridium-rich varieties - up to 6-7. Has malleability. The fracture is hooked. Cleavage is usually absent. Oud. weight-15-19. A connection between a reduced specific gravity and the presence of voids occupied by natural gases, as well as inclusions of foreign minerals, was noted. It is magnetic, paramagnetic. Conducts electricity well. Platinum is one of the most inert metals. It is insoluble in acids and alkalis, with the exception of aqua regia. Platinum also directly reacts with bromine, dissolving in it.

When heated, platinum becomes more reactive. It reacts with peroxides, and upon contact with atmospheric oxygen, with alkalis. A thin platinum wire burns in fluorine with the release of a large amount of heat. Reactions with other non-metals (chlorine, sulfur, phosphorus) are less active. With stronger heating, platinum reacts with carbon and silicon, forming solid solutions, similarly to the metals of the iron group.

RESERVES AND PRODUCTION

Platinum is one of the rarest metals: its average content in the earth's crust (clarke) is 5 10 -7% by weight. Even the so-called native platinum is an alloy containing from 75 to 92 percent platinum, up to 20 percent iron, as well as iridium, palladium, rhodium, osmium, less often copper and nickel.

The explored world reserves of platinum group metals are about 80,000 tons and are distributed mainly between South Africa (87.5%), Russia (8.3%) and the USA (2.5%).

In Russia, the main deposits of platinum group metals are: Oktyabrskoye, Talnakhskoye and Norilsk-1 sulfide-copper-nickel deposits in the Krasnoyarsk Territory in the Norilsk region (more than 99% of the explored and more than 94% of the estimated Russian reserves), Fedorova Tundra (Bolshoy Ikhtegipakhk area) sulfide- copper-nickel in the Murmansk region, as well as placer Kondyor in the Khabarovsk Territory, Levtyrinyvayam in the Kamchatka Territory, the Lobva and Vyysko-Isovskoe rivers in the Sverdlovsk Region. The largest platinum nugget found in Russia is the "Ural giant" weighing 7860.5 g, discovered in 1904. at the Isovsky mine.

Native platinum is mined at mines, loose deposits of platinum are less rich, which are explored mainly by the method of schlich sampling.

The production of platinum in powder form began in 1805 by the English scientist W. H. Wollaston from South American ore.
Today, platinum is obtained from a concentrate of platinum metals. The concentrate is dissolved in aqua regia, after which ethanol and sugar syrup are added to remove excess HNO 3 . In this case, iridium and palladium are reduced to Ir 3+ and Pd 2+ . Ammonium hexachloroplatinate(IV) (NH 4) 2 PtCl 6 is isolated by subsequent addition of ammonium chloride. The dried precipitate is calcined at 800-1000 °C
The sponge platinum thus obtained is subjected to further purification by redissolving in aqua regia, precipitation of (NH 4 ) 2 PtCl 6 and calcining the residue. The purified spongy platinum is then melted down into ingots. When recovering solutions of platinum salts by a chemical or electrochemical method, finely dispersed platinum - platinum black is obtained.

ORIGIN

The platinum group minerals are mostly found in typical igneous deposits genetically related to ultramafic igneous rocks. These minerals in ore bodies stand out among the latter (after silicates and oxides) at the moments corresponding to the hydrothermal stage of the magmatic process. Platinum minerals poor in palladium (polyxene, iridescent platinum, etc.) are found in deposits among dunites, olivine feldspar-free rocks rich in magnesia and poor in silica. At the same time, they are paragenetically closely related to chrome spinels. Palladium to nickel-palladium platinum is predominantly distributed in the main igneous rocks (norites, gabbro-norites) and is usually associated with sulfides: pyrrhotite, chalcopyrite and pentlandite.
Under exogenous conditions, in the process of destruction of primary deposits and rocks, platinum-bearing placers are formed. Most minerals of the platinum subgroup are chemically stable under these conditions. Platinum in placers occurs in the form of nuggets, flakes, plates, cakes, concretions, as well as skeletal forms and spongy secretions ranging in size from 0.05 to 5 mm, sometimes up to 12 mm. Flattened and lamellar grains of platinum indicate a significant distance from primary sources and redeposition. The range of platinum transfer in placers usually does not exceed 8 km, in oblique placers it is longer. The palladium and cuprous varieties of platinum in the hypergenesis zone can be "ennobled", losing Pd, Cu, Ni. The content of Cu and Ni, according to A.G. Betekhtin, in platinum from placers can be reduced by more than 2 times compared to platinum from the primary source. In the placers of many regions of the world, newly formed chemically pure platinum and palladium platinum are described in the form of sintered forms of a radial-radiant structure.

