Recovery of valuable metals from the hydrochloric leaching solution of reduction smelted metallic alloys from spent lithium‐ion batteries

BACKGOUND The recycling of valuable metals from spent lithium-ion batteries (LIBs) has attracted much attention. This work investigated the recovery of cobalt (Co), nickel (Ni), copper (Cu), iron (Fe) and manganese (Mn) from metallic alloys generated from the reduction smelting of spent LIBs by a hydrometallurgical process. RESULTS The complete leaching conditions for metals from the alloys were optimized as: 2.0 mol L–1 hydrochloric acid (HCl), 5% (v/v) hydrogen peroxide (H2O2) with 30 g L–1 pulp density at 60 °C within 150 min. Metal ions such as Co(II), Ni(II), Cu(II), Fe(III), Mn(II) and silicon [Si(IV)] from HCl leachate were separated sequentially in four steps using solvent extraction and oxidative precipitation. First, Fe(III) was completely extracted over others using 0.5 mol L–1 Di-(2-Ethyl Hexyl) phosphoric acid (D2EHPA). Second, Cu(II) from the Fe(III)-free raffinate was selectively extracted using 0.25 mol L–1 Cyanex301. Fe(III) and Cu(II) were quantitatively stripped from their loaded phases using 50% (v/v) aqua regia. Third, Co(II) from the Fe(III)- and Cu(II)-free raffinate was selectively extracted over Ni(II), Mn(II) and Si(IV) with 0.25 mol L–1 ALi-SCN and stripped with 10% (v/v) ammonia (NH3). Finally, Mn(II) from the raffinate containing Ni(II) and Si(IV) was separated at pH 3 by oxidative precipitation of MnO2 after adding 10% (v/v) sodium hypochlorite (NaClO). Mass balance analysis of the whole process indicated that the recovery and purity percentage of the metal ions were >99.9%. CONCLUSION With its effective and selective performance, the application of this process to real-life recovery of valuable metals from spent LIBs can be considered. © 2021 Society of Chemical Industry (SCI).