Tin (lat. Stannum; denoted by the symbol Sn) - an element of the 14th group of the periodic table of chemical elements (according to the outdated classification - an element of the main subgroup of group IV), the fifth period, with atomic number 50. Belongs to the group of light metals. Under normal conditions, the simple substance tin is a ductile, malleable and fusible shiny metal of a silvery-white color. Tin forms three allotropic modifications: below 13.2 °C, α-tin (gray tin) with a cubic diamond-type lattice is stable; above 13.2 °C, β-tin (white tin) with a tetragonal crystal lattice is stable. γ-Tin is white, in the temperature range 161°C–232°C (melting point), metallic, brittle.
Content
- 1. History
- 2 Origin of the name
- 3 Being in nature
- 3.1 Deposits
- 3.2 Prevalence in nature
- 3.3 Forms of location
- 3.3.1 Solid phase. Minerals
- 3.3.2 Mineral forms proper
- 3.3.2.1 Native elements, alloys and intermetallic compounds
- 3.3.2.2 Tin oxide compounds
- 3.3.2.3 Tin sulfide compounds
- 3.3.3 Colloidal form
- 3.3.4 Forms of tin in the liquid phase
- 3.4 Industrial types of tin deposits
- 4 Production
- 5 Physical properties
- 6 Tin Plague
- 7 Application
- 8 Isotopes
- 9 Physiological action
Production of such metal
The technology for obtaining tin is directly related to the form of its occurrence. Otherwise, it is not too different from traditional methods for producing non-ferrous metals. The scheme includes the following stages:
- ore processing;
- reduction smelting – production of rough metal;
- refining of rough metal using acceptable methods.
Necessary equipment and materials
- The form of tin presents significant difficulties in its production. It is considered appropriate to process ore containing 0.1% metal. And in placers its content may be even less - 0.01%. Tin is often accompanied by valuable and rare earth metals - W, Zr, Ta, Nb, which makes the processing of low-grade ore more promising.
- The most famous mineral form of the substance is cassiterite - tin oxide. This is actually called not an oxide, but an ore mineral. The oxide forms grains, precipitates and aggregates, in which the grain size can be 3–4 mm. The mineral has a very wide range of colors - from yellow to black. The red stone is called "ruby tin". Clear crystals are extremely rare and highly prized.
Cassiterite is included in minerals as microinclusions, various kinds of precipitates and inclusions. The most famous deposits are in Russia, Malaysia, Indonesia and China.
- Sulfide compounds - stannines - are the second group of industrial importance. In Russian deposits this form is very common.
- Minerals are being developed that contain hydroxide compounds, as well as silicates and spinels - nigerite, for example.
Receiving raw materials
The method of extraction and obtaining raw materials suitable for smelting depends on the type of deposit. Placer minerals, for example, are easier to develop.
Placer deposits are usually composed of fine-grained sands. They are developed by dredging or using sand pumps.
- Dredging – includes elements of gravity enrichment. A dredge is a mining and processing plant that extracts ore from the bottom of rivers, lakes or artificial reservoirs. At the same time, all other gravity enrichment procedures are carried out - screening, jigging, concentration. Waste is dumped during operation.
- When using sand pumps , the soil is opened by some mechanical method, and then the sand is washed off with water jets into an artificial reservoir. The ore is then transported by a sand pump to the washing gallery - a system of long washing trays. Since cassiterite is quite heavy, it settles at the bottom. Then the concentrate is collected and served on the enrichment table.
The primary deposit is most often an inclined, less often a vertical adit. The ore is fed to mills and jaw crushers where it is crushed into sand. The ore is then enriched: pyrite and rock tailings are separated using gravity or flotation concentration methods. Sulfide ores are annealed or leached - this is how lead, gold, and copper are captured. Since the ore of the primary deposit is poorer, after roasting, gravity enrichment is again carried out.
In general, alluvial deposits produce cassiterite concentrate with a metal share of 70–76%, and primary deposits – 18–60%.
This video will tell you about tin mining:
Technologies
The ore that is already enriched goes to the non-ferrous metal smelting plant. If necessary, the enrichment process is repeated, for example, by sublimation of tin. The ore is then crushed into powder and washed using special devices. In this way, ore concentrate is obtained.
The concentrate must be fired to remove arsenic and tungsten. To extract tungsten, sintering with soda can be performed.
Reduction smelting
For reduction, that is, obtaining metal from oxide, smelting with carbon-containing compounds is used. Two types of devices are used as equipment.
- Mine tin smelting – the oxide is reduced by charcoal, which is loaded layer by layer along with cassiterite. When heated, the metal is restored.
- Reverberatory furnaces - here the ore is fed along with coal and limestone.
In both cases, the resulting slags are too “rich” - containing up to 25% of the substance, so they are subjected to secondary smelting at a higher temperature and with new portions of coal. As a result, rough tin with a large proportion of iron is smelted - ferrous furnace coating.
Story
Tin was known to man already in the 4th millennium BC. e. This metal was inaccessible and expensive, so products made from it are rarely found among Roman and Greek antiquities. There are mentions of tin in the Bible, the Fourth Book of Moses. Tin is (along with copper) one of the components of tin bronze, invented at the end or middle of the 3rd millennium BC. e.. Since bronze was the most durable metal and alloy known at that time, tin was a “strategic metal” throughout the “Bronze Age”, more than 2000 years (very approximately: 35-11 centuries BC).
Drop of molten tin
Refining of extracted material
The purity of the extracted resource directly depends on the initial quality of the ore. To obtain the highest quality tin, materials are refined in the following ways:
- Thermal. It involves the use of specialized boilers, where the entire purification process takes place. The boiling temperature inside is brought to 300 degrees. Adding coal or sulfur allows you to break down iron and copper.
- Electrolytic. The procedure is performed in separate electrolysis baths, where the necessary auxiliary equipment is installed. The operating temperature is fixed at 35 degrees. Tin obtained in this way is the purest.
