All about osmium

Osmium - a rare metal, belongs to the platinum group. It was discovered in England as a result of experiments on the reaction of platinum. The name osmium is given in Greek and in translation means "smell". What is this noble metal like? What are its features and what is its use?

The discovery of this element happened by accident in 1803 by English chemists Smithson Tennant and William H. Wollastan. As a result of experiments on the reaction of platinum to a mixture of acids (sulfuric and nitric), the resulting precipitate developed an unpleasant aroma, reminiscent of the stench of chlorine and rotten radish. Similar experiments were carried out by Colle-Descoti, Antoine de Fourcoy and Vauquelin in France. As a result of their research, they also found an unknown substance in the insoluble sediment from platinum.

The discovery of these chemical elements was presented to the Royal Society in London by Tennant's written communication dated June 21, 1804. In the periodic table of chemical elements of Mendeleev, the metal is located under the ordinal number 76. The metal does not occur in its pure form by nuggets, therefore its chemical formula is presented in dissolved form.

The element is extracted from secondary raw materials as a result of its separation from iridium, platinum, platinum-palladium ores or copper and nickel ores. The annual production of the entire element in the world does not exceed the size of 1 ton.

The world's largest deposits are worth noting such zones as Ural mountains and Siberia in Russia, northern state Alaska and western state California in America, Canada in North America, Colombia in South America and some South African countries, Australia, Island Tasmania... Currently, a significant osmium deposit is considered Bushwell Complex in South Africa, most of the substance is mined there. Taking into account that the largest deposits of the metal are in South Africa, the world prices for this rare earth metal are quite high. Kazakhstan is considered the only major exporter of osmium-187 in the world. Although China has platinum ore reserves, it does not have significant amounts of osmium.

The substance is stored in powder form and since it does not melt in the form of crystals, it is not possible to put a stamp on it due to its physical properties. For the manufacture of ingots of this metal, electron-beam or arc heating from a powder is used; heating in a crucible is also used.

Osmium looks like a silvery bluish metal. It is one of the densest elements, its density is 22,600 kilograms per cubic meter, but at the same time, the substance is quite fragile, easily breaks and crumbles. It has a high specific gravity and is able to shine even at rather high temperature influences. Due to its parameters and significant melting temperature, it is difficult to machine it. In nature, it exists in the form of seven isotopes, six of which are considered stable, these are osmium-184, osmium-187, osmium-188, osmium-189, osmium-190 and osmium-192. Radioactive metal isotopes with mass numbers from 162 to 197 were obtained in the laboratory, and some nuclear isomers were also artificially obtained.

Almost all compounds with this metal cause damage to internal organs, visual and auditory disorders. In case of poisoning with osmium vapors, irreversible disturbances in the body and death can occur. Scientists conducted experiments on animals, the results of which were the rapid development of anemia, the lack of normal lung function. It was concluded that this is a rapidly developing edema. Osmium tetroxide, which is used in medicine, is a very corrosive substance. Has the nastiest odor in the world. In case of poisoning, the skin suffers, it changes color to green or black, often accompanied by ulcers and cracks, which will take a very long time to heal.

Employees of production facilities are at the highest risk; according to all safety standards, they work only in respirators and special clothing. All containers containing osmium oxide are sealed and stored in accordance with the rules. To obtain the minerals of nevyanskite, platinum is converted into a solution by means of aqua regia. Then, the resulting precipitate is exposed to zinc in an 8-fold amount - such an alloy is relatively easily converted into a powdery state, which is then fused with barium peroxide. The next stage is the processing of the resulting mass with aqua regia, distillation through the apparatus for separating osmium tetroxide.

By acting on the substance with an alkali solution, salt is obtained. The saline solution is affected hyposulfite, as a result of which, with the help of ammonium chloride, the metal precipitates already in the form of Fremy's salt. The precipitate is washed, filtered and calcined. The result of all these actions is spongy osmium. Subsequently, it is cleaned with acids, reduced in an electric furnace under a stream of hydrogen, and cooled. So get osmium samples up to 99.9%.

