Separation of Arsenic from Tin Anode Slime by Vacuum Distillation

Tin anode slime (TAS) is a high-value waste produced by electrolytic refining of crude tin. In order to reduce the discharge of harmful waste and realize rational recycling, a process of removing arsenic from TAS by vacuum distillation was proposed, and theoretical and experimental studies were carried out. The saturated vapor pressure of each element in TAS and the activation energy of arsenic evaporation during vacuum distillation was calculated. The evaporation temperature and holding time of vacuum distillation for arsenic removal were investigated. The effects of evaporation temperature and holding time on arsenic removal were discussed. The results showed that the residual arsenic content is 0.32-0.19%, and the removal rate of arsenic is 84.87-91.90% at 1153 K and the range of holding time is 30-120min. When the temperature is 1353 K and the holding time from 30 to 120 min, the residual arsenic content is 0.029-0.025% and the removal rate is 99.43-99.59%. The activation energy for the evaporation of arsenic from TAS in vacuum distillation is EAs = 52.76 kJ/mol. The removal of arsenic improves the recycling value of TAS, and provides ideas for treating harmful substances from industrial wastes and recovering valuable metals.