The use of semiconductor technology involves additional purification by zone melting.
origin of name
The Latin name stannum, related to the Sanskrit word meaning "steady, durable", originally referred to an alloy of lead and silver, and later to another alloy imitating it, containing about 67% tin; by the 4th century, this word began to be used to refer to tin itself.
The word tin is common Slavic, having correspondences in the Baltic languages (cf. Lit. alavas, alvas - “tin”, Prussian alwis - “lead”). It is a suffix from the root ol- (cf. Old High German elo - “yellow”, Latin albus - “white”, etc.), so the metal is named by color.
Properties of tin
When entering a chemical reaction, polymorphism appears. In open air and aquatic environments, the surface of the tin is quickly covered with an oxide film, which protects the material from corrosive effects. It has several structural forms:
- gray powder, classified as semiconductors;
- white tin is a modification of a silver-colored malleable metal;
- hard, white, quite fragile.
Tin reacts with non-metals without problems, but interacts quite problematically with concentrated sulfuric and hydrochloric acids. If the acids are diluted, then the reaction with the metal will not occur. It reacts with nitric acid in different ways; the result of the reaction can be nitrate or tin acid.
It reacts to alkaline elements only with strong heating. Upon contact with oxygen, several oxides can be formed, having oxidation states of 2 or 4. The metal acts as the basis for the entire class of organotin compounds.
Being in nature
Tin is a rare trace element; tin ranks 47th in terms of abundance in the earth's crust. The Clark content of tin in the earth's crust ranges, according to various sources, from 2·10−4 to 8·10−3% by mass. The main mineral of tin is cassiterite (tin stone) SnO2, containing up to 78.8% tin. Much less common in nature is stannin (tin pyrite) - Cu2FeSnS4 (27.5% Sn).
Place of Birth
The world's tin deposits are located mainly in China and Southeast Asia - Indonesia, Malaysia and Thailand. There are also large deposits in South America (Bolivia, Peru, Brazil) and Australia.
In Russia, tin ore reserves are located in the Chukotka Autonomous Okrug (Pyrkakai stockworks; Valkumey mine/village, Iultin - mining was closed in the early 1990s), in the Primorsky Territory (Kavalerovsky district), in the Khabarovsk Territory (Solnechny district, Verkhnebureinsky district ( Pravourmiyskoye deposit)), in Yakutia (Deputatskoye deposit) and other areas.
Prevalence in nature
The prevalence in nature is shown in the following table:
| Geol. an object | Kamen. meteorites | Dunits and others. | Basalts, etc. | Diorites, etc. | Granitoids | Glina, etc. | Ocean water | Live matter (% of live weight) | The soil | Plant ash |
| Contents, weight. % | 1·10−4 | 5·10−5 | 1,5·10−4 | − | 3·10−4 | 1·10−3 | 7·10−7 | 5·10−5 | 1·10−3 | 5·10−4 |
In unpolluted surface waters, tin is found in submicrogram concentrations. In groundwater its concentration reaches several micrograms per dm³, increasing in the area of tin ore deposits, it enters the water due to the destruction primarily of sulfide minerals, which are unstable in the oxidation zone. PDKSn = 2 mg/dm³.
Cassiterite crystals - tin ore
Tin is an amphoteric element, that is, an element capable of exhibiting acidic and basic properties. This property of tin also determines the characteristics of its distribution in nature. Due to this duality, tin exhibits lithophilic, chalcophilic and siderophilic properties. Tin in its properties is close to quartz, as a result of which the close connection of tin in the form of oxide (cassiterite) with acidic granitoids (lithophilicity), often enriched in tin, is known, up to the formation of independent quartz-cassiterite veins. The alkaline behavior of tin is determined by the formation of quite a variety of sulfide compounds (chalcophilicity), up to the formation of native tin and various intermetallic compounds known in ultrabasic rocks (siderophilicity).
Forms of location
The main form of occurrence of tin in rocks and minerals is scattered (or endocript). However, tin also forms mineral forms, and in this form it is often found not only as an accessory in acidic igneous rocks, but also forms industrial concentrations mainly in oxide (cassiterite SnO2) and sulfide (stannine) forms.
Solid phase. Minerals
Cassiterite crystals
In general, the following forms of tin occurrence in nature can be distinguished:
- Scattered form ; the specific form of tin in this form is unknown. Here we can talk about an isomorphically dispersed form of tin occurrence due to the presence of isomorphism with a number of elements (Ta, Nb, W - with the formation of typically oxygen compounds; V, Cr, Ti, Mn, Sc - with the formation of oxygen and sulfide compounds). If tin concentrations do not exceed certain critical values, then it can isomorphically replace the named elements. The mechanisms of isomorphism are different.
- Mineral Form : Tin is found in concentrating minerals. As a rule, these are minerals in which iron Fe+2 is present: biotites, garnets, pyroxenes, magnetites, tourmalines, etc. This relationship is due to isomorphism, for example, according to the scheme Sn+4 + Fe+2 → 2Fe+3. In tin-bearing skarns, high concentrations of tin are found in garnets (up to 5.8 wt.%) (especially in andradites), epidotes (up to 2.84 wt.%), etc.
In sulfide deposits, tin is included as an isomorphic element in sphalerites (Silinskoye deposit, Russia, Primorye), chalcopyrites (Dubrovskoye deposit, Russia, Primorye), and pyrites. High concentrations of tin were detected in pyrrhotite from greisen from the Smirnovskoe deposit (Russia, Primorye). It is believed that due to limited isomorphism, solid solutions decompose with micro-precipitates of Cu2+1Fe+2SnS4 or tillite PbSnS2 and other minerals.