The properties of this element, from the point of view of chemistry, are amazing. The most basic of them are the following.

1. Osmium does not react at all with alkalis and acids. Forms water-soluble osmates in reaction with alkaline melts. Interaction with a mixture of nitric and hydrochloric acids gives an extremely slow reaction.
2. Very toxic, even in microscopic doses. Especially toxic is osmium oxide, which is released from platinum.
3. It is impossible to determine the boiling point of the metal, since it is especially refractory.
4. The metal in the powder easily enters into a heating reaction with such substances: pure oxygen, halogens, sulfuric or nitric acids.
5. In various compounds, oxide numbers from -2 to +8 are obtained. The most common are +2, +3, +4 and +8.
6. Able to form cluster compounds.
7. The main minerals are related to solid solutions and are represented by alloys of iridium with osmium - they are sysertskite and nevyanskite. Moreover, syserskite has a different name - iridious osmium, and nevyanskite - osmous iridium.

Density osmium is approximately 22.61 grams per cubic centimeter. Crystals have a beautiful silvery sheen, with different shades from gray to blue. In the ingots, a dark blue color appears, in the powder it is violet. All metal has a silvery sheen. The toxicity of the element prevents its use in the jewelry industry. The main physical properties are as follows.

1. The melting point of this element is quite high, melting is possible at temperatures over 3000 degrees Celsius.
2. Metal has no magnetic properties.
3. Amazing firmness. Alloys with the addition of this metal acquire increased wear resistance, durability, corrosion resistance, and resistance to mechanical stress.
4. The boiling point is 5012 ºC.
5. The Mohs hardness is 7.
6. Vickers hardness is 3-4 GPa.

Due to the significant cost of the element itself, this metal is rarely used in mass industrial production. Osmium is mainly used in the chemical industry, where it is used as a catalyst. Osmium tetroxide is used in some medicines. In laboratory analyzes, it is used for staining living tissues, ensures the preservation of the cell structure.

In the aerospace industry, osmium is used in electronic equipment of equipment for aviation and rocket technology, as well as in the manufacture nuclear weapons. Due to the lack of magnetic properties, the metal is used in the manufacture of branded watches such as Rolex. Alloy of osmium with platinum is used when creation of surgical implants Are pacemakers or pulmonary valves.

1. Under a pressure of about 770 GPa in osmium, electrons interact in internal orbitals, the structure of the substance remains unchanged.
2. Osmium in the rocks contains half a percent of the total mass of ore deposits.
3. Due to the high density the appearance and actual weight of the metal varies greatly. So, a 0.5 liter plastic bottle filled with this metal powder will be heavier than a 10 liter bucket filled with water.
4. This metal is in the five most costly.
5. The cost of a triple ounce of osmium is a trade secret, in open sources you can find the approximate price for 1 gram of the substance.
6. Because of the refractoriness of osmium noted in the history of the electric lamp. Scientist K. Auer von Welsbach from Germany made a proposal to replace the carbon filament in a light bulb with an osmium filament. The bulbs turned out to be 3 times less energy-intensive, and the lighting has improved markedly. True, it was soon replaced by the more common tantalum, which, in turn, was replaced by tungsten.
7. A similar situation happened with the rare metal in the ammonia production. The currently used method of ammonia synthesis, developed in 1908 by the chemist Fritz Haber from Germany, is impossible without the use of catalysts.Initially, the catalysts used at that time showed their properties only in the presence of significant temperature conditions and did not have high efficiency, so the search for a replacement was very urgent. Scientists from the laboratory of the Higher Technical School in Karlsruhe made a proposal to use finely atomized osmium as a catalytic element. The test results confirmed that this idea is worthwhile, the catalytic temperature has dropped by more than 100 ºC, and the release of ammonia has increased significantly. True, in the future they refused from osmium, but he helped in solving such an important problem.

Osmium and other rare and unique metals play significant role in various industries... Even with all its toxicity, it saves lives and health of people.

For more information on osmium, see the following video.