ABSTRACT A mathematical modeling of a dual temperature ion-exchange separation system is reported. The nonlinear nonequilibrium model created takes into account the following physicochemical processes: kinetics, ion-exchange reactions, complex formation accomplishing the chemical equilibria. The model was applied for a system containing Cu2+ and Zn2+ in acidic sulfate solutions and the iminodiacetic ion-exchange resin Amberlite IRC-718. Good agreement to the experimental data was found. The dependence of the separation efficiency on different factors was tested. The advantage of nonequilibrium operations for the effective separation was shown. The optimal separation cycle was calculated for a sulfate solution containing 2.5 mM Cu and 20 mM Zn at pH 2.05. An ion-exchange column can process 207 bed volumes of the treated solution during one cycle. The effluent is separated for three fractions. The first fraction (75 bed volumes) is the solution containing the 9 times reduced Cu concentration. The second one (36 bed volumes) is the concentrate of Cu. The third fraction is mixed and recycled for repeated treatment.