Actually mineral forms
Native elements, alloys and intermetallic compounds
Although the concentrations of these minerals in rocks are very low, they are distributed in a wide range of genetic formations. Among the native forms, along with Sn, Fe, Al, Cu, Ti, Cd, etc. were identified, not counting the already known native platinoids, gold and silver. These same elements also form various alloys with each other: (Cu + Sn + Sb), (Pb + Sn + Sb), etc., as well as solid solutions. Among the intermetallic compounds, stistaite SnSb, atakite (Pd,Pt)3Sn, shtumyrlite Pt(Sn,Bi), zvyagintsevite (Pd,Pt)3(Pb,Sn), taymyrite (Pd,Cu,Pt)3Sn and others were identified.
The following forms of occurrence of tin and other elements are found in various geological formations:
- A group of intrusive and effusive igneous rocks: traps, picrites of the Siberian platform, hyperbasites and gabbroids of Kamchatka, kimberlites of Yakutia, lamproites of Aldan, etc.; granitoids of Primorye, Far East, Tien Shan.
- A group of metasomatically and hydrothermally altered rocks: copper-nickel ores of the Siberian platform, gold deposits of the Urals, the Caucasus, Uzbekistan, etc.[9]
- Group of modern ore formation: pelagic sediments of the Pacific Ocean, products of the Great Fissure Tolbachik eruption, Uzon hydrothermal system in Kamchatka, etc.
- A group of sedimentary rocks of various origins.
Tin oxide compounds
The most famous form is the main mineral of tin - cassiterite SnO2, which is a compound of tin with oxygen. According to nuclear gamma resonance spectroscopy, the mineral contains Sn+4.
Cassiterite
Main article: Cassiterite
Cassiterite (from the Greek kassiteros - tin) is the main ore mineral for the production of tin. Theoretically contains 78.62% Sn. It forms separate secretions, grains, continuous massive aggregates, in which the grains of the mineral reach a size of 3 - 4 mm and even more.
- Density 6040-7120 kg/m³ (lowest for light-colored cassiterites).
- Hardness 6½.
- The shine is matte, the edges are diamond-like.
- Cleavage is imperfect.
- The fracture is conchoidal.
The main forms of cassiterite isolation:
- microinclusions in other minerals;
- accessory mineral deposits in rocks and ores;
- solid or disseminated ores: needle-shaped radial aggregates (Primorye), colomorphic and cryptocrystalline segregations and accumulations (Primorye); The crystalline form is the main form of cassiterite isolation. In Russia, cassiterite deposits are found in the Northeast, Primorye, Yakutia, and Transbaikalia; abroad - in Malaysia, Thailand, Indonesia, China, Bolivia, Nigeria, etc.
Hydroxide compounds
A secondary place is occupied by tin hydroxide compounds , which can be considered as salts of polytin acids. These include the mineral succulite Ta2Sn2+2O; solid solution of tin in magnetite of the type Fe2SnO4 or Fe3SnO3 (Brettstein Yu. S., 1974; Voronina L. B. 1979); “varlamovit” is a product of stannine oxidation; it is believed to be a mixture of amorphous and semi-amorphous Sn compounds, metatinic acid, a polycondensed phase and a hydrocassiterite phase. Hydrated oxidation products are also known - hydromartite 3SnOxH2O; mushistonite (Cu,Zn,Fe)Sn(OH)6; copper hydrostannate CuSn(OH)6, etc.
Silicates
A large group of tin silicates is known, represented by malayaite CaSn[SiO5]; pabstite Ba(Sn, Ti)Si3O9, stocasite Ca2Sn2Si6O18x4H2O, etc. Malayaite even forms industrial accumulations.
Spinelids
Among other oxide compounds, spinels are also known, for example, the mineral nigerite Sn2Fe4Al16O32 (Peterson EU, 1986).
Tin sulfide compounds
Includes various tin and sulfur compounds. This is the second most industrially important group of mineral forms of tin. The most important of these is stannine, the second most important mineral. In addition, frankeite Pb5Sn3Sb2S14, herzenbergite SnS, berndtite SnS2, tillite PbSnS2 and kesterite Cu2ZnSnS4 are noted. More complex sulfide compounds of tin with lead, silver, and copper, which are mainly of mineralogical significance, have also been identified. The close connection of tin with copper determines the frequent presence of chalcopyrite CuFeS2 deposits in tin ore deposits with the formation of the cassiterite-chalcopyrite paragenesis.
Stannin
Main article: Stannin
Stannine (from Latin stannum - tin), tin pyrite, a mineral from the class of sulfides with the general formula of the form Cu2FeSnS4. It follows from the chalcopyrite formula by replacing one Fe atom with Sn. Contains 29.58% Cu, 12.99% Fe, 27.5% Sn and 29.8 S, as well as impurities of Zn, Sb, Cd, Pb and Ag. A widespread mineral in tin ore deposits in Russia. In a number of deposits in Russia (Primorye, Yakutia) and Central Asia (Tajikistan), it is an essential element of sulfide minerals and often, together with varlamovite, makes up 10-40% of total tin. Often forms impregnations in ZnS sphalerite and chalcopyrite. In many cases, stannine decomposition phenomena with the release of cassiterite are observed.
Colloidal form
Colloidal and tin-silicon compounds play a significant role in the geochemistry of tin, although it has not been studied in detail. A significant place in the geology of the element is played by colomorphic compounds and the products of its crystalline transformations into cryptocrystalline varieties. Colomorphic cassiterite is considered as a form of expression of viscous gel-like solutions.
Independent studies have revealed an abnormally high solubility of SnO2 in chlorine-silicon solutions. Maximum solubility is achieved at a ratio of .
Analysis of the properties of the Sn(OH)4 compound and their proximity to the Si(OH)4 compound reveals its ability to polymerize, ultimately forming the compounds H2SnkO2k+1, SnkO2k−1(OH)2. In both cases, it is possible to replace the (OH) group with the F and Cl anions.
Thus, the polymerization of Sn(OH)4 molecules and their combination with Si(OH)4 molecules leads to the formation of a gel (colloid) and the appearance of HmSn2nSinOp chains, with m ≤ 8, or Hs[SiO2n(SnOm)d] (Nekrasov I. Ya. et al., 1973).
