Review of Gallium Extraction Methods: From State-of-the-Art to Sustainable Approaches

Abstract

This article provides an in-depth overview of techniques for extracting gallium from strategic sources, with a focus on industrial residues such as coal fly ash, aluminum industry waste, bauxite residues, and Bayer liquor. Conventional hydrometallurgical processes, including acid leaching and solvent extraction (e.g., with Cyanex 272 or TBP), can achieve gallium recovery rates of over 90% under optimized conditions, thanks to precise control of pH, temperature, and extractant selection. Innovative and more sustainable approaches are emerging, such as the use of supported liquid membranes based on bifunctional ionic liquids, which improve selectivity, reduce reagent consumption, and limit secondary pollution. Optimizing operating parameters (pH, temperature, extractant concentration, sorption conditions) and developing new organic extractants or ion exchange resins are essential to increase the efficiency of gallium recovery, even at very low concentrations. The article highlights major technological challenges, including selectivity with respect to impurities and economic viability on a large scale, while emphasizing the need for innovations to make these processes more sustainable and adapted to growing demand in the electronics and energy sectors.