Germanium recovery from zinc calcines using a hydrometallurgical procedure

In the final stage of zinc calcines processing, zinc is recovered by zinc electrowinning. However, the presence of germanium in the electrolyte seriously affects the current density in the electrowinning step. Since germanium is a critical and strategic material for the European Union according to the most recent foresight studies, this research has focused on an alternative route for the treatment of germanium concentrates (0.1 %wt Ge) obtained after the roasting step in conventional zinc processes. The results showed that this concentrate can be treated by leaching in mild acidic medium (90% germanium efficiency)-solvent extraction with an ionic liquid and alkaline stripping (99% germanium recovery), followed by neutralization and precipitation steps to yield GeO2 as end-product. The overall germanium recovery was around 85%.