One-Step Separation and Refinement of Sb from Pb–Sb Alloy by Electrolysis in Deep Eutectic Solvent: Leveraging Differential Anodic Dissolution Behavior

Antimony (Sb) is a critical strategic resource valued for its scarcity and wide-ranging industrial applications. However, the separation of lead (Pb) and Sb remains challenging due to their similar physicochemical properties. High Sb-Pb alloys (comprising 1-10 wt % Pb) often form as intermediate products during the pyrometallurgical processing of jamesonite (Pb₄FeSb₆S₁₄). Consequently, the development of effective methods for separating Pb and Sb represents a key research priority in metallurgy. This paper proposes a one-step electrolysis method to separate Sb powders from a high Pb-Sb alloy using a choline chloride-ethylene glycol + SbCl₃ deep eutectic solvent (ethaline + SbCl₃ DES) electrolyte. The difference in anode dissolution and cathode deposition of Pb and Sb is systematically investigated through the polarization curve and cyclic voltammetry. The results show that the oxidation potential of Sb is more positive than that of Pb in the ethaline + SbCl₃ DES, which implies Sb and Pb can be separated by electrochemistry. Moreover, across all tested temperatures, the initial reduction potential of Sb remains more positive than that of Pb, indicating the preferential reduction of Sb over Pb. Mechanism analysis reveals that the introduction of SbCl₃ inhibit the pb dissolution at the anode, leading to the accumulation of Pb as anode sludge. When Sb dissolves in the DES, it primarily forms [SbCl₆]^3- complexes, which are directly reduced to metallic Sb at the Ti cathode. Under optimized conditions, Sb with a purity of 99.98% is obtained, accompanied by a current efficiency of 93.57% and an energy consumption of 749.18 kW·h·t^-1. This study aims to provide an environmentally sustainable and straightforward approach for the separation and refinement of Sb from a high Pb-Sb alloy.