Extraction of Rare Earth Elements from Phosphogypsum (Fertilizer Production By-product)

The increasing demand for rare earth elements (REEs), used in technologically advanced products, has sparked the development of novel processes to recover REEs from secondary sources. Phosphogypsum (PG), the main by-product of fertilizer production contains some REEs, so it can be used as a secondary source. The current research focuses on: a thorough characterization analysis; acid leaching process; kinetics of the leaching process; recycling of consumed acid and effect of microwave pre-treatment on the REEs leaching. The results show that the leaching efficiency is controlled by the solubility limit of PG. Systematic leaching experiments using three acids under various operating conditions were performed. The results indicate the best operating conditions are 1.5 M, 80째C, solid-to-liquid ratio of 1/8 and 20 min residence time, but the leaching efficiency using nitric and hydrochloric acids are higher than the sulphuric acid. Furthermore, it was found that microwave pre-treatment improves the leaching efficiency of REEs.M.A.S