Antimony
Antimony is a chemical element that forms part of the group of metalloids with atomic number 51 located in group 15 of the periodic table of elements. Its name and abbreviation (Sb) comes from stibio, a term now in disuse, which in turn comes from the Latin stibium ("Bright gray sandbank"). Its main ore is stibnite.
This semi-metallic element has four allotropes. In its stable form it is a bluish-white metal. Black and yellow antimony are unstable nonmetallic forms. It is mainly used in metallic alloys and some of its compounds to provide resistance against fire, in paints, ceramics, enamels, rubber vulcanization and fireworks.
Main features
Antimony in its elemental form is a silvery-white, brittle, meltable, crystalline solid that exhibits low electrical and thermal conductivity and evaporates at low temperatures. This semi-metallic element resembles metals in its appearance and physical properties, but behaves chemically like a nonmetal. It can also be attacked by oxidizing acids and halogens.
Estimates of the abundance of antimony in the Earth's crust range from 0.2 to 0.5 ppm. Antimony is chalcophilic, occurring with sulfur and other elements such as lead, copper, and silver.
History
Archaeological and historical studies indicate that antimony and its sulfides have been used by humans for at least the last 6 millennia. In ancient times, antimonite or stibnite, Sb2S3, the most common form of antimony sulfide, was the main ingredient in kohl, a black paste used by Egyptians, among others, as eye makeup. The Babylonians knew how to obtain antimony from its compounds and used it as an ornament for vessels.
The alchemist Basil Valentine (1565-1624), sometimes presented as the discoverer of antimony, was the first to describe the extraction of antimony from its compounds in his treatise “Triumph Wagens des Antimonij” (The Triumph Wagon of Antimony)..
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The name antimony comes from a Latinization of the Arabic word انتيمون ("al-ithmīd"), which in turn consisted of an Arabization of the Latin word stibium.
Other theories suggest that antimony is a compound of the Latin words “anti"(fear) and “mono” (alone); which would refer to its existence in nature normally as a compound.
After the invention of the printing press in the 16th century, antimony was used as an alloy for typographic stamps. On cooling, liquid antimony has the unique property of expanding as it solidifies. In this way, he manages to fill in the cracks in the moulds, which is why the edges of the pieces obtained are very sharp. For this reason, it was used to make printing type. In the 19th century, its alloy with zinc (English metal) was used in cutlery, candlesticks and chandeliers.
After the invention of the electric accumulator, it was found that the use of lead and antimony alloys made them last much longer. During the First World War, a maximum of production was reached, due to its use as weapons, since this semi-metal greatly increases the hardness and mechanical strength of lead and tin. With the development of the automobile industry, the use of antimony has been increasing year after year, although World War I levels were not reached again until the 1990s.
Applications
Antimony is of increasing importance in the semiconductor industry in the production of diodes, infrared detectors and Hall effect devices.
Used in alloys, this semimetal greatly increases the hardness and resistance to mechanical stress of the alloy. It is also used in different alloys such as pewter, antifriction metal (alloyed with tin), English metal (formed by zinc and antimony), etc.
Some more specific applications:
- Batteries and accumulators
- Types of printing
- Cable coating
- Bearings and bearings
Antimony compounds in the form of oxides, sulfides, antimonates, and antimony halides are used in the manufacture of fire-resistant materials, enamels, glass, paints, and ceramics. Antimony trioxide is the most important and is mainly used as a flame retardant. These applications as flame retardants include different markets such as clothing, toys, or seat covers.
Metal uses
Since the electric lead-acid battery was developed in the 20th century, it has been by far the most important secondary (or rechargeable) battery throughout the world. They are used in motor vehicles, or as industrial batteries.
Industrial electric batteries include traction accumulator batteries in mine locomotives, golf carts, and so on, "emergency power" batteries. Antimony in alloy with lead is used for certain parts of electric accumulators for which resistance to corrosion is necessary.
Antimony is a minor but important component of many soft solders, which are solders that melt at temperatures below 625 K. These solders may contain between 0.5 and 3% antimony. The function of antimony in these solders is to strengthen the solder and suppress the formation of tin allotropes at low temperatures, which would otherwise degrade the structural integrity of soldered joints at temperatures below the point of phase transition (289 K). Antimony has been used as a hardener for the lead used in ammunition.
In the United States its use is largely confined to the manufacture of bullets and shot. Contamination of groundwater, soil, and the food chain with toxic lead has been a concern for many years, and environmental regulations have led to the replacement of lead for antimony with a tungsten alloy.
