Green Electrochemical Leaching: A Roasting-Free and Acid-Saving Route for REEs Recovery from Coal Slime

With the escalating global demand for rare earth elements (REEs), developing sustainable recovery pathways from secondary resources is imperative. Herein, a green electrochemical leaching route was developed as a roasting-free and acid-saving alternative to conventional thermochemical methods for recovering REEs from coal slime. Phase analysis revealed that the REEs were primarily hosted in carbonate/phosphate minerals. In the leaching experiment, a leaching efficiency as high as 99.3% was achieved for the representative rare earth element neodymium (Nd) after 24   h of treatment under the conditions of 1.5   V applied voltage, 0.3   mol/L H 2 SO 4 , and 2   wt% H 2 O 2 . Mechanistic investigations indicated that the applied electric field drives an in-situ electro-Fenton process by continuously regenerating Fe 2+ from inherent coal slime iron. The resulting ·OH radicals disrupt REE-bearing mineral lattices, working synergistically with protons to facilitate rapid dissolution. By transitioning from a chemical-intensive process to an efficient, electrically-driven mineral liberation strategy, this study offers a scalable, low-carbon engineering pathway for the sustainable valorization of secondary REE resources.