Abstract
Gallium (Ga) is a critical material for advanced semiconductor manufacturing, high-performance magnetic materials, and low-melting-point alloys. In response to China’s 2023 export restrictions, multiple international initiatives have emerged to develop secure, ex-China Ga supply chains. While many of these efforts focus on recovering Ga from primary alumina sources, i.e., Bayer liquor, recovery from other industrial process streams offers another potentially significant alternative.
This study evaluates two hydrometallurgical flowsheets developed for extracting Ga from an industrial byproduct stream (details withheld). Depending on upstream processing conditions and feed composition, this gallium-bearing stream typically contains 1000–2000 ppm Ga along with high concentrations of zinc (Zn) and iron (Fe). These contaminants must be selectively removed to produce an enriched Ga intermediate that is suitable for downstream processing at the Ga recycling facility of Neo Performance Materials in Peterborough, ON. To avoid the high CAPEX burden of solvent extraction technology, hydrometallurgical processing via successive selective precipitation and leaching steps using oxalic acid as a key reagent was investigated.
This paper compares two process design variations, highlighting the trade-offs between simplicity, recovery efficiency, and product quality, and provides guidance on selecting the optimal flowsheet based on feed composition and operational objectives. The first flowsheet variant reported here consists of a simple five-stage process based on sequential precipitation and leaching, achieving an overall Ga recovery of 54.6% and producing a final metal hydroxide intermediate with an average of 11.8 wt.% Ga(OH)₃. The second flowsheet incorporates an additional step to recover the lost Ga via selective leaching of an oxalate salt resulting from the first selective precipitation step. This additional unit operation recovered 67.7% of the Ga loss, improving the overall Ga recovery to 72.2% and enhancing product quality to 12.1 wt.% Ga(OH)3.