Assessment of the effect of acids application during the electrodialytic recovery of lithium from mine tailings

• A 2-compartment electrodialytic reactor was tested for Li + recovery from mine tailings • Inorganic and organic acids (0.1-0.5 mol/L) were coupled with the electro-based technology • Sample suspension and solid sample pre-heat was assessed to improve Li + recovery ratio • A maximum of 29.8% of Li + was recovered from mine tailings with oxalic acid • Li + that electromigrated to the cathode compartment can be further separated Energy transition has been driven by climate change and the need to decarbonize the transport sector. Herein, lithium-ion batteries play a prominent role in transports electrification and renewable energy sources integration, which has been increasing lithium demand worldwide. To alleviate lithium primary resources exploitation, the use of secondary resources of lithium are desirable, considering a circular perspective. Mine tailings are generated in massive volumes, due to low ore grades, and may present contents of lithium-based minerals. Therefore, proper management is required to guarantee the safety of this resource, offering also an opportunity for secondary recovery of critical raw materials, such as lithium. The present work aimed to analyse the potential of the electrodialytic process to recover lithium from mine tailings with lepidolite contents. The addition of inorganic and organic acids was tested, to address the synergy between the electrodialytic process and acids extraction. Pre-heat of the solid suspension and of the solid sample was also considered. Bench scale experiments were conducted considering a two-compartment electrodialytic reactor at 100 mA, with a cation exchange membrane interposed. Eight different acids, at concentrations of 0.1 mol/L and 0.5 mol/L, were tested individually and in mixture, during 3, 4 and 10 days. The highest lithium recovery ratio (29.8%) was obtained for the experiment conducted with oxalic acid at 0.5 mol/L and suspension pre-heated (55 °C) for 24 h. These conditions improved chemical reactivity and the dissolution of lithium minerals.