A review on extractive metallurgy of tantalum and niobium

peer reviewedOn-going technological developments, especially in the field of microelectronics and communication have reflected in concomitant increase in the demand for strategic metals such as tantalum (Ta) and niobium (Nb). The extraction of these two metals from ore deposits and secondary resources is based on the generic extractive metallurgical techniques known from the non-ferrous metals value chains. However, their operational particularities and especially the downstream refining remain a particular challenge. To this end, the existing and emerging processes from the Ta and Nb raw materials preparation and leaching to pure metals elaboration are reviewed. The upstream operations and the downstream extractive metallurgical processes are discussed. The different sub-processes making part of the hydrometallurgical processing of the two metals, including leaching and solvent extraction are described, with their advantages and limitations highlighted. The selective recovery of Ta and Nb from the leachates is most commonly realized by solvent extraction and stripping which are therefore extensively covered. In the same context, the most widely used and promising extractants are compared in the light of their separation efficiency and level of handling hazard