Recycling of metals from waste Sn-based alloys by vacuum separation

Abstract

In order to recycle waste Sn-based alloys, the vapor–liquid phase equilibrium composition diagrams of Sn–Pb, Sn–Sb and Sn–Zn binary systems were calculated. The calculated results indicate that Pb, Sb and Zn can be separated from Sn effectively. Based on the above calculation, the industrial experiments of vacuum distillation of Sn–Pb alloy, Sn–Pb–Sb alloy, Sn–Pb–Sb–As alloy, crude Sn and Sn–Zn alloy with different contents were carried out. The experimental results show that Pb (>99% Pb) and Sn (≤0.003% Pb) were obtained simultaneously while Sn–Pb alloy was subjected to vacuum distillation; the crude Sn (>90% Sn, ≤ 2% Pb, ≤6% Sb) and crude Pb (≤2% Sn) were obtained simultaneously while a single vacuum distillation was carried out for Sn–Pb–Sb alloy; the Pb and Bi contents in the Sn ingot (99.99% Sn) achieve the grade A of GB/T 728—2010 standard, more than 50% of As and Sb was removed after vacuum distillation of crude Sn; Zn (<0.002% Sn) and Sn (about 3% Zn) were obtained while vacuum distillation of Sn–Zn alloy was conducted at 1173 K, 20–30 Pa for 8–10 h.