Extraction of tantalum, niobium, and antimony fluorides

Niobium and tantalum recovery from the primary source and from tin slag, an industrial challenge: A review

“…The liquid–liquid extraction is an efficient way to separate Nb from Ta because of the ions generated in fluoride processes, TaF 7 2− /NbOF5 −2 . [ 21 ] This fluor complex structure presents a high negative charge, and it should be considered during the extraction process [ 52 ] ; they also present different solubility in the organic phases used, making them available for selective crystallization. [ 21 ]…”

“…Maiorov [ 52 ] explored the influences of HF and H 2 SO 4 in order to separate Ta, Nb, and Sb from a synthetic solution that simulates the fluoride liquor outcoming from the coltan fluoride leaching. It was observed that Ta has the higher recovery factor and Nb has the lesser.…”

“…[22] To be considered high purity Nb and Ta after the extraction process, the material should present impurities not higher than 10 pm-40 ppm. [52]…”

“…The liquid-liquid extraction is an efficient way to separate Nb from Ta because of the ions generated in fluoride processes, TaF 7 2À /NbOF5 À2 . [21] This fluor complex structure presents a high negative charge, and it should be considered during the extraction process [52] ; they also present different solubility in the organic phases used, making them available for selective crystallization. [21] This extraction was developed in the 1960s by applying two organic solvents, MIBK and tributyl phosphate (TBP), in contact with an aqueous phase of Nb and Ta diluted in HF-H 2 SO 4 .…”

“…[18,20] Ta and Nb can be coextracted or separated controlling the pH, as that way the most common solvent is MIBK due to its high selectivity; however, it requires higher control due its volatility and loss to the raffinate if its concentration is over 1.7% (w/w). [18] Maiorov [52] explored the influences of HF and H 2 SO 4 in order to separate Ta, Nb, and Sb from a synthetic solution that simulates the fluoride liquor outcoming from the coltan fluoride leaching. It was observed that Ta has the higher recovery factor and Nb has the lesser.…”