Solvent extraction technology for the separation and purification of niobium and tantalum: A review

Tantalum and Niobium Selective Extraction by Alkyl-Acetophenone

“…In this process, several solvents were studied for the extraction of Ta and Nb, namely bis-(2-ethylhexyl) phosphoric acid (DEHP) [10], trioctyl-phosphine oxide (TOPO) [11], dibenzo-18-crown-6 (B18C6) [12], tri-n-butyl phosphate (TBP) [13], ketones such as diisopropyl ketone, diisopropyl butyl ketone, n-butyl ethyl ketone [14,15], methyl isobutyl ketone (MIBK) [16] and cyclohexanone [13], amides such as dimethyl heptyl acetamide [17] and bis-2-ethylhexylacetamide [18], secondary and tertiary amines [19,20] such as tri-n-octylamine [21], Alamine™ 336 and tri-n-decylamine, quaternary ammonium salts [10], such as tri-n-octylmethylammonium, tri-n-octylpropylammonium and ethyl benzyl dimethylammonium chlorides, tetrahexylammonium iodide, tri-n-octylmethylammonium hydroxide, bis-tri-sulfate n-octylmethylammonium, bistetrahexylammonium sulfate and tri-n-octylmethylammonium nitrate, as well as long chain alcohols, such as 1-octanol, 2-octanol [9,15] and isoamyl alcohol [5,17]. Among these solvents, only MIBK, TBP, cyclohexanone and 2-octanol are used industrially.…”

“…Actually, MIBK, which is the most widely used in the world, has a relatively high solubility in water (of the order of 2 wt% weight percent) [5], a high volatility and a low flash point (14 • C). Therefore, MIBK displays safety problems since the mixers-settlers and the pumps that are used to recover Ta and Nb on an industrial scale must be able to operate in an explosive atmosphere.…”

“…TBP, which is more used in Russia and India, has a relatively low solubility in water (0.6 wt%) and a high flash point (193 • C) [5]. However, it is unstable in highly concentrated acidic solutions, especially in the presence of hydrofluoric acid and its hydrolysis products, such as phosphorus (V) acids, which has the consequence of decreasing the purity of Ta and Nb obtained [22].…”

“…This makes its use less hazardous than that of the MIBK. Nevertheless, it presents the double drawback of having a relatively high viscosity (8 MPa·s) and a low extraction performance for Ta and Nb [5].…”

Molecular modelling of tantalum in an aqueous phase

“…Solvent extraction (SX) is used for the separation and purification of various metals, including copper (Bidari, Irannejad, and Gharabaghi, 2013), nickel (Noori et al, 2014), iron (Li et al, 2011), platinum group metals (PGMs) (Kumar et al, 2008), zirconium (Biswas and Hayat, 2002), hafnium (Lee, Banda, and Min, 2015), and Ta, and Nb (Zhu and Cheng, 2011). Ungerer et al (2014) studied the separation of Ta and Nb (in the form of MF 5 ) by SX using safer and more environmentally friendly chemicals and techniques.…”