Platinum: properties and applications

Substances that exist in nature are an almost inexhaustible topic for stories. Moreover, not all of them are equally well known. It is imperative to find out, at least for general development, the main points associated with platinum, its properties and features of application.

Those who graduated from school a few decades ago would confidently say that platinum is a metal of a secondary subgroup of the 8th group of Mendeleev's Periodic Table of Elements. However, this classification is outdated and now platinum belongs to the 10th group of elements.

It is impossible to say how this metal looks in nature. Indeed, in its pure form, it can only be obtained artificially. Platinum ores have only small inclusions of the main substance. From a physical point of view, they are isomorphic mixtures of Pt with:

• copper;
• iron;
• nickel;
• silver;
• various platinum group metals.

Platinum ores are scattered everywhere. Most of them are concentrated in the New World. That's why the honor of the discovery of platinum belongs to the ancient Indians... Even experts do not know when exactly they began to mine this metal. But after the discovery of platinum by Europeans, its role in the economy turned out to be rather negative.

No wonder in 1735 in Spain they decided to prohibit the import of previously mined platinum into the metropolis. What was again mined in Colombia was ordered to be carefully separated from silver and flooded in rivers. And everything that they managed to import into Spain itself was drowned in the sea in a solemn atmosphere.

But it is curious that less than half a century has passed since Madrid, on the contrary, embarked on an increased import of platinum raw materials. Then they began to use it on a national scale to counterfeit coins from other precious metals. By 1820, according to various sources, there were from 3 to 7 tons of platinum in Europe. It was from it that the standards of the meter and kilogram were made in France. But it still did not have any serious application for a long time.

The specific gravity of pure platinum is 21.45 grams per cubic meter. see It melts at a temperature of about 1768 degrees Celsius. Boiling (evaporation) occurs at 3825 degrees. It is these temperature characteristics that for a long time did not allow not to isolate pure metal, much less to establish its use. In addition, platinum is harder than gold and silver, and it is rather difficult to machine it mechanically.

This metal is malleable and ductile. Its tensile strength is quite impressive.

It dissolves only in:

• royal vodka;
• liquid bromine;
• heated sulfuric acid (but extremely slowly).

Therefore, it makes no sense to bring it to a magnet to separate it from silver or gold. You just need to understand that there are no pure platinum jewelry. They can contain various concentrations of iron and nickel, and it is precisely these impurities that react quite well to the magnet.

Curious that in the microcosm, platinum may well have magnetic properties. Physicists in the experiment managed to find them near the atomic layer of the metal; the opening was announced in 2018. To impart ferromagnetic properties to a substance, an ionic liquid had to be used - a new type of substance specially created during research. As for the color of platinum, in nature it is painted in a silvery-white tone. Sometimes there are also dark gray specimens.

It is important to extract platinum ore from the bowels of the earth, for this there are several ways.

Despite the original finding of platinum deposits in South America, the largest deposit in the world in the 21st century is located in Africa. To be more precise, then in South Africa. Bushveld complex - a giant accumulation of platinum group metals; it is believed that it appeared 2 billion years ago as a result of volcanic processes. In shape, the South African field resembles a "plate" with a diameter of 370 km. The complex is composed of several horizons that are directed inland.

At the same time, the thickness of the deposits in 2 horizons out of three is only about 1 m. The Platrif horizon, which is currently being actively developed, has a thickness of 5-90 m in different places. It is mined in an open way. The complex was opened in 1924. It is from here that ¾ of all mined platinum goes to the world market.

But even today our country is included in the list of leading countries in the extraction of platinum ores. True, it is already in second place, 5.8 times behind South Africa. The precious metal is also exported from Russia. The third line in the world ranking is occupied by Zimbabwe, where about 3 times less platinum is mined (9 tons).

And also platinum is mined:

• USA (6000 kg);
• Canada (approximately 5000 kg);
• other states (6100 kg together).

This metal can be extracted both by open and mine methods. Quarries are mainly located where secondary placers are found. In these places, platinum was deposited after mechanical destruction of the primary deposits. But geologists have long found out that most of it is concentrated in underground layers of nickel ores. Mine mining differs little from working with other metallic minerals; it is worth noting only a significant proportion of manual labor.

