Selective extraction of nickel, cobalt and copper from alkaline glycine leach solution

Solvent extraction behaviour of nickel, cobalt and copper from ammonia–glycine alkaline solutions using ketoxime extractant LIX®84-IC was systematically investigated. Extraction kinetics, pH-dependent selectivity, equilibrium isotherms and multistage extraction performance were evaluated using single-metal and multicomponent simulated pregnant leach solutions (PLS). Kinetic studies revealed that copper exhibits significantly faster extraction than nickel and cobalt, and kinetic correlations showed that copper extraction is best described by a pseudo-first-order (PFO) model, while nickel and cobalt follow pseudo-second-order (PSO) behaviour. Extraction isothermal experiments demonstrated strong selectivity for copper at low pH, with nickel and cobalt becoming extractable only at higher pH values. Equilibrium isotherm analysis indicated that copper extraction follows typical adsorption behaviour and is well fitted to the Sips semi-empirical model across a wide concentration range. In contrast, nickel and cobalt extraction was strongly inhibited in single stage extraction due to preferential copper loading. Multistage extraction experiments confirmed that progressive copper removal alleviates the observed inhibition, enabling high overall extraction efficiency and selectivity for nickel and cobalt. A three-stage sequential extraction scheme achieved >99% copper extraction in the first stage, followed by cumulative nickel and cobalt recoveries exceeding 97% using higher extractant concentrations. These results demonstrate that ammonia–glycine systems combined with multistage solvent extraction provide a feasible pathway for extraction of Cu, Ni and Co from complex alkaline media.