Factors and challenges in the recovery of niobium and tantalum from mineral deposits, recommendations for future development – A review

Abstract

The separation and extraction of Nb/Ta metallic elements from mineral deposits have become challenging, involving complex and complicated separation process routes from the rest of the gangues/impurity elements composed in the ore mineral or deposit and from the value metals/elements themselves. Due to the presence of numerous impurities such as: refractory or metal oxides, rare earth (REE) and radioactive elements, and hence the complexity of the metal extraction process; Nb2O5/Ta2O5 are extracted hydrometallurgically from mineral deposits using hydrofluoric acid (HF) or a combination of HF and H2SO4 mineral acid dissolutions prior to extraction and recovery. Howbeit, HF’s high volatile, corrosive and toxic nature, as well as high chemical/reagent consumption, eco unfriendliness and waste generation of fluorides; contribute to Nb/Ta extraction difficulty, complexity and high equipment maintenance and/or operational cost. Also, the dangerous and non-biodegradable nature of HF to the ecosystem, health damage on inhalation of HF vapours, use of high cost corrosion resistant equipment and large complex number of operations are major constraints. As a result of these challenges, and thus the low Nb/Ta yield recovery and purity, as well as their numerous industrial applications in engineering/technology, the demand of Nb/Ta has consistently become somewhat higher than the supply. On this premise, there is need to develop fluoride-free mineral decomposition media under mild conditions as substitute/alternative extraction procedure for Nb/Ta recovery. Serious attention should also be given to mineral characterization techniques and to optimization procedures for optimum process parameters/conditions in mineral concentration and Nb/Ta extraction. This review study is therefore based on the factors/challenges relating to the beneficiation, Nb/Ta extraction and recovery from mineral deposits and recommendations for future trend/advancement.