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Highlights • IL-ME systems reveal improvements in metal extraction and separation. • IL acts as a diluent, synergist or cation precursor supplier in IL-ME systems. • IL-ME systems with different composition show different extraction behaviors. • ABC-BILs synthesized by acid/base coupling way show superior extraction efficiency. • Stripping from IL-ME systems is easy while regeneration is still in troubles. Abstract Ionic liquids (ILs), also termed "green" and "designer" solvents, have been proposed as promising solvents for diverse applications. This review focused on the improvements brought about by mixing ILs with molecular extractants (MEs) in solvent extraction processes for metal extraction and separation. Mixture systems consisting of IL with ME were collected and discussed on the basis of the functional cations of ILs, such as ammonium-type, phosphonium-type and imidazolium-type ILs. IL was found to play a role as an active component by generating a new acid/base coupling bi-functional ionic liquid (ABC-BIL) or as a diluent when combined with acidic or neutral ME in IL-ME mixture systems. The merits and drawbacks of IL-ME systems were reviewed and compared with conventional ME systems alone in terms of the preparation route, separation behavior and extraction mechanism. Further approaches to the improvement of IL-ME systems, such as extraction enhancement, stripping and regeneration, were discussed. The summaries and comparisons made in the present review may indicate future directions for the development and application of ILs in metal solvent extraction technology. [ABSTRACT FROM AUTHOR]

A hydrometallurgical process was developed to recover Co(II) and Ni(II) from the chloride leach liquor of laterite ore. Most of Co(II) and Ni(II) together with a small amount of Al(III) were selectively extracted over other elements by Cyanex 301 from the feed solution at pH 1 which contained Co(II), Ni(II), Al(III), Ca(II), Mg(II) and Mn(II). From the loaded Cyanex 301, Co(II) and Al(III) were selectively stripped by 3 M HCl solution, and then Ni(II) was completely stripped by 10 M HCl solution. The McCabe-Thiele plots for the extraction and stripping isotherms were constructed. Batch simulation experiments for the counter-current extraction and stripping indicated that the recovery percentage of Co(II) and Ni(II) was 92.6 and 95.7%, respectively. Moreover, the purity of Ni(II) in the stripping solution was reached 99.5%. A process flowsheet for the recovery of Co(II) and Ni(II) from the laterite leach liquor was proposed. [ABSTRACT FROM AUTHOR]

Hafnium can be selectively extracted over zirconium from strong sulfuric acid solutions by D2EHPA or PC 88A. Solvent extraction experiments have been performed to identify the reaction of Hf from strong sulfuric acid solutions (1 to 7 M) by these two extractants. Hafnium extraction was gradually decreased and then increased again with the increase of sulfuric acid concentration. By applying a slope method, the extracted Hf species was proposed to be HfA4·(HA)2by D2EHPA and Hf(HSO4)2A2·(HA)2by PC 88A, respectively. This difference in the nature of the extracted species was verified by FT-IR spectra. [ABSTRACT FROM PUBLISHER]

The extraction and separation behavior of Zr and Hf was investigated from sulfuric acid solutions by using amine-based extractants. In the sulfuric acid concentration range of 0.1–3 M, zirconium was selectively extracted over hafnium by using amines. Among the tested amines (Aliquat 336, Alamine 300, Alamine 308, Alamine 336, and TEHA), Alamine 308 led to the highest separation factor of 12.4 at 0.5 M H 2 SO 4 solution. The extraction behavior of Zr and Hf in sulfate medium by amines was compared with that by acidic extractants in terms of solvent extraction reaction and complex formation. Quantitative stripping of both metals from the loaded Alamine 308 was achieved by using low concentration of Na 2 CO 3 solution. [ABSTRACT FROM AUTHOR]