Improving the lithium recovery using leached beta-spodumene residues processed by magnetic nanohydrometallurgy

[Display omitted] •Leached spodumene residues can be purified using superparamagnetic nanoparticles.•Magnetic extraction leads to pure β-spodumene for lithium capture.•Magnetic nanohydrometallurgy improves the lithium capture from 68.5 to 95% yield.•Lithium ions can be recycled using magnetic nanohydrometallurgy. World's largest production of lithium is mostly performed through the acid lixiviation of β-spodumene mineral (LiβS), LiAlSi2O6. The process generates large amounts of leached spodumene residues (LSR) containing the protonated form, here denoted HβS, among the several impurities from the system. HβS preserves the structure of LiβS, and can be used for capturing and recycling lithium ions. In this work, a nanotechnological approach, called magnetic nanohydrometallurgy (MNHM), was applied to selectively extract HβS from the leached spodumene residues. Accordingly, maghemite nanoparticles functionalized with diethylenetriamine (MagNP) were employed, because of their great stability and large positive zeta potentials in the protonated form. Such nanoparticles interact strongly with the negatively charged β-spodumene particles, allowing their magnetic separation as MagNP//HβS composites. After releasing the HβS content by an acid treatment, the product was isolated in pure form and used for recovering lithium ions. This material performs with great efficiency, reaching a lithium content of 3.55% in the final composition, corresponding to 95.1% of the theoretical value (3.73%) predicted for this mineral. In comparison with the previously reported values using directly the leached spodumene residues for the capture of lithium ions, a great improvement has been achieved in this work. The MagNP//HβS composite also can be used for lithium ion capture. By increasing the HβS purity, MNHM can promote lithium recycling, in a sustainable way.