Novel Technology for the Removal of Fe and Al from Spent Li-Ion Battery Leaching Solutions by a Precipitation–Complexation Process

The conventional neutralization method for removing impurities Fe(III) and Al(III) from spent Li-ion battery (LIB) leaching solutions has encountered problems of low impurity removal efficiency or high loss of valuable metals. In this study, highly selective and effective separation of Fe(III) and Al(III) from spent LIB leaching solutions was achieved by the precipitation–complexation technology. It was found that almost all Fe(III) together with most of the Al(III) could be removed by preferential precipitation using NaHCO3 neutralization under an equilibrium pH of 3.3 at 95 °C. Phytic acid, as a selectively complexing agent, was then introduced to completely remove the residual Al(III) from Fe-removed solutions with an Al/PA molar ratio of 3:1 at 60 °C. As a result, more than 99.5% Fe(III) and 97.08% Al(III) could be removed from the actual solutions, with a total loss of Ni, Co, Mn, and Li of only 1.1%. Furthermore, the obtained Al-phytates could be decomposed to form Al(PO3)3 products at 1000 °C. The whole process not only realized the efficient removal of Al(III) and Fe(III) at low pH with minimal loss of Ni, Co, Mn, and Li but also reduced the emission of wastes and utilized the Al resources.