Available evidence suggests that the colloidal form is a natural intermediate in the precipitation of tin from hydrothermal solutions.
Forms of tin in the liquid phase
The least studied part of the geochemistry of tin, although cassiterites in the form of prisoner minerals have been established in gas-liquid inclusions (Kokorin A. M. et al., 1975). There are no works on the analysis of specific tin-containing natural solutions. Basically, all information is based on the results of experimental studies, which speak only about the probable forms of tin in solutions. A significant role in the development of the methodology for these studies belongs to Academician V. L. Barsukov
The entire set of experimentally established forms of tin in solutions is divided into groups:
- Ionic compounds . These compounds and their structure are described in terms of classical valence and stereochemical concepts. Subgroups are distinguished: Simple ions Sn+2 and Sn+4 are mainly found in magmatic melts, as well as in hydrothermal solutions with low pH values. However, in existing hydrothermal systems, reflected by the composition of gas-liquid inclusions, such conditions have not been established.
- Salts of halide acids - SnF2, SnF40, SnCl40. The role of chlorine in the transport and deposition of tin and associated metals is believed to be more significant than that of fluorine.
- Hydroxyl compounds of tin. Under alkaline conditions, the starting compounds are H2SnO2, H2SnO4, H2SnO3. These forms are often established based on known mineral forms. Some of these forms are of both artificial (CaSnO3, Ca2SnO4) and natural (FeSnO2, Fe2SnO4) origin. In acidic environments, these compounds behave as weak bases such as Sn(OH)2, Sn(OH)4. It is believed that one of the forms of manifestation of such compounds is varlamovit. According to experimental data, Sn(OH)4 is deposited only at T < 280 °C in slightly acidic or neutral conditions at pH = 7 - 9. The compounds Sn(OH)4 and Sn(OH)3+ are stable at pH = 7 - 9, then as Sn(OH)2+2 and Sn(OH)+2 - at pH < 7. Quite often, (OH)−1 groups are replaced by F and Cl, creating halogen-substituted modifications of tin hydrocompounds. In general, these forms are represented by the compounds Sn(OH)4-kFk or Sn(OH)4-kFk-nn. In general, the Sn(OH)3F compound is stable at T = 25–50 °C, and Sn(OH)2F² at T = 200 °C.
- Sulfide compounds. According to experimental data, the solution contains SnS4−4 or SnS3−2 compounds at pH > 9; SnS2O−2 (pH = 8 - 9) and Sn(SH)4 (pH = 6). There is mention of the existence of a compound of the Na2SnS3 type, which is unstable in an acidic environment.
Industrial types of tin deposits
The geochemical features of tin described above are indirectly reflected in the formational classification of tin ore deposits proposed by E. A. Radkevich with subsequent additions.
A. Formation of tin-bearing granites . Cassiterite is installed in the accessory part of granites.
B. Formation of rare metal granites . These are granites of the lithionite-amazonite-albite type (apogranites according to A. A. Beus). Cassiterite in the accessory part together with columbite-tatnatlite, microlite, etc.
B. Formation of tin-bearing pegmatites . Tin mineralization is characteristic of Be-Li-, Be-Ta-, F-Li- types.
D. Feldspar-quartz-cassiterite formation . Iv is highlighted. F. Grigoriev. These are quartz-feldspar veins with cassiterite and other minerals.
D. Quartz-cassiterite formation . Distributed to NE Russia. These are vein zones, greisens with quartz, muscovite, wolframite, cassiterite, etc.
E. Cassiterite-silicate-sulfide formation with tourmaline and chlorite types. One of the main productive formations of Primorye Russia.
G. Cassiterite-sulfide formation . Also the main tin-producing formation. It identifies the main types:
- stockwork tin-tungsten mineralization;
- ore bodies of quar-cassiterite-arsenopyrite type;
- productive quartz veins of sulfide-cassiterite-chlorite type;
H. Tin-skarn formation .
I. Woody tin formation (rhyolite formation).
K. Formation of basic and ultrabasic rocks (according to I. Ya. Nekrasov)
L. Formation of alkaline rocks of Ukraine (according to V.S. Metallidi, 1988).
Tin deposits
The main tin production is concentrated in deposits located in southeast Asia, mainly in China, Indonesia, Malaysia and Thailand. In addition, deposits of this metal are present in the countries of South America, namely in Bolivia, Peru, and Brazil. Russian industry really needs tin. Our country consumes approximately 6.5–7 thousand tons annually. However, 90% of this amount is imported. The main deposits of tin ore in our state are located in the eastern regions. About thirty years ago, the tin mining production cluster included nine mining and processing plants and more than 20 mines in Yakutia, the Khabarovsk region, the Primorsky and Transbaikal regions, as well as in the Jewish Autonomous Region. But some enterprises quickly went bankrupt. Over the past few years, the situation has begun to change for the better, but it is still very far from “Soviet” volumes. The establishment in 2013 of a zero tax rate on the mining of tin ores located in the Far East did not have a significant impact. This year, a major investment program is being implemented, the goal of which is to increase production efficiency.
Production
During the production process, the ore-bearing rock (cassiterite) is crushed to particle sizes of an average of ~ 10 mm in industrial mills, after which cassiterite, due to its relatively high density and mass, is separated from the waste rock by vibration-gravity method on dressing tables. In addition, the flotation method of ore enrichment/purification is used. In this way, it is possible to increase the tin content in the ore to 40-70%. Next, the concentrate is roasted in oxygen to remove impurities of sulfur and arsenic. The resulting tin ore concentrate is smelted in furnaces. During the smelting process, it is restored to a free state through the use of charcoal in the reduction, the layers of which are laid alternately with layers of ore, or aluminum (zinc) in electric furnaces: SnO2 + C = Sn + CO2. Particularly pure tin of semiconductor purity is prepared by electrochemical refining or the zone melting method.
Smelting.
