Extractive metallurgy of columbite-tantalite ore: A detailed review

The increased demand of metals such as tantalum (Ta) and niobium (Nb) reflect the on-going development in modern science, engineering and technology. The extraction of these two metals from columbite-tantalite ore is based on generic extractive metallurgy. However, the upstream purification of ore and downstream extraction of Ta and Nb remain a particular challenge. Commercial and innovative pyrometallurgical (direct reduction), hydrometallurgical (pure leaching) and pyro-hydrometallurgical (NH4HF2 or alkali fusion followed by leaching) technologies for the purification and separation of Ta and Nb from columbite-tantalite ore are reviewed in this paper. The selective recovery of Ta and Nb from the leachates using various extractants and different stripping processes are compared. The reduction, or even elimination, of HF as reagent to extract Ta and Nb in the ore beneficiation processes is vital for a greener technology in the mining industry, and might be effected by the novel processes discussed in this article.