Electrostatic separators are commonly employed for the sorting of insulating and conducting fractions of granular mixtures. However, separation of the various metals that compose the conductive fraction still represents a major challenge for the recycling industry. The aim of this paper is to identify the conditions in which a roll-type electrostatic separator could be used for distinctly recover the copper and aluminum from waste electric wires. A numerical model of particle trajectories was employed to predefine these conditions and guide the experimental study. The electrostatic separation experiments were carried out using a reverse-S-type-plate high-voltage electrode. The visualization of particle trajectories using a high-speed camera paved the way to an original design. Thus, a metallic trap was attached to the high-voltage electrode, to facilitate the collection of the aluminum flake-like particles from a mixture that also contains copper strands. With a plastic trap replacing the metallic one, to avoid electric field modification, 68.6% of the copper was recovered with a purity attaining 99%.