Recovery of P from Decomposed Monazite by Fusion Followed by Separation of REEs, Th and U from Chloride Leach Liquor of Monazite Using Solvent Extraction and Precipitation Techniques

Monazite sand is a significant phosphate source of rare earth elements (REEs), thorium (Th), phosphorous (P) with a small amount of uranium (U). REEs are economically significant because of their numerous applications in high technology and various applications. Th and U are crucial elements in nuclear industries, while P has important application as a fertilizer in agriculture. Initially, decomposition of monazite by using sodium hydroxide (NaOH) fusion resulted in trisodium phosphate (Na3PO4) and a oxides of REEs, Th and U. Recovery of P was achieved through a water leaching process, which efficiently recovered over 85% of the Na3PO4. Oxides of REEs, Th and U were dissolved in hydrochloric acid (HCl) using a specific catalyst to accelerate the dissolution chemical reaction. This resulted in the formation of a solution containing chlorides of REEs, Th and U. Separation of Th was achieved through solvent extraction using DEHPA extractant in a kerosene diluent [10%], which resulted in an extraction of more than 95.84%. After the separation of Th, the separation of REEs was achieved by using oxalic acid precipitation, resulting in a precipitation efficiency of 99.97%. Extraction of U was achieved from the solution by a synergetic effect of temperature and a NaOH solution to adjust the pH value at 7. Efficiency of Precipitation of U had an efficiency of 84.85%. The overall process was efficient and acceptable in recovering the four valuable elements.