Recovery of Niobium, and Rare Earth Elements from Mineralized Pegmatite of Gabal El-Faliq, South Eastern Desert, Egypt

Abstract This study presents a novel hydrometallurgical strategy for recovering niobium (Nb) and rare earth elements (REEs) from mineralized pegmatite ore at Gabal El-Faliq, Egypt. The ore, containing economically significant concentrations of Nb (0.83%), REEs (2.3%), zirconium (4.3%), and tantalum (0.03%), was processed via optimized sulfatization pug leaching. At 250 °C, 3 h curing time and acid input (1080 g/kg), this method achieved exceptional extraction efficiencies of 91.8% for Nb and 93.3% for REEs surpassing conventional acid agitation leaching by > 15%. Kinetic analysis using the Shrinking Core Model revealed a chemically controlled reaction mechanism (activation energies: 40.2 kJ/mol for Nb, 41.05 kJ/mol for REEs), demonstrating that surface reactions not diffusion governed the leaching kinetics. This insight resolves a key bottleneck in refractory ore processing. Downstream, a fluoride-free solvent extraction process selectively recovered Nb from sulfate leach liquor using Alamine 336/kerosene, achieving 95.8% Nb extraction with minimal REE co-dissolution (< 3.5%). The raffinate underwent oxalic acid precipitation, yielding high-purity REE oxalates (99.3% recovery), which were calcined to RE₂O₃. Final products (Nb₂O₅ and RE₂O₃) were validated by SEM-EDX, confirming industrial-grade purity.