To restore cassiterite, it is melted with carbon-containing materials in reverberatory or special types of shaft furnaces. Tin mine furnaces have been used since ancient times; In them, charcoal, which serves as a reducing agent, is burned using blast, which is loaded in layers alternating with layers of cassiterite. The more common reverberatory furnaces use coal as fuel; they operate similarly to open hearth steel furnaces, with the ore mixed with anthracite and limestone. Furnaces of both types produce slags rich in tin (up to 25%). The slag is processed by melting at a much higher temperature with the addition of new amounts of reducing agent. The result is rough tin with a high iron content - the so-called iron furnace coating. The process requires strict control, otherwise the secondary slag will contain too high a percentage of tin.
Tin Plague
Gray and white tin
At temperatures below 13.2 °C, the specific volume of pure tin increases by 25.6%, and it spontaneously transforms into another phase state - gray tin (α-Sn), in the crystal lattice of which the atoms are arranged less densely. One modification changes to another the faster the lower the ambient temperature. At −33 °C the transformation rate becomes maximum. The tin cracks and turns to powder. Moreover, the contact of gray tin and white leads to “infection” of the latter. The combination of these phenomena is called the “tin plague.” The current name for this process was given by G. Cohen in 1911. The scientific study of this phase transition began in 1870 with the work of the St. Petersburg scientist, academician J. Fritzsche. It has been established that this is a process of allotropic transformation of white tin into gray tin with a diamond-type structure. Many valuable observations and thoughts about this process were expressed by D. I. Mendeleev in his “Fundamentals of Chemistry”.
White tin is a silvery-white, shiny metal with a specific tetragonal structure and an s2p2 electronic state - the β phase. Gray tin is a covalent crystal with a diamond structure and an sp3 electronic state - the α phase. Phase transitions of tin from white to gray and back are accompanied by a restructuring of the electronic structure and a strong (25.6%) volume effect. White tin can be supercooled to helium temperatures (phase α-β equilibrium temperature of about +13.2 °C).
One way to prevent the “tin plague” is to add a stabilizer, such as bismuth, to the tin. On the other hand, the catalyst accelerating the transition of white tin to gray at not very low temperatures is ammonium chlorostannate (NH4)2SnCl6.
Interesting facts:
- The “tin plague” is one of the reasons for the death of Scott’s expedition to the South Pole in 1912. It was left without fuel due to the fact that fuel leaked from tin-sealed tanks affected by the “tin plague.”
- Some historians point to the “tin plague” as one of the circumstances of the defeat of Napoleon’s army in Russia in 1812 - severe frosts led to the transformation of tin buttons on soldiers’ uniforms into powder.
- The “Tin Plague” destroyed many valuable collections of tin soldiers. For example, in the storerooms of the St. Petersburg Museum of Alexander Suvorov, dozens of figurines turned into dust - in the basement where they were stored, the heating radiators burst in winter.
Tin is one of the key metals for global industry. Despite the rapid development of technology, even manufacturers of newfangled electronic gadgets cannot do without this metal. What then can we say about the much more conservative food and construction industries? And although the age of pewter is long gone, the demand for pewter continues to grow, especially in the last two decades. Let's try to figure out what is happening and how will it affect the Russian market?
World Tin
Tin is one of the oldest used metals in the world. It was with him, by and large, that the metallurgy of mankind began. The fusion of native copper with tin allowed people for the first time to obtain a new material and products with better “consumer properties” than nature could initially offer.
Naturally, with such a long history of use, tin is one of the most studied minerals in terms of available resources. Everything that “lay on the surface” in Europe was collected and dug up in the Middle Ages. Subsequent searches led Europeans to Southeast Asia and Latin America, where they discovered fairly rich deposits that are still being mined. For this reason, the regional structure of the distribution of tin deposits and its mining largely coincides (Fig. 1).
In fact, since those times no significant and accessible resources have been identified. As the American Geological Survey dispassionately records, over the past 15 years, reserves of tin, the extraction of which is economically profitable, have decreased from 7 million to 4.8 million tons, despite a threefold increase in prices. However, the situation is not as sad as it could be - over the same period, tin production increased by only a quarter. Moreover, the growth of production stopped in the early 80s of the 20th century, when it was almost equal to the modern one and then even decreased. The explanation for this phenomenon is purely economic - the decline in prices on the market during and after the economic crisis of 1980–1982. (Fig. 2) made the development of deposits with high production costs uninteresting and turned the attention of producers to the secondary metal market.
As a result, over 10 years, production worldwide decreased from 230 thousand to 130–150 thousand tons per year and remained at this level for quite a long time. If we do not count China, then in recent years it amounted to 150–180 thousand tons. At the same time, the production of refined metal decreased significantly less, and in the 2000s it returned to the level of the 1970s (200–230 thousand tons).
The contribution of rapidly industrializing China, of course, turned out to be significant in this industry - a threefold increase in production and production made it the world leader in these indicators (Fig. 3).
China still has room to expand - it has just reached a level of tin consumption comparable to the leading Western powers (Fig. 4), and now it will clearly strive to reach their per capita consumption figures.
Moreover, one cannot count on strong savings due to high technologies here. After all, most high-tech companies in Western countries are persistently moving the production of electronics and household appliances to Asia: as a rule, to China. The result of such a policy was a rapid increase in the country's need for solders, superimposed on the general increase in consumption due to industrialization.
However, despite the transfer of significant production capacity to Southeast Asia, the demand for tin is in no hurry to decline in the West, even in the electronics sector. Thus, in the USA over the past 20 years, requests for this metal have decreased only from the construction side (Fig. 5). In the packaging industry, demand is constant, mechanical engineering, and especially the automotive industry, still cannot abandon Babbitt bearings, and tin is not losing its position in other areas of application.
This means that further growth in global demand for tin is guaranteed.
Russian tin
In less than a hundred years, the Russian tin mining and processing industry has experienced both an emergence from oblivion and a virtual return to it.
