Liquid-liquid extraction and separation of copper(II) and nickel(II) using LIX®984N

In recent years, the demand for copper and nickel has risen world-wide due to their use in printed circuit boards, batteries, application in marine alloys (due to excellent resistance to corrosion by seawater), and a wide range applications in day-to-day life (Doebrich, 2009). Increasing demand for these metals is leading to rapid depletion of high-grade resources. Alternative sources, such as ewastes, lithium ion batteries, copper converter slags, polymetallic nodules etc., are needed to meet future demand. The copper-nickel system was chosen for this investigation because some slags (copper converter slag, anode slag of Hindustan Copper, and by-products of UCIL Jaduguda) contain high amounts of both copper and nickel. Hydrometallurgical routes play a vital role in the processing of these secondary sources. Solvent extraction is a well-established technique for the removal and separation of various metal ions. About 30% of the world’s copper is produced by acid leaching, solvent extraction (SX), and electrowinning (Cox, 2004). Hydroxyoximes are well-known extractants which are widely used for copper extraction from dilute acidic sulphate solutions (Ritcey and Ashbrook, 1979; Szymanowski, 1993; Szymanowski, 1990). Only two classes of extractants, i.e. ketoximes and aldoximes, have gained commercial acceptance as reagents for solvent extraction from acidic leach solutions. Oxime mixtures have been shown to be advantageous over the individual group ketoximes and aldoximes (Kordosky et al., 1985). Rodriguez et al. (1997) studied the extraction of several metal ions using LIX® 984, which is a 1:1 volume blend of LIX® 860 and LIX® 84 in n-heptane. They reported the equilibrium constant values for the extraction reactions, and proposed the species extracted into the organic phase. Fouad (2007) studied the extraction equilibria of copper(II) with Cyanex 301, LIX® 984N, and mixtures of these two reagents. The enthalpy change (ΔH) of the individual extractants and their mixtures was determined and the endothermic process elucicated. Kul and Cetinkaya (2009) developed a complete hydrometallurgical process on a laboratory scale for recovering copper from copper electroplating second rinse bath liquor containing 2.5 g/L copper using LIX® 984N-C in kerosene. Recovery of copper from waste printed circuit boards (PCBs) by nitric acid leaching and extraction using LIX® 984N was reported by Long Le et al. (2011). They first studied the co-extraction of other metals (Pb, Zn, Fe, and Ni) from a diluted leach liquor with 10% LIX® 984N, and found that the co-extraction of these metals was negligible up to pH 1.9, except for iron (6.4%). Based on these results, they used 50% LIX® Liquid-liquid extraction and separation of copper(II) and nickel(II) using LIX®984N