Microwave-Assisted Pretreatment for Enhanced Rare Earth Element Recovery from Vietnamese Bastnaesite Ore

Rare earth elements (REEs) are essential for modern technologies, yet their extraction from bastnaesite remains challenging due to its refractory fluorocarbonate structure. Conventional processing methods, such as alkali roasting and acid baking, require high energy input and generate significant chemical waste. This study investigates microwave-assisted pretreatment with alkali additives as an alternative to conventional methods, aiming to improve REE leachability while reducing energy consumption. Bastnaesite concentrate was pretreated with NaOH, Na₂CO₃, and K₂CO₃, under microwave irradiation, followed by hydrochloric acid leaching. Among the tested additives, NaOH proves most effective, achieving nearly complete REE recovery due to its lower decomposition temperature. The process was optimized using the design of experiment methodology, revealing that HCl concentration, solid-to-liquid ratio, and NaOH-to-bastnaesite ratio significantly influence leaching efficiency. Under optimal conditions, 98.4% REE recovery was successfully achieved. This research demonstrates the potential of microwave-assisted pretreatment in enhancing REE extraction efficiency while minimizing environmental impact.