Complexation Assisted Solvent Extraction of Ni with LIX84-I for the Selective Separation from Sulfate Battery Leaching Solutions

This study investigates the selective separation of nickel by solvent extraction at the final stage of the hydrometallurgical battery recycling process from sulfate battery leaching solutions, with a focus on optimizing recovery and purity through mini pilot-scale implementation using mixer-settler units. Initial experiments investigated several extractants, including Cyanex 272, PC88A, Versatic 10, and LIX 84-I, across varying pH levels. Under these extractants, complexation of nickel with ammonia was investigated specifically for LIX 84-I and Versatic 10. Among these, LIX 84-I demonstrated high selectivity and extraction efficiency. In lab scale experiments, extraction efficiency of 99.89 % Ni and 0.22 % of Li were achieved, while under optimized conditions in small-pilot-scale experiment the process achieved 99.18 % nickel extraction and 0.87 % lithium co-extraction, with a contact time of 7 minutes, an organic-to-aqueous (O/A) phase ratio of 1:1, and a temperature of 40 °C. The results confirm that complexation-assisted solvent extraction using LIX 84-I enables highly selective nickel recovery with minimal lithium losses, effectively eliminating the need for an additional scrubbing step. Scaling up to a small-pilot scale setup with mixer-settler units confirmed consistent performance, indicating the feasibility of the setup for larger-scale applications. Nickel sulfate monohydrate was succesfully recovered from the scaled-up process with a final purity of 99.86 %.