How is gallium extracted?

Gallium is mainly a by-product of extracting aluminum from bauxite or zinc from zinc mine, and a small amount of gallium comes from the recovery of gallium, an associated element in coal. At present, more than 90% of the world's primary gallium is extracted from the seed mother liquor of alumina production.

Gallium is a grayish blue or silvery white metal with element symbol Ga and atomic weight of 69.723. Gallium has a low melting point but a high boiling point. Pure liquid gallium has obvious supercooling tendency and is easily oxidized in air to form oxide film.

It becomes silvery white liquid at 29.76℃. Liquid gallium is easily supercooled (that is, it will not solidify when cooled to 0℃). Slightly soluble in mercury, forming gallium amalgam. Gallium can penetrate glass, so it is not suitable for storage in glass containers.

When heated to the melting point, it becomes liquid, and then cooled to 0℃ without solidification. When it changed from liquid to solid, its volume increased by about 3.2%. The hardness is 1.5 ~ 2.5. Gallium is stable in dry air at room temperature. Pure gallium is silvery white, can penetrate glass, has high boiling point and extremely low vapor pressure, about 1500℃.

Main applications

Making semiconductor doping elements of gallium nitride, gallium arsenide, gallium phosphide and germanium; Pure gallium and low melting point alloys can be used as heat exchange media for nuclear reaction; Filling material of high temperature thermometer; Catalysts for diesters in organic reactions. Gallium -68 can emit positrons and can be used for positron tomography. Gallium indium alloy can be used as a substitute for mercury.

The industrial application of gallium is still primitive, although its unique properties may be applied in many aspects. Liquid gallium can be used in high-temperature thermometers and high-temperature manometers because of its wide temperature range and low vapor pressure.

Gallium compounds, especially gallium arsenide, have attracted more and more attention in the electronic industry. There is no accurate world gallium production data, but the output in neighboring areas is only 20 tons/year.

Reference to the above content: Baidu Encyclopedia-Gallium