Abstract
The growing demand for refractory rare metals, such as niobium, necessitates the development of efficient extraction methods from alternative sources, including industrial waste from metallurgical plants enriched with niobium and zirconium. This study investigates the solvent extraction of niobium from a fluoride-sulfuric acid solution obtained by leaching rare-metal-containing waste from titanium-magnesium production. The efficiency of niobium recovery using a trialkyl phosphine oxide-based extractant (Cyanex 923) was evaluated, with attention to extraction selectivity and phase behavior. Spectral analysis of the organic phase confirmed the formation of niobium and zirconium fluorocomplexes such as [NbOF5]�?, [NbOF4]?, [ZrF7]�?, and [ZrF6]�?. Re-extraction using ammonium fluoride was found to be effective even at low concentrations. Subsequent precipitation using ammonium hydroxide at pH 9�10 enabled selective recovery of niobium as Nb(OH)5, which was then calcined to produce niobium pentoxide (Nb2O5). The final product was characterized by X-ray diffraction, fluorescence, and electron microprobe analysis, revealing a crystalline phase dominated by niobium oxide. The results demonstrate the feasibility of niobium recovery from industrial waste and provide data for optimizing hydrometallurgical processes for processing secondary resources containing rare metals.