APPLICATION

Platinum compounds (mainly aminoplatinates) are used as cytostatics in the treatment of various forms of cancer. Cisplatin (cis-dichlorodiammineplatinum(II)) was the first to be introduced into clinical practice, but more effective carboxylate complexes of diammineplatinum - carboplatin and oxaliplatin - are currently used.

Platinum and its alloys are widely used for jewelry production.

The world's first platinum coins were issued and were in circulation in the Russian Empire from 1828 to 1845. Minting began with three-rouble coins. In 1829, “platinum duplons” (six-ruble notes) were established, and in 1830, “quadruples” (twelve-ruble notes). The following denominations of coins were minted: denominations of 3, 6 and 12 rubles. Three-ruble coins were minted 1,371,691 pieces, six-ruble notes - 14,847 pieces. and twelve rubles - 3474 pcs.

Platinum was used in the manufacture of insignia for outstanding services: the image of V. I. Lenin was made from platinum on the Soviet Order of Lenin; the Soviet order "Victory", the order of Suvorov of the 1st degree and the order of Ushakov of the 1st degree were made from it.

• Since the first quarter of the 19th century, it has been used in Russia as an alloying additive for the production of high-strength steels.
• Platinum is used as a catalyst (most often in an alloy with rhodium, and also in the form of platinum black - a fine powder of platinum obtained by reducing its compounds).
• Platinum is used to make vessels and stirrers used in the melting of optical glasses.
• For the manufacture of chemically and strong heat-resistant laboratory glassware (crucibles, spoons, etc.).
• For the manufacture of permanent magnets with high coercive force and residual magnetization (an alloy of three parts of platinum and one part of cobalt PlK-78).
• Special mirrors for laser technology.
• For the manufacture of durable and stable electrical contacts in the form of alloys with iridium, for example, contacts of electromagnetic relays (alloys PLI-10, PLI-20, PLI-30).
• Galvanic coatings.
• Distillation retorts for the production of hydrofluoric acid, obtaining perchloric acid.
• Electrodes for the production of perchlorates, perborates, percarbonates, peroxysulfuric acid (in fact, the use of platinum determines the entire world production of hydrogen peroxide: electrolysis of sulfuric acid - peroxysulfuric acid - hydrolysis - distillation of hydrogen peroxide).
• Insoluble anodes in electroplating.
• Heating elements of resistance furnaces.
• Production of resistance thermometers.
• Coatings for elements of microwave technology (waveguides, attenuators, resonator elements).

Platinum - Pt

CLASSIFICATION

Strunz (8th edition)	1/A.14-70
Nickel-Strunz (10th edition)	1.AF.10
Dana (7th edition)	1.2.1.1
Dana (8th edition)	1.2.1.1
Hey's CIM Ref	1.82

PHYSICAL PROPERTIES

OPTICAL PROPERTIES

CRYSTALLOGRAPHIC PROPERTIES

dot group	m3m (4/m 3 2/m) - isometric hexaoctahedral
space group	Fm3m
Syngony	cubic
Cell Options	a = 3.9231Å
Twinning	total by (111)

“This metal from the beginning of the world until now has remained completely unknown, which is no doubt very surprising. Don Antonio de Ulloa, a Spanish mathematician who was in partnership with the French academicians sent from the king to Peru... is the first to mention her in the news of his journey, published in Madrid in 1748. Note that soon after the discovery of platinum, or white gold, they thought that it was not a special metal, but a mixture of two known metals. Glorious chemists considered this opinion, and their experiments destroyed it ... "
So it was said about platinum in 1790 on the pages of the "Shop of Natural History, Physics and Chemistry", published by the famous Russian educator N. I. Novikov.

Today platinum not only a precious metal, but - what is much more important - one of the important materials of the technical revolution. One of the organizers of the Soviet platinum industry, Professor Orest Evgenyevich Zvyagintsev, compared the value of platinum with the value of salt in cooking - you need a little, but without it you cannot cook dinner ...
The annual world production of platinum is less than 100 tons (in 1976 - about 90), but the most diverse areas of modern science, technology and industry cannot exist without platinum. It is indispensable in many critical units of modern machines and devices. It is one of the main catalysts of the modern chemical industry. Finally, the study of compounds of this metal is one of the main "branches" of modern chemistry of coordination (complex) compounds.

