A recovery strategy of Sm, Co for waste SmCo magnets by fatty acid based ionic liquids

Cleaner and lower-cost recovery and separation of samarium(III) and cobalt(II) from waste SmCo magnets can effectively alleviate supply risks of the strategic metals. Based on this goal, a family of renewable, low-cost, biocompatible, non-toxic fatty acid-based ionic liquids (FAILs), including [N1888][DA], [N1888][LA] and [N1888][PA] were synthesized and developed for the separation of Sm(III)/Co(II) from samarium-cobalt simulated solution. The effect factors, i.e. equilibrium time, FAIL molar concentration, salting-out agent concentration and initial pH of aqueous solution were investigated. The extraction mechanism was proposed to be ion association by slope analysis and FT-IR. Under the optimized extraction conditions, a higher purity CoCl 2 (99.5%) product was obtained by a simple extraction-stripping-washing process with the consumption of Na 2 C 2 O 4 and NH 3 ·H 2 O. The produced salty wastewater with lower concentration from the process could be recycled. Sm 2 O 3 with a purity of 99% were obtained by roasting the Sm 2 (C 2 O 4 ) 3 at 800 °C for two hours. The whole process was simple and sustainable, illustrating its potential for industrial applications.