Pretreatment of lead anode slime with low silver by vacuum distillation for concentrating silver

LI Liang(李亮)^1,2,3, TIAN Yang(田阳)^1,2, LIU Da-chun(刘大春)^1,2,3, ZHOU Hou-jun(周厚军)^1,2, DAI Yong-nian(戴永年) ^1,2, YANG Bin(杨斌)

(1. National Engineering Laboratory for Vacuum Metallurgy
(Kunming University of Science and Technology), Kunming 650093, China;
2. State Key Laboratory Breeding Base of Complex Non-ferrous Metal Resources Clear Utilization,
Kunming 650093, China;
3. Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province, Kunming 650093, China)

Abstract:The feasibility of separation of lead anode slime with low silver by vacuum distillation was analyzed theoretically. The volatilization rates and mass fractions of elements, influenced by distillation temperature, heat preservation time and material thickness, were investigated under laboratory conditions. The experimental results indicate that almost all of lead and bismuth can be separated from silver-contained multicomponent alloy at 1 223 K for 45 min when the chamber pressure maintains at 10-25 Pa. Silver can be easily enriched in the residue and its mass fraction increases from 3.6% to 27.8% when the distillation temperature is between 1 133 K and 1 373 K. Due to the forming of intermetallic compounds Cu₂Sb, Cu₁₀Sb₃ and Ag₃Sb, the antimony could not be evaporated completely during the vacuum distillation. EDS analysis indicates that the condensate has a columnar crystal structure.

Key words:Ag-contained multicomponent alloy; vacuum distillation; separation; intermetallic compounds