White gold

"White gold", "rotten gold", "frog gold"... Under these names, platinum appears in the literature of the 18th century. This metal has been known for a long time; its white heavy grains were found during gold mining. But they could not be processed in any way, and therefore platinum did not find application for a long time.

Until the 18th century this most valuable metal, together with waste rock, was thrown into the dump, and in the Urals and Siberia, grains of native platinum were used as shot when shooting.
In Europe, platinum began to be studied from the middle of the 18th century, when the Spanish mathematician Antonio de Ulloa brought samples of this metal from the gold deposits of Peru.
Grains of white metal, which do not melt and do not split when struck on an anvil, he brought to Europe as a kind of funny phenomenon ... Then there were studies, there were disputes - whether platinum was a simple substance or "a mixture of two known metals - gold and iron", as he believed , for example, the famous naturalist Buffoy.
The first practical use of this metal was already in the middle of the 18th century. found counterfeiters.
At that time, platinum was valued at half the value of silver. And its density is high - about 21.5 g / cm 3, and it fuses well with gold and silver. Taking advantage of this, they began to mix platinum with gold and silver, first in jewelry, and then in coins. Having found out about this, the Spanish government announced the fight against platinum "damage". A royal decree was issued ordering the destruction of all platinum mined along with gold. In accordance with this decree, the officials of the mints in Santa Fe and Papaya (Spanish colonies in South America) solemnly, in front of numerous witnesses, periodically drowned the accumulated platinum in the Bogotá and Nauka rivers.
Only in 1778 this law was repealed, and the Spanish government, acquiring platinum at very low prices, began to mix it with the gold of the coins itself ... They adopted the experience!
It is believed that pure platinum was first obtained by the Englishman Watson in 1750. In 1752, after Schaeffer's research, it was recognized as a new element. In the 70s of the XVIII century. the first technical products from platinum (plates, wire, crucibles) were made. These products, of course, were imperfect. They were prepared by pressing sponge platinum under high heat. The Parisian jeweler Janpetit (1790) achieved high skill in the manufacture of platinum items for scientific purposes. He fused native platinum with arsenic in the presence of lime or alkali, and then burnt out the excess arsenic with strong calcination. The result was malleable metal suitable for further processing.
In the first decade of the XIX century. high-quality products from platinum were made by the English chemist and engineer Wollaston, the discoverer of rhodium and palladium. In 1808-1809. in France and England (almost simultaneously) platinum vessels were made almost a pood in weight. They were intended to produce concentrated sulfuric acid.
The appearance of such products and the discovery of the valuable properties of element No. 78 increased the demand for it, the price of platinum rose, and this, in turn, stimulated new research and searches.

Chemistry of Platinum #78

Platinum can be considered a typical element of group VIII. This heavy silver-white metal with a high melting point (1773.5 ° C), high malleability and good electrical conductivity was not without reason classified as noble. It does not corrode in most aggressive environments, it is not easy to enter into chemical reactions and with all its behavior it justifies the well-known saying of I. I. Chernyaev: "The chemistry of platinum is the chemistry of its complex compounds."
As befits an element of group VIII, platpa can exhibit several valences: 0, 2+, 3+, 4+, 5+, 6+ and 8+. But, when it comes to element No. 78 and its analogues, almost the same as valency, another characteristic is important - the coordination number. It means how many atoms (or groups of atoms), ligands, can be located around the central atom in the molecule of the complex compound. The most characteristic oxidation state of platinum in its complex compounds is 2+ and 4+; the coordination number in these cases is four or six, respectively. Complexes of bivalent platinum have a planar structure, while those of tetravalent platinum are octahedral.
In the schemes of complexes with a platinum atom in the middle, the letter A denotes ligands. Ligands can be various acidic residues (Cl -, Br -, I -, N0 2, N03 -, CN -, C 2 04 ~, CNSH -), neutral molecules of simple and complex structure (H 2 0, NH 3, C 5 H 5 N, NH 2 OH, (CH 3) 2 S, C 2 H 5 SH) and many other inorganic and organic groups. Platinum can even form complexes in which all six ligands are different.
The chemistry of platinum complex compounds is varied and complex. Let's not burden the reader with significant details. Let's just say that in this complex area of ​​knowledge, Soviet science has invariably gone and is going ahead. Characteristic in this sense is the statement of the famous American chemist Chatt.
“Perhaps it was no coincidence that the only country that devoted much of its chemical research effort in the 1920s and 30s to the development of coordination chemistry was also the first country to send a rocket to the moon.”
Here it is appropriate to recall the statement of one of the founders of the Soviet platinum industry and science - Lev Aleksandrovich Chugaev: "Each precisely established fact concerning the chemistry of platinum metals will sooner or later have its practical equivalent."

