Abstract: Nickel, cobalt and copper were separated by solvent extraction with P204. The experimental results show that ［Co(NH₃)₆］³⁺ is an inert complex in extraction kinetics, therefore cobalt can be separated from nickel and copper by non-equilibrium solvent extraction. Under the conditions of temperature 25℃,contact time of two phases 10min, phase ratio 1∶1, aqueous pH 10.10 and concentration of P204 20%,［Co(NH₃)₆］³⁺ is hardly extracted by P204, while the percentage extractions of nickel and copper are 79.3%and 93.9% respectively. Nickel and copper are separated by equilibrium solvent extraction with P204. Under the conditions of temperature  25℃,contact time of two phases 1 min,phase ratio 1∶1, equilibrium pH 4.01 and concentration of P204 20%,the separation factor of copper and nickel is 216.

Key words:  non-equilibrium solvent extraction; equilibrium solvent extraction; nickel; cobalt; copper; di(2-ethylhexyl) phosphate