Until the 1930s The country's needs for tin were satisfied exclusively through imports. Only in 1932–1937. In Eastern Siberia, Kazakhstan and the Far East, large-scale geological exploration was carried out, revealing large-scale deposits of this metal, vital for metallurgy. As a result, even in wartime, tin mining developed rapidly, especially in the Far Eastern region, mainly through the use of prison labor.
How profitable such methods of work are is a controversial issue, since in a planned economy and a fixed exchange rate of the ruble against other currencies it is not easy to choose the correct basis for comparison. And “fair” prices for this metal in different regions were very different. If in the United States during the Great Depression it was barely $1 per kg (USGS data), then in pre-war Europe prices were significantly higher due to the sharply increased needs of mechanical engineering. The Soviet Union, which had very limited access to the flows of inexpensive colonial tin that went along ocean routes to Western countries, was forced and willing to pay significantly more. Therefore, the cost of Kolyma tin, which was an order of magnitude higher than the world market prices, did not bother anyone.
But the main problem of Russian tin was not even the cost of production, but the colossal remoteness of the deposits from all the infrastructure available at that time. The lack of electricity, fuel, roads and a very short period of Arctic navigation predetermined the refusal to process ore “on site”.
It is characteristic that attempts to obtain tin metal in Magadan were made back in 1937, but the central authorities immediately banned them, since this would require the supply of additional volumes of fuel to the region. There was no need to talk about alternative energy supply options then - they were just learning how to build hydroelectric power stations in the much more familiar Central Russia, no one had heard anything about nuclear power plants yet, and half a century remained before other methods of generating electricity.
As a result, tin concentrate from the Far East traveled across the whole country - processing was carried out in Podolsk near Moscow. During the war, the enterprise was evacuated to Novosibirsk, where it remained, turning into plant No. 520 and only later receiving the name for its main type of activity - the Novosibirsk Tin Plant.
Gradually, with the improvement of mining and processing technology, with a reduction in the share of manual labor and the development of energy in the eastern part of the country, the cost of produced tin decreased until it approached average world prices. But here we must make a reservation that in our calculations we did not operate with the official dollar exchange rate in the USSR, but with the “black market” one, which was closer to the real purchasing power of the Soviet currency. If we rely on the official exchange rate, then tin mining in the USSR has always been deeply unprofitable. The fact that this is not entirely true is confirmed by the rather long period of existence of NOC after 1991. Having survived the collapse of the domestic industry and a sharp reduction in demand for tin within the country, the enterprise still exports it.
However, “getting closer” does not mean “reaching” market prices. According to our estimates, the cost of tin produced in Novosibirsk from domestic raw materials during the crisis did not fall below $10-12 thousand per ton, which is quite high by world standards and serves as one of the main sources of problems for the plant when stock exchange quotes fall to the indicated level.
The second (more precisely, another first) problem of the enterprise is raw materials and their availability. The quality of Russian ores is, on average, approximately twice as bad as in the world's main mining regions, and therefore their processing is more expensive. But this is if there is something to recycle.
The constantly decreasing amount of incoming raw materials has long been included in the standard list of risks for the enterprise’s activities, but after the sale of half of the shares in 2008, this risk naturalized in the form of a cessation of shipments from the largest supplier of raw materials for the plant. According to the Chairman of the Board of Directors of NOC Vladimir Sherstov, Sakhaolovo was the largest supplier of NOC with a share of up to 50% of the total volumes of raw materials. “However, in 2007, Sakhaolovo LLC reduced production by 70% compared to 2006,” he said, explaining the current situation.
The government of the Republic of Sakha indicated that there were claims on both sides: Sakhaolovo was dissatisfied with the too low purchase prices offered by the NOC, and preferred to send its own products for export. Mr. Sherstov said that “the company had problems related to the verification of tin concentrate, which was pledged against large budget loans.”
After the “divorce” with the main supplier, NOC was going to switch to imported raw materials, but, judging by the dynamics of production indicators, this did not help much.
Such a popular technique as diversification was tried to be put into practice at NOC back in 1995 by organizing solder production. The share of solders consistently ranged from a third to a half of the plant's production by tonnage, but the revenue from their sales did not always reach 20% (Fig. 7). And the problems that arose during the sale were no less than with tin. Thus, the plant explained the reduction in solder output in 2003 by the unsatisfactory solvency of the majority of consumers in the solder products market.
In addition, there is quite high competition in this market - only in Russia there are several fairly large manufacturers, such as Novosibirsk, Ryaztsvetmet and others, and there are also smaller enterprises and a very significant flow of imports, especially from China. As a result, even NOC itself estimates its share of the domestic solder market at a modest 12–15%.
The plant's position on the primary tin market is slightly better - both according to its own statements and according to our estimates, its share is about 25 - maximum 30%. The rest comes from imports, since there are no other producers of primary tin in the country. In other words, out of approximately 4.5 thousand tons of tin consumed in the country, 3.5 thousand tons come from abroad.
The management sought a way out of the systemic crisis in business in additional sources of income, as a result of which the enterprise’s subsidiaries included car service centers, glass and woodworking factories, and even development activities quickly became very significant in income - if in 2005-2006. They brought no more than 10% of revenue, but in 2010 they already provided a quarter of all funds received by the enterprise.
The most problematic subsidiary, perhaps, turned out to be a glass factory launched in April 2008, whose EBITDA indicators in 2009–2010 were. turned out to be negative – 57 million and 6 million rubles. respectively. Although, on the other hand, we can say that positive dynamics were evident.
However, in 2010 the tin plant no longer had time for its subsidiaries. Having sold 46% of the shares of the glass factory in December 2009 (according to some sources - to its own “granddaughter” represented by the Financial Manager Management Company), which literally a month later found itself in a state of bankruptcy, NOC paid the income on several bond issues, after which it declared itself bankrupt. And by mid-2010, he also sold controlling stakes in Daliolova and Vostokolov. Around the same time, one of NOC’s creditors, the Russian Funds Investment Group, received another important asset, Pravourmiyskoye LLC (mines in the Verkhnebureinsky district of the Khabarovsk Territory, tin reserves - more than 100 thousand tons), which gave the plant 10– 15% of raw materials, Vedomosti wrote.
