چكيده به لاتين
Gallium, as a rare and valuable metal, finds applications in advanced industries. Given the global demand and limited resources, optimizing its extraction methods is of particular importance. The Bayer solution is one of the significant sources of gallium. Among the various methods for extracting gallium from Bayer process solutions, the ion exchange method is recognized as the most efficient due to its advantages such as compact process circuit, rapid kinetics, high recovery, and appropriate selectivity of gallium over aluminum and vanadium. In this study, amidoxime TY-CH550 adsorbent was used for gallium adsorption, with experiments conducted in both batch and continuous systems at laboratory and bench scales. In the batch system, operational conditions were optimized using Design Expert software and the response surface methodology (RSM). The results indicated that under optimal conditions, including a temperature of 30°C, a contact time of 200 minutes, a sodium hydroxide concentration of 350 g L⁻¹, and a liquid-to-solid phase ratio of 400 ml g⁻¹, the adsorption process efficiency reached approximately 20%, and the gallium adsorption capacity was 13.1 mg g⁻¹. In the continuous system, experiments were conducted at both the laboratory and bench scales. The Thomas kinetic model exhibited the highest accuracy in matching the experimental results. At the laboratory scale, the optimal conditions were found with an adsorbent column height of 3.5 g and a flow rate of 5 ml min⁻¹. At the bench scale, after the adsorption process, gallium was desorbed and precipitated, resulting in 2.3 g of impure gallium hydroxide. The Thomas model proved to be more consistent with the experimental data in this system as well.
