Enhancing Antimony Electrowinning from Copper Electrolyte Waste by Coupling Ion-Exchange Membrane and Mechanical Stirring

Abstract

The availability of antimony is limited, as known mineral reserves are estimated at just 2 million tons. To ensure a stable supply of antimony, it is necessary to find alternatives to its primary production. The regeneration of the ion exchange resin, used in controlling impurities in the copper electrolyte, generates a hydrochloric acid waste stream containing approximately 1 g L⁻¹ Sb. Thus, this work investigated the electrowinning of antimony from a synthetic solution emulating this condition in a single-compartment cell as well as in a membrane cell in static and stirring environment. The results demonstrated that using a cationic membrane and mechanical stirring, as a mechanism to improve mass transfer, led to a significant gain in cathodic efficiency associated with higher antimony recovery rates. The optimal condition was found when a current density of 5 mA cm⁻² was imposed for 120 min under stirring, reporting an Sb recovery rate of 80.4% with a cathodic efficiency of 60.9%. Along with the high Sb recovery rate from a copper production byproduct, the proposed electrowinning process avoids generating toxic chlorine gas, highlighting its affinity with circular economy principles and environmental friendliness. The results obtained from this work are an important step towards the development of membrane processes to recover Sb from copper electrorefining waste, which have great application potential.