Preparation of high-purity antimony by electrodeposition

Detailed studies were carried out on the electrowinning of antimony from SbCl₃–HCl–H₂SO₄ and SbCl₃–HCl baths using a graphite anode and a tantalum cathode, the anode being enclosed in a cylindrical glass compartment provided with a sintered disc. Disintegration of the graphite anode increased with increase in anode current density and duration of electrolysis. Analysis of gas evolved at the anode indicated that the presence of sulphuric acid increased the production of CO₂. The anodic disintegration was reduced to a negligibly low value by circulation of 6m HCl through the anode compartment. Optimum conditions were determined for electrowinning of antimony from a SbCl₃–HCl bath. The tantalum content in the metal was 0.1–0.2 p.p.m.