Fractional and simultaneous precipitation: recovering critical metals from multicomponent solutions

Abstract

This study explores fractional and simultaneous precipitation methods to recover metals from a synthetic solution containing the major components from lithium-ion battery recycling leachates: Co, Ni, Mn, Li, and H2SO4. Thermodynamic simulations analyzed the behavior of the metal-bearing solutions during hydroxide precipitation to guide process design. The fractional precipitation process was divided into three steps: pH-adjustment (D1), Co and Ni recovery (D2), and Mn recovery (D3). D2 achieved 89.7% Ni and 76.8% Co recovery; alongside Mn and Li were also removed (15% and 25% respectively). D3 showed mainly Mn recovery (68%) along with 18.7% Co and 7.3% Ni. Simultaneous precipitation resulted in over 99.7% recovery of Co, Ni, and Mn, with a small amount of Li (15%) being recovered from the solution. Na removal from the solution was observed across all experiments. X-ray diffraction analysis revealed that the phases formed were distinct from the predictions. Regardless of the presence of NH4OH as a chelating agent in solution, a mixed nickel-cobalt-manganese oxide could be obtained after calcination. This approach offers a potentially less laborious method for recovering metals in products relevant to cathode precursors in a single step from recycling leachate.