Microwave‐assisted leaching of rare earth elements (Y and Eu) from waste cathode ray tube phosphor

Abstract

BACKGROUND Phosphor in discarded cathode ray tube (CRT) contained valuable metals, yttrium (Y) and europium (Eu), which are categorized as technology‐critical elements (TCEs) in terms of their supply risk and importance in emerging technologies. Microwave‐assisted leaching was applied to recover Y and Eu from waste CRT with sulfuric acid (H2SO4) solution as the leaching agent in the current study. It is aimed to develop an alternative leaching method of valuable metals from waste CRT phosphor. RESULTS The effects of microwave power and acid concentration on leaching efficiency of Y and Eu were investigated. Shrinking‐core model could describe the leaching kinetics of Y and Eu well and it was controlled by chemical reaction and diffusion through the product layer. Higher leaching efficiency was found when microwave power increased from 200 to 600 W, and was also found as acid concentration increased from 0.5 to 2 mol L−1. Leaching efficiency of Y and Eu were 78.07% and 100%, respectively, for Y and Eu within 60 min at microwave power of 400 W, using 2 mol L−1 of H2SO4 at 10 g L−1 of solid to liquid ratio. Compared with conventional leaching, microwave‐assisted leaching is an alternative technology that could shorten reaction time significantly. CONCLUSIONS The concentration of acid and microwave power affected microwave‐assisted leaching of Y and Eu from waste CRT phosphor. Microwave‐assisted leaching could be an alternative process for rare earth elements recovery. © 2019 Society of Chemical Industry

Microwave-assisted method investigation for the selective and enhanced leaching of manganese from low-grade pyrolusite using pyrite as the reducing agent

“…1. The dissolution of hydrogen ions will increase the impact and contact to metal minerals [41,42], thus accelerating the leaching of manganese ions. The peak value for microwave-assisted leaching rate (95.07%) was much higher than that of conventional heating leaching (75.08%) under the same experimental condition.…”

Efficiency and sustainable leaching process of manganese from pyrolusite-pyrite mixture in sulfuric acid systems enhanced by microwave heating

“…It can be seen that microwave heating can obviously reduce the amount of pyrite (at least 20%) and improve the leaching efficiency of manganese. The reason is that the strong convection of the solution induced by microwave electromagnetic fields increases the collision contact between magnetic ions or ion groups in the solution, which speeds up the occurrence of the reaction [37,38]. However, it can be seen in the figure that when the amount of reducing agent is more than 10:2, the leaching rate under microwave radiation increases slowly, and the use of reducing agent will also lead to increased cost and the production of sulfur element in the side reaction：…”

Closed-vessel microwave leaching of valuable metals from spent lithium-ion batteries (LIBs) using dual-function leaching agent: Ascorbic acid

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