Separation of cobalt and nickel via solvent extraction with Cyanex-272: Batch experiments and comparison of mixer-settlers and an agitated column as contactors for continuous counter-current extraction

The separation of cobalt and nickel was carried out via solvent extraction using the commercial extractant bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex-272). Solvent experiments were performed on a batch scale to optimize concentration, saponification degree, equilibration time, organic-to-aqueous phase ratio (O/A), stripping conditions. High selectivity over obtained at an concentration as low 0.2 M (or 20% v/v), with degree 40% O/A 1/1. Furthermore, eleven diluents, covering different aliphatic– aromatic compositions tested evaluate their effect nickel. Cobalt efficiencies not significantly impacted by nature diluent. However, co-extraction approximatively 10% higher when toluene used diluent in comparison aliphatic Shell GS270. process validated continuous mode battery mixer-settlers agitated Kühni column. recovery negligible achieved both cases. specificities, advantages, challenges operation types liquid-liquid equipment further discussed.