Antimony

Description

Antimony (Sb) has been known since antiquity, and its early use as a cosmetic continues even today. Often mixed with lead or other heavy metals, this mascara-type cosmetic is known as kohl. Believed to possess powers to shield the eye from the sun and disease, it served purposes in both cosmetics and mysticism. Antimony has been found in many artifacts in the Middle East, and seems to have been used in the creation of small personal ornamentation or vessels.

Chemical properties

Antimony is a silvery-white metal found in the earth’s crust. It is insoluble in hot or cold water, but soluble in hot concentrated sulfuric acid and hot nitric acid, and reacts with oxidizing acids and halogens (fl uorine, chlorine, or bromine). It does not react with water at room temperature, but will ignite and burn in air at higher temperatures. Ores of antimony are mined and later mixed with other metals to form antimony alloys, which are used in lead storage batteries, solder, sheet and pipe metal, bearings, castings, and pewter. Antimony oxide is added to textiles and plastics to prevent them from catching fi re. It is also used in paints, ceramics, and fi reworks, and as enamels for plastics, metal, and glass. Antimony is alloyed with other metals, such as lead, to increase its hardness and strength; its primary use is in antimonial lead, which is used in grid metal for lead acid storage batteries. Antimony salts are used in the treatment of leishmaniasis and schistosomiasis.

Chemical properties

Antimony is a silvery-white, lustrous, hard, brittle metal; scale-like crystals, or dark gray lustrous powder

Physical properties

Physically, antimony's properties are related to sulfur and some of the nonmetals, butchemically, its properties are related to metals. It behaves like a metal and is often found innature along with other metals. In its pure form it is rather hard and brittle with a grayishcrystal structure.


Roughly 1/20th of the thermal conductivity of copper. The thermal conductivity of antimony depends on the grain size and the direction in the crystal. Electrical resistivity at 0℃: 30.0×10^-6Ω cm; Molar susceptibility at 20℃: -99.0×10^-6.

Physical properties

Energy gap E_g=0.11 eV (β-Sb) and Hall coefficient 2.55×10^-8 (m³ /C) are reported for the film with the thickness 570 nm on the glass substrate.

Isotopes

There are 53 isotopes of antimony. They range from Sb-103 to Sb-139 (a fewhave two forms). Their half-lives range from 150 nanoseconds to 2.7 years. The twostable isotopes of antimony and their contribution to the natural abundance of antimonyon Earth are as follows: Sb-121 = 57.21% and Sb-123 = 42.79%.

Origin of Name

The element’s name comes from the Greek words anti and minos, which mean “not alone,” and antimony’s symbol (Sb) is derived from the name for its ancient source mineral, stibnium.

Occurrence

Although antimony is not a rare metal, it is not well known, despite having been knownand used for many centuries. It is the 63rd most abundant element on Earth, and it occursmainly as sulfide ores or in combination with the ores of other metals. The ore that is theprimary source of antimony is the mineral stibnite (antimony sulfide, Sb₂S₃). Antimony is alsofound in copper, silver, and lead ores. Breithauptite (NiSb) and ullmanite (NiSbS) are twoores containing nickel. Dicrasite (Ag₂Sb) and pyrargyrite (Ag₃SbS₃) are silver ores containingsome antimony.

History

Antimony was recognized in compounds by the ancients and was known as a metal at the beginning of the 17th century and possibly much earlier. It is not abundant, but is found in over 100 mineral species. It is sometimes found native, but more frequently as the sulfide, stibnite (Sb2S3); it is also found as antimonides of the heavy metals, and as oxides. It is extracted from the sulfide by roasting to the oxide, which is reduced by salt and scrap iron; from its oxides it is also prepared by reduction with carbon. Two allotropic forms of antimony exist: the normal stable, metallic form, and the amorphous gray form. The so-called explosive antimony is an ill-defined material always containing an appreciable amount of halogen; therefore, it no longer warrants consideration as a separate allotrope. The yellow form, obtained by oxidation of stibine, SbH3, is probably impure, and is not a distinct form. Natural antimony is made of two stable isotopes, ¹²¹Sb and ¹²³Sb. Forty-five other radioactive isotopes and isomers are now recognized. Metallic antimony is an extremely brittle metal of a flaky, crystalline texture. It is bluish white and has a metallic luster. It is not acted on by air at room temperature, but burns brilliantly when heated with the formation of white fumes of Sb²⁰³. It is a poor conductor of heat and electricity, and has a hardness of 3 to 3.5. Antimony, available commercially with a purity of 99.999 + %, is finding use in semiconductor technology for making infrared detectors, diodes, and Hall-effect devices. Commercial-grade antimony is widely used in alloys with percentages ranging from 1 to 20. It greatly increases the hardness and mechanical strength of lead. Batteries, antifriction alloys, type metal, small arms and tracer bullets, cable sheathing, and minor products use about half the metal produced. Compounds taking up the other half are oxides, sulfides, sodium antimonate, and antimony trichloride. These are used in manufacturing flame-proofing compounds, paints, ceramic enamels, glass, and pottery. Tartar emetic (hydrated potassium antimonyl tartrate) has been used in medicine. Antimony and many of its compounds are toxic. Antimony costs about $1.30/kg for the commercial metal or about $12/g (99.999%).

