Extraction of iron(III) from acidic chloride solutions by Cyanex 923

The extraction of iron(III) from hydrochloric acid solutions has been investigated using Cyanex 923 (TRPO) in xylene. Extraction increases with increasing concentration of both hydrochloric acid and extractant. The species extracted into the organic phase appears to be HFeCl4 with 2 mol of the solvent. The extraction behaviour of iron(III) was compared with other metal ions: titanium(IV), chromium(VI) and vanadium(V), which are associated with iron in ilmenite leach liquors. The stripping percentage of iron(III) with hydrochloric acid from the loaded Cyanex 923 was found to decrease with an increase in acid concentration. The 100% stripping efficiency of iron(III) can be achieved with 0.4-M hydrochloric acid in two counter-current stages at an aqueous:organic phase ratio of 3:1. The nature of the diluent on the extraction of iron(III) with Cyanex 923 has also been studied and correlated with dielectric constants. (C) 1998 Elsevier Science B.V. All rights reserved.