Antimony

File:Antimon.PNG

Antimon

File:Antimony massive.jpg

Antimony massive

File:SbAs lattice.png

SbAs lattice

File:Stibnite.jpg

Stibnite

File:Antimony-pentafluoride-monomer-3D-balls.png

Antimony-pentafluoride-monomer-3D-balls

Antimony is a chemical element with the symbol Sb (from Latin: stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient times and were used for cosmetics; metallic antimony was also known, but it was erroneously identified as lead upon its discovery. The largest applications for metallic antimony are as alloying material for lead and tin and for lead antimony plates in lead-acid batteries. Alloying lead and tin with antimony improves the properties of the alloys which are used in soldiering, bearings, and pewter. It is also used in semiconductors, diodes, infrared detectors, and Hall-effect devices.

Properties

Antimony in its elemental form is a silvery, hard, brittle material. It exhibits poor electrical and thermal conductivity and expands upon cooling, similar to water, silicon, gallium, and bismuth. When antimony is compounded, it can take on a variety of oxidation states, but the +3 oxidation state is the most common.

Occurrence

Antimony is not abundant in the earth's crust. The most important source of antimony is the sulfide mineral stibnite (Sb2S3), which is mined in China, Russia, Bolivia, South Africa, and other countries. It can also be found in ores such as valentinite (Sb2O3) and kermesite (Sb2S2O).

Production

The extraction of antimony from ores depends on the quality and composition of the ore. Most antimony is mined as the sulfide; lower-grade ores are concentrated by froth flotation, while higher-grade ores are heated to 500–600°C, the temperature at which stibnite melts and separates from the gangue minerals. Antimony can also be isolated from the sulfide by reduction with scrap iron: \[ \text{Sb}_2\text{S}_3 + 3 \text{Fe} \rightarrow 2 \text{Sb} + 3 \text{FeS} \]

Uses

1. 1. 1. Antimony Trioxide ###

Antimony trioxide is the most important of the antimony compounds and is primarily used in flame-retardant formulations. These flame-retardant applications include such markets as children’s clothing, toys, aircraft, and automobile seat covers.

1. 1. 1. Alloys ###

Its alloys with lead are used in lead-acid batteries, solder, small arms and tracer bullets, cable sheathing, and other products. Antimony alloys are also used in bushings, bearings, pewter, and other engineering materials.

1. 1. 1. Other Uses ###

Antimony compounds are used in medicines, such as antiprotozoal drugs and antimony potassium tartrate. It is also used in the semiconductor industry to make infrared detectors, diodes, and Hall-effect devices.

Health Effects

Exposure to antimony can occur in the workplace or from environmental sources. It can cause irritation of the eyes, skin, and lungs. Long-term exposure to antimony can lead to more serious health effects, including lung diseases, heart problems, and adverse effects on the liver and kidneys. It is considered a potentially toxic element with both acute and chronic health effects.

Environmental Impact

Antimony enters the environment during its mining and processing, from wear and tear of antimony-containing products, and from industrial emissions. It can have harmful effects on organisms and ecosystems by entering the food chain and accumulating in organisms.

See Also

• Metalloid
• Lead-acid battery
• Semiconductor devices
• Environmental pollution

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