Need for platinum

Over the past 20-25 years, the demand for platinum has increased several times and continues to grow. Before World War II, over 50% of platinum was used in jewelry. From alloys of platinum with gold, palladium, silver, copper, they made settings for diamonds, pearls, topaz ... The soft white color of the platinum setting enhances the play of the stone, it seems larger and more elegant than in a frame made of gold or silver. However, the most valuable technical properties of platinum made its use in jewelry irrational.
Now about 90% of the consumed platinum is used in industry and science, the share of jewelers is much less. The reason for this is a complex of technically valuable properties of element No. 78.
Acid resistance, heat resistance and stability of properties upon ignition have long made platinum indispensable in the manufacture of laboratory equipment. “Without platinum,” Justus Liebig wrote in the middle of the last century, “it would be impossible in many cases to analyze the mineral ... the composition of most minerals would remain unknown.” Platinum is used to make crucibles, cups, glasses, spoons, spatulas, spatulas, tips, filters, and electrodes. Rocks are decomposed in platinum crucibles - most often by fusing them with soda or treating them with hydrofluoric acid. Platinum glassware is used for particularly precise and responsible analytical operations...
The most important areas of application of platinum were the chemical and oil refining industries. About half of all platinum consumed is now used as catalysts for various reactions.
Platinum is the best catalyst for ammonia oxidation reaction to nitric oxide NO in one of the main processes for the production of nitric acid. The catalyst here appears in the form of a grid of platinum wire with a diameter of 0.05-0.09 mm. The rhodium additive (5-10%) was introduced into the mesh material. A ternary alloy of -93% Pt, 3% Rh and 4% Pd is also used. The addition of rhodium to platinum increases the mechanical strength and increases the service life of the weave, while palladium slightly reduces the cost of the catalyst and slightly (by 1-2%) increases its activity. The service life of platinum nets is a year and a half. After that, the old grids are sent to the refinery for regeneration and new ones are installed. The production of nitric acid consumes significant amounts of platinum.
Platinum catalysts accelerate many other practically important reactions: hydrogenation of fats, cyclic and aromatic hydrocarbons, olefins, aldehydes, acetylene, ketones, oxidation of S0 2 to S0 3 in sulfuric acid production. They are also used in the synthesis of vitamins and some pharmaceuticals. It is known that in 1974 about 7.5 tons of platinum was spent for the needs of the chemical industry in the USA.

