Solvent extraction of titanium(IV) from acidic chloride solutions by Cyanex 923

The extraction behaviour of titanium(IV) from hydrochloric acid solutions h as been investigated using Cyanex 923 (TRPO) in xylene as an extractant. Th e effects of the concentration of HCl, H+ and Cl- in the aqueous phase and the extractant concentration in the organic phase were studied. The extract ion of titanium(IV) increases with the total chloride concentration in the aqueous phase, as well as with the extractant concentration in the organic phase. The species extracted into the organic phase appears to be TiCl4 wit h one or two molecules of Cyanex 923. The equilibrium constants of the extr acted complexes have been obtained by non-linear regression analysis, takin g into account complexation of the metal ion with inorganic ligands in the aqueous phase and all plausible complexes extracted into the organic phase. The effect of the nature of the diluent on the extraction of titanium(IV) with Cyanex 923 has been studied and correlated with dielectric constants. The extraction behaviour of titanium has also been compared with that of ot her metal ions viz. iron(III), chromium(VI) and vanadium(V), which are asso ciated with titanium in ilmenite processing leach liquors and also in waste solutions of TiO2 production. (C) 1999 Published by Elsevier Science B.V. All rights reserved.