Characteristics

There are two allotropes of antimony. The native metallic form is one allotrope, and theother allotrope is an amorphous grayish form. Antimony is a true metalloid that is brittle witha low melting point. And similar to nonmetals, it is a poor conductor of heat and electricity.
Antimony is unique in that when it solidifies from a molten liquid state to a solid state, itexpands, which is just the opposite of most metals. This is useful in making some typesettingcastings in which the expansion assures an accurate reproduction of the letter mold.

The Uses of Antimony

Antimony is used to make alloys such asBabbit metal, white metal, and hard lead; inbullets and fireworks; and for coating metals.
Also, it is used in lead storage batteries,solder bearings, castings and pewter. Antimonyoxide has numerous applications. It isused in paints, ceramics and fireworks andis added to textiles. The average concentrationof antimony in the urban air in USA isestimates as 0.001μg/m³.

The Uses of Antimony

In manufacture of alloys, such as Britannia or Babbitt metal, hard lead, white metal, type, bullets and bearing metal; in fireworks; for thermoelectric piles, blackening iron, coating metals, etc.

The Uses of Antimony

Today the most common use of antimony is as an alloy metal with lead to make the leadharder. This lead–antimony alloy is used for electrical storage batteries, for sheathing for electricaland TV cables, in the making of wheel bearings, and as solder.
Although it is a brittle metal, it has found a use in the semiconductor industry in theproduction of diodes and infrared devices. It is also used to flameproof material and vulcanizerubber and can also be a component in paints, ceramic enamels, glass, pottery, andfireworks.
Antimony has few other uses except as an alloy to harden other materials. One recentdevelopment was to add antimony oxide to polyvinyl chloride (PVC pipe) to act as a flameretardant.

Definition

antimony: Symbol Sb. An elementbelonging to group 15 (formerly VB)of the periodic table; a.n. 51; r.a.m.121.75; r.d. 6.68; m.p. 630.5°C; b.p.1750°C. Antimony has several allotropes.The stable form is a bluishwhitemetal. Yellow antimony andblack antimony are unstable nonmetallicallotropes made at low temperatures.The main source isstibnite (Sb₂S₃), from which antimonyis extracted by reduction withiron metal or by roasting (to give theoxide) followed by reduction withcarbon and sodium carbonate. Themain use of the metal is as an alloyingagent in lead-accumulator plates,type metals, bearing alloys, solders,Britannia metal, and pewter. It is alsoan agent for producing pearlitic castiron. Its compounds are used inflame-proofing, paints, ceramics,enamels, glass dyestuffs, and rubbertechnology. The element will burn inair but is unaffected by water or diluteacids. It is attacked by oxidizingacids and by halogens. It was first reportedby Tholden in 1450.

What are the applications of Application

It is important as wire materials of the thermocouples for spectroscopic measurements. The alloy with other metal is used because the material is fragile.

Manufacturing Process

Antimony metal is recovered from ore primarily by pyrometallurgical techniques. Either antimony(III) sulfide is converted into the oxide, which is then reduced, or the ore is partially roasted and allowed to react with sulfide to form the metal and sulfur dioxide. Sulfide ores with antimony contents between 5 and 25% are roasted to give volatile Sb2O3, which is reduced directly to the metal. In many smelters mixed oxide – sulfide ores are processed in water-jacketed furnaces together with recycled material and byproducts containing antimony. Reverberatory furnaces are used mostly for reducing rich oxide materials.

General Description

A silvery or gray solid in the form of dust. Denser than water and insoluble in water. Toxic by inhalation and by ingestion. May burn and emit toxic fumes if heated or exposed to flames. Used to make electric storage batteries and semiconductors.

Reactivity Profile

ANTIMONY is spontaneously flammable in fluorine, chlorine, and bromine. With iodine, the reaction produces heat, which can cause flame or even an explosion if the quantities are great enough [Mellor 9:379 1946-47]. Even at 10° C. bromine trifluoride reacts with antimony incandescently. Bromine trifluoride reacts similarly with arsenic, boron, bromine, iodine, phosphorus, and sulfur [Mellor 2:113 1946-47]. Bromoazide explodes on contact with antimony, arsenic, phosphorus, silver foil, or sodium. Antimony is very shock sensitive. Explosions of chloric acid have been due to the formation of unstable compounds with antimony, bismuth, ammonia, and organic matter [Chem. Abst. 46:2805e 1952]. The reaction of finely divided antimony and nitric acid can be violent [Pascal 10:504 1931-34]. Powdered antimony mixed with potassium nitrate explodes when heated [Mellor 9:282 1946-47]. When antimony or arsenic and solid potassium permanganate are ground together, the metals ignite [Mellor 12:322 1946-47]. Sodium peroxide oxidizes antimony, arsenic, copper, potassium, tin, and zinc with incandescence [Mellor 2:490-93 1946-47].