Lead alloys that contain about 2 to 8% antimony are resistant to atmospheric use and corrosion, which is why they are used in the construction of channels and moisture barriers. In the chemical industry, alloys containing from 4 to 15% antimony provide protection against various liquid states of chemicals, especially sulfuric acid or sulfur. Alloyed with bismuth, lead, and tin, antimony is a component of some of the fusible alloys used in fire safety devices. The metal used for the manufacture of characters and other typographic material is obtained with an alloy of lead, antimony and tin. Lead is used for easy melting and to make the alloy ductile and compact. The antimony serves to give more resistance to the metal so that it does not crush so easily during the repeated and numerous throws. The alloys are diverse, according to the sizes of the types and the use to which they are destined.
So for the manufacture of the metal intended for targets, the following alloy, called ordinary, is usually used: 75 parts of lead, 20 parts of antimony and 5 parts of tin. Small amounts of high purity antimony are used in video discs (DVDs).
Non-metallic uses
The tip of safety matches contains antimony trisulfide. Combustion is an exothermic reaction sustained by internally generated free radicals and radiant heat. Halogen flame retardants work by interfering with the radical chain mechanism in the gas phase (the flame). When used by themselves, halogen flame retardants must be used in very large amounts. This problem is avoided by adding antimony trioxide, which works in conjunction with the halogens, reducing the amount of flame retardant needed and also reducing the overall treatment cost. Several attempts have been made to explain the mechanism of antimony and halogens working together, but none is definitive.
Many common plastics are susceptible to degradation by heat and ultraviolet (UV) light, and products made from them must be protected during their service lives by the addition of compounds known as stabilizers. Antimony has been used since the 1950s as an effective heat stabilizer for PVC, especially the rigid forms of the plastic.
Antimony trioxide is used as a catalyst in the polymerization of PET, which is a plastic used in bottles, films, food packaging, and many other products. Antimony compounds, along with germanium dioxide, are the preferred catalysts for PET.
Germanium dioxide gives a product with better transparency than antimony, but is too expensive for many PET applications. Antimony trioxide is also used as a white pigment for exterior paints, where its resistance to wear by atmospheric action made it a valuable object; however, when its toxic capacity was discovered, antimony trioxide has been supplanted by carbon dioxide. titanium (TiO2).
It is still used in significant amounts as a color stabilizer where it is important to maintain color intensity and prevent hue shift, for example in yellow paints used for school buses (American and South African) and yellow stripes applied to road pavements.
The electrically conductive pigments of tin oxide (SnO) with antimony have been introduced in recent years for incorporation into plastic coatings that protect computers and other electronic components from static electricity.
Antimony was used in medicine for its good expectorant, emetic and purgative qualities. And treatises on its medical qualities were written. Until it was decided to officially declare it a poison on August 3, 1866. In the form of antimony salts Sb(OH)2Cl (Sbv) or as pentavalent antimony, it is still mentioned as a treatment Initial against leishmaniasis.
Antimony and environment
Antimony is released into the environment from natural and industrial sources. It can remain in the air attached to very small particles for many days. Most airborne antimony settles to the ground, where it adheres firmly to particles containing iron, manganese, or aluminum. High levels of antimony in the air we breathe for very long periods of time can irritate the eyes and lungs and cause respiratory, heart and stomach problems.
The occupational exposure limit is 0.5 mg of antimony per m³ of air for an 8-hour workday. The maximum allowed level of antimony in drinking water in Europe is 0.006 ppm.
In urban air, the main source of antimony is the combustion of fossil fuels in motor vehicles, power plants, and incinerators.
The United States Environmental Protection Agency (EPA) toxic inventory for the period from 1993 to 2005 showed that U.S. industrial plants released more than 900 tons/year of antimony in all forms into the land and about 25 t/year to groundwater. Of the antimony released to earth by major industries, primary copper smelters account for about 60%; primary smelters for other non-ferrous metals, 20%; secondary non-ferrous smelters, 7% and oil refineries, 2%. The remaining 11% is attributed to the manufacture of various antimony products. Post-consumer release of antimony from waste end-use products is also of importance.
There is concern, especially in Europe, about the leaching of antimony pigments, heat stabilizers, and flame retardants from waste plastics products. These concerns have contributed to a shift to calcium-zinc stabilizers in Europe and to tin-based stabilizers in the United States and Japan. It is believed that the country that releases the most antimony into the atmosphere is China, due to the great use made of this element in that country, since it has the main antimony mines in the world. However, due to the political regime, there are no data.
