Comparative study of tantalite dissolution using different fluoride salts as fluxes

Six different fluoride salts, NH4F·HF, KF, KF·HF, CaF2, NaF and HF·NaF, were evaluated as fluxes in the fusion dissolution of Ta/Nb containing minerals, and compared with the commercially employed HF dissolution. The cold fusion products were dissolved in dilute H2SO4 for both the dissolution and matrix matching purposes. Analytical results indicated that the KF, KF·HF and NH4F·HF dissolution procedures were the most effective for dissolving and recovering the main elements from the tantalite mineral. CaF2, NaF and NaF·HF yielded the lowest recoveries of Ta and Nb from the tantalite mineral sample under study. This comparative study indicated that the dissolution and separation of Ta and Nb from one another and from other elements in minerals depended heavily on fluoride concentration, acidity as well as temperature for the formation of the metal–halogen complexes. ution of the minerals using KF·HF and NH4F·HF as fluxes are recommended as alternatives to HF dissolution due lower energy demands, elemental recoveries, cost, separation efficiency and ease of the dissolution step.