Equally important are platinum catalysts in the oil refining industry. With their help, high-octane gasoline, aromatic hydrocarbons and industrial hydrogen are obtained from gasoline and naphtha oil fractions at catalytic reforming units. Here, platinum is usually used in the form of a finely dispersed powder deposited on alumina, ceramics, clay, and coal. Other catalysts (aluminum, molybdenum) also work in this industry, but platinum ones have undeniable advantages: high activity and durability, high efficiency. The US oil refining industry purchased in 1974 about 4 tons of platinum.
Another major consumer of platinum has become the automotive industry, which, oddly enough, also uses the catalytic properties of this metal - for afterburning and neutralizing exhaust gases.
For these purposes, the US automobile industry purchased 7.5 tons of platinum in 1974 - almost as much as the chemical and oil refining industries combined.
The fourth and fifth largest buyers of platinum in 1974 in the US were the electrical and glass industries.
The stability of the electrical, thermoelectric and mechanical properties of platinum plus the highest corrosion and thermal resistance have made this metal indispensable for modern electrical engineering, automation and telemechanics, radio engineering, and precision instrumentation. Platinum is used to make fuel cell electrodes. Such elements are used, for example, on the spacecraft of the Apollo series.
An alloy of platinum with 5-10% rhodium is used to make spinnerets for the production of glass fiber. Optical glass is melted in platinum crucibles when it is especially important not to disturb the recipe at all.
In chemical engineering, platinum and its alloys serve as excellent corrosion-resistant materials. Equipment for the production of many highly pure substances and various fluorine-containing compounds is coated with platinum from the inside, and sometimes entirely made of it.
A very small part of platinum goes to the medical industry. Surgical instruments are made from platinum and its alloys, which, without being oxidized, are sterilized in the flame of an alcohol burner; this advantage is especially valuable when working in the field. Alloys of platinum with palladium, silver, copper, zinc, nickel are also an excellent material for dentures.
The demand of science and technology for platinum is constantly growing and is not always satisfied. Further study of the properties of platinum will further expand the scope and possibilities of this most valuable metal.
"SILVER"? The modern name of element No. 78 comes from the Spanish word plata - silver. The name "platinum" can be translated as "silver" or "silver".
STANDARD KILOGRAM. From an alloy of platinum with iridium in our country, a kilogram standard was made, which is a straight cylinder with a diameter of 39 mm and a height of 39 mm. It is stored in Leningrad, at the All-Union Scientific Research Institute of Metrology named after V.I. D. I. Mendeleev. It used to be a standard and a platinum-iridium meter.
PLATINUM MINERALS. Raw platinum is a mixture of various platinum minerals. The mineral polyxene contains 80-88% Pt and 9-10% Her; cuproplatia - 65-73% Pt, 12-17% Fe and 7.7-14% Cu; nickel platinum, along with element No. 78, includes iron, copper and nickel. Natural alloys of platinum with only palladium or only with iridium are also known - there are traces of other platinoids. There are also a few minerals - compounds of platinum with sulfur, arsenic, antimony. These include sperrylite PtAs 2 , cooperite PtS, braggite (Pt, Pd, Ni)S.
THE BIGGEST. The largest platinum nuggets displayed at the exhibition of the Diamond Fund of Russia weigh 5918.4 and 7860.5 g.
PLATINUM BLACK. Platinum black is a finely dispersed powder (grain size 25-40 microns) of metallic platinum, which has a high catalytic activity. It is obtained by acting with formaldehyde or other reducing agents on a solution of complex hexachloroplatinic acid H 2 [PtCl 6 ].
FROM THE "CHEMICAL DICTIONARY", PUBLISHED IN 1812. "Professor Snyadetsky in Vilna discovered a new metal creature in platinum, which he called the Beast"...
“Fourcroix read an essay at the Institute, in which he announces that platinum contains iron, titanium, chromium, copper and a metallic being, hitherto unknown” ...
“Gold combines well with platinum, but when the amount of this latter exceeds 1/47, then gold turns white, without significantly increasing its weight and malleability. The Spanish government, fearing this composition, banned the release of platinum, because they did not know the means to prove the forgery "...
FEATURES OF PLATINUM WARE. It would seem that platinum dishes in the laboratory are suitable for all occasions, but this is not so. No matter how noble this heavy precious metal, when handling it, it should be remembered that at high temperatures platinum becomes sensitive to many substances and influences. It is impossible, for example, to heat platinum crucibles in a reducing and especially sooty flame: red-hot platinum dissolves carbon and becomes brittle because of this. Metals do not melt in platinum dishes: relatively low-melting alloys may form and precious platinum may be lost. It is also impossible to melt metal peroxides, caustic alkalis, sulfides, sulfites and thiosulfates in platinum dishes: sulfur for red-hot platinum is a certain danger, just like phosphorus, silicon, arsenic, antimony, elemental boron. But boron compounds, on the contrary, are useful for platinum dishes. If it is necessary to clean it properly, then a mixture of equal amounts of KBF 4 and H 3 BO 3 is melted in it. Usually, for cleaning, platinum dishes are boiled with concentrated hydrochloric or nitric acid.

Synonyms: white gold, rotten gold, frog gold. polyxene

Origin of name. It comes from the Spanish word platina - a diminutive of plata (silver). The name "platinum" can be translated as silver or silver.

Under exogenous conditions, in the process of destruction of primary deposits and rocks, platinum-bearing placers are formed. Most minerals of the subgroup are chemically stable under these conditions.

Place of Birth

Large deposits of the first type are known near Nizhny Tagil in the Urals. Here, in addition to primary deposits, there are also rich eluvial and alluvial placers. Examples of deposits of the second type are the Bushveld igneous complex in South Africa and Sudbury in Canada.

In the Urals, the first finds of native platinum, which attracted attention, date back to 1819. There it was discovered as an admixture to alluvial gold. Independent richest platinum-bearing placers, which are world famous, were discovered later. They are common in the Middle and Northern Urals and are all spatially confined to outcrops of ultramafic rock massifs (dunites and pyroxenites). Numerous small primary deposits have been established in the Nizhne Tagil dunite massif. Accumulations of native platinum (polyxene) are confined mainly to chromite ore bodies, consisting mainly of chrome spinels with an admixture of silicates (olivine and serpentine). From the heterogeneous ultramafic Konder massif in the Khabarovsk Territory, platinum crystals of cubic habit, about 1–2 cm in size, come from the edge. A large amount of palladium platinum is mined from the segregation sulfide copper-nickel ores of the deposits of the Norilsk group (North of Central Siberia). Platinum can also be extracted from the late magmatic titanomagnetite ores associated with the main rocks of such deposits as, for example, Gusevogorskoye and Kachkanarskoye (Middle Urals).

