An environmentally friendly system for high efficient silver recovery from anode slime

Abstract

Anode slime is an extremely valuable secondary resource for the recovery of silver and has attracted wide attentions. Effective metal recovery is usually constrained by either environmental hazards or high consumption of lixiviant for cyanide and non-cyanide leaching reagents. To tackle these issues in the process of silver recovery from anode slime, this research demonstrated a new leaching system with using an efficient oxidant which encapsulates cyanide into ferric complexes to ensure it not releasing into the environment while effective silver recovery was achieved. Comparing with the traditional tetra-amine copper oxidant, it was found that the dissolution rate of silver was significantly improved and leachate consumption was largely decreased. The effects of stirring speed, sodium thiosulfate concentration, oxidant concentration, solution pH and time on silver dissolution were investigated. When the novel system of iron-encapsulated cyanide was applied to extract silver from anode slime, the final conversion rates of silver was 97% after 60 minutes. This system has great potential in silver recovery from anode slime.