A chemical element having the symbol Sb (derived from the Latin term stibium), antimony has an atomic number 51. Antimony is a shining grey colored metalloid and is mainly found in the nature in the form of sulphide mineral stibnite (symbol Sb2S3). People have known various compounds of antimony since the ancient times. These compounds were pulverized into powder and used in the form of medicines and in cosmetics. The cosmetic made from this chemical element is usually identified by its Arabic name – kohl. People were also familiar with metallic antimony, but when it was discovered people mistook it for another metal – lead. The earliest recorded description of antimony is found in the West. An Italian metallurgist named Vannoccio Biringuccio is credited to have described it first way back in 1540.
For a while, China was the largest producer of both antimony as well as its compounds. Most of the production of antimony and its compound in China was in the Xikuangshu Minein Hunan. In those times, the industrial process of refining antimony involved roasting the compound with carbon or reducing stibnite using iron directly.
The most widespread of metallic antimony is developing an alloy along with tin and lead. In addition, lead antimony plates are used in lead-acid batteries. Alloys comprising antimony with lead and tin have enhanced characteristics and are used in bullets, solders and simple bearings. Moreover, compounds of antimony are important additives for bromine and chlorine-containing fire retardants, which are found in several domestic as well as commercial products. Currently, the use of metallic antimony is gradually gaining popularity in microelectronics.
Antimony (Sb) is an unadulterated element. Some forms of antimony are metallic, while there are some non-metallic forms of this element too. This element has various industrial applications, including in batteries, many paints and even rubber. Often antimony is considered as an environmental problem and talked about its cleanup because this element has a wide variety of uses in non-recyclable products. This is also because this element possesses toxic properties.
According to the etymology of the term antimony, Basil Valentine, a German monk, once threw some of this element to the pigs in the monastery. The pigs, who consumed them became healthy and were quickly fattened. This led the monk to believe that antimony possessed some healing properties. With this belief, the monk fed some of the element to his fellow brothers and all of them died subsequently owing to the toxicity of antimony. Hence, it is believed that the element derived its name from the French word antimoine, which translated to English means “anti-monk”. Though this etymology appears to be highly passionate, it is quite likely that the element got its name from the Greek terms “anti” and “monos”, which together denote “not alone”.
Antimony belongs to the group of elements called metalloids. Metalloids are substances that possess properties of both metals as well as non-metals in the periodic table. In fact, antimony is also called a semimetal – referring to the manner in which this element conducts energy. It is worth mentioning here that arsenic and bismuth are also semimetals. There are many other metalloids, such as boron, germanium and silicon.
In its stable form, antimony is a metallic element having blue-white hue and an atomic mass of 121.76g/mol. This metallic element has a melting point of 1167°F (630°C). This metallic element is a reasonably good semiconductor. Though antimony appears to be metallic, this chemical element does not possess the chemical responses similar to that of any other true metal. Often antimony is added to lead to enhance its strength.
These days antimony has a wide range of industrial applications. This chemical element is used in various products including batteries, lead-free solders, matches, plumbing, bullets and even medicines. For several thousand years, antimony has been occurring naturally and has been used in medicine. Even a tiny amount of this element can destroy specific parasites without affecting the recipient’s health even slightly. When used in a compound, antimony possesses remarkable flame-retarding properties. Therefore, compounds of antimony are used for treating things like toys, seat covers and also children’s clothing.
Similar to several other metalloids, antimony possesses somewhat toxic properties. The toxic effects of antimony are akin to that of arsenic. It causes acute vomiting that eventually leads to death. While our body can process trace amounts of antimony quite well, when taken in small doses it may cause minor side effects like headaches, vertigo and dizziness.
Of the entire antimony produced, almost 60 per cent of the element is used in flame retardants, while 20 per cent of it is utilized in compounds to make plain bearings, batteries and solders. Antimony is primarily utilized in the form of the trioxide present in flame-proofing compounds. Apart from polymers containing halogen, antimony is always used together with halogenated flame retardants. Antimony trioxide possesses flame retarding effects and this is attributed to the creation of halogenated antimony compounds that interact with hydrogen atoms and also in all probability with oxygen atoms as well as OH radicals thereby holding back fire. There is a wide market for such flame retardants and they include automobile seat covers, aircraft, children’s toys and children’s clothing. Moreover, in fibreglass composites, they are added to polyester resins that are mainly meant for covering light aircraft engines. While the resin will be on fire when there is a fire generated externally, it will douse the fire as soon as the external flame is taken away.
When combined with lead, antimony is a very useful alloy, as lead not only increases its hardness, but also the mechanical strength of this element. In most of the application where lead is involved, different amounts of antimony is used to make the alloy. For instance, adding to antimony to lead-acid batteries enhances the strength of the plate, in addition to improving the properties of the batteries. Antimony is also utilized in antifriction alloys like Babbitt metal, in lead shots and in bullets. It is also used to make type metal (for instance, linotype printing machines), electrical cable sheathing, solders (in fact, a number of lead solders contain about 5% antimony), in making alloys harder with low content of tin for manufacturing organ pipes and in pewter.
Aside from the above mentioned applications of antimony, the remaining supply of this element worldwide is used for three other purposes. Its other application includes its use in the form of a stabilizer and using it in the form of a catalyst for polyethylene terephthalate production. In addition, antimony is also a fining agent that works to get rid of infinitesimal bubbles in glass, which are mainly manufactured for television screen. This property of the element is attributed to the fact that the ions of antimony react with oxygen thereby repressing the latter’s tendency to form bubbles. The third application of antimony includes its use in manufacturing pigments.
These days antimony is being used more and more in the manufacture of semiconductors. In silicon wafers meant for diodes, this element serves as dopant n-type. Antimony serves the same purpose in Hall-effect devices and infrared detectors. Collectors and emitters found in n-p-n alloy junction transistors were doped with minute beads of an alloy made from antimony and lead in the 1950s. In addition, indium antimonide is employed as a material.
Antimony has a number of uses in biology and medicine too. Treatments involving antimony are called antimonials – wherein the element is used in the form of emetics. Compounds of antimony are also utilized in the form of antiprotozoan drugs. From 1919 onwards, potassium antimonyl tartrate (also called tartar emetic) was used in the form of anti-schistosomal drug. Subsequently, this drug was substituted by praziquantel. In fact, antimony as well as compounds containing this chemical element are used in may veterinary drugs – for instance lithium antimony thiommalate and antiomaline. It has been established that antimony possesses conditioning or nourishing properties and this effect is evident in the animals’ keratinized tissues.
Some drugs based on antimony, for instance meglumine antimoniate, are considered to be choice medications for various treatments, especially leishmaniasis which inflicts domestic animals. It is unfortunate that while these drugs have low remedial indices, they have negligible penetration of the bone marrow which forms the habitat of some Leishmania amastigotes. Hence, it is very difficult to cure the disease, particularly the visceral form. There was a time when people used elemental antimony in the form of an antimony pill to cure ailments. This pill could be reused by other people too once it was ingested and eliminated by the first user.
The compound antimony (III) sulphide is still utilized in the heads of a number of safety matches.
Moreover, antimony sulphides are effective in stabilizing the friction coefficient in materials used in automotive brake pads.
Among the other uses of antimony, this element is widely used in art glass, paints, bullets and bullet tracers. In addition, this chemical element is also used in enamel in the form of an opacifier. Unadulterated antimony is employed in manufacturing specific types of semiconductors such as diodes and infrared detectors. It is also used to make lead harder and enhance its durability.