Gallium Recovery With Purolite Resins

Gallium is a vital component in advanced electronics, particularly semiconductors and LEDs, making it essential to modern technologies and the energy transition. Its strategic importance has grown due to its use in defense applications and its limited natural availability, often extracted as a byproduct from other extraction processes. As global demand rises and supply chains face geopolitical pressures, gallium’s role as a critical mineral highlights the need for secure, sustainable sourcing.

Gallium minerals are scarce and are typically recovered as a byproduct when mining other metals, notably aluminium from bauxite ores, zinc ores and coal. Secondary sources include red mud (the solid tailings produced when processing bauxite ores) and waste from the electronics industry. The majority of the annual gallium supply is from the processing of bauxite ores.

The Bayer process is the most commonly used method to recover aluminium from bauxite ores. It involves the dissolution of aluminium under highly alkaline conditions. In typical operation, approximately 70% of the gallium in the ore also dissolves together with the aluminium, while the other 30% can be found in the red mud tails.

The Bayer liquor produced during the leaching of bauxite contains approximately 140 to 160 g/L caustic, 40 to 60 g/L aluminium and 100 to 200 mg/L gallium.

The gallium concentration in the liquor builds up over time, due to recycling of the solution within the plant. This may have a detrimental effect on the quality of the final aluminium product, and it is thus desirable to maintain the gallium concentration below a predetermined level. Control may be achieved by periodic bleeding, but the drawback is the loss of valuable reagent.

Removal of the gallium via ion exchange resin offers an attractive alternative. Purolite MTS9100, a special chelating resin with amidoxime functionality, has a strong affinity for gallium from Bayer liquor. Thanks to its excellent affinity for gallium over aluminium, no valuable aluminium is lost during the gallium removal process. The loaded resin is eluted with acid, and the resin can be used for multiple adsorption-desorption cycles.

Advantages of using ion exchange over other technologies include:

• The engineering is mature and well-understood.
• Ion exchange plants are fully automated, requiring minimal operator interference.
• Ion exchange resins are stable and will not contaminate downstream processes.
• Decreased operational hazard.