A Study on the Separation of Cerium from Rare Earth Precipitates Recovered from Waste NiMH Battery·

Abstract

In order to recover the cerium contained in the spent nickel metal hydride batteries (NiMH battery), the recovered rare earth complex precipitates from NIMH were converted into rare earth hydroxides through ion exchange reaction to react with NaOH aqueous solution at a reaction temperature of 70 °C, for 4 hours. Rare earth hydroxides were oxidized by injecting air at 80 °C for 4 hours to oxidize Ce to Ce. The oxidation rate of cerium was confirmed to be about 25 % through XPS, and the oxidized powder was separated from the rest of the rare earth using the difference in solubility in dilute sulfuric acid. The finally recovered powder has a crystal phase of cerium hydroxide (Ce(OH)4). The cerium purity of the final product was about 94.6 %, and the recovery rate was 97.3 %.