YTTRIUM RECOVERY: A SELECTIVE LEACHING STRATEGY FROM FUSED XENOTIME

Abstract

This research investigates a selective leaching strategy aimed at efficient recovery of yttrium (Y) from fused xenotime in response to the increasing demand for this essential rare earth element (REE) in various high-tech applications. The development of selective leaching strategies is vital for the sustainable and economically viable production of Y. The proposed research adopts a hydrometallurgical approach, utilizing selective leaching to recover Y from fused xenotime while minimizing the dissolution of other matrix components, thereby simplifying separation processes. The leaching process requires careful control of several factors, including the selection of leaching agents (hydrochloric acid (HCl), nitric acid (HNO₃), sulfuric acid (H₂SO₄), and acetic acid), acid concentration, duration, temperature, and solid-to-liquid ratio, to optimize the recovery and selectivity of Y. The fused xenotime and the leachates were analyzed using X-ray fluorescent (XRF) techniques to determine the elements present in the samples. Experiments were conducted at room temperature for one hour with varying molarities of leaching agents; the maximum recovery for Y was found to be 79%, 61%, 58%, and 36% for leaching with 4 M HNO₃, 2 M HCl, 3 M acetic acid, and 1 M H₂SO₄, respectively. However, uranium (U) began to appear in the leachate at low concentrations (0.2 M) of H₂SO₄ and acetic acid and at 1.5 M of HNO₃ and HCl. Additionally, thorium (Th) began to be detected in the leachate after using 0.5 M H₂SO₄, 2 M acetic acid, 2 M HNO₃, and 6 M HCl. Therefore, it is recommended to use 1.5 M HNO₃ for leaching the fused xenotime, as this concentration can effectively prevent the dissolution of U and Th while still achieving a high recovery of Y (66%). Following the selective leaching stage, solvent extraction techniques can be utilized to further purify the Y-rich leachate and eliminate any residual contaminating metal ions that may have co-dissolved during the leaching process.