After enrichment, its concentration rises by 3 orders of magnitude. At the Bushveld complex, the extraction of 1 kg of platinum ultimately (taking into account technological losses) requires the lifting of 500-1500 kg of ore. Then the semi-finished product is processed in refining metallurgical furnaces and special converters; but the final result is achieved only after refining, when the metal concentration is 99.5%.

Platinum is better than gold because it is stronger than it. Therefore, the service life of platinum products is much higher. It is much more difficult to scratch them. As a result, these types of jewelry (and not only) are less likely to be repaired. Aged platinum is even more different from gold.

Thanks to the patina, it acquires a gray color with a matte sheen. Many wearers try to get rid of this effect and polish their jewelry. According to other people, the patina makes the precious metal, if not even more valuable, then in any case more interesting. Without seeing it live, it is unlikely that it will be possible to make the right decision. The rhodium layer on the white gold will gradually wear off and it will turn much yellower.

They also gradually fade, and they will have to be systematically cleaned. After all silver is chemically active, and it will inevitably react with the most common substances, even with atmospheric oxygen. However, all this difference in favor of platinum is overshadowed by the fact that it is noticeably less available than gold and even more so silver.

Tungsten is similar to platinum. But it is significantly cheaper, while the strength of tungsten products is also high. The problem is that tungsten is much harder to process into its normal shape. Redesigning a tungsten ring, adjusting its size is not an easy task, even with the technology of the 21st century. The same difficulties arise when using titanium imitations.

There are quite a few types of platinum alloys. Most of the jewelry is made from 950 metal, which contains 95% pure platinum. Sometimes you can find the 900th alloy. Its obvious disadvantages are not too saturated color and inexpressive shine. Therefore, in aesthetic terms, it loses a lot to 950 metal.

Alloys of platinum with iridium are widespread. The more this second component, the more refractory the compound will be. The crystallization range of platinum-iridium alloys is relatively narrow. The hardness and strength of the substance also increases significantly.

For various purposes, platinum can also be alloyed with:

• copper;
• ruthenium;
• palladium;
• nickel;
• rhodium.

A very large proportion of platinum is used in industry. Technologists highly appreciate the property of this metal to accelerate various chemical reactions without consuming. Nowadays it is sometimes used in medicine, primarily for dental prosthetics. Already in the middle of the last century, this use accounted for several percent of all platinum mined. This number is gradually increasing.

Its use is also widespread in the production of nitric acid (as an ammonia oxidizer). True, in this case, a platinum-rhodium alloy is more often used, and not a pure metal. The reasons for this preference are of interest only to technologists and are beyond the scope of this article.Another precious metal is used in the production of sulfuric acid, hydrogenation of hydrocarbons, acetylene, ketones.

But platinum is also widely used in the oil refining industry. It is an excellent catalyst to accelerate the production of gasoline. In the distillation columns, not a mesh, as is sometimes thought, is placed, but a finely dispersed platinum powder. It is more durable than both molybdenum and vanadium. And also in favor of platinum is evidenced by the increased efficiency.

Platinum can be used in resistance contacts of electric furnaces. You can find it in many other electrical contacts.

Platinum-cobalt alloy is needed to create magnets that combine compactness and great performance.

Many motorists implicitly use platinum for themselves every day. In automobiles, it is mainly contained in catalysts. This metal helps to reduce the toxicity of exhaust gases, thereby improving the condition of the urban atmosphere. The platinum coating in the catalyst is applied to a monolithic ceramic element.

Returning to medicine, it is worth noting that unique surgical instruments are made on the basis of platinum. They can be disinfected with alcohol burners without the need for special reagents. Dentists love to work with instruments coated with a thin layer of platinum. Platinum-iridium electrodes are used to control the rhythm of the heart, and for prosthetics for hearing problems.

But one cannot fail to mention the role of "white metal" in other areas.

So, it is in high demand in glass production... Or rather, not window glass, but high quality optical glasses. Rhodium-platinum compound helps to make fiberglass dies less than 1 mm thick. It has been functioning for many thousands of hours at a temperature of 1400-1500 degrees, which develops inside glass furnaces.

Elite Czech glass, which costs almost fabulous money, is made inside platinum crucibles.

