Recovery of gallium from Bayer liquor: A review

摘要

Bayer liquor is the biggest raw material resource for gallium production. Four kinds of methods have been developed to recover gallium from Bayer solutions, including fractional precipitation, electrochemical deposition, solvent extraction, and ion exchange. The fractional precipitation method is based on Al-Ga precipitation with CO_2 and subsequent separation of Al and Ga with lime milk or sodium aluminate solutions. This approach is more environmentally friendly and with low cost, but the process is complicated. The electrochemical method includes both mercury cathode electrolysis and cementation. The electrolysis with mercury cathode has been prohibited in most countries because of high toxicity of mercury. Cementation is an electrochemical process realized by a displacement reaction between gallium and reductants, such as sodium amalgam, aluminum and aluminum-gallium alloy. Solvent extraction is an efficient method and by using Kelex 100 system about 80% of the gallium in Bayer liquor can be extracted.