Hydrometallurgical, pyrometallurgical and electrometallurgical extraction of niobium and tantalum: an overview.

This review paper focuses on the extraction processes of niobium and tantalum, detailing hydrometallurgical, pyrometallurgical, and electrometallurgical methods used to recover these metals from their ores. Hydrometallurgical techniques involve aqueous leaching, solvent extraction, and precipitation, offering high selectivity and lower environmental impact but requiring careful chemical management. Pyrometallurgical methods use high-temperature treatments such as calcination, roasting, and smelting, suitable for large-scale and fast processing but associated with high energy consumption and emissions. Electrometallurgical processes, including electrowinning and electrorefining, utilize electrolysis in aqueous or molten salt media to produce high-purity metals, though they demand significant energy and complex equipment. The paper also addresses environmental concerns linked to each method and highlights recent developments aimed at improving efficiency and sustainability, such as the use of ionic liquids, deep eutectic solvents, greener reagents, and advanced heating technologies.