Gallium metallurgy

Gallium is an element with properties similar to those of aluminum. It is a by-product of the Bayer process for treating bauxite. Small quantities also come from zinc metallurgy residues.

Gallium is recovered by hydrometallurgy from :

• Bayer liqueurs. It is produced by various processes, such as :

  • precipitation by controlled carbonation,

    • case-hardening,

    • solvent extraction,

    • resins,

    • electrolysis ;

• zinciferous residues, after leaching. It is extracted by processes based on solvent extraction and resin separation.

The main gallium compounds, mainly used in electronics, are :

• gallium arsenide, GaAs, which can convert electricity into light (light-emitting diodes, LEDs) and, conversely, sunlight into electricity (solar panels). It is also used in integrated circuits;

• gallium nitride, GaN, used to manufacture LEDs and laser diodes (also used in integrated circuits).

Annual world production of primary gallium was around 95 tonnes in 2008. France, the United States and Japan are the main refiners. Recycling, from manufacturing offcuts and electronic uses, is a significant source of gallium.

The gallium market is closely linked to the demand for GaAs and GaN in optoelectronics. There are no satisfactory substitutes for gallium.