Abundance and obtaining
Antimony is found in nature in many minerals, although it is a rare element. But it is possible to find it free, it is normally in the form of sulphides; the main antimony ore is antimonite (also called stibnite), Sb2S3.
Roasting antimony sulfide produces antimony(III) oxide, Sb2O3, which can be reduced with coke to obtain antimony.
- 2Sb2O3 + 3C → 4Sb + 3CO2
It can also be obtained by direct reduction of sulphide, for example with scrap iron:
- Sb2S3 + 3Fe → 2Sb + 3FeS
| 1. | China China | 89 000 |
| 2. | Russia Russia | 30 000 |
| 3. |  Tajikistan | 28 000 |
| 4. | Burma Burma | 6000 |
| 5. | Bolivia Bolivia | 3000 |
| 6. | Turkey Turkey | 2400 |
| 7. | .svg){kind=small} Australia | 2030 |
| 8. | Iran Iran | 500 |
| 9. | Vietnam Vietnam | 310 |
| 10. | Mexico Mexico | 300 |
| 10. | Kazakhstan Kazakhstan | 300 |
Source: USGS. NOTE: No data has been published for the United States.
Compounds
Its most common oxidation states are 3 and 5.
The terms crude antimony and crudum apply to ore containing more than 90 percent antimony, and liquefied sulfide ore, which is essentially an antimony-sulfide mixture containing 70 percent or more antimony. Refined antimony metal is the common stable form of antimony.[citation needed]
Antimony yellow or alpha-antimony is produced by the action of ozone in liquid SbH3, -90 °C. It is amorphous and sparingly soluble in carbon disulfide. Yellow antimony is highly unstable and readily transforms at temperatures above -90°C to black antimony, which can also be formed directly from liquid SbH3 and oxygen at -40°C. Black antimony spontaneously oxidizes in air to ordinary rhombohedral antimony or beta-antimony. The fourth allotrope of antimony is explosive antimony, which is formed from the electrolysis of antimony chloride.[citation needed]
This form transforms at 475 K into the most common allotrope producing an explosion. There are studies trying to show that yellow antimony is actually impure antimony and not a true allotrope of antimony.
Due to its hardness, brittleness, and lack of malleability, antimony has no uses as a metal by itself except for small amounts used for ornamental castings and semiconductor devices. However, it is a minor component in many lead-tin alloys.
Most antimony that is used in the metallic state, such as in LA batteries, cable jacketing, and various other uses, is used as some form of lead antimony, which can contain up to 25% antimony, but it most commonly contains single-digit percentages. Antimony is also a component of various tin alloys, such as Brittany metal, antifriction metal, and tin-antimony-silver solder used to assemble potable water pipes.
Antimony forms a very large number of inorganic compounds. Sulfides predominate in nature and are commercially available as processed antimony ores. In terms of the amounts produced, the most important synthetic compound of antimony by far is trioxide (Sb2O3), which is used by itself for some applications..
Other compounds used in substantial amounts are pentoxide (Sb2O5), trisulfide (Sb2S3 ) and pentasulfide (Sb2S5). These compounds are used as flame retardants, in pigments, heat and radiation stabilizers in plastics, and in catalysts.
All of its trihalides, SbX3, and the pentafluoride and pentachloride, SbX5, are known. Trifluoride is used as a fluorinant. The pentafluoride together with HSO3F forms an SbF5-FSO3H system with superacid properties. Different complexes can be prepared with these halides. The hydride SbH3 (stibnite) is known, but it is not very stable and decomposes very easily.
Antimony trioxide, Sb2O3 and pentoxide, Sb2O5 are known..
Precautions
Antimony and many of its compounds are toxic, so care must be taken when handling them. Reacts violently with strong oxidants (example: halogens, alkaline permanganates and nitrates) causing fire and explosion hazard. It reacts in an acid medium with nascent hydrogen producing a very toxic gas (stibamine). These compounds are formed in the presence of metals that can be attacked by the acid being used, such as iron, so metallic objects (containers, tongs, etc.) should never be used when cleaning antimony minerals with acid.
Its autoignition temperature is 900 °C, and it must be stored separately from food and feed, strong oxidants, acids, reducing substances. It must be handled with gloves and protective glasses.