Extraction of iron(III) at macro-level concentrations using TBP, MIBK and their mixtures

Iron(III) extraction has been carried out at about 1 molar concentration from hydrochloric acid solutions using tri-n-butyl phosphate, methyl-iso-butyl ketone and their mixtures as solvents, Extraction increases with increasing concentration of both acid and solvent. The species extracted to the organic phase appears to be HFeCl4 with 3 mole of the solvent. A solvent mixture consisting of 70 vol.% TBP and 30 vol.% MIBK was found suitable to achieve faster phase separation with no third phase formation. The two solvents, when used together, were also found to exert a synergistic effect on iron extraction. Extraction and stripping isotherms were obtained with the above solvent mixture for a typical solution containing 56.4 kg m(-3) of iron and 73.7 kg m(-3) of hydrochloric acid. Greater than 99.4% extraction and 100% stripping efficiencies of the metal have been achieved in 5 stages.