Characteristics: A silver-white, crystalline metalloid, pure antimony is brittle and not easily formed. It is resistant to attack by acids, and is a poor conductor of heat and electricity. Stable in air at room temperature, but reacts with oxygen if heated, to form antimony trioxide (Sb2O3). Antimony is estimated to compose 0.2 to 0.5 parts per million of the earth’s crust, and is found in over 100 mineral species. It is sometimes found natively, but most frequently it is found as the sulfide mineral stibnite.
Derivation: Ores are crushed and ground, then concentrated by flotation. Sulfide ore or liquated antimony sulfide is reduced to metal by iron precipitation. Antimony trioxide may be volatilized from sulfide ores, and can be reduced to metal with charcoal in reverberatory furnaces. Antimony product may also be produced by blast furnace smelting or hydrometallurgical methods. China is the world’s largest producer of antimony. In the US some antimony production is derived from recycling of antimonial lead recovered from spent lead-acid batteries.
Applications: Antimony trioxide, in conjunction with a halogen, is used to form a flame retardant system for coatings, fiberglass, paper, plastics, paints, textiles and rubber. Antimony metal is used to alloy with lead for batteries, ammunition, tank linings and bearings. Antimony compounds are also used in ceramics, glass and rubber products, and as a pigment in paints.
Hazards: IARC categorizes antimony trioxide as possibly carcinogenic to humans. Exposure Limits (Antimony and compounds): 0.5 mg/m3