Only in the spring of 2011 did good news arrive - it was possible to reach an agreement with the Siberian Bank of Sberbank on the restructuring of Severskstekl's debt in the amount of 560 million rubles.
But already in July 2011, a monitoring procedure was introduced at NOC, trading in shares was suspended and a series of non-payments on bonds was allowed. In November of the same year, however, arbitration manager Viktor Kugushev supported NOC’s request to suspend bankruptcy proceedings until July 2012, since it would not be possible to consider the claims of all creditors, especially foreign ones, in the allotted six months.
It is worth noting that, in the opinion of the arbitration manager, the steps taken by the plant may only be a delay for the opening of bankruptcy proceedings. “Without diversifying production activities and curtailing production of those types of products that are no longer attractive on the market, NOC will not be able to cope with its debt burden,” he noted in an interview with the Kommersant newspaper after the meeting.
What's next?
To summarize, I would like to say that the demand for tin is clearly not going to decline significantly in the foreseeable future. The same cannot be said about its reserves. Now they last for about 18–20 years, whereas 15 years ago this figure was 38–40 years. It is clear that geological exploration will help replenish them, but growing China is already putting quite significant pressure on the other side of the scale.
If China “outweighs”, we can safely expect a rise in prices and the subsequent activation of scrap processors and low-profit mines. And in this regard, Russia’s interests coincide with those of China: mining not too rich ores in permafrost in the Far East, given the lack of transport infrastructure, will never be a cheap activity. But if this production does not develop there, then it is useless to expect the region to create infrastructure - there is simply no money for it. And high prices for raw materials in this sense are a salvation for local residents and local industry. If only the laws of the world economy work in Russia...
Application
- Tin is used primarily as a safe, non-toxic, corrosion-resistant coating in its pure form or in alloys with other metals. The main industrial uses of tin are in tinplate (tinned iron) for food containers, in solders for electronics, in household piping, in bearing alloys, and in coatings of tin and its alloys. The most important alloy of tin is bronze (with copper). Another well-known alloy, pewter, is used to make tableware. About 33% of all mined tin is consumed for these purposes. Up to 60% of tin produced is used in the form of alloys with copper, copper and zinc, copper and antimony (bearing alloy, or babbitt), with zinc (packaging foil) and in the form of tin-lead and tin-zinc solders. Recently, there has been a revival of interest in the use of metal, since it is the most “ecologically friendly” among heavy non-ferrous metals. Used to create superconducting wires based on the Nb3Sn intermetallic compound.
- Tin disulfide SnS2 is used in paints that imitate gold leaf (“potal”).
- Artificial radioactive nuclear isomers of tin 117mSn and 119mSn are sources of gamma radiation, are Mössbauer isotopes and are used in gamma resonance spectroscopy.
- Intermetallic compounds of tin and zirconium have high melting points (up to 2000 °C) and resistance to oxidation when heated in air and have a number of applications.
- Tin is the most important alloying component in the production of structural titanium alloys.
- Tin dioxide is a very effective abrasive material used to “finish” the surface of optical glass.
- A mixture of tin salts - the "yellow composition" - was previously used as a dye for wool.
- Tin is also used in chemical current sources as an anode material, for example: manganese-tin element, mercury-tin oxide element. The use of tin in a lead-tin battery is promising; for example, at the same voltage, compared to a lead battery, a lead-tin battery has 2.5 times greater capacity and 5 times greater energy density per unit volume, its internal resistance is much lower.
- Isolated two-dimensional layers of tin (stanene), created by analogy with graphene, are studied.
Tin brands
Tin alloys are often used as antifriction materials or solders. With the help of anti-friction compounds, specialists are able to preserve machines and equipment by reducing friction losses. And solders are used to hold together the metal components of mechanisms. Among the antifriction alloys, the most popular are babbitts. All grades of tin are produced in the form of ingots. According to the chemical composition, the following brands are distinguished:
- O1
- O1pch
- O2
- O3
- O4.
Isotopes
Main article: Tin isotopes
Natural tin consists of ten stable nuclides with mass numbers 112 (in a mixture of 0.96% by mass), 114 (0.66%), 115 (0.35%), 116 (14.30%), 117 (7. 61%), 118 (24.03%), 119 (8.58%), 120 (32.85%), 122 (4.72%) and 124 (5.94%). For some of them, double beta decay is energetically possible, but it has not yet been observed experimentally (2014) because the predicted half-life is very long (more than 1020 years).
Tin has the largest number of stable isotopes of all elements, which is due to the fact that 50 (the number of protons in tin nuclei) is the magic number - it constitutes a filled proton shell in the nucleus and thereby increases the binding energy and stability of the nucleus. Two doubly magic isotopes of tin are known, both of them are radioactive, since they are far from the beta stability band: neutron-deficient 100Sn (Z = N = 50) and neutron-rich 132Sn (Z = 50, N = 82).
Tin isotopes 117Sn and 119Sn are Mössbauer isotopes and are used in gamma resonance spectroscopy.