Of great importance in the platinum mining industry is an analogue of Norilsk - the well-known Sudbury deposit in Canada, from whose copper-nickel ores platinum metals are mined along with nickel, copper and cobalt.

Practical use

In the first period of mining, native platinum did not find proper use and was even considered a harmful impurity to alluvial gold, with which it was captured along the way. At first, it was simply thrown into the dump when washing gold or used instead of shot when shooting. Then attempts were made to falsify it by gilding and handing it over to buyers in this form. Chains, rings, barrel hoops, etc., were among the very first items made from native Ural platinum, kept in the St. Petersburg Mining Museum. The remarkable properties of the platinum group metals were discovered somewhat later.

The main valuable properties of platinum metals are hard melting, electrical conductivity and chemical resistance. These properties determine the use of metals of this group in the chemical industry (for the manufacture of laboratory glassware, in the production of sulfuric acid, etc.), electrical engineering and other industries. Significant amounts of platinum are used in jewelry and dentistry. Platinum plays an important role as a surface material for catalysts in oil refining. The extracted "raw" platinum goes to refineries, where complex chemical processes are carried out to separate it into its constituent pure metals.

Mining

Platinum is one of the most expensive metals, its price is 3-4 times higher than gold, and about 100 times higher than silver.

The extraction of platinum is about 36 tons per year. The largest amount of platinum is mined in Russia, the Republic of South Africa, Caiade, the USA and Colombia.

In Russia, platinum was first found in the Urals in the Verkh-Isetsky district in 1819. When washing gold-bearing rocks, white shiny grains were noticed in gold, which did not dissolve even in strong acids. Bergprobier of the laboratory of the St. Petersburg Mining Corps V. V. Lyubarsky in 1823 examined these grains and established that “the mysterious Siberian metal belongs to a special kind of raw platinum containing a significant amount of iridium and osmium.” In the same year, the highest command followed to all mining chiefs to look for platinum, separate it from gold and present it to St. Petersburg. In 1824-1825 pure platinum placers were discovered in the Gorno-Blagodatsky and Nizhny Tagil districts. And in the following years, platinum in the Urals was found in several more places. The Ural deposits were exceptionally rich and immediately brought Russia to the first place in the world in the production of heavy white metal. In 1828, Russia mined an amount of platinum unheard of at that time - 1550 kg per year, about one and a half times more than was mined in South America for all the years from 1741 to 1825.

Platinum. Stories and legends

Mankind has known platinum for more than two centuries. For the first time, members of the expedition of the French Academy of Sciences, sent by the king to Peru, drew attention to him. Don Antonio de Ulloa, a Spanish mathematician, being on this expedition, was the first to mention it in travel notes published in Madrid in 1748: "This metal has remained completely unknown from the beginning of the world until now, which is no doubt very surprising."

Under the names "White gold", "rotten gold" platinum appears in the literature of the XVIII century. This metal has been known for a long time, its white heavy grains were sometimes found during gold mining. It was assumed that this was not a special metal, but a mixture of two known metals. But they could not be processed in any way, and therefore platinum did not find application for a long time. Until the 18th century, this most valuable metal, along with waste rock, was thrown into dumps. In the Urals and Siberia, grains of native platinum were used as shot for shooting. And in Europe, dishonest jewelers and counterfeiters were the first to use platinum.

In the second half of the 18th century, platinum was valued two times lower than silver. It fuses well with gold and silver. Using this, platinum began to be mixed with gold and silver, first in jewelry, and then in coins. Having found out about this, the Spanish government declared war on platinum "damage". A Kopolevsky decree was issued, which ordered the destruction of all platinum mined along with gold. In accordance with this decree, the officials of the mints in Santa Fe and Papaya (Spanish colonies in South America) solemnly, with numerous witnesses, periodically drowned the accumulated platinum in the Bogotá and Cauca rivers. Only in 1778 this law was repealed, and the Spanish government itself began to mix platinum with gold coins.

It is believed that the Englishman R. Watson was the first to receive pure platinum in 1750. In 1752, after research by G. T. Schaeffer, it was recognized as a new metal.

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