Optimization by response surface methodology. Application to rare earth elements recovery

This work focuses on the leaching process of rare earth elements (REEs) from phosphor powder (PP) in order to reach optimal conditions of REEs recovery. Investigated PP was characterized in our previous work, after recovering from waste linear tube fluorescent lamps (FLs). Hydrochloric acid effect on leaching efficiency of REEs from PP is studied. Response surface methodology is used to determine the optimum leaching conditions. Obtained results show that, using 24.S% (v/v) HCl at 90°C, 140ml/gL/S ratio and 3h of leaching time, 99% of yttrium is leached out from the studied PP. Due to the highest content of major contaminant (calcium) present in obtained leach liquor, leachant agent (HCl) employed in this study may affect subsequent processes.