Recovery of Y and Eu from waste CRT phosphor using closed-vessel microwave leaching

Abstract

• Closed-vessel microwave is effective for Y and Eu leaching from CRT phosphor. • It is energy-efficient with total energy requirement of 456.7 kJ (217 W) within 30 min. • 86.67% of Y and 100% of Eu were leached out using 2 M of H 2 SO 4 at 125 °C. • The recovery efficiency was 96.9% for Y and 86.6% for Eu as (Y 0.95 Eu 0.05 ) 2 O 3. Yttrium (Y) and europium (Eu) are critical rare earth elements (REEs) due to their high supply risk and importance for clean energy technologies. Their presence in electronic waste (e-waste) provides great potential of recovery and reuse. This study focused on recovery process of Y and Eu from waste cathode ray tube (CRT) phosphor using closed-vessel microwave leaching, followed by precipitation by oxalic acid and calcination. The effects of acid concentration and energy efficiency of closed-vessel microwave leaching were investigated. Leaching efficiency of Y and Eu was 86.67% and 100%, respectively, at the optimum operation conditions (10 g/L of solid concentration, 2 mol·L −1 of H 2 SO 4 solution, 125 °C, 30 min of leaching time). When comparing with conventional heating process, closed-vessel microwave leaching process proved to be rapid, effective and efficient for Y and Eu recovery from waste CRT phosphor. Oxalic acid precipitation and calcination recovered 96.9 ± 0.26% of Y and 86.6 ± 0.76% of Eu as the crystallized product of (Y 0.95 Eu 0.05 ) 2 O 3 .