Separation of tin, silver and copper from waste Pb-free solder using hydrochloric acid leaching with hydrogen peroxide

Abstract

The waste lead (Pb)-free solder leaching process in hydrochloric acid (HCl) solution with hydrogen peroxide (H2O2) followed by separation of copper (Cu) and tin (Sn) was investigated to separate tin, silver (Ag), and copper as an individual component from waste Pb-free solder. The dissolution of Sn increased with increasing temperature and HCl concentration. The concentrations of Sn and Cu increased to 27090 g·m-3 and 191 g·m-3, respectively, under the leaching condition with 1 kmol·m-3 HCl, 0.8 kmol·m-3 H2O2 at 50° C and 400 rpm for 120 min, while Ag is not detected in all leaching tests. The Sn and Cu components are thus successfully separated from Ag by hydrochloric acid leaching with hydrogen peroxide. To precipitate selectively Cu ions from the leach solution, the method to add Sn powder has been investigated. Thus, 92.8 g·m-3 (1.46 mol·m-3) of Cu could be removed successfully from the leach solution with Sn under the following conditions; 30°C in temperature; 400 rpm in agitation speed; 0.3 ml min-1 in N2 flow rate; 0.1 g Sn powder addition to 100 cm3 leach solution.