Platinum

History of platinum

Antonio de Ulloa

The ancient world already knew metal platinum. During archaeological excavations in Egypt, in the ruins of ancient Thebes, an artwork was found, which the specialists attributed to the 7th c. BC. e. In this relic of the ancient world there was a grain of platinum-rich iridium.

In the early I c. n. e. the washing of gold-bearing sands in Spain and Portugal began to show a significant interest in the useful use of "white lead", or "white gold", as they called platinum. According to the Roman writer Pliny the Elder (author of the 37-volume book "Natural History"), "white lead" was extracted from the gold placers of Valissia (Northwest Spain) and Lusitania (Portugal). Pliny says that the "white lead" was collected during washing with gold to the bottom of the baskets and melted separately.

Long before the conquest of South America by the Spanish and Portuguese conquistadors, platinum was extracted by the cultural indigenous people-the Incas, who not only owned the secret of cleaning and forging this precious metal, but also knew how to skillfully decorate various objects and ornaments from it.

The epoch of the fall of the Roman Empire is marked by the disappearance of jewelers and jewelers from platinum. Many centuries passed, and only in the second half of the XVIII century. platinum and its physico-chemical properties began to interest scientists.

In 1735, the Spanish mathematician Antonio de Ulloa, in Equatorial Columbia, drew attention to the frequent finding together with gold of a metal unknown to him, whose brilliance somewhat resembled the brilliance of silver, but with all other qualities more resembling gold. This outlandish metal interested de Ulloa, and he brought to Spain samples of Colombian platinum.

In the 18th century, when platinum was not yet in industrial use, it was mixed with gold and gold and silver products. The Spanish government learned about this "damage" of precious metals. Fearing the possibility of mass forgery of the gold coin, it decided to destroy all the platinum mined together with gold in the colonial possessions of the kingdom. In 1735, a decree was issued, prescribing the destruction of all the platinum mined in Colombia. This decree acted for several decades. Special officials in the presence of witnesses periodically threw the available platinum stocks into the river.

At the end of the XVIII century. Spanish kings themselves began to "spoil" the gold coin, mixing it with platinum.

Technical use of platinum

Coin from platinum

In 1752, the director of the Swedish mint, Schaeffer, announced the discovery of a new chemical element, platinum. Satellites of platinum - palladium, iridium, rhodium, ruthenium and osmium - were discovered much later, in the XIX century. The six listed chemical elements, standing in the eighth group of the Mendeleyev periodic system, constitute a group called platinum metals. All these metals have many similar physical and chemical properties and are found in nature mostly in common.

At the dawn of the introduction of platinum into technology, scientists studied it mostly from the same curiosity, but as the study of the properties of platinum began, it quickly began to find wide application, especially in the chemical industry. It turned out that platinum is soluble only in aqua regia, insoluble in acids and constant with incandescence.

Following the appearance of the first samples of chemical utensils made of platinum, it was used to make distillation apparatus for sulfuric acid. From that moment, the growth in the processing of platinum began to increase dramatically, as it began to be used in the production of acid-proof and heat-resistant laboratory chemical equipment, tools and various instruments (crucibles, flasks, boilers, forceps, etc.).

In pyrometry, the exceptional resistance of platinum and its alloys to high temperatures is used.

Valuable, and sometimes irreplaceable properties of platinum and palladium have long been used in catalytic processes. A significant amount of platinum is spent on making a contact for sulfuric acid plants, where it serves as a catalyst in the oxidation of sulfur dioxide gas to sulfuric anhydride. Platinum in the form of a grid serves as a catalyst in the oxidation of ammonia in apparatuses of various systems. Numerous organic syntheses also require the use of a platinum catalyst. Palladium catalyst is used in the production of synthetic ammonia and in the production of certain organic preparations. In the production of synthetic ammonia for Gaber-Rosennol, osmium is also used.

In electrical engineering, platinum metals, as a rule, are used in the form of alloys. Here is not a complete list of parts of electrical devices where platinum alloys are used: burning needles, instruments for electrical measurements, electrodes (cathodes and anti-cathodes for X-ray tubes), wires and bands for resistance of electric furnaces, magneto contacts (cars, internal combustion engines), contact points (telegraphy, telephony), lightning rod tips, etc.

In electrochemistry, platinum is used in the preparation of various electrolytic products. Medicine and dentistry are among the oldest consumers of platinum. We also note the use of platinum for surgery in the form of the tips of devices serving for cauterization, syringes for injection and infusion, and so on.

Application of platinum

Jewelry art occupies a leading position as a consumer of platinum in the form of alloys. Platinum frames for precious stones give better shine and cleaner water than rims from other noble metals.

Finally, in the form of salts, platinum and its satellites are required for photography, for the manufacture of medicinal preparations (rhodium and ruthenium salts) and for the preparation of paints on porcelain (rhodium, iridium - black paint, palladium - silver).

Platinum is also used in the military share, for example, for making contacts that serve for the production of detonation in the explosion of mines, and so on.

Extraction of platinum

How do they extract platinum

The first place in world production of platinum belongs to the Ontario area in Canada. Here in 1856, large deposits of copper-nickel ores of Sudbury were discovered, in which platinum is also present along with gold and silver.

Before the First World War, Canadian platinum did not attract attention, and practical interest in it arose only in 1919, when, as a result of the civil war in the Urals, Russian platinum mining fell sharply, and the world market began to feel a great defect in this valuable metal. Since 1919 Sudbury copper-nickel slurry has been subjected to thorough processing with the purpose of extracting platinum group metals, especially since the cost price of associated extraction of platinum and its satellites is very low.

The second place in the world for the extraction of platinum is occupied by Russia. Noticeable quantities of platinum are mined in Colombia. Of other countries producing platinum, you can indicate Ethiopia and Congo. Extracted directly from the bowels of platinum, as well as platinum, obtained from ores, is subjected to special processing or refining. Refining consists of ordinary processes used on a small scale in the practice of analytical laboratories - dissolution, evaporation, filtration, deposition, etc. As a result of these operations, pure platinum and its satellites are obtained separately.

World reserves of platinum and platinum deposits in Ukraine

Scheme of deposits (1) and ore occurrences (2) of gold and manifestations of platinoids (3) on the territory of Ukraine.

Almost 90% of the world's confirmed reserves of platinum group metals (PGM: platinum, palladium, iridium, rhodium, osmium, ruthenium) is contained in the platinoid deposits of late-magmatic genesis proper. World resources of platinoids in the bowels of more than 30 countries are estimated at 120-140 thousand tons and most of them (75-85 thousand tons) are located in the Bushveld Massif of South Africa. The volume of world production of PGM is about 370 tons, of which platinum is 160 tons, palladium is 180 tons.

The study of the platinoid content of geological complexes in Ukraine has a history of only half a century - beginning with the discovery in 1951 of platinum (0.1-0.2 g / ton) in the hyperbasites of the Obitochka (Western Azov Sea). A few years later, the presence of platinum and palladium was discovered in rocks of several other regions of the Ukrainian shield and in placers of the Dnieper-Donets basin.

Among the perspective geological objects for the discovery of platinum (and PGM) mineralization in Ukraine are various breeds of the Ukrainian Shield, the Carpathians, Volhynia, the Krivoy Rog and the Donetsk basins, the Middle Dnieper and Pobuzhye (see the map).