A native element, antimony metal is extracted from stibnite and other minerals. Antimony is used as a hardening alloy for lead, especially storage batteries and cable sheaths, also used in bearing metal, type metal, solder, collapsible tubes and foil, sheet and pipes, and semiconductor technology.
Stibnite is the most important ore for antimony. Stibnite is used for metal antifriction alloys, metal type, shot, batteries, and in the manufacture of fireworks. Antimony salts are used in the rubber and textile industries, in medicine, and glassmaking.
Background
Antimony is a silvery-gray, brittle semi-metal with chemical symbol Sb and atomic number 51. It rarely occurs in nature as a native element, but is found in a number of different minerals, the most important of which is Stibnite (Sb2S3). Antimony is often called a semi-metal, because in pure form it is not shiny and malleable like true metals.
Antimony is not an element which most people see daily in a recognizable form. However, it is present in many products in everyday use.
Antimony minerals, particularly stibnite, have been known and used since ancient times. Because it is so soft, stibnite was used in ancient times as black eye makeup. The Roman historian, Pliny, wrote about its use as a medicine. Artists used finely-ground stibnite in the Middle Ages as a black pigment. Ancient “scientists” were interested in antimony because of their belief that it may be useful in the process of changing common metals into gold. This field was known as alchemy.
Uses
The most important use of antimony is in chemicals used to impregnate plastics, textiles, rubber, and other materials as a flame retardant – that is, a form of fireproofing. This is required by national laws for certain childrens’ clothing. For example, over half the annual United States antimony consumption is for the manufacture of flame retardants and a portion is in antimony alloys.
Antimony is mixed (that is, alloyed) with other metals, such as Lead, to make the lead harder and stronger for use in lead-acid batteries. On the other hand, some alloys such as Babbitt Metal (an alloy of Antimony, Tin, Copper, and sometimes Lead) are useful as machine bearings because they are soft and slippery. Antimony is also alloyed with tin to make pewter items such as plates, pitchers and cups, used mostly for decoration. One use of antimony, which is declining, is to make type metal for printing newspapers and magazines. Antimony is one of very few substances (Bismuth and water are two others) which expands when it cools and freezes. Antimony-bearing type metal thus fills every corner of a mold used to prepare sharp type for printing. With the advent of computer printing, this use has greatly decreased.
Antimony is also used for pigments in plastics, paints, rubber, and for a wide variety of minor uses, including medicines, fireworks, and others. Antimony oxide is a brilliant yellow color, accounting for much of the pigment use.
A tiny amount of highly purified antimony metal is used in the computer industry to make semiconductors. To be useful in this application, antimony has to be 99.999% pure!
Substitutes and Alternative Sources
Antimony could be replaced by Chromium, Tin, Zinc, and Titanium compounds in the paint industry. Cadmium, sulfur, copper, and calcium can be used to harden lead. A number of organic compounds can be used as fire retardants. Recycling, mining, and smelter production will meet the demand for antimony and antimony compounds for many decades to come.
Sources
Antimony rarely occurs in its native metallic form in nature. It easily combines with other elements, usually including sulfur, to form over 100 different minerals. Of these minerals, only stibnite is mined commercially as a source for metallic antimony. Antimony is found in trace (that is, very minor) amounts in Silver, Copper and Lead ores, and it is usually economically possible, as well as environmentally desirable, to extract the antimony from these ores when they are smelted.
Most of the antimony mined each year comes from China, which supplies over three-quarters of the world total. The remainder is from Russia, South Africa, Tajikistan, Bolivia, and a few other countries. Some antimony is produced as a by-product of smelting ores of other metals, mainly gold, copper and silver, in countries such as the United States, Canada, and Australia.
Recycling of old lead-acid batteries (such as automobile batteries) contributes to antimony production.