Hazard

The powder and dust of antimony are toxic and can cause damage to the lungs. The fumesof antimony halogens (chlorides and fluorides) are especially dangerous when inhaled or incontact the skin.
Many of the salts of antimony are carcinogenic and can cause lung cancer if inhaled, as wellas other cancers if ingested. This is a major hazard with the radioisotopes of antimony used inindustry. Some of its sulfide compounds are explosive.

Health Hazard

The toxicity of antimony is of low order,much less poisonous than arsenic. The symptoms of acute poisoning include weightloss, loss of hair, eosinophilia, and congestionof heart, liver, and kidney. GI disorder(vomiting and diarrhea) and respiratory distressmay arise from high doses. Chronic oralexposure may cause disorder in blood andliver. The toxic routes are primarily inhalationof its dusts or fumes, skin absorption oringestion of contaminated food.

Fire Hazard

May react violently or explosively on contact with water. Some are transported in flammable liquids. May be ignited by friction, heat, sparks or flames. Some of these materials will burn with intense heat. Dusts or fumes may form explosive mixtures in air. Containers may explode when heated. May re-ignite after fire is extinguished.

Pharmaceutical Applications

Antimony presents itself in a metallic grey form. Antimony is obtained from stibnite (Sb₂S₃) after reduction with iron.

Industrial uses

Antimony is a bluish-white metal, symbol Sb,with a crystalline scalelike structure that exhibitspoor electrical and heat conductivity. It isbrittle and easily reduced to powder. It is neithermalleable nor ductile and is used only in alloysor in its chemical compounds. Like arsenic andbismuth, it is sometimes referred to as a metalloid,but in mineralogy it is called a semimetal.The element is available commercially in99.999+% purity and is finding increasing usein semiconductor technology.
Antimony is produced either by roasting thesulfide with iron, or by roasting the sulfide andreducing the sublimate of Sb4O6 thus producedwith carbon; high-purity antimony is producedby electrolytic refining. Antimony is one of thefew elements that exhibits the unique propertyof expanding on solidification. Antimony isordinarily stable and not readily attacked by airor moisture. Under controlled conditions it willreact with O2 to form oxides. The chief uses ofantimony are in alloys, particularly for hardeninglead-base alloys.
Antimony imparts hardness and a smoothsurface to soft-metal alloys, and alloys containingantimony expand on cooling, thus reproducingthe fine details of the mold. This propertymakes it valuable for type metals. When alloyedwith lead, tin, and copper, it forms the babbittmetals used for machinery bearings. It is alsomuch used in white alloys for pewter utensils.Its compounds are used widely for pigments.

Safety Profile

An experimental poison by intraperitoneal route. Questionable carcinogen with experimental carcinogenic data. Moderate fire and explosion hazard in the forms of dust and vapor when exposed to heat or flame. See also POWDERED METALS. When heated or on contact with acid it emits toxic fumes of SbH3. Electrolysis of acid sulfides and stirred Sb halide yields explosive Sb. It can react violently with NH4NO3, halogens, BrN3, BrF3, HClO3, Cl0, ClF3, HNO3, m03, KMn04, K2O2, NaNO3, oxidants.

Potential Exposure

Exposure to antimony may occur during mining, smelting or refining; alloy and abrasive manufacture; and typesetting in printing. Antimony is widely used in the production of alloys, imparting increased hardness, mechanical strength, corrosion resistance, and a low coefficient of friction. Some of the important alloys are Babbitt, pewter, white metal, Britannia metal and bearing metal (which are used in bearing shells), printing-type, metal, storage battery plates, cable sheathing, solder, ornamental castings, and ammunition. Pure antimony compounds are used as abrasives, pigments, flame-proofing compounds, plasticizers, and catalysts in organic synthesis; they are also used in the manufacture of tartar emetic, paints, lacquers, glass, pottery, enamels, glazes, pharmaceuticals, pyrotechnics, matches, and explosives. In addition, they are used in dyeing, for blueing steel; and in coloring aluminum pewter; and zinc. A highly toxic gas, stibine, may be released from the metal under certain conditions.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contactsthe skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove fromexposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing hasstopped and CPR if heart action has stopped. Transferpromptly to a medical facility. When this chemical hasbeen swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make anunconscious person vomit.Note to physician: For severe poisoning BAL [British AntiLewisite, Dimercaprol, dithiopropanol (C3H8OS2)] has beenused to treat toxic symptoms of certain heavy metals poisoning—including antimony. Although BAS is reported to havea large margin of safety, caution must be exercised, becausetoxic effects may be caused by excessive dosage. Most canbe prevented by premedication with 1-ephedrine sulfate(CAS: 134-72-5).

