Removing arsenic from anode slime by vacuum dynamic evaporation and vacuum dynamic flash reduction

In crude lead or copper electrorefining, the by-product anode slime is an important material of recycling precious metals. However, the existing methods for treating arsenic-rich anode slime are less than satisfactory not only for the removal effect of arsenic but also for the environment protection. Therefore, a new technology for treating arsenic-rich anode slime was proposed in this paper, namely the two-step process of vacuum dynamic evaporation (VDE) and vacuum dynamic flash reduction (VDFR). Through this two-step process, silver from the anode slime was left behind in distilland as the silver alloy, and the trivalent oxide of arsenic was evaporated in the distillate. The experimental results showed that the removal ratio of arsenic was 99.96%. Moreover, these vacuum technologies offer improvements in metallurgical and environmental performance.

► Arsenic can be satisfactorily removed from anode slime by two-step vacuum methods.
► Silver from anode slime was left behind in the distilland as the silver alloy.
► Impurity elements including arsenic and antimony were evaporated in the distillate.
► Vacuum methods eliminate much of the air pollution and metal losses.