Abstract

Gallium is a scarce but not a rare element. It is found most commonly in association with its immediate neighbors in the Periodic Table, ie, zinc, germanium, and aluminum. The concentration of gallium in the earth’s crust, 10–20 g/t (10–20 ppm), is comparable to that of lead and arsenic. There is an abundance of aluminum ores and alumina plants, and less importantly to gallium production zinc ores and plants; these are the main sources of gallium. The physical properties of gallium, especially its thermal properties, are exceptional. It is easily supercooled. In accordance with its normal potential, gallium is chemically similar to zinc and is somewhat less reactive than aluminum. A minor amount of gallium is extracted as a by-product from the zinc industry. The significant amount of primary gallium is recovered from the alumina industry. The main source is the sodium aluminate liquor from Bayer-process plants that produce large quantities of alumina.

A large part of the wastes from the gallium arsenide industry is recovered for both economical and environmental reasons. Several processes are effective and are being used to recover both the gallium either as a metal, a salt, or a hydroxide for recycling, and the arsenic in some form for recycling or disposal. Gallium either comes from mining sources or is recycled from scrap.

Gallium has complete miscibility in the liquid state with aluminum, indium, tin, and zinc. No compounds are formed.

Numerous intermetallic gallium–transition element compounds have been reported. The toxicity of metallic gallium or gallium salts is very low. Gallium is used in the production of electronics and magnets, in medicine, as a petroleum industry catalyst, and in the solar reactions experiment.