Bioleaching Gallium From E-Waste: Comparative Techno-Economic Analysis

Abstract Gallium demand is rising, especially for thermally stable and optoelectronic applications, due to the unique properties of GaN and GaAs. However, primary gallium production is limited to the energy-intensive Bayer process. Recycling e-waste, particularly LEDs—the dominant application of Ga—presents a promising pathway for domestic Ga production, with bioleaching as a potential method; however, the cost-effectiveness of this approach requires further analysis. This study conducts a comparative techno-economic assessment of three gallium extraction methods: primary Ga production from Bayer liquor, acid leaching of Ga from waste LEDs (hydro-annealing route), and bioleaching of Ga from waste LEDs. The average total cost (ATC) results show that bioleaching ($576/kg Ga) is more cost-effective than acid leaching ($1321/kg Ga) but still requires further cost reduction to compete with primary production ($368/kg Ga). For average variable cost (AVC), bioleaching ($219/kg Ga) is also more favorable compared to acid leaching ($793/kg Ga). The high costs of acid leaching are primarily attributed to leaching reagents and electricity consumption, which account for over 60% of direct costs, while bioleaching incurs higher costs due to the extensive reactor usage required (57 reactors). Reducing reaction time in bioleaching to minimize reactor demand and sourcing cheaper electricity for acid leaching are identified as effective strategies for further cost reductions. Overall, this analysis highlights bioleaching’s potential viability as a sustainable alternative for Ga recovery, pending optimization of operational costs.