Extraction of Rare Earth Elements from Phosphogypsum Using Mineral Acids: Process Development and Mechanistic Investigation

• DOI: 10.1021/acs.iecr.1c03576
• Publication Date: 2021-12-14T14:34:16Z
• Authors: Sicheng Li; Monu Malik; Gisele Azimi
• Keywords: Phosphogypsum; Neodymium; Dysprosium; Hydrochloric acid; Nitric acid

A hydrometallurgical process is developed to leach yttrium, neodymium, and dysprosium from phosphogypsum using three mineral acids, namely, nitric acid, hydrochloric sulfuric acid over a wide range of conditions. Hydrochloric selected as the best leachant, resulting in 94.6% neodymium 86.1% leaching efficiency under optimum operating conditions 45 °C, 2.5 M, 29.8 mL/g L/S ratio. systematic investigation statistical analyses empirical modeling was performed determine leachant that result high rare earth element (REE) reported literature. Thorough characterization techniques, thermodynamic modeling, kinetic analysis are utilized elucidate mechanism. The results indicate highly correlated with solubility. occurrence modes elements determined time-of-flight secondary-ion mass spectrometry (ToF-SIMS), which shows earths present both isomorphous Ca2+ substitutions separate phases such oxides sulfates trapped inside crystal. Hence, achieving yield requires destruction lattice through attack dissolution.