The removal of antimony from copper electrolytes using amino-phosphonic resins: Improving the elution of pentavalent antimony

An effective method is presented to elute Sb(V) from the amino-phosphonic resins that are used industrially to control the antimony concentration in copper electrolytes. Unlike Sb(III), which is amenable to elution with HCl and other reagents, Sb(V) is extremely difficult to elute from amino-phosphonic resins. Consequently, in industrial practice, a gradual build-up of Sb(V) often takes place on the resin beads, and this reduces the resin capacity and useful life. In this project, it was found that solutions containing 0.5–1.0 g/L of thiourea in 5–7 M HCl are effective eluting agents for Sb(V). It is postulated that thiourea reduces Sb(V) to Sb(III), a reaction that can only take place in concentrated HCl. The main parameters influencing the elution of Sb(V) with thiourea and HCl are presented and discussed.