Selective recovery of rare earth elements (REEs) from spent NiMH batteries by two-stage acid leaching

The current study investigated selective recovery of rare earth elements (REEs) from spent nickel metal hydride (NiMH) batteries using two-stage acid leaching followed by precipitation at acidic pH. The first-stage conventional leaching using 2.5 M of waste phosphoric acid (H3PO4) at 25 °C for 60 min removed 60–100% heavy metals, such as Ni, Co, Zn and Cd, and converted more than 90% REEs into insoluble phosphate precipitates, REE(PO4)....