Carcinogenicity

Existing experimental data suggest that antimony may be an animal carcinogen, but there is lack of data on the possible carcinogenic properties of antimony and antimony compounds for human exposures. The ACGIH refers to unpublished data on a large antimony smelter in the United Kingdom in the 1960s where workers were exposed to antimony trioxide ranging from 0.5 to 40mg/m³. The data may indicate increased mortality in lung cancer among the heavily exposed workers, but the workers were also exposed to zirconium making the data cited dif?cult to interpret.

Environmental Fate

The toxicity of Sb is a function of the water solubility and the oxidation state of the Sb species under consideration. Antimony( III) is generallymore toxic than antimony(V) and inorganic forms are thought to be more toxic than organic forms. Stibane gas (SbH3) when inhaled is the most toxic. Antimony toxicity often parallels that of arsenic, although antimony salts are less readily absorbed than arsenic. It is presumed that antimony, like arsenic, complexes with sulfhydryl groups of essential enzymes and other proteins. By analogy, antimony can uncouple oxidative phosphorylation, which would inhibit the production of energy necessary for cellular functions. Antimony’s trivalent compounds are more toxic than its pentavalent compounds.

storage

Color Code—Blue: Health Hazard/Poison: Store ina secure poison location. Prior to working with this chemicalyou should be trained on its proper handling and storage.Store in tightly closed containers in a cool, well-ventilatedarea away from oxidizers, halogens, strong acids, and heat.Sources of ignition, such as smoking and open flames, areprohibited where this chemical is used, handled, or stored ina manner that could create a potential fire or explosion hazard. Contact with acids forms deadly stibine gas. Beforeentering confined space where this chemical may be present,check to make sure that an explosive concentration does notexist.

Shipping

UN2871 Antimony powder, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Toxicity evaluation

Antimony is found naturally in the Earth’s crust and can be released into the environment as windblown dust or sea spray or from volcanic eruptions or forest fires. However, the emission of antimony into the environment is overwhelmingly the result of human activity, with the emission of antimony trioxide, tetroxide, and pentoxide forms being the most significant. Antimony trioxide is emitted as a result of coal burning, or with fly ash when antimony-containing ores are smelted. Humans are exposed to low amounts of antimony from the air, drinking water, and food contaminated with soil. Antimony concentration in the atmosphere is thought to be 1.4–55 ng m^-3. The more water soluble forms of antimony are very mobile in aqueous media while the less soluble forms of antimony are found attached to particles of soil, clay, and sediment in rivers and lakes. The concentration of antimony in the Pacific Ocean was found to be 0.2 mg l-1 and in the Rhine river at 0.1 μg l^-1. The trivalent state of antimony is the form most often released by anthropogenic activities. In terms of soil concentrations, it was reported by a US Geological Survey to be less than 1–8 ppm in soil, with an average of 0.48 ppm. Studies have estimated an exposure of less than 5 mg day
1 on average from food and water and appears to be significantly higher than exposure by inhalation.

Structure and conformation

The space lattice of most stable metallic antimony (often called gray antimony) belongs to the hexagonal system, and its arsenic type structure (two atoms within a unit cell) has a lattice constant of a=0.449762 nm, a=57°6.6', u=0.233. Black antimony and yellow antimony are known, but these are unstable and transform to metallic antimony

Incompatibilities

Pyrophoric. Finely dispersed powder may form explosive mixture in air. Strong oxidizers; strong acids , produce a violent reaction, and deadly stibine gas (antimony hydride). Heat forms stibine gas. Mixtures with nitrates or halogenated compounds may cause combustion. Forms an explosive mixture with chloric and perchloric acid. Note: Stibine is formed when antimony is exposed to nascent (freshly formed) hydrogen.

Waste Disposal

Recovery and recycling is an option to disposal which should be considered for scrap antimony and spent catalysts containing antimony. Dissolve spilled material in minimum amount of concentrated HCl. Add water, until white precipitate appears. Then acidify to dissolve again. Saturate with H2S. Filter, wash and dry the precipitate and return to supplier. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.

Precautions

Antimony trioxide is incompatible with bromine trifl uoride, strong acids, strong bases, reducing agents, perchloric acid, and chlorinated rubber. The release of the deadly gas, stibine, and its inhalation cause adverse effects on the respiratory, gastrointestinal, and cardiovascular systems. Workers must wear impervious protective clothing, including boots, gloves, laboratory coat, apron or coveralls, as appropriate, to prevent skin contact.