Effect of leaching media on selective precipitation of Al, Ni, Co, and Mn in the NMC battery recycling process
Mehrdad Kordloo, Gholamreza Khodadadmahmoudi, Mohammad Reza Barati, Ali Rezaei
Abstract
In hydrometallurgical processes, separation and purification pose significant challenges, which are also evident in battery recycling. This study investigates the effect of leaching media on the selective precipitation of Al, Ni, Co, and Mn at specific pH values in the presence of NaOH as a precipitant in the NMC battery recycling process. A novel method for producing 99 wt% pure aluminum metal before acidic leaching via thermal treatment is presented. Different inorganic acids, including H 2 SO 4 (1 M and 2 M), HCl (2 M), and HNO 3 (2 M), subjected the resulting block mass to acid leaching at specific pH values in the presence of NaOH as a precipitant to selectively precipitate Al, Ni, Co, and Mn. The investigation was carried out at pH 4.6, 8.5, and 9.2, and all precipitates obtained at these pH values were analyzed using FTIR, ICP, SEM, and XRD analysis. It was found that the concentration of the target elements in the precipitates was significantly influenced by the type and concentration of acid, along with the pH of the solution during precipitation. The phase identification results showed that in acidic conditions, Al-containing forms amorphous AlOOH while Ni hydroxides crystallize into α-Ni(OH) 2 and β-Ni(OH) 2 phases. Additionally, α-Co(OH) 2 precipitated independently within the pH range for Ni hydroxide formation. Highly crystalline precipitates like ε-MnO 2 , Mn 3 O 4 , and CoMn 2 O 4 were obtained from pregnant leach solution (PLS) with pH levels ranging from 9.2 to 9.5, depending on the type of acidic media used. The produced precipitates have potential applications in catalysis, environmental remediation, battery technology, and as pigments.