Receipt
Prom. It is advisable to obtain oxygen if its content in placers is 0.01% by weight, in ores 0.1%. Typically, oxygen ores contain W, Zr, Cs, Rb, Ta, Nb, rare earth and other elements. Primary raw materials are enriched: placers - preim. gravitational, ore - flotation or flotation-gravity method. Concentrates containing 50–70% O are fired to remove sulfur and purified from iron by the action of HCl; if impurities of wolframite (Fe,Mn)WO4 and scheelite CaWO4 are present, the concentrate is treated with HCl; the resulting WO3·H2O is extracted using NH3 solution. Smelting concentrates with coal in electric. or in flame furnaces, rough O. (94–98% Sn) containing impurities of Cu, Pb, Fe, As, Sb, Bi is obtained. When released from the furnaces, rough oxygen is filtered at a temperature of 500–600 °C through coke or centrifuged, separating the base. mass of iron impurities. The residual amount of Fe and Cu is removed by adding sulfur to the liquid metal; impurities float to the surface in the form of solid sulfides, which are removed from the surface of the oxide. The impurities of arsenic and antimony are removed from the oxide by adding aluminum, and lead is removed using SnCl2. Bi and Pb impurities are also separated by vacuum. Electrolytic by refining and zone recrystallization, especially pure O is obtained. This means. Part of all metal produced is secondary metal; it is obtained from waste tinplate, scrap and decomposition. alloys (the degree of oxygen recycling is more than 20%).
The volume of world O. production is approx. 340 thousand tons (2010).
Physiological action
Almost nothing is known about the role of tin in living organisms. The human body contains approximately (1-2) 10-4% tin, and its daily intake from food is 0.2-3.5 mg. Tin metal is non-toxic, which allows it to be used in the food industry. Tin poses a danger to humans in the form of vapors and various aerosol particles and dust. When exposed to tin vapors or dust, stannosis can develop - lung damage. Stannan (tin hydrogen) is a powerful poison. Some organotin compounds are also very toxic. The temporary permissible concentration of tin compounds in atmospheric air is 0.05 mg/m3, the maximum permissible concentration of tin in food products is 200 mg/kg, in dairy products and juices - 100 mg/kg. The toxic dose of tin for humans is 2 g.
Harmful impurities contained in tin under normal conditions of storage and use, including in the melt at temperatures up to 600 °C, are not released into the air of the working area in volumes exceeding the maximum permissible concentration in accordance with GOST. Long-term (15-20 years) exposure to tin dust has a fibrogenic effect on the lungs and can cause pneumoconiosis in workers.
Properties
The configuration of the outer electron shell of the O atom is 5s25p2; in compounds it usually exhibits oxidation states +2 and +4, the latter being more stable; ionization energies during the transition from Sn0 to Sn5+ are 7.34, 14.63, 30.50, 40.73 and 70.30 eV, respectively; Pauling electronegativity 1.8; atomic radius 158 pm.
In its free state, O. is a shiny silvery-white metal, heavy, soft and ductile; melting point 231.9 °C, boiling point 2629 °C. Forms two polymorphic modifications. Crystallic. the lattice of ordinary β-Sn (white O.) is tetragonal, density 7265 kg/m3 (20 °C). Below 13.2 °C, α-Sn (gray O.) is stable, with a diamond-type cubic structure with a density of 5769 kg/m3. The transition of white O. to gray is accompanied by the transformation of the metal into powder and the destruction of metallic materials. products due to a significant (25%) increase in the specific volume of metal (“tin plague”). Temperature coef. linear expansion (273 K) 1.99 10–5 K–1, thermal conductivity (293 K) 65.26 W/(m K); heat capacity β-Sn 27.11 J/(mol·K), α-Sn 25.79 J/(mol·K); specific electrical resistance 11.5 10–8 Ohm m (293 K). Mechanical O.'s properties depend on its purity and processing temperature; Brinell hardness for α-Sn at 293 K is 62 MPa, for β-Sn 152 MPa. When bending O. rods, a characteristic crunch is heard from the mutual friction of the crystallites (“tin scream”). White O. is weakly paramagnetic; at melting temperature it becomes diamagnetic. Gray O. is diamagnetic. The transition temperature to the superconducting state is 3.72 K.
Air oxygen passivates oxygen, leaving a film of chemically stable SnO2 on its surface. Therefore, oxygen practically does not oxidize in air and water up to 100 °C. O. reduces hydrogen from dilute HCl and H2SO4 in the cold, forming SnCl2 chloride and SnSO4 sulfate, respectively. Sn(II) compounds are strong reducing agents. In hot concentrated H2SO4 dissolves when heated, forming Sn(SO4)2 and SO2. Cold diluted HNO3 converts oxygen into Sn(NO3)2. When heated with conc. HNO3 O. is oxidized to form a precipitate of hydrated tin(IV) oxide SnO2 xH2O. When heating O. in concentrated. In alkali solutions, hydrogen is released and hydroxostannates M2[Sn(OH)6] (M – Na, K) are formed.
When burned in air, SnO2 is formed. The lower oxide SnO is obtained only indirectly; in air it quickly oxidizes. SnO2 exhibits predominant acidic properties, SnO – basic. O. does not react directly with hydrogen; the unstable stannane SnH4 is formed by the interaction of Mg2Sn and HCl.
With halogens, oxygen produces compounds of the composition SnX2 and SnX4. The latter (except SnF4) are hydrolyzed by water, but are soluble in non-polar organic matter. liquids By reacting oxygen with dry chlorine, SnCl4 tetrachloride is obtained (a colorless liquid that dissolves sulfur, phosphorus, and iodine well). SnX4 tetrahalides form complex compounds with H2O, NH3, nitrogen oxides, PCl5, alcohols, ethers, and many others. organic connections. With hydrohalic acids, oxygen halides form complex acids that are stable in solutions, for example. H[SnCl3] and H2[SnCl6]. When diluted with water or neutralized, simple and complex chlorides hydrolyze and give slightly soluble products: respectively, basic tin(II) salts of the type SnOHCl and hydrated tin(IV) oxide SnO2 xH2O. With sulfur, oxygen forms sulfides insoluble in water and dilute acids: brown SnS and golden yellow SnS2.
O. and most of it is inorganic. compounds are low toxic. Inhalation of O. vapors or dust in production. conditions can lead to the development of stannosis (a form of pneumoconiosis). Stannan SnH4 is highly toxic (acute poisoning is characterized by convulsions, imbalance; death is possible). Organic O. compounds are highly toxic.
