Use of ferric salt solutions as leaching agents of Co, Ni, Cu, Fe, and Mn from metallic alloys of spent lithium-ion batteries and separation of iron from the leaching solution

Abstract

Smelting reduction of spent lithium-ion batteries (LIBs) results in metallic alloys containing Co, Ni, Cu, Fe, and Mn. In order to recover the valuable metals contained in the metallic alloys, they need to be dissolved. In this work, the mixture of Fe2(SO4)3 and FeSO4, single Fe2(SO4) and FeCl3 solutions were used as leaching agents and the effects of parameters such as ferric salt concentration, reaction temperature and time, and pulp density on the leaching of the metals were studied. The difference in the leaching percentage of the metals due to the type of the ferric solutions was insignificant. In these leaching systems, ferric and hydrogen ions act as oxidants and sulfate/bisulfate and chloride anions act as ligands. Optimal conditions for the complete leaching of metals by single ferric solutions were 0.35 mol/L Fe2(SO4)3 or 0.7 mol/L FeCl3 at 12.5 g/L pulp density for 60 min at 22oC. The addition of H2O2 to the leaching solution for the oxidation of Fe(II) to Fe(III) enhanced the selective extraction of iron over Co(II), Ni(II), Cu(II), Mn(II), and Si(IV) by D2EHPA. Stripping of iron from the loaded D2EHPA with aqua regia resulted in a pure iron solution. Compared to HCl and H2SO4 solutions, the use of single ferric solution showed some advantages such as fast reaction kinetics at 22?C and the reduction in the dosage of acids and oxidants.