Of course, the chemical industry could not pass by such a substance so resistant to heat and the most caustic reagents. It is used to make crucibles from platinum, other utensils for research and expert laboratories, for especially clean industries.

So, exactly on the basis of Pt create some devices used in the creation of semiconductor crystalsv. Only inside them it is possible to create such conditions when the concentration of impurities will be less than 1 atom per million. Even in platinum crucibles, crystals are produced that are necessary for creating lasers and for contacts in low-current electrical engineering.

This metal goes further into:

• mirrors used inside lasers;
• retorts for the production of hydrofluoric and perchloric acids;
• insoluble anodes for electroplating equipment;
• resistance thermometers;
• separate parts of microwave equipment;
• drugs that suppress some forms of cancer;
• production of coins and insignia, medals and orders;
• equipment for synthesizing vitamins and some other pharmacological preparations.

From the very beginning, you need to focus on the price. Platinum with an identical fineness will be at least three times more expensive than gold... Moreover, there are not so many jewelers working with it. The overwhelming majority of such craftsmen work in Western Europe. It is advisable to focus on jewelry from there. But do not trust the price tag and the words of the sellers, but demand official certificates.

The addition of cobalt and ruthenium can increase the product's lifespan. Iridium-added jewelry is more likely to scratch, but it saves money. The sample must be chosen first of all taking into account your financial capabilities.

And a few more tips:

• platinum is combined visually with any precious stones;
• the best option (if funds are available) would be to combine it with diamonds;
• the stones inserted must correspond to the general concept;
• engraved lettering and designs can quickly go out of style;
• and of course, you need to go to an official jewelry store, and not to the first retail outlet you come across on the way or to a kiosk in the middle of an underpass.

There are no specific requirements here. Cleaning is usually done with platinum-specific cleaning agents. You can buy them at most jewelry stores. Some people use unsaturated soapy water or highly diluted ammonia. Sometimes liquid dishwashing detergents are also used; however, soaps and gels are thought to cause a loss of gloss.

It is carried out only by experienced jewelers using special equipment. Store the platinum item separately from jewelry made of other metals. This will protect them from deformation when touched with a harder object.

The high value of platinum is due not only to its own unique properties, but also to its comparative rarity. It is estimated that even in deposits (as in the entire earth's crust), the concentration of Pt is 30 times less than the concentration of gold. From 1828 to 1845 platinum coins were made in our country. Their face value was 3, 6 and 12 rubles, and the total amount of consumed metal exceeded 14 tons. Platinum fell into the category of precious metals only in 1751 - about 200 years have passed since it became known in Europe.

And in our country, in the very first 10 years of mining, as much platinum was extracted as in the entire America during the centuries preceding the discovery of the Ural deposits. AND it was in Russia that both the largest (generally remelted) and the largest of the extant nuggets were found. Platinum received the status of a chemical element in 1735, when the Italian D. Scaliger proved its indissolubility; previously it was thought to be a simple substance.

Chemically pure platinum was isolated from the ore only 68 years later in England. In its metallic form, it is completely biologically neutral. However, individual compounds (primarily with fluorine) can be extremely life-threatening. And in 1867, all Russian stocks of platinum (immediately after the lifting of the moratorium on sales) were bought by England. But even in the first years of the twentieth century, our country accounted for at least 90% of world production (because fantastic reserves in southern Africa were found only in the mid-1920s).

It is not surprising, therefore, that in May 1918 a special institute for the study of platinum was created. Now it is part of the Institute of General and Inorganic Chemistry. Certain platinum-containing minerals also contain antimony, arsenic or sulfur, but they are less common than compounds with metals. Thus, the mineral Norilskite mined in the north of the Krasnoyarsk Territory contains 25% iron and 26% nickel. It is curious that at one of the stages of the industrial production of platinum, a sugar solution can be used.

And the names of this metal are quite diverse: it is called both "rotten gold" and "frog gold". Its small crystals have a cubic shape. Initially, in the first half of the 19th century, rings and hoops for barrels were made from platinum in our country. In terms of electrical conductivity, this metal is inferior to copper, and aluminum, and silver. Platinum begins to oxidize with atmospheric oxygen only at temperatures above 200 degrees.

For more information on platinum and its properties, see the video.